*All Things Motorcycle* - Safety Articles/Videos

en-us Thu, 02 Sep 2010 12:29:15 -0500 ATM@msgroup.org 60 *All Things Motorcycle* - Safety Articles/Videos http://www.msgroup.org/forums/mtt/ *All Things Motorcycle* for Guest http://www.msgroup.org/forums/mtt/ http://www.msgroup.org/forums/mtt/rss_32.png *All Things Motorcycle* RSS Feed 144 47 Tips 261 - 280 - 262: 5 mph is NOT trivial!James R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=12062Tips 261 - 280 Thu, 22 Jul 2010 12:11:00 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=12062 5 mph
is NOT trivial!

By: James R. Davis

Speed, it seems to me, is not taken too seriously by motorcyclists. Well, what I mean to say is that DRIVERS of any kind of vehicle seem not to understand just how important small speed differences are.

Cash and I were talking the other day and I discovered what I think is a common misunderstanding relative to speed and I want, here, to examine what that misunderstanding is and why it exists. Mostly, however, I want our readers to fully understand that a small speed different is NOT a trivial matter as it can mean the difference between life and death.

When we are riding it is very normal for us to be traveling at just OVER the speed limit. Sometimes as much as 10 mph over the limit, usually closer to 5 mph over, but in any event, consistent with the traffic around us. My guess is that you do the same.

Cash's contention is that so long as there is a very low chance of cross traffic or an accident ahead, it makes almost no difference how fast we are moving relative to the speed limit so long as we are close to it. Instead, she argues, her concern is with our speeds when we are coming to a stop in an aggressive manner - such as when we must avoid a wandering deer ahead of us. I fully agree with her. But I wanted to see if she understood just how big a deal it is to be riding just a little over the speed limit when it comes to that emergency stop.

Some of you know that I was recently involved is a court case where a woman motorcyclist died when she collided with a car when she was moving at only 18 mph. EIGHTEEN MILES PER HOUR!

I asked Cash if the speed limit was 60 mph and we were traveling at 60 mph, did she know that we could come to a complete stop in almost exactly 150 feet. (Assuming we could achieve a deceleration rate of 0.8g's.) She said that she didn't know the number but that sounded about right. I then said that if a deer was 150 feet ahead of her when she began braking, clearly she would NOT collide with that deer, but if she had been traveling at 65 mph when she began braking, then certainly she would hit it (if it did not get out of the way), and she again agreed. Then I asked her how fast the collision speed would be in that case.

Her answer was probably close to what your own answer would be: somewhere between 5 and 10 mph.

You would probably survive a collision at such low speeds. But as it turns out, she was VERY WRONG in her guess. In fact, she would hit that deer at a speed of 25 mph. TWENTY FIVE MILES PER HOUR!

The problem in her perspective, and probably yours, is the tendency to think in linear terms.

For example, let's look at a graph that shows how long it takes to stop your motorcycle starting at various speeds and again assuming a deceleration rate of 0.8g's.

Observe, please, that the blue line shows that you can come to a complete stop from a speed of 30 mph in 1.70 seconds. Then notice that if we double the speed to 60 mph, the green line, that it takes you exactly twice as long to stop (3.40 seconds). There is clearly a linear relationship between time to stop and speed.

But now let's look at stopping distance versus speed.

Here we observe that it takes 37.5 feet to come to a complete stop starting at 30 mph, but if we double the starting speed to 60 mph, it takes FOUR times as much distance to come to a complete stop (150 feet) instead of twice (75 feet). Obviously, stopping distance is NOT a linear function. Instead, it varies with the SQUARE of your speed. Why? Because when you double the speed you increase the kinetic energy of the moving vehicle by the square of that increase - and all of that kinetic energy must be scrubbed (converted to heat) by your brakes.

Now observe from the two diagrams above that by increasing our starting speed by only 5 mph to 65 instead of 60, it takes us only 1 quarter of a second longer to stop, actually 0.29 seconds, but in that quarter of a second we traveled an extra 26 feet!

Since as we brake from 65 mph to zero mph we must pass through 60 mph, there can be no difference in the stopping time nor distance to stop between the last 60 mph starting at 65 and the entire graph starting from 60 mph. Therefore, that extra 26 feet of stopping distance came at the beginning of our braking effort, not at the end of it.

This should also be obvious from the fact that we see that we can scrub a full 30 mph in just 37.5 feet while it takes us an additional 26 feet of stopping distance to scrub just 5 mph from a starting speed of 65 mph.

So let's now look at how fast you are traveling while decelerating from 60 mph and from 65 mph.

We can see that the green portion of the speed curves is identical, of course, because they show the deceleration from 60 mph to zero in both curves. The red portion of the top curve shows that the only difference, in terms of speed and distance between stopping from 65 mph and 60 mph is 26 feet and 5 mph and that it happens at the start of deceleration, not at the end.

Now we look at the bottom right of the chart and we see that when stopping from 65 mph we are traveling at 25 mph when we have crossed the 150 foot mark. That is, we would COLLIDE WITH THE DEER AT 25 MPH if we began braking at 65 mph at a distance of 150 foot from it.

Now you see why that 'trivial' 5 mph of extra speed is not so trivial after all. It can kill you.

Now some of you techie types will claim that the actual collision speed will be considerably higher than my chart shows because if both vehicles noticed a threat at the same time, and if both drivers take the same amount of time to Perceive the threat, Decide what to do about it, and React (PDR), then the faster moving vehicle will travel farther before its brakes are applied.

It will surprise you to learn that delayed start of braking because of PDR time IS TRIVIAL compared to that extra 5 mph of starting speed we discussed.

Here is a new chart to demonstrate that.

If we assume 1.0 seconds of PDR, then the bike moving at 65 mph will travel 7 feet farther during PDR than will the bike moving at 60 mph. (65 mph = 95 feet per second, 60 mph = 88 feet per second.)

Delaying the start of braking by 7 feet for the vehicle traveling at 65 mph results in a collision speed of 27 mph instead of 25 mph.

Copyright 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)
]]>Tips 261 - 280 - 261: Insurance can cost you dearlyJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=11802Tips 261 - 280 Mon, 24 May 2010 10:22:17 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=11802 Left Turner in front of Motorcycle
Gets what he paid for

By: James R. Davis

Sometimes people driving cars turn left across the path of a motorcyclist. In a perfect world, there would always be time for the motorcyclist to stop or swerve around that car without a collision, but it is not a perfect world. If a collision does occur, does the fact that a person turned left in front of that motorcyclist mean that he caused the accident? Not necessarily.

He CAUSED the accident only if the motorcyclist HAD TO do something to avoid it, AND IT WAS IMPOSSIBLE FOR HIM TO DO SO. If the motorcyclist could have avoided the accident, then the driver and the rider BOTH contributed to the cause of the accident and their contributed percent of negligence determines just how 'at fault' the driver was.

This is a case where an elderly man, driving his car on a three lane surface street, one lane in each direction with the center lane used for turning across the opposing lane, moved into that center lane in preparation for a left turn into a shopping area parking lot, then turned left and was struck by a motorcycle that was approaching in the opposite direction.

Already the odds are that you have decided that the person driving the left turning car was negligent and responsible for the collision. I will show you that jumping to such a conclusion is inappropriate and can cause unbelievable damage and injustice.

The car (green) was traveling east bound (from left to right) on the street while the motorcycle (red) was traveling west bound (right to left). When the car turned left into the driveway the rider of the motorcycle aggressively applied her rear brake (there is no indication that she used any front brake at all) and immediately began a skid with the rear-end of her bike yawing counterclockwise as it left a 43.5 foot skid mark. At the end of that skid mark the rider released her rear brake and as a result of that the bike high-sided. The bike flew about 11 feet before it landed on its right side and then, without flipping over or into the air again, scraped along the roadway for an additional 27.5 feet before coming to rest.

As a result of the high-side, the rider was launched into the air and flew for about 27 feet before colliding into the right side of the car. That collision resulted in breaking the back of the rider and the severing of her spine which caused a permanent and complete paralysis below her waist.

The bike did not collide with the car as it slid on the ground and passed just behind it.

The driver of the car claims not to remember seeing the motorcycle but argues that it must have been traveling at least 50 mph in the 30 mph zone she was riding in because of the length of her skid mark, the fact that he was certain it was safe to make the left turn, and that he did not even rush the left turn he made into the parking lot.

The rider claims that when she noticed the car turning to the left she had no time to do anything else other than brake and that despite what the car driver claims, she was not going faster than 30 mph at the time.

There were no other witnesses to the event.

An accident reconstructionist claims that the motorcycle was traveling at from 28 to 31 mph when she began her skid.

Let's look at how such a conclusion could be made from the evidence we have so far to see if we can find agreement with it or to find areas with which we disagree.

In order to determine a speed at any point along the bike's path of travel, we must start with a KNOWN (or derived) speed at any other point in its path. Since the bike did not impact the vehicle, we cannot use a typical crush analysis to obtain an estimated speed of impact. (The amount of damage done to the rider, however, suggests that she struck the car with considerable force which, in turn, suggests considerable speed.) What we do know, for certain, is the speed of the motorcycle at the end of its path of travel - zero mph.

Since there were no gouge marks along the scrape path, and because there is absolutely no indication that the bike's left side touched the ground (no scrapes of dents of any kind), we are certain that the bike skidded on its right side while leaving the 27.5 foot scrape on the roadway following the high-side.

Chrome, steel and plastic sliding on this roadway generates a coefficient of friction of somewhere between 0.3 and 0.5. To get a reasonable estimate of the speed lost during the bike's slide on its side we will assume a CofF of 0.4 and can revise our estimate, if necessary, following the complete analysis.

With a CofF of 0.4, we calculate the bike's speed at the time that it began sliding on its side to be slightly more than 18 mph. Since the accident reconstructionist's report finds that the motorcycle was traveling at between 18 and 21 mph at the time of the high-side, our numbers agree, so far.

Because there is an 11 foot gap in terms of roadway markings between the end of the skid marks and the beginning of the scrape marks, we can conclusively assume that the bike flew through the air a distance of 11 feet as a result of the high-side. Since air resistance at speeds around 20 mph is insignificant, we can also conclude with very high confidence that the speed the bike was moving at the time the high-side occurred was also slightly higher than 18 mph. Similarly, we can conclude with just as high confidence that the motorcyclist impacted the car at that speed. It is simply amazing how damaging to the body such a relatively slow speed collision can be!

Since the motorcycle was traveling at just over 18 mph when the high-side occurred, we can continue with our analysis and determine what its speed must have been when the skidding began.

First, we need to determine the drag factor to use. The drag factor is the product of the CofF between the bike's tires and the roadway multiplied by the braking efficiency used during the stop. The CofF, though not measured, was approximately 0.8 (the roadway was cement, it was dry and had no loose sand or gravel on it, and there was no grade or slope). Given that there was a skid mark showing only one tire, and because there had been a high-side, it is extremely likely that the mark was made by the rear tire. Since a rear tire skid using only the rear brake indicates a braking efficiency of only about .4, but because an imminent collision was known as a threat by the rider, it is reasonable to conclude that the rider did use some front brake and that the overall braking efficiency was on the order of .6. This, it turns out, is the amount of braking performance expected of even a rank amateur new motorcycle rider. That is terrible performance when your life depends on it.

Thus, the drag factor was approximately .48 (0.8 * 0.6).

Using a drag factor of .48 and a skid mark of 43.5 feet ending at a speed of just over 18 mph, we calculate that the speed of the bike at the beginning of the skid was slightly greater than 30 mph.

This is consistent with the claim of the motorcyclist. And, since our review of the physics described above is consistent with the reconstructionist's conclusion that the bike was traveling at from 29 to 31 mph when the skid marks began, we have no basis for challenging that reconstructionist's methods or calculations.

So, does that mean the left turning car driver caused this accident?

Well, in almost every state in the country there is a legal definition called contributory negligence (actually, most states have revised this tort rule and now call it COMPARATIVE negligence which is somewhat more fair to all parties involved) by which the parties to a suit can try to ascertain to what extent each of them contributed to the accident. So, for example, if the plaintiff is asking the court to award it $1,000,000 in damages (the present value that those damages have or will cost the plaintiff) , but the plaintiff is found to have contributed, say, 40% of the negligence resulting in the accident, then the plaintiff is awarded about 60% of the value of the damages sought, or $600,000.

How much negligence did this rider (the plaintiff) contribute to the cause of this accident?

Even if the motorcycle had been traveling at 31 mph when braking began, it was entirely reasonable to presume that it could have come to a complete stop, without losing control, and remaining on its tires, within a distance of less than 40 feet. Indeed, almost any experienced rider can achieve an aggressive (emergency) deceleration rate of 0.8gs (recall that virtually any rank amateur/beginner can achieve a deceleration rate of 0.6gs) which means a stopping distance of 40 feet.

Since this rider left a skid mark of 43.5 feet and was still traveling at about 18 mph at the end of the skid, it is patently obvious that WERE IT NOT FOR INEFFECTIVE/INAPPROPRIATE BRAKE USAGE THERE WOULD NOT HAVE BEEN A COLLISION. In terms of contributed negligence, this rider provided far more than 50% of the causative negligence and had the ability to completely avoided the collision.

With proper brake usage she could have stopped at least THIRTY FEET prior to the impact.

Who was responsible for this accident? Clearly, the motorcycle rider.

Now, about the things that the car driver did wrong ...

He failed to notice the motorcyclist.
He relied on the legal skills of 'his' attorney when, in fact, the attorney was provided by his insurance company and was actually representing THEIR interests ahead of the insured. This is an obvious conflict of interest!!

Let me spell out that last mistake for you. Suppose that you have an insurance policy that provides you the minimum protection required by the law in your state. For example, say it provides you $50,000 of liability coverage.

Then suppose you are involved in a case such as this one and you are sued with a claim of $1,000,000 damages. The insurance company CANNOT lose more than $50,000 and has HIGH incentive to limit their costs to that amount. That is, a payment of $50,000 plus the expenses they pay for in defending your case (attorney cost and the cost of experts, for example). They can minimize their costs by simply settling the case (with your agreement). The plaintiff, however, if they believe that they can win the case based on its facts, will have no incentive to settle the case. Even if the attorneys on both sides agree to a settlement of, say, $500,000, you are stuck with a judgment against you in the amount of $450,000 and the insurance company still pays only $50,000.

Why should the insurance company spend more than a minimal amount on your case if the plaintiff is going to settle for, or outright win, a meaningful amount in excess of $50,000? That is NOT a consideration on your behalf - it is a consideration on behalf of the insurance company. A conflict of interest that is obvious.

A 'fender bender' gets taken care of by the insurance company assigned lawyer. A major case merits your retaining an attorney to look out for YOUR interests.

In this case, because the plaintiff's side could prove with reasonable certainty that she was not speeding and that the car driver did turn left in front of her, it had a terrific case to present to the jury. The car driver's attorney had to prove that the motorcyclist contributed significantly in terms of negligence resulting in the collision, but had NO INCENTIVE TO PAY WHAT IT WOULD COST TO DEVELOP THAT PROOF.

Then there was the problem of using an inexperienced expert witness, an MSF RiderCoach, who knew how to repeat dogmatic phrases such as using 'emergency braking' instead of 'panic braking', but who failed to explain what happened in terms that the jury could understand. Let me be clear about that. This witness claimed that the motorcyclist used emergency braking with her rear brake but no braking with her front brake when she should have used both brakes, just as she had been taught during her MSF training. In response, the plaintiff's attorney turned his own words on this witness and made sure that the jury heard him say that the motorcyclist was placed in an EMERGENCY SITUATION because the car driver had turned left in front of her, and was, as a result, confused about how to properly brake. What the witness SHOULD have said was that the motorcyclist AGGRESSIVELY USED her rear brake without using her front brake at all and that this was particularly troubling to him because there was NO EMERGENCY ACTION REQUIRED. That it was NOT AN EMERGENCY but, instead, required NORMAL and COMPETENT motorcyclist behavior. (You get the picture.)

It is the job of an expert witness to educate the jury so that they can make an informed decision in the case. If he is a motorcycle safety expert, then you should expect him to tell the jury that it is NEVER, EVER, NOT ONCE IN YOUR LIFETIME appropriate for a motorcyclist to aggressively use his rear brake. Had that message been conveyed properly, the jury would have better understood the case and perhaps allocated a significant percentage of negligence on the part of the motorcyclist which would have saved this defendant a huge amount of money.

And if that witness failed to understand the importance of his words, the defense attorney certainly did not, yet failed to help that witness 'clarify' his testimony. The jury was left hearing only the dogmatic MSF words - 'Emergency braking', and the case was lost as a result.

The car driver ends up with a judgment against him of several hundred thousand dollars even though HIS NEGLIGENCE WAS INSIGNIFICANT AS COMPARED TO THAT OF THE MOTORCYCLIST.

Copyright 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)
]]>Tips 241-260 - 260: Who Killed the Lady Motorcyclist?James R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=11209Tips 241-260 Tue, 15 Dec 2009 03:43:08 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=11209 Motorcyclist dies
Who killed her?

By: James R. Davis

A motorcyclist is riding on a one-way street in the middle of town near where she lives. She has ridden her bike along this street hundreds of times in the past. It is well familiar to her.

As she approaches an intersection, another one-way street, where there are stop signs preventing traffic from entering from her right - she has the right of way - and she knows from experience that it is not a busy intersection. She finally notices a car easing its way into the intersection.

Shortly thereafter she died - after she collided with that car.

Speed limit on the street she was riding on was 30 mph. The crush damage to the vehicle and motorcycle suggest an impact speed of about 40 mph. She left a 40 foot skid mark before the collision.

Oh, did I happen to mention that there was a double-parked delivery truck near the intersection on her right side? Witnesses, including the driver of the car, claimed that the truck obscured sight lines.

The driver of the car was uninsured.

The estate of the deceased hired an attorney seeking monetary relief. After all, the lady died and "it wasn't her fault". So what if the driver of the car she struck was uninsured?

You guessed it - they sued the trucking company claiming that their double-parked truck caused this accident. The trucking company, after all, had 'deep pockets' and nobody else did.

Do you agree?

Witnesses agreed that the car properly stopped at the stop sign then inched forward until it was almost all the way across the intersection.

Other witnesses disagreed about the presence of the double-parked truck. Some placed it five miles away from that intersection at the time of the accident, based on GPS data recorded by the company. Others said the truck had been there earlier than the accident. Still others said that the truck was definitely there at the time of the accident.

Most states have laws which allow for contributory negligence to be determined and affect monetary compensation. If, for example, the trucking company can show that its negligence in the matter, if any, was less than 50%, it is possible that it would not be liable for any financial costs.

What did the police who investigated this accident have to say? Well, they wrote a ticket to the driver of the car for failing to yield the right of way. They did not see a double parked truck at the scene but they documented that witnesses claimed such a truck had been there at the time of the accident.

Should the trucking company be held liable for this lady's death?

Let's first talk about the driver of the car she ran into. Its driver could not see traffic at all from his position at the stop line near the stop sign. He stopped. Then he moved very cautiously into the intersection. What else could he do? Should he have remained stopped until the double-parked truck, if it was actually there, moved out of the way? If his wait had lasted an hour, should he have been required to remain in place still longer?

He certainly DID fail to yield the right of way. His ticket was 'righteous'. But it was unintentional and there were extenuating circumstances that any jury would understand. When he finally did see the motorcycle it was too late for him to do anything to avoid the collision. Even if he did have insurance, was it likely that it would pay handsomely because of the death of the rider? Well, that goes back to the issue of contributory negligence, doesn't it?

So now it's time to look at the motorcyclist's responsibility in this matter. We learn that she was properly licensed (had a motorcycle endorsement on her license) and that she had taken and passed an MSF class. We begin being critical by acknowledging that she was driving too fast. She was traveling at least 40 mph when she crashed and it was a 30 mph zone. But just how important was that in the bigger scheme of things? I mean, had that double-parked truck not been there, then the accident probably would not have happened at all, right? So what if she was speeding a little bit, just like you and I do every time we drive or ride?

Time, I guess, to look at some details. Let's start with that skid mark.

It was 40 foot long. Obviously that means that the rider noticed the car when she was traveling faster than the speed of impact because she scrubbed some speed during that skid. But how much faster?

The police determined that the Dynamic Coefficient of Friction between the bike's tires and the roadway was 0.79. No grade, no rain or ice on the ground, middle of the afternoon with good lighting and no weather issues.

How much speed is scrubbed during a 40 foot skid under those conditions?

Pay attention here, please. A skid mark does not tell you how fast a person was traveling during that skid. The skid mark ONLY tells you that a certain amount of energy was transformed during the skid. That is, a certain amount of kinetic (moving) energy was converted into heat during the skid. It doesn't matter how fast the person was going during the skid - essentially the same amount of energy is converted regardless of speed. The faster you go, the less time it takes to scrub that energy, but the amount of energy converted is essentially the same.

But we do know some other things about a skid mark other than its length. We know that it results from a locked brake and a skidding tire, and that a brake does not lock by itself, normally. That is, it took an effort on the part of the biker to lock her brake. By the way, we also know that it is almost always true that a skid mark is from the rear tire of a motorcycle because if it is from the front tire, the bike loses all control and quickly ends up on its side.

Ever heard of PDR? That stands for Perception, Decision, Reaction time. Before you can lock your brake(s) you must first perceive a need to do so, decide to do so, then move your hands and feet to the levers as a reaction to a threat. The amount of time it takes to do that is called PDR time (or, in some places, simply PR time).

Tests have been conducted that document that professional riders who KNOW that a threat is about to present itself (a signal light is about to change colors, for example) CAN have a PDR as low as 0.2 to 0.3 seconds!!! However, those same riders take on average about 1.5 seconds of PDR when a threat is not anticipated (a car ahead suddenly begins skidding its tires). Indeed, about 70% of all motorists take about 1.5 seconds to begin applying their brakes when a threat is NOT anticipated.

We can assume, therefore, that the lady riding her bike that day took about 1.5 seconds to begin applying her brakes.

Well, there is a little more reason to support that assumption. You see, witnesses claimed that she had been stunting her bike prior to the accident. That is, she had just done a wheelie, and when she came off that wheelie she began accelerating. You MUST conclude that she did NOT anticipate the presence of a threat at the time.

So, now what do we know about how fast she was going before she began her skid? We actually have enough information to make that call, but we want something else to increase our confidence in it. Fortunately, we recall that witnesses claimed to have seen her going between 30 mph and 50 mph just before she crashed. Since we have very good reason to believe that she was going at least 40 mph when she did crash, we know that the low end of those witness estimates was too low. She had to have been traveling in excess of 40 mph before she started skidding, but if the witness estimate was believable, she could not have been traveling more than 50 mph. In other words we have excellent reason to believe that she was traveling at about 45 mph before she began her skid.

Can we confirm that with the skid length evidence? You bet.

A skid would be 40 feet long if the rider used 100% braking efficiency (i.e., both brakes maximally applied) and came to a dead stop (without a collision), if she started skidding at just under 31 mph.

Where:
'v' = velocity at start of skid
'f' = drag factor
'd' = Skid mark distance

The drag factor (f) is

Where:
'u' = Coefficient of Friction
'n' = braking efficiency

Since grade = 0 ...

v = 30 * 0.79 * 1.00 * 40
v = 30.79 mph

Had the braking efficiency been 60%, v would equal 23.85 mph.

(This value (v) shall henceforth be called the 'energy equivalent speed'. It is the Kinetic energy converted to heat during a 40 foot skid, no matter how fast we are moving when we start the skid, assuming a given drag factor.)

Since there was only one skid mark it is not possible that she used 100% braking efficiency. Had she used only her rear brake she would have been able to attain no more than 40% braking efficiency as at that point she would have transferred virtually all the weight off her rear tire and no more braking was possible. Because she was faced with an imminent collision we can assume that she used at least SOME front brake along with her rear brake. Since the MSF tests braking skills to determine if even a rank amateur (newbie) can achieve a 60% braking efficiency, we can be confident that she used at least 60% and less than 100% braking efficiency during her skid. To be conservative, we will estimate that she used 60%.

It is easy to calculate that if she used 60% braking efficiency, she had to have been traveling at just under 47 mph at the start of her skid. Obviously, the greater her braking skills, the faster she was traveling when she began skidding, but we took a conservative approach to this analysis.

V_start = Velocity at the start of the skid
V_scrubbed = Energy equivalent speed
V_collision = Velocity at end of skid

V_start = 46.6 mph

It is entirely proper and defensible, assuming rounding of numbers, to conclude that she was traveling at no less than 47 mph before she began her skid.

In other words, her 40 foot skid scrubbed approximately 7 mph off her speed.

Now we have enough data. Using a 1.5 second PDR and a speed of 47 mph, we know that the lady traveled 103 feet before her skid started. That means that the lady FIRST NOTICED the car in the intersection when she was 143 feet away from it (40 + 103).

We just learned an interesting fact: Had the car driver simply crossed the intersection at normal speed instead of creeping along, since she crashed into his car near its rear, the accident would not have happened. That is, had the car driver acted irrationally, there would not have been an accident. Yeah, but so what? He did act rationally and the accident did happen.

Well, doing a 'what if' makes a lot of sense when trying to determine proportionate negligence, as I'll now show you.

What if the motorcyclist had been traveling at or below the speed limit?

We know that no matter what her speed was before she locked her brake, she could and did see the car when she was 143 feet away from it.

If she had been traveling at 30 mph, then she would have traveled 66 feet before her skid began. That means that she would begin skidding 77 feet from the car. And that means that she would NOT HAVE COLLIDED as she would have come to a dead stop within 63 feet, or 14 feet shy of hitting the car.

In the language of the law, and what any jurist would understand ... Were it not for her speeding, there would not have been an accident.

Said differently, whether there was a double parked truck or not, this accident would not have occurred if the lady had not been speeding.

Speeding killed this rider, not a car driver who crept into an intersection, and not as a result of a double-parked truck, whether it was there or not.

All that had to be done in this case was to do that 'what if' analysis and as a result the jury could well come back with an apportioned negligence something like:

Trucking company = 10%
Motorcyclist = 90%

The payment awarded to the estate of the motorcyclist would almost certainly be ZERO dollars.

Who killed her? She did.

Copyright 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)
]]>Tips 241-260 - 259: Left Turning Green Car, Kills a MotorcyclistJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=11190Tips 241-260 Wed, 09 Dec 2009 09:51:34 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=11190 Driving a Green Car Results In Our ...
KILLING A MOTORCYCLIST

By: James R. Davis

My guess is that every one of my readers has heard of a motorcyclist who was injured or killed when someone turned left in front of them and a collision resulted.

That left turner was always the 'bad guy', right?

But surely you, like all the rest of us, have made left turns with our vehicles and we would never cause such an accident - because we remain alert, drive defensively, and maintain 'situational awareness'.

For example, let's say that we are driving our car along a country road and must make a left turn into our driveway when we arrive at home. We can see at least 1000 feet in front and behind us. There is only one car in the oncoming lane. We turn on our left turn signal and wait ...

The white car passes us ...

We turn left toward our driveway ...

And we discover that we have just KILLED A MOTORCYCLIST!

How can that be? We did everything right! We were not speeding, not drunk, not talking on a cell phone ... but there lies a dead motorcyclist and you can be absolutely certain that we will get a day in court to explain why we killed him. Especially after we say "I didn't see him!"

Any thoughts on the matter?

Well, let me give you a hint. You would expect, I'm guessing, that the motorcyclist crashed into the passenger side of our green car because, after all, we have crossed over almost the entire oncoming lane. But you would be wrong as what actually happened is that the motorcycle hit our LEFT-FRONT bumper.

Have any other thoughts now?

Oh, he hit us at 40 mph, the legal speed limit. That is, he had not been traveling at 100 mph and just appeared out of nowhere - there was 1,000 feet of unobstructed visibility both ahead of and behind us.

What I will demonstrate for you here is that motorcyclists MUST drive defensively. Part of defensive driving is a concept called 'conspicuity' - visibility.

That does not simply mean 'drive with your headlights on', and it does not simply mean 'wear light colored and/or reflective clothing'. It means 'SEE' and 'BE SEEN'.

In this particular scenario there is only one possible way for the accident to have happened - the motorcyclist really was not visible to us.

For example, he was 'tailgating' the white car ...

Observe that from our perspective (driver of the green car), there is no motorcycle or any other traffic in the oncoming lane other than the white car. This has been true since the white car first became visible to us when it was over 1,000 feet ahead. The white car obscured our sight lines.

Then, as the white car began to pass us, for merely a moment, part of the motorcycle becomes visible, but immediately thereafter that 'A pillar' begins to obstruct the motorcyclist (that metal column on the left edge of your windshield that supports the roof and windshield).

Now let me ask you, "Why did the motorcyclist hit our left-front bumper instead of the passenger side of our car?"

Again, you know the answer to that question. New riders who have not, through practice, internalized the concept of counter-steering and use it instinctively, tend to NOT use it during a crisis. No rational thinking person would turn their motorcycles toward the front of a left-turning vehicle as in this scenario because that would result in hitting the vehicle at its front, AND being run over by the vehicle after the collision. They would, if possible, turn toward the rear of the left-turner.

But new, inexperienced, riders - having forgotten everything they ever 'knew' or had heard about counter-steering, would try to turn their handlebars to the left and find that the bike 'fights them' - simply will not go to the left. In fact, the harder they try, the more the bike turns to the right. The result, a collision with the front of our green car instead of merely a close call.

Oh, it doesn't really matter whether or not our car is green. Just as it is incorrect to assume that 'green' is the 'bad guy', so, too, is it incorrect to assume that the left-turner is at fault.

Rider errors killed this motorcyclist.

Copyright 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 241-260 - 258: 'Advanced' or 'Performance' Training and Track DaysJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=10559Tips 241-260 Sat, 11 Jul 2009 10:09:31 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=10559 'Advanced' or 'Performance' Training
and Track Days

By: James R. Davis

Over the past several years you have heard more and more about courses offering advanced or performance oriented training and there has been increasing interest shown by riders in 'Track Days' - the ability to learn how to handle your motorcycle near its (and your) limits away from our public roads on a relatively safe race track.

I have received several criticisms recently for failing to endorse or encourage my readers to participate in these courses along with claims that my advice seems stuck at the fundamentals level and aimed primarily at beginning riders. The claim has been made that by my failure to encourage these alternative riding courses I am deliberately discouraging rider skill growth and the learning of advanced techniques.

I confess! That is exactly my intention.

Let me be perfectly clear about that. I have very high regard for many of the advanced and performance oriented courses, the skills and techniques taught by them, the instructors, and even most of their students. What I oppose and find essentially intolerable from my safety oriented perspective is any suggestion that these courses prepare riders to become better in the sense that they will increase their odds of surviving riding motorcycles on our public roads based on what they learn during these classes.

To the contrary, learning how to handle your motorcycle at speeds of 100 mph or greater, how to lean off your motorcycle, or how to pick your 'best' line through a curve, to my mind, encourages unsafe behavior on our public roads, and illegal behavior at that.

Apparently the DOT's National Highway Transportation Safety Association has a similar opinion as this extract from their April 2009 paper (DOT HS 811 108) makes clear:

quote:
Another way driver education can worsen the problem is through courses that unintentionally encourage risky driving. Specifically, courses that teach advanced driving maneuvers can produce adverse outcomes. These courses are currently very popular in the United States as a way to supplement basic driver education. The courses are generally taught by police or in advanced driving schools using test track facilities. Several studies, however, have shown that young people, particularly males, who take these courses are more likely than comparable drivers without such training to be in crashes (Jones, 1993; Glad, 1988; Katila et al., 1995). It is not entirely clear why this occurs, but it is clear that superior skills do not necessarily translate to superior driving records and in fact may result in more crashes. Highly trained and experienced racecar drivers, for example, have been found to have worse crash records than run-of-the-mill drivers, adjusting for age, gender, and mileage (Williams & ONeill, 1982). Advanced skills can translate to overconfidence and risk-taking. For young drivers, the immaturity factor, involving decision-making and peer influences, may also contribute. Young people may create extra opportunities to try out the advanced maneuvers, showing off for their friends. This is an example of how skills learned through driver education can interact with developmental and lifestyle factors typical of young people and produce unintended results.

(emphasis added)

Let's look at just those three teachings more closely. There is not a road in the United States where it is legal or safe to ride at speeds of 100 mph or greater. Only a motorcycle in top mechanical condition has even a reasonable chance of surviving the effort, assuming the rider is also in top physical condition and the roadway is free of all defects, the weather is clear, there is no traffic, and you KNOW with certainty that there are no blind curves (actually, curves of any kind) ahead of you. A policeman who happens to observe or captures your speed with his radar equipment will not be in the least bit sympathetic that you learned how to handle your motorcycle at such speeds in a well regarded class run by people who hoped that you would become a safer rider as a result of their training.

Hanging off your motorcycle is a technique taught by some as a way to 'smoothly' and 'properly' handle curves and as an advanced skill that will help you avoid dragging a peg in a fast curve - and it looks so cool. What that really translates into is how to increase your odds of making it through a curve at ILLEGAL SPEEDS. There is not a speed signed road in this country that requires you to lean your bike more than 20 degrees (closer to 15 degrees) when you are riding AT the posted speed. No body lean, whatever, is required to negotiate ANY speed marked curve in the country at legal speeds. You may look cool when your knee is reaching for the ground in a turn, but you will not look quite so well in a hospital bed, though your body will definitely be cool on the slab in the morgue. (Unless the sign specifying a speed for a turn contains the words 'speed limit' it is a 'speed ADVISORY' rather than a maximum speed.)

Picking the best line in a curve is a racing performance objective. Usually, the smoothest line through a curve is the one that requires the least steering correction though the turn because that line is the least destabilizing and requires the least lean angle. A safer line can often be chosen such as one known alternatively as one requiring a 'late apex' or 'late entry', but both of those safer lines require more aggressive steering inputs and steeping lean angles than the smoothest line. Selecting a line through multiple consecutive curves is certainly an advanced technique, but selecting it to maximize your speed through those curves is anything but safety oriented. And if truth be known, at any legal speeds on speed marked curves, you can choose virtually any path (line) through it without requiring any aggressive steering inputs.

So, I don't encourage riders to get 'advanced' or 'performance' training and I don't encourage 'track days' because they lead some participants in such programs, particularly those who are dumb, stupid, naive, immature, foolish, and/or crazy (of whom the population of said participants is greater than zero) to overconfidence and risk taking on our public roads that can, in turn, KILL and injure riders. You learn to control your motorcycle, no matter what, and you learn to control yourself. That results in competence and increasing your odds out there. The rest is putting your toes over the edge - for fun or thrills, not survival.

Copyright 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)
]]>Tips 241-260 - 257: Standing on your Pegs - Control AND VisibilityJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=10551Tips 241-260 Fri, 10 Jul 2009 07:45:54 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=10551 Standing on your Pegs
Control AND Visibility

By: James R. Davis

As many of you know from reading other of the safety tip articles I have written, Cash and I have found ourselves riding for dozens of miles at highway speeds while standing on our pegs. In our cases, the usual reason for doing that is that we are a long way from a place to pull off the road for a break when the sky opens up and it begins raining on us - hard. It is almost impossible to see clearly through the raindrops accumulating (actually washing in waves) down our windscreens and our helmet visors. We stand on the pegs to improve our ability to see - our visibility. (Cash has declared that that is one reason she is glad not to have forward controls because standing on the pegs is one behavior we sometimes need to do.)

It is well known that standing on your pegs while negotiating difficult pavement (or dirt) at slow speeds can aid in your control of the bike in that it is far easier to move a bike to one side or the other without having to move yourself with it.

But there is one other time you might wish to consider standing on your pegs while moving, even at highway speeds, and it again involves enhancing your visibility - this time for others. Suppose, for example, that you are riding down a two-lane road that's marked with a line between traffic moving in opposite directions and you notice a commercial area to your right. What are the odds that an oncoming car, particularly one with their left turn blinker flashing, might decide to turn left across your path to enter that area?

That's right, the odds depend on whether or not the driver of that oncoming vehicle notices you or not.

Your BEST behavior in that condition is to slow down in anticipation that you might have to stop or dodge that left-turner (with a cell phone glued to his/her ear). But that might not be enough and is not the only thing that you can do to increase your odds out there.

You can make yourself more visible! In advance, you can do that, (and by law you must), by having your headlights on, and you can wear light colored clothes with reflecting patches. Rather than in advance of needing to, you THEN can also turn on a headlight modulator or flash your brights on and off. (I don't like that last idea one bit because it might be interpreted as a signal by you giving the other driver 'permission' to encroach on your right of way.) You can also gently swerve from side to side within your lane.

Or, you can simply stand on your pegs!!! That certainly makes you more visible to others. It does not destabilize the bike. It cannot be misinterpreted as a signal giving away your rights.

On the other hand, if you happen to get into an accident and there are witnesses who saw you standing on your pegs, you will need to be ready to defend your actions in court. Particularly non-riding public 'understanding' of what you were doing out there standing on your pegs will vary from 'showing off' to 'stunting' to 'racing' (regardless of whether or not you are speeding), and probably not a single suggestion that you were trying to make yourself more visible in order to diminish the likelihood that an accident would occur.

Here is one expert witness who will stand up for your side and describe such behavior as being rational and intelligent instead of 'rider error'.

It doesn't need to be said, but just in case ... If that driver does make a left turn in front of you while you are standing on your pegs, you sit back down as you aggressively use your brakes.

Copyright 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)
]]>Tips 241-260 - 256: Neutral Steering (fact or fancy?)James R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=10479Tips 241-260 Sat, 27 Jun 2009 14:21:01 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=10479 Neutral Steering
(Fact or Fancy?)

By: James R. Davis

Motorcycle dynamics are hugely complex and difficult to quantify, let alone understand. Because they are so complex it is generally true that even experienced riders resort to over-simplifications, short-cuts, concept only, and abbreviated reality (snapshots in time) when describing them. As a result, any discussion that purports to be a critical analysis of the subject is easily sidetracked with honestly held claims and counter-claims by the participants about the specifics. I will here try to broaden our understanding of just one such dynamic: the behavior of a motorcycle while in a turn with a specific focus on steering inputs required to MAINTAIN a curved path. That is, the part played by 'counter-steering' once a bike is leaned over and already riding a given radius curve.

Some background ...

In any discussion of counter-steering it becomes obvious that in order to begin a change of direction (enter a curve, for example), the rider, if traveling at speeds greater than about 10 mph, MUST provide a steering input that involves a 'negative torque' relative to the direction the rider wishes to move. By that I mean that if a rider wishes to cause his motorcycle to move to the RIGHT, he must input a LEFTWARD (counter-clockwise) steering torque. As a result of that negative torque, the bike will lean to the RIGHT and THEN begin changing direction to the right.

I have maintained that the rider MUST maintain some measure of negative torque throughout the turn in order to maintain it. That is, he must maintain a certain amount of forward pressure on the inside grip throughout the turn else the bike will, of its own accord, attempt to straighten itself out and abort the turn - ending up moving in a straight direction. However, there are 'tuning points' where a specific speed and turning radius can result in a motorcycle that requires no steering input to maintain its path.

Others, notably a very experienced (and credible) sport bike rider, alleges that his bike provides 'neutral steering' so that once he gets into his turns he is able to provide ZERO steering input in order to maintain them. Indeed, he claims that he could even take his hands off the grips entirely and the bike would continue the course it was in before he did so.

Those two positions sound entirely impossible to reconcile as they appear to be making diametrically opposite claims. But is that really the case? Could it be that both positions are valid and demonstrably correct? By the time you complete this article (and absorb it) you will find that both positions are correct and can be demonstrated. They are both 'concept statements' utilizing a host of assumptions and simplifications of reality, and both involve 'snapshots in time'.

A motorcycle's handling behavior cannot be reduced to some magical number, an index, where the higher or lower that number is, the better it is. A touring bike, for example, is expected to be stable at virtually any speed yet it is lacking in agility, while a sport bike must be able to be quickly leaned into a turn (flickable), particularly at higher speeds, but most sportbikes are not well known for being stable while moving in a straight line (steering head wobble, for example). Which 'handles better' is a rider's personal choice.

The principal design elements in determining how a motorcycle behaves (its dynamics) include choice of tires (size, rubber compounds, profile), suspension, front-end (rake, trail), wheelbase length, location of its Center of Gravity (CG), steering damper resistance, frame flexibility, shock absorber size and flexibility, and much more. [Tires are ALWAYS the first design consideration and almost all other design decisions utilize that consideration. People who cavalierly decide to replace a motorcycle's rear tire with an automobile tire have not the slightest idea how that change effects nearly all handling characteristics of their bikes - but that's another story.]

Most of you know that a motorcycle is generally an over-steering machine while automobiles are generally under-steer machines. What that means is that a motorcycle, while in a turn, will have a greater slip angle of the rear tire than of its front tire. Indications of that are that if you pass the critical speed of your motorcycle in a turn, the rear tire will be the most likely one to slide out from under you leaving your bike pointed INTO the turn.

An over-steering machine tends to carve a tighter turn while an under-steer machine tends to carve a wider turn for any given steering input.

A neutral-steering machine has the same slip in both the front and rear tire while in a turn and the turn that is described as a result is known as an 'ideal'. Note that we have just discovered a problem with the sport biker's assertion that his bike has 'neutral steering': He does NOT mean that his front and rear tires develop the same slip angles in a turn! He means that he requires ZERO steering input to maintain a turn once it has started. The use of an otherwise well known and defined term like 'neutral steering' to mean something other than its formal definition is at the very least confusing, but we know from the context of the argument what he actually means.

There are only three degrees of movement freedom for a motorcycle when traveling on a flat surface: Pitch (where the bike's front-end gets higher or lower than its rear-end), Roll (where the bike leans to the left or right), and Yaw (where the bike's front-end turns to the left or right relative to its rear-end).

These are NOT independent of each other in the case of a motorcycle. For example, when a motorcycle rolls (leans) to the right, because the front tire is narrower than its rear tire, there is an automatic YAW of the bike to the LEFT!

This is a graphic showing the front and rear ties of a typical bike from the rear with the bike absolutely vertical and with zero steering angle. Note that the center of their contact patches is in the dead center of each tire.

Now we roll (lean) the bike over to the right by 30 degrees and maintain a zero angle steering input. (In other words, we just lean the bike over.)

Who in their right mind would have believed that by merely leaning a motorcycle to the right that motorcycle would veer to the left, given that its steering angle remained zero? But that's a fact! By leaning it to the right you automatically yaw the bike to the left.

So now you already see that determining the dynamics (how a bike behaves) is not at all a simple effort. One cannot simply assert that leaning a bike to the right results in a turn to the right.

From other discussions on the matter we have seen that when a bike leans to the right as a result of counter-steering input turning the handlebars to the left, what immediately follows is an automatic turn of the front wheel to the right. This, the result of the 'righting moment' generated by trail. And as a result of that steering input the bike begins to move in a new path, to the right of where it was pointing when the counter-steering began.

So now we are at the point where we begin to see the problem we are trying to deal with: how do we maintain that directional change?

Maintaining the path ...

Let's say that you are riding your bike in a perfectly circular path that has a radius of 78.7 feet. (I chose that size to make what follows easier to understand.)

You may do so at an infinite number of different speeds, of course, though at no higher a speed than what exists when a hard part firmly strikes the ground.

What's different between the dynamics of the bike when you maintain a turn radius and just vary the speed? Well, for certain the bike's lean angle is different. We know that the faster you go in that turn, the greater will be the lean angle.

We also know that the faster you go in that turn, the higher will be the lateral (centrifugal) force. That, in fact, is why the lean angle is greater. But that also means that the amount of tire slippage on the front and rear tires changes (gets larger). But do they get larger in equal proportion?

It turns out, as most of you know, that the faster you go in a turn, the smaller your steering angle will be. At highway speeds, for example, your steering angle never reaches a significant size as compared to when you are doing parking lot practice at appropriate speeds. Thus, along with greater lean angles, greater lateral force, greater slip angles, there is a smaller steering angle. And that means that the amount of out-tracking done by the front tire (essentially its slip angle) is NOT simply larger than it is at slower speeds.

The faster you go in that turn, the LESS negative torque (forward pressure on the inside grip) is required to maintain that turn!!! Indeed, based on the geometry of the front-end as well as the length of the bike's wheelbase, there can be as little as ZERO torque required to maintain that turn, and if you increase speed even more, you will begin to need a positive torque on the steering stem to maintain it.

What I have just said is that there are tuning points for any bike where the speed and radius of a turn result in what our sport bike advocate claims is 'neutral steering'. I also just said that the vast majority of speeds used to ride that turn REQUIRE a counter-steering pressure to maintain it.

Let's look at what a world famous academic expert on motorcycle dynamics (Vittore Cossalter) has to say about this. Here is a reproduction of page 316 from his second edition of 'Motorcycle Dynamics' looks like:

We will examine the rather confusing graph at the top later in some detail but for now I ask you to read the paragraph at the bottom of that page. In that paragraph he tells you why requiring a negative steering torque (forward pressure on the inside grip) is the preferable state for riding in a curve.

Look at the diagrams at the bottom of that page and you will see what happens to the bike's path when you remove your hands from the grips if positive torque is required (on the left) or negative torque is required (right). You see on that the path on the right suddenly gets tighter (the result of the righting moment) which acts as a counter-steering input to widen the path and straighten the bike up to vertical. But in the case where a positive torque is required, removing your hands from the grips results in the path opening up and the bike becoming unstable and FALLING OVER.

What our sport bike advocate declares is that 'neutral steering' results in no change in the path of the bike if he removes his hands from the grips.

So now let's look closely at the top graph and make sense of it. Here I have added mph and feet translations for the metric meters per second and meters indexes along the top and bottom of the graph.

Along the left axis is what is called the Acceleration Index. That is merely the amount of torque required divided by the amount of lateral force, When that number is negative it means a negative steering torque is required to maintain a turn; when it is positive, a positive steering torque is required (and the bike becomes unstable if you stop doing so); and finally, if it is zero then the bike is in what our sport bike advocate claims to be a state of 'neutral steering' where NO steering torque is required to maintain the turn.

Along the bottom is the speed the turn is being made at and along the top we see the radius of the turn being made.

A VERY INTERESTING part of this chart is that for this bike (a sport bike, by the way), counter-steering appears to start at just less than 9 mph!!!!!

Anyway, each of the curves on the chart represents a set of measurements of required steering torque to maintain a turn of a given radius.

For example, the second curve from the left shows the measurements of steering torque required to maintain a path on a circle with radius of 78.7 feet at speeds from about 9 mph to as high as about 30 mph.

Notice that as speed increases the amount of negative steering torque decreases until you finally get to a point that the bike is 'neutral steering' and that at any speed above that point the bike requires positive steering torque (and is unstable).

I have highlighted with colors three of the test measurements made for the 78.7 foot radius curve to make this crystal clear to you.

The green dot shows that if you are moving at a speed of only about 13 mph you MUST employ a forward pressure on your inside grip of magnitude greater than TWO. (The bike will have a lean angle of about 8 degrees.)

Increasing your speed (and maintaining the 78.7 foot radius) to about 25 mph, is shown with the blue dot where you will be very close to having 'neutral steering' (and the bike will have a lean angle of about 28 degrees.)

Increasing speed to about 30 mph, as is shown with the red dot results in your having to provide a POSITIVE steering torque (pushing forward on the OUTSIDE grip) with a magnitude of nearly one, your bike will be unstable, and it will be leaning about 37 degrees.

Touring bikes and cruisers have curves that are wider than sport bikes so that you rarely, if ever, can find a 'tuning point' with them where you can experience 'neutral steering'. Even at high speeds in a turn the amount of friction from any steering damper is not a significant factor in offsetting the righting moment so you must maintain some forward pressure on the inside grip to maintain your course with these bikes.

Though I don't know this to be true, it seems reasonable that because the faster you go in a turn the greater will be the lean angle and the lesser will be the amount of negative steering torque required, it just might be that many of us find it very difficult to lean a bike over far enough to scrape a peg as the steering input simply feels 'strange' (weak) the closer you get to that point.

Anyway, clearly both arguments are valid and demonstrably correct.

Copyright 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)
]]>Tips 241-260 - 255: Another retread who has trouble with counter-steeringJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=10397Tips 241-260 Sun, 14 Jun 2009 14:41:45 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=10397 Another Retread Has Trouble With Counter-steering
... And Believes that the MSF's BRC is a 'Safety Course'

By: James R. Davis

Yet another retread has written me and asked for help in understanding why he is having trouble negotiating curves. Indeed, in this case, why he was UNABLE to make his bike turn properly and ended up crashed at the side of the road.

Here is a part of his e-mail that eliminates any indication of who he might be:

quote:
Bought a bike in Mar. 08. First time on a bike in over 20 yrs. Have never had trouble before. Crux of my inquiry as follows. Was on country road recently on a tight curve to left. Speed was good, lean angle was good. Bike momentum kept pulling me to right and ended up in ditch, when I was trying to steer left through turn. Make sense? Can not figure out what I did wrong. Wonder if I was target fixated or if I was under-steering. Am reading with interest your articles on counter-steering, and related articles on curves. Will be taking safety course at first opportunity, but in mean time,am still re-learning and practicing.

Sound familiar? His bike was 'fighting him' on that turn.

Here is most of my response presented to you because I think there is something of value in it for all of our readers generally:

quote:
Thanks for reaching out and for your kind comments. I will, of course, try to help you with this issue.

First, I would like you to clear your mind of EVERYTHING you may have read or believe relative to counter-steering. I will attempt to replace that bulk of knowledge with a disciplined and rational real world set of information that you can absolutely believe without any confusion (or time lags) - thus USE as needed.

I'm sure that in your reading you have learned about gyroscopic effects and camber thrust and associate those with counter-steering. Forget about them! They do NOT cause counter-steering to work. Instead, they make counter-steering smooth and effortless. You need to understand what counter-steering actually is and how to control it, and that's all.

At speeds below about 10 mph you can ONLY direct-steer. That means that you can ONLY turn your handlebar in the direction you want to go, cause the bike to lean, and then use BALANCE and speed to complete that turn. Notice the word BALANCE is in caps - that, because ONLY when you are moving at speeds less than about 10 mph are you required to assist your bike in maintaining its attitude and not fall over. At higher speeds (by that I mean more than 10 mph) there is NO BALANCE WHATEVER required by you in order to help the motorcycle stay upright - NONE!

The reason for that is that virtually everything about a motorcycle involving its attitude reverses at about 10 mph. For example, if you are turning while moving at, say, 5 mph, and your bike begins to fall, you can save it by merely increasing its speed. But if you are turning while moving at, say, 20 mph, and your bike feels like it is leaning too far (and, thus, in your mind might fall onto its side), if you increase your speed the lean angle will get LARGER (the lean angle will increase). That's right, it leans more when you INCREASE speed and it 'falls' UP instead of down when you reduce your speed while in a turn. The fact is that at any speed over about 10 mph the bike, BY ITSELF - without input from you - determines what the right lean angle should be. YOU CANNOT establish the lean angle. Note that I am now talking about the angle of lean of the combined bike and you. You can, of course, cause the bike itself to lean a little more or less by shifting your body lean angle in the opposite direction, but doing so IN NO WAY changes the lean angle of the combined bike and rider.

That is just another way of saying that balance is not only unnecessary, it is also USELESS at speeds over about 10 mph.

So how does a motorcycle establish its own lean angle? It is simply as a result of centrifugal force offsetting gravity. The faster you travel in a turn, or the tighter that turn is, the greater will be the resulting centrifugal force. Gravity remains constant so a larger centrifugal force supports a greater lean angle, automatically. I know, one would think based on experience that greater centrifugal force would try to make the bikes body lean AWAY from a turn instead of into it, and so now we need to look at what's really happening with a more critical eye. [Think of centrifugal force pushing your contact patches to the outside of the turn instead of the top of your bike.]

When you make a turn it is your perception that you are leaning the top of your body along with the top of the bike INTO that turn. But that is NOT what actually happens. Imagine holding an inverted broom on the palm of your hand, bristles at the top. Balancing that broom is no big deal. If the top of the broom starts to move to the right, you move your hand to the right and that saves it. But now imagine that you want the top of the broom to move to the right.

Clearly the way you make that happen is to move your hand to the left. The top of the broom then SEEMS to be moving to the right but what is actually happening is that your hand is moving to the left and the top of the broom is essentially staying in place. That's because of INERTIA. Mass tries to stay in whatever attitude it is in.

EXACTLY the same thing happens when you are moving at speeds greater than about 10 mph and you want to turn your bike to the right. You do that by moving the contact patches of your wheels to the left. Inertia tries to keep the top of the bike and your head in place while the wheels OUT-TRACK to the left. The result is that it appears that you have leaned the bike to the right. What happens after that starts the lean to the right is that your front wheel is AUTOMATICALLY forced to turn slightly to the right. That is NOT the result of your turning the handlebar to the right but, rather, it is because you LET the handlebar turn to the right. And, as a result, the bike begins traveling in a new direction - to the right of where it was pointed when you began the direction change.

I just described how counter-steering actually works and how you start it. Note that counter-steering is not a momentary thing that you use to begin a change of direction - it is the only way you can change direction (like making it go even more sharply to the right) at speeds over about 10 mph. That comment about letting the handlebar turn to the right is EXTREMELY important for your understanding of counter-steering. You see, you MUST MAINTAIN some counter-steering pressure on your handlebar in order to continue turning to the right for as long as you want to keep turning to the right!

It is simple to visualize the concept of out-tracking when you start a turn. For example, if you are moving straight ahead and you turn your front wheel slightly to the LEFT of dead ahead, you now know that will cause the bike to APPEAR to lean to the right, but the reality is that the front wheel contact patch (like your palm when balancing that broom) moves to the left. What is not so obvious is that when the front wheel of the bike then begins to turn to the right IT CONTINUES TO OUT-TRACK. That is, it continues to point slightly to the LEFT of your INSTANTANEOUS direction of travel.

Now you need to know about one more less obvious force at play here: the RIGHTING FORCE. You know, I'm sure, that your motorcycle tries all by itself to ride in a straight line, vertical. If you removed your hands from the grips and simply sat on your saddle, the bike would try to go in a straight line. That, because of TRAIL. Trail causes the front tire to try to turn in the direction of instantaneous travel. In other words, it tries to make the front wheel point in the direction of the green arrows. In the above diagram trail would try to make the front wheel turn to the right. And if it is successful in turning the wheel so that it points in the direction of the green arrow, the bike would THEN BE MOVING STRAIGHT AHEAD. So, the righting force is what is pushing against your inside grip hand and it is what you must push against in order to continue turning. Now I think you understand that counter-steering is not just how you start a turn, it is how you continue that turn.

The righting force is STRONGER than your steering input!!!!!! If, for example, you pressed forward on the right grip to cause the front wheel to out-track to the left, the righting force would push back against your input and IF YOU ALLOW IT TO (as you must), the front wheel turns back from out-tracking to the left and now points slightly to the right of where it was pointing when you started the turn, though it is still out-tracking to the left of the instantaneous direction of travel. If you had simply locked your elbows and stiff armed your right grip, the bike would immediately fall over to the right as the righting force is, as I said, STRIONGER than your input. You push hard, it pushes back harder. You complete the turn and control your bike by MANAGING THE AMOUNT OF PRESSURE YOU APPLY TO THE INSIDE GRIP.

So now lets PROVE it to you and make this understanding part of your reality.

Take the bike out onto a large parking lot and begin riding a LARGE oval or rectangle with LARGE curved corners. This is not an exercise in which you are trying to make a tight turn!!! All I want you to do is, while riding that circuit, lift your fingers off the grips and steer using only the palms of your hands. While moving in a straight line portion of that circuit I want you to press forward on the RIGHT GRIP of your handlebar with the palm of your right hand ONLY. You can take your left hand entirely off the grip if you want to, but in any event you are not to press forward with your left hand. You are trying to turn to the right by doing this. I assure you that the front wheel will momentarily OUT-TRACK to the left and immediately turn to the RIGHT and your motorcycle will actually turn to the right. Your job was merely to manage how hard you pressed FORWARD (NOT DOWN) on the right grip and observe that the harder you push, the sharper the turn will get.

Press forward with the palm of the left hand and that will reverse the turn - getting it to go straight again - or, if you wish, continue pressing on the left grip and the bike will begin moving to the left.

NO BODY LEAN INVOLVED AT ALL. No body english at all. Just out-tracking the front tire results in the turn. THAT IS COUNTER_STEERING.

Your accident was the result of your not believing or understanding counter-steering. You tried to turn to the left but the bike FOUGHT YOU and was not as responsive as you needed it to be. The harder you tried, the harder it fought. In other words, you tried to direct-steer or use body English or leaning when all you had to do was press FORWARD HARDER on the LEFT grip and the bike would have INSTANTLY and without any fight at all, complied.

Now please note another FUNDAMENTAL problem evidenced by this retread - he BELIEVES that the MSF BRC is a 'Safety Course' instead of a motorcycle control fundamentals class. He BELIEVES that he already knows how to control his bike (the current problem notwithstanding) and merely needs to 're-learn' what he knew. My bet is that 20 years ago he never even heard of counter-steering, let alone 'knew how to use it'.

Copyright 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)
]]>Tips 241-260 - 254: A case against counterbalancing ... and a few other MSF teachingsJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=10332Tips 241-260 Thu, 04 Jun 2009 09:13:57 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=10332 A Case Against Counterbalancing
... And A Few Other MSF Teachings

By: James R. Davis

I can't begin to remember the number of times I have had someone tell me that the reason they do certain things on their bikes is because "the MSF says that's what you are supposed to do". While what the MSF teaches is more often right than wrong, they utterly fail at conveying an understanding of WHY their students are well advised to do certain things, and even worse, on many occasions their 'rules' make sense ONLY while riding on an MSF range during training, but that is not explained either.

For example, there is an exercise in the BRC that promotes the use of counterbalancing while doing slow speed tight turns. In that exercise the student is to shift his body weight toward the OUTSIDE of the turn that is to be made. (Just the opposite of shifting body weight INTO a turn and reaching for the pavement with the inside knee favored by the racing and sport bike crowd.)

So which of these body shifts is right? Which leads to most control of the bike? Why does the MSF teach a technique that is eschewed by the vast majority of 'performance' riders? Since the MSF teaches this counterbalancing to rank amateurs, does that mean it is the safest and most appropriate way to handle slow speed tight radius turns?

In order to understand this discussion you first need to have a fundamental understanding of the fact that almost everything about controlling a motorcycle when it is moving at speeds greater than about 10 mph is the reverse of what you do at slower speeds. Honest! Trust me!

You know, I'm sure, that at speeds slower than about 10 mph you push on the right grip in order to cause your bike to change direction to the LEFT, while at greater speeds you push of the right grip in order to change the bike's direction to the RIGHT (counter-steering). But have you consciously thought about the fact that while in a turn moving at slow speeds, if you slow down your bike will fall DOWN, but if you are moving at speeds greater than about 10 mph and you slow down, your bike will 'fall' UP? By that I mean, of course, that slowing down while in a turn at, say, 50 mph, will cause the bike to stand taller, not lean farther.

Thus, it should not be difficult for you to conclude that at speeds slower than about 10 mph the effect of counterbalancing (leaning to the outside of a turn) has some value that DOES NOT EXIST at greater speeds and that leaning your body INTO a turn (with knee reaching for the ground) has some value at greater speeds that DOES NOT EXIST when riding at slower speeds. The MSF teaches skills designed to safely navigate a training range at speeds of 20 mph or less. They teach counterbalancing for SLOW SPEED turns but DO NOT teach shifting the body INTO the turn.

You have, so far, decided that counterbalancing, therefore, must have something to do with SAFELY handling your bike at slow speeds. You would be wrong.

Instead, counterbalancing is taught as a useful skill, a tool in the tool bag if you will, to help newer riders control THEMSELVES in a slow speed sharp turn. That is, some (perhaps many) new riders are afraid of leaning their bikes at slow speed so they 'choke' and abort slow speed tight turns. The MSF provides their students with a practice TO OVERCOME THEIR FEAR OF LEANING where counterbalancing is used in order to keep the student's *BODY* (not the bike) more vertical and still make those turns. In fact, as you probably understand intellectually, what that causes is the *BIKE* to lean even farther than is necessary in order to make that turn.

Since you then can see that the bike can handle an even greater lean than you thought it could and make that turn while you are more comfortable being almost vertical, it follows that the bike could make that sharp slow-speed turn with ease if you didn't counterweight.

And now you are beginning to see a new picture. Rather than for purposes of showing a student how to more SAFELY handle a slow speed turn, they teach counterbalancing as a means for students to overcome their FEAR of leaning in order to accomplish a slow speed tight turn - though the MSF would rather claim that they teach it to make it EASIER for the student rather than less FEARFULL. Indeed, the use of counterbalancing is LESS SAFE, generally, than keeping your body in-line with the bike when you make a turn AT ANY SPEED.

Let me back that last sentence up a bit. Turning at slow speeds has as its greatest risk, falling down. That risk maximizes as the lean angle OF THE BIKE increases to where a peg drags. Counterbalancing results in the greatest BIKE LEAN ANGLE POSSIBLE - it encourages/invites that maximum risk level. Since the only body shifting technique taught by the MSF to beginning riders is counterbalancing, then it should not be a surprise to you that newly trained riders tend to do just that while in higher speed turns as well as during those parking lot practice sessions. They lean AWAY from turns where the bike lean angle is already getting large and THAT is when a peg drags.

Of course racers and 'performance' junkies on public roads do exactly the opposite and shift their bodies INTO their turns instead of counterbalancing - that makes the bike's lean angle less severe.

So, what about that practice is less safe than staying in-line with your body regardless of speed? Well, the answer to that is simply speed itself. There is not a road in this country where riding at the posted speed limit (or advisory speed) results in your bike leaning more than 30 degrees - well below the angle where peg dragging occurs. In other words, THE ONLY REASON 'performance' junkies lean INTO a turn is so that they can exceed the legal speed limit!!!

About fear ... it is life saving! It tends to keep you from standing with the toes from both feet over the edge of the cliff instead of just one while you are learning your limits. If you make a mistake and only have one set of toes over the edge when that edge gives way, you survive the mistake. Once you have mastered the fundamentals you no longer have any toes over the line and fear level disappears (or, better, has been converted to respect.)

After almost 50 years of riding there are times when I find myself to be afraid. Something new or unexpected presents itself as a threat. You can be sure that that fear causes just enough adrenalin to focus my attention and stimulate my response to that threat. One thing that INVARIABLY, for me, causes such an adrenalin reaction is dragging a peg. I do not EVER deliberately drag a peg so if it happens you can be sure that I have gotten my speed or estimate of the curve's radius wrong and that DEMANDS my reactive attention. And why I mention that is because as I said earlier, counterbalancing INVITES the dragging of a peg. So, I have never found its use appropriate, at least in my case. Better, by far, is to control the bike without adding the complexity of weight shifts and greater than necessary bike leans.

The MSF teaches counterbalancing. That is not a good enough excuse for you to use the technique, now that you know better.

There are other things that the MSF teaches during its Beginner Rider Course (BRC) that you should look closely at and understand before blindly following their advice. They, for example, tell you NOT to cover your front brake lever - indeed, will not allow you to do so during the class. Covering your front brake lever shaves about 1/10th of a second of reaction time in an emergency. That time occurs while you are travelling at your greatest speed. In other words, it will reduce your stopping distance by almost NINE FEET if you are traveling at 60 mph and need to do an emergency stop. Not covering that lever makes marginal sense while you are doing slow speed maneuvers during an MSF BRC class, but it is absolutely goofy advice to follow, generally. Better, by far, than simply prohibiting new riders from covering their brake lever while in the BRC in order to protect the student from their own UNINFORMED MISTAKES in the use of that lever, they should TEACH STUDENTS HOW TO USE THAT FRONT BRAKE LEVER WHENEVER IT IS NEEDED, REGARDLESS OF SPEED!!!

Similarly, they insist that you place one foot (the left one) on the ground when you come to a stop. That, they insist, leaves your right foot on the brake pedal (as if your front brake by itself is insufficient to keep you from moving). That advice also lacks sufficient justification to be followed in the real world as you can EXPECT, from time to time, to find yourself on a sloped roadway or with a roadway depression right where your left foot lands when you stop your bike. Virtually all motorcycles are larger and heavier than those used to train students by the MSF. Very few people have legs strong enough to prevent a modern/heavy street legal bike from falling over if it starts to fall over at a stop, which is exactly what will happen when you 'short leg' the beast. You are well advised to plant BOTH FEET on the ground when you bring your bike to a stop - every time.

So, please, don't explain to me that the REASON you do this or that with your bike is because the MSF told you to do so unless you UNDERSTAND WHY!!! You learn that, unfortunately, someplace other than during an MSF training class.

Copyright 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)
]]>Tips 241-260 - 253: Book Learnin Ain't EnufJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=10190Tips 241-260 Sun, 10 May 2009 10:44:39 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=10190 Book Learnin
Ain't Enuf!

By: James R. Davis

Cash and I took a relatively new rider out for some parking lot practice this morning in preparation for his joining us on a day ride next week some time.

He used to ride dirt bikes perhaps 10 or 15 years ago and totaled about 3,000 miles doing that. Recently he came back to riding and obtained a new Moto Guzzi. One sweet bike, and one that is obviously a bit more powerful than he is used to. In any event, he completed a BRC class and has amassed another 1,000 miles on his new bike, but admits that he does not, yet, feel like he is in complete control of that bike. So, Cash invited him to join us this morning for that PLP so we could help identify where any problems might be with his control of that bike.

Let me tell you a little bit about this man. His balance and his sense of self-competence (confidence, generally) are superb. He is a martial arts expert and I'm sure that's where those attributes came from. He was properly dressed with the exception that he did not wear gloves of any kind. His safety gear in all other respects was top notch.

Why I'm posting this here is that it took only two questions from me to learn, long before watching him handle his bike, that he had not the slightest idea of how to steer his bike or what the dynamics of that bike really are. And because it took exactly ONE PLP exercise to FIX the majority of his problems.

Question one: "How do you steer your bike into a left turn when moving at about 20 mph?"

Question two: "How much balance is required of you to steer your bike through a left turn at 20 mph?"

After he explained how he leans and then 'controls' the direction of the bike by turning the handlebars to the left, and that he feels that a great deal of balance is required to make that turn at 20 mph, we all knew (except him) that he had not the slightest idea what he was talking about.

When I then asking him what counter-steering means, he replied that he was not sure, but he imagined that it had something to do with SLIDING the front or rear tire during a turn, like when you are on ice.

This guy rides motorcycles? Is he dumb, or what?

Yes, he rides motorcycles. No, he is not dim in the slightest - he is actually a very bright guy. He is bright enough, for example, to admit without hesitation that he doesn't feel like he is really in control of his bike. THAT is why he was with us this morning!

Now let me restate something I said earlier, this man had VERY RECENTLY taken and passed the BRC. Yet he did not know what counter-steering was, had never heard of a 'righting force', believed - absolutely believed! - that steering was accomplished as a result of leaning, and that balance was fundamentally important in keeping his bike from falling over at 20 mph.

The single exercise that I had him perform (other than some fundamentals to assure us all that he had good control of his levers), was to ride a LARGE course at 20 mph and make LARGE GENTLE turns on it, while his fingers were pointed into the air and only the palms of his hands were touching the grips, AND while sitting straight up - no leans whatever! He was to see if 'push right in order to go right' actually worked. If for any reason he felt that the bike was not doing what he wanted it to do he was to abandon the effort and wrap his fingers around the grip and steer any way he felt would safely work, but that he had to at least 'try' to make a turn by merely pushing forward on the inside grip.

He did that for two laps of the lot and came back to where Cash and I were waiting. He stopped his bike and turned it off, then took off his helmet. There was an ENORMOUS grin on his face. "IT WORKS! I tried it and it did exactly what you said it would do. I pushed on the right grip and it turned effortlessly to the RIGHT. I would never have believed it without trying it. I'm Amazed!"

And now let me tell you what *I* learned today. No matter how smart your student is, no matter how carefully you draw word pictures and explain dynamics to them, until and unless they EXPERIENCE what you are trying to teach them, they PROBABLY DO NOT GET IT.

Copyright 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 241-260 - 252: Your Neck - Racing Gear Hits The StreetsCash Anthonyhttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=10095Tips 241-260 Mon, 27 Apr 2009 08:39:38 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=10095 Your Neck
Racing Gear Hits The Streets

By: Cash Anthony

One argument made against the wearing of motorcycle helmets is that it causes injuries more severe than the ones it prevents, pointing to broken necks. The reality is that such accidents are very rare in statistical terms, but they can cause complete disability.

This point usually comes up in a discussion that focuses on government requirements, but it confuses two issues. One issue is political, related to the power of the government versus the rights of the individual. The other is a safety debate. And claims that riders are just as safe with or without helmets are demonstrably false.

But even for riders who never go out without a helmet, there's a part of the body that has, until recently, lacked any protection: the neck.

Riders who do motocross events have used chest protectors and neck braces for years, but for street riders, it's relatively new. Several manufacturers have now come out with these neck and back braces for street riders, including the HANS Device (see it here), the Leatt Brace (see it here), the so-called helmet for your neck, and BMW's Motorrad The Neck Brace System.

The inventor of the most common braces is Dr. Chris Leatt. Leatt witnessed a rider die from a cervical spine injury at an enduro event and was inspired to leave his studies in neurosurgery to develop a brace designed specifically to prevent the kind of neck injuries that killed his friend.

To test the effectiveness of the Leatt product, researchers conducted pendulum tests on inverted dummies, banging their helmeted heads into a steel block. To see a video of this test for one model, with and without the brace, go to test.

Many dealerships have several versions of the brace. I tried three of them on recently. Some doctors, including mine, are suggesting that their rider-patients look into them. I could see that fit will be important, so that you can move your chin down some and look over your shoulder without hindrance; but once the rider is used to adding this piece of gear every day - it goes on over your jacket - it should become scarcely noticeable. Unless you need it.

The Leatt company itself says that a recent survey in Motocross Action magazine asked, "What was the most significant MX product in the last decade, and why?" Most readers (about 70%) responding to the survey said "the Leatt brace". For why, one man whose boy competes in motocross said, "It gives me peace of mind." For street riders to have more peace of mind about neck protection when managing all the risks of commuting, touring or city driving would be a good thing.

Copyright 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org
]]>Tips 241-260 - 251: Informed ConsentJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=9959Tips 241-260 Sun, 05 Apr 2009 11:11:27 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=9959 Informed Consent
Signing a liability Waiver should mean something beyond giving away your rights

By: James R. Davis

Doctors are professionals. As a consequence of that, they are required to provide their patients adequate information about a proposed treatment, such as an operation, so that the patient can make an INFORMED DECISION as to whether or not to allow that procedure. And when they have made up their mind, they must evidence that agreement by signing a LIABILITY WAIVER - an indication that they are providing INFORMED CONSENT.

So what does that have to do with riding motorcycles?

Well, let's start with the idea that virtually everbody knows that motorcyclists can die or become horribly damaged if they have an accident while riding their motorcycles on our public streets. Even potential motorcycle training students know all about those possibilities because they can hardly escape the news of such incidents being splashed on newspapers radio or television.

Of course riding a motorcycle is dangerous. No motorcyclist, however, has to sign a liability waiver to engage in that dangerous activity at highway speeds on any roadway in the country. By doing it they are expressing a form of 'informed consent'.

But there are motorcyclists in-waiting out there who wish to begin riding on our streets and though they more or less fully understand the risks involved out there, they have absolutely no way of determining what the risks are of learning how to ride. Even with the utmost concern on their parts about safety, realities conspire to HIDE those risks from these potential new riders.

Realities? Let's look at a few.

If you crash a motorcycle that is moving 60 mph, you cannot help but expect to be severely injured or die, but while learning to ride you will never be allowed to move faster than about 20 MPH. The odds are very good that you could survive such a crash, right?
You see experienced motorcyclists riding on our roadways without a helmet all the time. It is obvious to you that if you crash without a helmet on your odds of survival are not very good, but while you are in training you are REQUIRED to wear a helmet, and that increased your odds of surviving a slow-speed crash, right?
Road rash is ugly and painful and disfiguring and though you see experienced riders on our roadways that are not even wearing jackets, while in training you are REQUIRED to wear one (at least a long-sleeved shirt) so that the odds of getting road rash are small while in training, right?
You are certain that a lot of crashes that happen to motorcyclists involve some inattentive car driver, possibly talking on a cell phone, turning their cars into the path of the motorcyclists, but there are no cars on the range while you are in training and no 'traffic' of any kind exists that might turn across your path of travel so a collision is really unlikely while in training, right?
You have heard of a lot of motorcycle accidents occurring where the rider simply fails to make a turn and runs off the road and into a tree or fence or building, but that is exactly why you are about to take a formal riding class - to learn how to control your motorcycle and make those turns every time, right?
You know that many motorcycle crashes occur because of obstacles that they run into on our roadways like rocks, debris from shredded truck tires, stuff that falls out of truck beds, curbs, and, of course, an occasional deer that runs into the road, but there are no obstacles on a training range - no rocks or potholes of curbs or light poles or buildings - and no deer, so such a crash can't happen to you while in training, right?
You know that motorcycles on the roadway have never been bigger than they are today in terms of weight and engine power and that these contribute to crashes, especially for new riders, but when in training you will be allowed to use only 'small' motorcycles in terms of weight and engine size, so even a beginner should be able to handle these 'underpowered' 'beginner' motorcycles without their likely losing control of them, right?
You know that a lot of people learn to ride by being 'coached' by well intentioned friends who don't have the slightest idea of how to teach and who may not be very safety conscious themselves, but you are going to be trained by 'professionals' who are CERTIFIED by the Motorcycle SAFETY Foundation, so they know everything about their motorcycles and about how to teach you all about how to SAFELY ride a motorcycle, right?

And so, in your mind, the odds of dying or being horribly mangled as a result of an accident while being trained in how to SAFELY ride a motorcycle are essentially non-existent. You are going to be trained so that you, unlike those other foolish 'stunters' and 'street racers', can ride on our roadways with relative safety - because training is all about SAFETY and happens on a SAFE training range and is provided by Motorcycle SAFETY Foundation CERTIFIED instructors who will not allow UNSAFE behaviors by the other students and while wearing all the SAFETY gear that you think is necessary to SAVE YOU from road rash and/or collision damage even if a crash does occur at the SLOW SPEEDS you will be allowed to ride at during the time you are being provided the EXPERIENCE and SKILLS necessary to ride at highway speeds on our roadways. After all, your State seems to think that is so as they will issue you a motorcycle endorsement upon successfully completing this training class evidencing that THEY think you will then be qualified to do so.

So it comes as a bit of a surprise to you that before you are allowed to swing a leg over the seat of a motorcycle during your class you are REQUIRED to sign a liability waiver which says, TWICE, once in BOLD FACE type, that you could be severely injured or even KILLED during training and that you understand and accept that risk and will hold the Motorcycle SAFETY Foundation harmless should that happen.

Do you REALLY understand the risks involved to you during training? What are the odds that you will crash your motorcycle during training? What are the odds that you will be severely injured or even die while in training? The fact is, you have NO IDEA!!!!!!!

Any claim that you are providing 'informed consent' by signing that document is absurd in the extreme. How, for example, could you possibly understand the risks you are about to take when your instructors don't even know what they are???

Sure, they know that you COULD crash and suffer injuries or even die, but do they know what the odds are? THEY DO NOT! The MSF HIDES that information from them. DO they know that DEATHS have occurred during basic rider training? Yes, but not how many and not as a result of the MSF advising them. They know because a couple of people, like myself, have collected the facts about these 'incidents' and made that information public.

Students lose control of their motorcycles during training and run right off the range, often at full throttle, STRAIGHT into buildings, parked cars, pedestrian onlookers, even parked motorcycles or OVER CLIFFS! (And you thought the training ranges were 'safe', right?)

Students ROUTINELY drop their bikes during training and end up on the ground as a result. Sometimes without injury, other times with bruises or broken bones OR FACIAL SCARING or BROKEN TEETH. But you were sure that because you are required to wear a helmet that such things couldn't happen, right? Did you know that 36% of all head impacts during motorcycle accidents occur in the CHIN area of the face and you are NOT required to wear a full-face helmet during training?

Did you know that a few years ago the MSF increased the engine size of the motorcycles that could be used for training to 500cc's (so that Harley-Davidson, one of their sponsoring owners, could use there Buell motorcycles for training and thus enhance SALES of their brand) and do you think that was done with your SAFETY in mind?

Rather than SAFETY being their principal training objective, did you know that the Motorcycle SAFETY Foundation changed their curriculum by dumbing it down in order to make is more 'FUN' and 'EASY'?

And did you know that for the first 25 YEARS of motorcycle rider training there was not one single fatality, and then there was one (in Pennsylvania). After that death the Motorcycle SAFETY Foundation dumbed down their curriculum, and in the last seven or eight years there have been no fewer than NINE DEATHS or NEAR-FATAL accidents that have occurred during basic rider training classes? This new dumbed down curriculum is the one you will be taking.

So when you sign that 'liability waiver' in order to learn how to SAFELY ride a motorcycle are you now of the opinion that had you not read this article you would have been providing 'informed consent'?

If a doctor wanted you to begin taking a new medication of some kind and you asked him/her if it had any dangerous side effects, would you be satisfied (or informed) if he told you that in all the years that medicine has been available to combat your illness only five people have died, or would you expect him to tell you that five people out of the 5,000 who have taken that particular medicine have died as a result?

So if your instructor were to say that "the MSF has graduated 4 million students over a period of about 35 years of training and only 10 deaths or near fatalities have occurred during that time" that you were being properly 'informed'? Or would you EXPECT him to say that "before we changed the curriculum only one person ever died while in training over a period of 25 years, but since we changed the curriculum [to make it more FUN and EASIER, the one that you will be taking,] over the past seven years several hundred thousand students have taken the course and there have been AT LEAST nine deaths or near-fatal accidents during that training[, and, by the way, that 'improved' curriculum uses a NEW AND IMPROVED method of teaching we like to call 'learner based' where you more or less get to teach yourself how to ride safely]"?

They will not do so. Of course what is bracketed and in red is what they might not say if the message was actually a marketing message instead of answering your question. You don't think the MSF would stoop to using marketing messages?

Copyright 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)
]]>Tips 241-260 - 250: Not all 'beards' are hairyJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=9931Tips 241-260 Tue, 31 Mar 2009 09:45:51 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=9931 Not all 'beards' are hairy
('Not-For-Profit' does NOT, necessarily, mean 'Charitable')

By: James R. Davis

When George gets an agreement from Tom to 'back him up' should George's wife ask if the two of them were playing poker together the other night, when, in fact, George was having an interlude with Sharon that night, Tom is acting the part of a 'beard'. Of course, Marsha and Jenny could be playing the same game. Not all beards are hairy.

???

Stick with me, please.

Not all scams are illegal, even though they, by definition, are immoral. For example, ...

Assume that a man named John was hired by the manufacturers of Ford, Chevrolet, Toyota, General Motors and Honda to teach oil drilling techniques designed to be environmentally friendly. But John would not be paid based on how environmentally friendly the drilling his students did actually was. Indeed, John would NOT even be paid based on how many students he taught in his classes - no commissions for John. There is a certain sense of 'conflict of interest' associated with commissions.

But he was well paid, nonetheless. Oh, and they made him the president of a company they set up for him.

Then the makers of Mack trucks and Peter built, and a few others heard about John and so they hired him to teach oil drilling techniques designed to be environmentally friendly and which would, incidentally, provide the rigs used by the students while learning to drill in environmentally friendly ways. But John would not be paid based on how environmentally friendly his students drilled their wells, nor on how many students he trained - no commissions for John - but he would receive a handsome salary. However, John would not have to quit his first job, he could have both at the same time. Oh, and they would make John president of a company they set up for him, a different company than the one he is already president of, and he can remain president of that other company, too.

Lest that 'feel' somewhat unfair to you, not to worry, because the manufacturers of drilling rigs heard about John and they got together and hired him to teach environmentally friendly drilling methods, using their drilling rigs. John would receive no commissions based on how environmentally friendly his students drilled their wells, nor on how many students he taught - no commissions for John - but he would receive a large salary and they allowed him to create and become president of a company that provides the curriculum to be used by others when teaching how to drill environmentally friendly wells. Oh, and he would not have to resign from either of the other two companies John is also president of, and they agree, he can continue to receive his huge salaries - but no commissions.

So, John is president of three companies and receives three full-time salaries, but no commissions, so that people will all know that John is not out to 'get rich' by providing environmentally friendly drilling instruction. He identifies himself as being president of a 'Not For Profit' company, not three of them. The fact that he cannot work 8 hours per day for each of the companies does not seem to bother all those stockholders - because John does seem to manage to eat and sleep and otherwise enjoy the good life, despite being paid for 24 hours per day of work.

It just happens to be true that as a result of John's efforts there are more cars and trucks and drilling rigs sold than ever before - just a coincidence, of course. As to safety ... well, there are more deaths, more serious injuries, and environmental damage that result from John's efforts - results for which he is not compensated in any way to prevent - even occurring during John's training classes. But John is compensated and holds these 'jobs', because sales and profits of his stockholders products continue to grow. Despite that, it is clear that what John does is promote environmentally friendly drilling, and safety.

Fantasy? Hardly. Tim Buche is the president of the Motorcycle Safety Foundation (MSF), which is a not-for-profit (INDUSTRY GROUP) corporation owned by the major manufacturers of motorcycles. His company provides the curriculum used to teach rider education. They have an annual budget of slightly more than $8,500,000.

He is also the president of the Motorcycle Industry Council (MIC), which is also a not-for-profit (INDUSTRY GROUP) corporation owned by the major manufacturers of motorcycles. His company is chartered to LOBBY governments and provide assistance in getting motorcycle favorable legislation passed in the United States. They have an annual budget that is 'substantial', but not made public for some reason.

He is also the president of the Specialty Vehicle Institute of America (SVIA), which coincidentally is a not-for-profit (INDUSTRY GROUP) corporation owned by the manufacturers of Arctic Cat, Polaris, Suzuki, Honda, etc. (You know, manufacturers of snow and water vehicles and ATV's.) No idea what their annual budget is.

So Tim Buche is president, a full-time job, usually, for three different companies each of which is owned by manufacturers and is formed as a not-for-profit. That is, they are EACH of them, industry group (501 (c)(6) corporations whose sole purpose in life is to improve the profits of their stockholder corporations.

So why is it that when asked, Mr. Buche implies that he is president of a not-for-profit (education and charitable) corporation? (These are 501 (c)(3) organizations.)

Why, of course, because Tim Buche is ALSO president of yet another corporation - a fourth full-time presidency. He is president of a company called National Motorcycle Safety Fund (NMSF) which IS an education and charitable nonprofit. It has an annual budget of less than $25,000. What does it do? Why it solicits DONATIONS for its owning organization, the MSF! It also publishes some educational and motorcycle promotional material and gives or sells helmets to MSF training providers, (though last year they purchased exactly ONE helmet for $188 so this is not a significant activity). Tim's salary is ZERO for his role as president of this organization. This is, after all, a real, though tiny, educational and charitable organization (which the MSF has apparently no idea what to do with.)

It could also be called a 'beard'.

Any questions?

Copyright 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)
]]>Tips 241-260 - 249: Parking Lot Practice to MASTER your clutch and front-brake leversJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=9917Tips 241-260 Sun, 29 Mar 2009 12:15:11 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=9917 Parking Lot Practice to MASTER
your Clutch and Front-brake Levers

By: James R. Davis

Some readers are already trained in how to ride a motorcycle yet are less than masters of their clutch and front-brake levers. Since those two controls can save your life, it makes a lot of sense to me that you should MASTER their usage. This article describes a simple set of parking lot practices designed to help you do that as well as to dispose of some likely misunderstandings or misconceptions about what those controls do.

I will describe a possible practice for you in an effort to plant the objectives in your head, not just a simple set of 'rules'.

Please note that this all assumes that you are already trained and can ride a motorcycle - this is not a set of exercises that trains a total newbie how to ride!

As mentioned earlier, the two controls you must MASTER early in your riding career are the clutch lever and the front brake lever. What you must learn in regards to your clutch lever is how/when to use the friction zone and how to ALWAYS ease it out rather than 'release' it.

What you need to learn about the front brake lever is how to comfortably cover that lever for extended periods of time (so that you don't cramp), and how to SQUEEZE it rather than 'grab a handful' of it in order not to overuse it. You need to learn that your brakes are not binary switches that are either on or off and to recognize, as a matter of 'feel', the appropriate amount of pressure to use on that lever to accomplish TRIVIAL to increasingly significant rates of deceleration. In other words, how to use your front brake like a reverse throttle.

On a parking lot your principal challenge is working at low speeds - the most difficult aspect of controlling a motorcycle. Other than avoiding hitting anything while moving, you need only realize that your job at low speeds is to keep the bike on its tires instead of on its side - something you do not have to do at higher speeds. So, what that means is that you need to provide some amount of balance assistance to a bike that is moving at slow speeds and that requires that you can 'feel' your attitude with some confidence - which requires that you be healthy and that your vision is not impaired. So, you do NOT practice slow speed control in the fog, nor do you do so under the influence of drugs (legal or otherwise), and you do not practice slow speed control at night unless the area is WELL LIGHTED.

I propose that you focus entirely on ONE CONTROL to learn how to use it properly. Further, and this might sound goofy, but I propose that you learn turning maneuvers at relatively fast (for a parking lot) speeds of, say, around 20 mph, but that you learn slow speed control beginning at VERY SLOW SPEEDS (less than 10 MPH) while moving in a straight line.

The very first exercise I suggest that you MASTER is starting to move - from a dead stop - and slowing to NEARLY a dead stop. That is, while your bike is pointed straight ahead, you hold your throttle in such a way as to get your engine running at about twice your idle speed AND LEAVE IT THERE! Starting to move your motorcycle does NOT necessitate that you 'rev' your engine, nor does it involve your leaning your body forward and 'launching' with a push-off with your feet! Your objective is to begin to move the bike using ONLY the easing out of your clutch lever - and by that I mean, INTO the friction zone BUT NOT ALL THE WAY THROUGH IT!!!

Your bike will begin to move at which time your objective is to plant BOTH FEET on your pegs. If in the beginning you need to take a step or two while the bike is still unstable, so what? Soon you will not have to do that, but this exercise is to get control of your clutch lever, not your feet or balance. You are to continue moving and easing the clutch out slightly more in order to increase your speed until you are STABLE.

For some of you, whether experienced or not, while doing this exercise you may stall your engine. That means, of course, that you did NOT hesitate as you entered your friction zone to allow your engine speed and rear wheel speed to synchronize. If that happens with any regularity at all, I propose that you make the exercise HARDER - by learning how to start from a dead stop in SECOND GEAR instead of first. When you can do that, you can certainly do it in first gear without ever stalling your engine.

Then you are to reverse the direction of clutch lever movement - drawing it toward the grip instead of releasing it - which will cause your bike to slow down. I am not suggesting that you here 'grab' your clutch lever and draw it to your grip, but that you begin EASING IT OUT OF THE FRICTION ZONE - but not all the way. Continue that until you are no longer stable and THEN reverse the direction of movement on your clutch lever (now easing it out and more deeply into the friction zone again) until you recover bike stability with a slight increase in speed.

Continue this easing in and then easing out of your clutch lever until you are certain that you know where the friction zone is and how to use it to modestly control your SPEED. Note that you have not touched your brakes or varied the throttle at all! Instead, what you have learned is that, like your brakes, your clutch is not a binary device - either engaged or disengaged. Rather, it is a vernier device that controls in a very precise manner, the amount of engine torque that reaches the rear wheel.

Obviously you use your brake(s) at the end of this straight line when you want to STOP - and squeeze your clutch lever all the way to the grip.

Once you have EXCELLENT control of your friction zone as a result of this practice you move on to a similar exercise - friction zone control while in a turn. You do that by getting your bike up to a reasonably fast parking lot speed of about 20 mph and start riding a LARGE open course - either a HUGE circular path or a large box with LARGE quarter circle corners. Again, your objective is to learn to use your friction zone to control your speed while in a turn. No brakes!

You establish a fixed speed with your throttle and LEAVE IT THERE. Then, while in a turn, squeeze the clutch lever INTO THE FRICTION ZONE but not all the way through it. Note that the bike slows down, modestly, and also note that the bike stands a little taller and your path of travel slightly widens. Reverse your clutch movement - now allowing it to go back through the friction zone on the way out. Note that your bike speed increases and the bike leans slightly MORE as its path of travel also tightens modestly.

You should pay attention to what a 'modest' change in speed is and what it feels like as you do these simple exercises because you are now ready for the first front brake exercise.

Ease your clutch out all the way and leave it out. Maintain the same path and speed (about 20 mph) on the LARGE circuit you have been using. Now the only control that you are going to practice using is your front brake lever. You begin your practice by COVERING THAT LEVER with as many fingers as you want, finding the most comfortable, for you, position possible.

This might sound goofy as well, but the first thing you should learn how to do is 'tap' your brake lever without causing any noticeable speed decrease. Indeed, your ONLY objective in doing this is to light your brake lights. You are to 'tap' your brake lever TWICE in order to get familiar with how that feels and how little energy is used by you to do it. You have just learned the universal CAUTION-WARNING-DANGER signal that you can, as a courtesy, provide anyone who is following you (whether a bike or not) to indicate that you MAY have to make a fast stop soon.

You also learned that your brake lever can be used for other than STOPPING. What you are about to practice is using it to GENTLY SLOW DOWN - NOT STOP!

While you are in the curved portion of that path GENTLY apply braking pressure with however many fingers you have used to cover the front brake lever. What you want to do is MIMIC the same modest deceleration that you experienced when practicing friction zone management.

What you will quickly discover is that it is virtually impossible to be that gentle with the brake lever. Compared to your friction zone, the brake lever is a very crude/coarse control of modest speed changes. But it IS POSSIBLE to get close if you are gentle enough.

You should, using only the front brake lever, reduce your speed from 20 mph to 15 mph, then EASE the brake lever back out in order to regain a speed of 20 mph.

Notice that there was not the slightest possibility of falling down while you were using your brake to slow down!!!! Because you were GENTLE with it.

Please also note that, again, just as was true when you used the clutch lever to slow down, when traveling at speeds over about 10 mph, when you slow down the bike tends to stand taller and your path of motion tends to widen.

Now you are ready to begin SLOW SPEED practice. 10 mph is actually pretty fast. You need only think about how fast you are moving when you turn a corner on a surface street to recognize that fact.

Get your speed down to 10 mph and maintain it as you begin a LAZY circle. That is, a circle large enough that you can EASILY maintain it at 10 mph. This is NOT an exercise to learn how to do a tight turn!!! Select a lazy circular path and maintain it. Keep your fingers OFF the brake lever (uncover it). This first exercise is clutch control. Do NOT change the setting of your throttle. This is ENTIRELY clutch control.

Using your friction zone ONLY, reduce your speed to 5 mph and then increase it back to 10 mph. What you are to notice is that at very slow speeds when you slow down your bike will lean MORE and your path of travel will tend to tighten up instead of what you experienced at 20 mph. You have just verified that counter-steering happens somewhere just south of 10 mph!!!

You also are to notice that because this is a lazy circle you are riding that the bike does not simply FALL DOWN when you slow down, as long as you do so GENTLY. This is enormously important for you to get hold of as a concept because you will soon be doing the same thing using your front brake lever instead of the clutch lever. You must not be afraid of your controls! They are YOUR CONTROLS.

While you are practicing this slow speed maneuver you should with some frequency reverse directions of that lazy circle so that you avoid dizziness!!

After you have MASTERED the friction zone usage so that you can with absolute confidence increase or decrease your SPEED with it while in a curve, you ride out of that lazy circle and then reestablish that path of travel at 10 mph while covering your front brake lever and NOT covering your clutch lever. You are now going to practice using ONLY the front brake to VERNIER CONTROL your speed while in a slow speed turn. No clutch action! Leave your throttle in the same place and use ONLY your front brake lever to GENTLY reduce your speed from 10 mph to 5 mph, then release that lever and get back up to 10 mph.

What you will notice, again, is that your brake lever is a clumsy way to control trivial amounts of speed difference as compared to your clutch lever. But it can be done, and safely.

To wrap up the training session, after you have reoriented yourself and gotten rid of any slight dizziness, do the final exercise a couple more times using BOTH the clutch lever and the front brake lever at the same time!!!! Learn how they can compliment each other - that if your speed, for example, increases to 15 mph it is easier to use a GENTLE bit of brake to get it back down to 10 mph than it is to use the clutch to do that, but if your speed gets too low you MUST use your clutch lever to increase your speed as your brake lever simply doesn't work that way.

Anyway, those are my thoughts on practicing clutch and brake usage in slow speed turns. Enjoy yourself while out there. Practice is only stressful when you use it to get better at something. As you get better, stress levels disappear. That's where you want to be - without stress, out there merely confirming that you still 'have it'.

Copyright 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)
]]>Tips 241-260 - 248: Why Counter-steering is so hard to understandJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=9679Tips 241-260 Wed, 18 Feb 2009 10:08:07 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=9679 Why Counter-steering
is so hard to understand

By: James R. Davis

One of the most difficult motorcycling concepts to teach is counter-steering. There are riders with 40 years of experience who don't even believe in it, and will argue the point endlessly. People who have never ridden a two-wheeled vehicle frankly simply CAN'T believe it works. And any detailed discussion of HOW it works is usually met with a deaf ear and blind eye - the audience being totally shut off. Educators insist that you must teach students using the simplest ideas first, then moving on to details once/if the student understands those fundamentals. Try that with counter-steering and all you get are students who think you are talking about motorcycle 'magic'.

The fact remains that counter-steering DOES work and is, by far, the most efficient and most effortless way to control the direction your motorcycle travels in.

I believe I have stumbled upon why it is that so many riders and especially non-riders have trouble with the concept of counter-steering. They think in terms of hard coupled mechanical devices.

Nothing wrong with that except that your motorcycle is anything but a hard-coupled mechanical device.

Specifically, when one of these people hears or reads that you initiate a turn to the right by pressing forward on the RIGHT grip of their handlebar, they can easily visualize that such action will result in the front wheel turning to the LEFT. What they apparently cannot then visualize is that the bike, by itself, pushes back against your right hand and TURNS THE FRONT WHEEL TO THE RIGHT as it also leans in that direction.

So, and they would be entirely correct for a hard coupled device, they are left with a mental image of the front wheel pointing to the left while the bike begins moving to the right - well on its way to hitting the ground!

Counter-steering is accomplished using feedback management, not raw strength or leverage or using body 'english' (lean or position).

Disregarding entirely the WHY of how it happens, let's just look at making a right-hand turn.

If you turned the front wheel to the left with some form of mechanical device (an electric motor and gears connected to the steering stem), THAT BIKE WOULD IMMEDIATELY FALL DOWN AS YOU BEGAN TO TURN.

Your body, however, REACTS to the push back delivered to your hand by the bike and ALLOWS the now left pointing handlebar to TURN TO THE RIGHT simply by MAINTAINING THE SAME AMOUNT OF PRESSURE ON IT, NOT BY INSISTING THAT THE AMOUNT OF MECHANICAL TRAVEL IMPARTED BE MAINTAINED. By maintaining the same amount of pressure you have ALLOWED the front wheel to be turned to the RIGHT BY THE BIKE.

No person without some experience riding a bike of some kind could possibly understand, at least not instinctively, how pressing on the right hand grip will result in a greater pressure pushing back (not the same amount) on that hand and, thus, that the motorcycle itself makes the front wheel change the direction it is pointing to toward the direction you actually want to go. Counter-steering becomes 'magic' to them, until they either experience it or have it explained in detail.

So much for the argument of keeping it simple.

Copyright 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)
]]>Tips 241-260 - 247: Path traveled - not at all obviousJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=9425Tips 241-260 Sun, 11 Jan 2009 16:18:14 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=9425 Path Traveled
(Not at all obvious)

By: James R. Davis

When you are moving in a straight line, or when you are travelling in a curve at very slow speeds, the path the bike travels is perfectly obvious. But when you are in a turn at higher speeds that path is not at all obvious, despite what you think.

This article will attempt to put together a lot of concepts that have been discussed in other technical articles here such as Traction, Centrifugal force, Center of Gravity (CG), Steering angle, Drift, Slip angle (often confused with drift), Under- and Over-steering, Tire pressure, and Load. Individually, these are easy to visualize and understand, but in a dynamic world it is often hard to put together a set of them into a meaningful understanding of an issue. We will use the issue of 'Path travelled' to help you do just that.

First, a quick review. Tires are flexible. Even with the maximum air pressure that they can safely be inflated to, they flex. As a result of that flexing, when you are in a turn at any reasonable speed, there is a difference between the direction the wheel is pointing and the direction the tire's contact patch is pointed.

In addition, whenever you input a steering angle other than straight ahead, the contact patch slips a little as it attains the new direction. That is, a percentage of the contact patch is literally sliding across the pavement, not just rolling on it. This slippage results in what is known as a slip angle which is the difference in direction pointed to by the tire and the direction of travel. There MUST BE a slip angle or you could not change the direction your motorcycle is traveling. Combined, the flexing of the tire and the slippage of the contact patch result in a drift angle - the difference between the actual direction of travel and the steering angle used. This is called 'drift' because your vehicle is drifting slightly toward the outside of the path you told it to move in via the steering angle you input.

I will make these preliminary comments clear as we go on.

We start with a diagram that shows a view of a motorcycle from overhead while it is making a turn at VERY SLOW SPEED in that the motorcycle is assumed to be standing absolutely vertical. The dark arrowhead represents the instantaneous direction of travel of the front tire.

By drawing a perpendicular line through the axles of each tire to the point that they meet, we derive the Origin (O) of the radius of the turn that is being ridden. The dashed grey circle, then should be understood to NOT be the path of travel of the motorcycle. Rather, it merely shows a constant relationship between the TWO radii in a turn - the relationship that defines NEUTRAL steering (more about that soon). The dashed vertical line shows the radius described by the rear tire and the angled dashed line shows the radius described by the front tire. Because the radius for the rear tire is ALWAYS shorter than that of the front tire, you must recognize that the rear tire ALWAYS turns INSIDE the circle described by the front tire.

Let's add the location of the CG for the bike and connect that to the origin of the circle as well. The new line is marked 'R' as it is the actual radius of the turn described by the CG.

If that was all there was to it, this would be a very short lesson. You could plot the actual path traveled by the CG as follows:

Now we get into the fun stuff. < grin >

When that motorcycle is traveling at any meaningful speed, that dark black arrowhead no longer points in the direction the front tire is moving in that instant. Instead, because of tire flex and slip, both tires have an instantaneous velocity (V) which are pointing to the OUTSIDE of the actual path of travel. Drift, remember?

Furthermore, the bike is no longer vertical as it is leaning toward the inside of the turn. The result of that lean is that the wheelbase gets longer. (We will ignore that very minor fact in the diagrams that follow but you should understand the truth of that statement as it means that the radius of the actual path of travel becomes very modestly longer.)

If we assume that the drift angle for both tires is essentially equal (say, 10 degrees), then we can draw a new picture of how we locate the origin of the actual path traveled as follows:

With identical drift angles you see that the new radius (R¹ is ALMOST identical in length to that of the original radius (R) but more obvious is that the new origin (O¹) is almost exactly riding on that relationship circle. These will not be exactly the same but because the length of the wheelbase is so much smaller than the length of the radius and the placement of the CG is very close to the midway point between the contact patches, that difference is trivial.

But the drift angles for the front and rear tires are usually NOT the same.

The greater the load carried by a tire and the lower the tire pressure inflating those tires, the greater will be the drift angles. This explains, by the way, why after your tires warm up your bike will not drift as much as it does when the tires are cold. Furthermore, the greater the longitudinal forces exerted on the tires (acceleration and braking), the greater will be the drift angle.

In another article on this site I claimed that automobiles tend to be UNDER_STEER vehicles while motorcycles tend to be OVER-STEER vehicles. In a car where the engine and transmission are both in the front you see an extreme example of this. Motorcycles, with the rider in place, tend to have more weight on the rear tire than the front and that is substantially increased when you add a passenger.

Let us diagram again, this time using 15 degrees for the drift angle of one of the tires while the other remains at 10 degrees.

To see the effect of under-steering (a greater drift angle in the front), look at this diagram:

While over-steering (a greater drift angle in the rear) is diagrammed here:

From the last two diagrams you see that an under-steering vehicle goes WIDE in a turn while an over-steering vehicle cuts a tighter turn. One more thing that is not shown but you should be aware of is that if you take a turn too fast (beyond its critical speed) in an under-steering vehicle, the front tire(s) lose traction first while, because most motorcycles are over-steering vehicles, their rear tires lose traction first.

This is all VERY GOOD news, actually. From a 'feel' point of view, your motorcycle handles with a positive feedback - confirming that you are making the turn as you desire while a vehicle with under-steer characteristics feels less than 'sure-footed' - like it is not quite doing what you ask of it.

Any questions?

Copyright 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)
]]>Tips 241-260 - 246: You should *NOT* ride at your skill levelJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=9300Tips 241-260 Mon, 22 Dec 2008 09:42:10 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=9300 You should *NOT* ride at your skill level
(Always have an 'escape path')

By: James R. Davis

Huh?

A fundamental concept for newbies as well as experienced riders is that you should ALWAYS have an escape path while riding a motorcycle. I can think of nobody who would argue with that bit of wisdom. Yet there are far too many injuries and deaths that result from failing to understand that very concept.

It is a little bit like being advice that is too obvious to be taken seriously. Advice like "Look where you want to go" or "If you look at that pothole you are approaching, you will hit it" involves UNDERSTANDING the essence of target fixation before they have attention getting meaning to the listener.

Similarly, advice like "Ride your own ride" requires that you UNDERSTAND that some riders have better skills than you do at a particular task so that if you follow the herd there WILL be times (tasks) that you will confront that are beyond your abilities. Unless you have a background, and temperament, that allows you to see a 'bigger picture', the advice is trivial and easily ignored - meaning that it has no value for you.

So let's get back to the theme of this message.

You have practiced and developed a certain skill level at all the common tasks required of you while riding. You can, for example, confidently and smoothly handle a given curve in the road at, say, 55 MPH without dragging a peg or losing traction. My advice to you is that you should *NOT* ride that curve at 55 MPH. Simple advice but you seem unwilling to accept it, yet.

You need that experience (background) and temperament going for you before you can UNDERSTAND it and allow yourself to be persuaded to accept the advice as meaningful.

When you ride your motorcycle you are OFTEN confronted with the unexpected. Riding would be boring if it were not for those moments. You have come to believe that you can handle virtually anything in the way of 'unexpected' because you have, so far, successfully managed to do so. Your reflexes are quick, your judgement is sound, you tend not to panic, and both you and your motorcycle are 'healthy'. But sooner or later an 'unexpected' will occur that is slightly (or grossly) beyond your abilities to deal with. Then what?

We will go back to that skill you demonstrably have: the ability to handle a particular curve at 55 MPH. At 60 MPH you will have dragged a peg or lost traction. *YOUR* skill level at that particular task is 55 MPH. So what do you do if it turns out that for one reason or another you find yourself moving at 60 MPH in that curve, or that what looked like a 55 MPH curve to you turns out to be ever so slightly tighter than you thought? What happens, of course, is that you find yourself forced outside of your skill range.

And now you find yourself dragging a peg. Catastrophe? Not at all, so long as you can change the lean angle of your BIKE. You could, for example, simply lean your body (not the bike) deeper into that curve and the result of that behavior is that your bike's lean angle will diminish and your peg will no longer be dragging. A pucker moment that safely passes because you HAD SOMETHING IN RESERVE - an ESCAPE PATH (or RECOVERY TECHNIQUE).

We are almost there, dear reader.

So far we have discussed skill levels as if they were limits - beyond which you CANNOT safely continue. And I want you now to consider that if you ride *AT* your skill levels you are always at a threshold of loss of control. Such behavior is simply not the way to maximize your odds of escaping your experience without injury or death - because there WILL BE an 'unexpected' event in your future that pushes you beyond your limits.

Again, let's go back to that curve. We know that if we drag a peg we can almost always recover by simply leaning our bodies into the turn. So, from a skill level point of view, why not make it a practice of ALWAYS leaning our bodies into our turns? In that way we have increased our skill level (say, for example, to 60 MPH on that particular curve). But what we have simultaneously done is removed the escape path - the recovery technique - from our tool bag. And now when that 'unexpected' occurs, we have nowhere to go but DOWN!

It makes far more sense to NOT ride *AT* your skill level and to always keep a little bit of reserve. Call that 'defensive riding', 'having an escape path', 'having a recovery technique in your tool bag', or 'maintaining a reserve' - I don't care at all, but if you ride *AT* your limits you can call it 'eating the pavement'.

[It should be clear that stunters and racers often ride at their skill limits. I do not write safety articles for them. Instead, I write these articles for people who do not want to EVER experience an injury or death because of riding their motorcycles.]

Copyright 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)

]]>Tips 241-260 - 245: You got your endorsement. Now what?James R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=9258Tips 241-260 Thu, 11 Dec 2008 14:01:17 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=9258 You got your endorsement.
Now what?

By: James R. Davis

First, welcome to the 'family'!

You have taken the first rational step and gotten yourself trained and licenced, but now you wonder what you should do next to advance your skills to the point of being able to ride in traffic and on the highways.

First bit of advice from me - start practicing in an open parking lot.

You see, the problem you have now is that you are riding with insufficient experience and insufficient CONFIDENCE borne of practice (that experience I first mentioned). You need to spend a good deal of time EARNING that confidence and developing skills on a parking lot.

I know ... what you really want to do is go out there and learn to handle that traffic and highway speeds - neither of which are accomplished in a parking lot - so you are about to stop reading and look for more 'advanced' advice. That could cost you your life.

Let's talk about what kind of skills you really need to focus on now, and before we do that, let's talk turkey.

It takes ZERO skill and ZERO balance to ride a motorcycle at speed. Once you have attained a speed of, say, 30 MPH, all you as the rider can do to affect your motorcycle is to change its path of travel (steering) and to change its speed. Lean angles, for example, are dialed in automatically for you by the bike - NOT YOU!

Where balance and skill comes into to play is at slow speeds. And THAT is why you practice - to gain experience at the HARD PART of riding a motorcycle.

No matter how big or heavy a motorcycle is, while it is moving on its wheels instead of on its side, ALL of that weight is on its tires - not you or your feet or ankles, etc. YOUR JOB IS MERELY TO INSURE THAT IT REMAINS TOTALLY ON ITS TIRES. That means that you need to practice keeping the bike VERTICAL when it is stopped! (Which involves GETTING IT TO BE VERTICAL as it gets close to being stopped!!!)

The 'feel' you need to experience and develop is that of CENTRIFUGAL FORCE. You need to experience making turns and feeling how your body remains sitting in the saddle with 'weight' directly in-line with the bike - that is, that in a turn you do NOT, unlike in a car, feel like you are being forced to slide off your saddle. That 'feel' is the secret of balance. Once you become convinced that no matter what lean angle your bike has dialed in for you, that the weight of that bike, including yourself, is still being carried by the tires and that, THEREFORE, the bike CANNOT FALL DOWN SO LONG AS THOSE TIRES DON"T LOSE TRACTION. Then you will be able to focus on developing the more subtle skills such as picking your line through a turn or selecting proper following distances or deciding to avoid behaviors that you should avoid, for whatever reason, despite the rest of the biker community inviting you to follow them. That is called riding your own ride.

To go back to the earlier point about slow speed control. Because your job is to keep the weight of the bike on its tires, which means that you must manage the lean angle at slow speeds, parking lot practice, for you, should consist of starting, stopping, turning and speed adjustments while in turns! Keep your fingers OFF the front brake lever at slow speeds! Practice getting the bike vertical before you stop. Practice 'playing with' the friction zone so that the clutch lever is not viewed by you as simply a switch that is either engaged or disengaged - it is a vernier adjustment device and you should practice using it to manage your speed (at slow speeds) instead of your brakes.

And sooner rather than later you will suddenly wake up to the fact that *YOU* are controlling your bike and are not simply reacting to what it does *TO* you because CONTROL is just that - making the bike do what you want it to do and KNOWING with absolute certainty that it can do what you ask of it, and what its limits are.

The traffic and highways will be there when you are ready for them.

Copyright 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 241-260 - 244: Lower Gear or Brakes on a Downhill or Turn?James R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=9025Tips 241-260 Wed, 22 Oct 2008 10:02:02 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=9025 Lower Gear or Brakes?
(On a Downhill or Turns)

By: James R. Davis

An interesting everyday kind of question was asked recently:

quote:
If you have a long, descending, curving highway merge ramp, do you use a lower gear to provide some engine braking if you have to let off the throttle, or do you use a higher gear and use your brakes in the curve if you encounter slower traffic, trucks, etc.?

Most experienced riders will virtually always opt to use a lower gear whenever they are about to enter an off ramp or when dealing with a meaningfully sharp turn. This affords then the best responsiveness (acceleration as well as engine braking) potential possible to deal with the unexpected.

But the question was really more about brakes than about gearing.

On a long downhill you want to use engine braking whenever possible for two reasons:

To prevent premature brake wear
To prevent temporary overheating of those brakes

If you do mostly touring (long distance, and therefor high-speed highway riding), you should have little concern about premature brake wear as you use your brakes infrequently compared to miles travelled.

On the other hand, temporary overheating is a major concern from a safety point of view.

Your brakes work by converting kinetic energy (movement) to heat. In the process the brakes can get VERY HOT as they can only dissipate that heat at a modest rate. When brakes overheat they lose efficiency. In other words, it takes more braking effort for hot brakes to scrub a given amount of speed than it does for cooler brakes.

Further, if that overheating gets severe enough it will no longer be a temporary loss of efficiency as they can bake and glaze into surfaces that are permanently less efficient at doing their job.

Copyright 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 241-260 - 243: Lock-step Synchrony is Bad FormJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=8777Tips 241-260 Wed, 10 Sep 2008 11:07:12 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=8777 Lock-Step Synchrony is Bad Form
(Be a traffic shock absorber)

By: James R. Davis

With a great deal of attention being paid to various hurricanes in the gulf area over the past couple of weeks I have been thinking about evacuation problems and, of course, what we might learn from them as motorcyclists.

It seems a stretch, I know, but there really is some relevance. Consider, for example, the danger to you of a rear-ender - not just the cell-phone talker who fails to realize that traffic is stopping ahead, but the every-day Joe who happens to accelerate just as traffic begins to slow down. If you are the vehicle ahead of him, you are the most likely to get hurt.

So it seems to me that driving in lock-step synchrony with traffic ahead of you just might be a significant CAUSE of problems behind you, and that, in turn, becomes YOUR problem.

Let me explain. Traffic around you, ahead and behind, are moving at 45 mph. You have a 2-second gap between you and the vehicle ahead of you. That vehicle, for whatever reason, begins to decelerate. So, too, should you, of course. In the process you will find that your gap is somewhat less than it was because it took you a moment to realize and then react to the slowing car ahead. Just how much shorter a gap should you allow?

The answer, as we all know, is still 2-seconds worth. Well, I'm not quite so sure of that. It may well be that you want to allow that gap to narrow just a bit more than 2-second's worth. Why? Because that leading vehicle may well reverse the deceleration trend and regain its original speed - the slow down was an anomoly, a slight variance that quickly disappears.

If you allow that gap to get a bit smaller, that means that you did not slow down as much as did the vehicle ahead of you - and NEITHER DID ALL THE VEHICLES BEHIND YOU.

What you have done is smooth out the flow of vehicles. Maybe a dozen, maybe a hundred, vehicles behind you did not slow as much as the vehicle ahead of you, and potentially THOUSANDS of following vehicles didn't have to slow down at all.

Naturally I do not mean to imply that you place yourselve into a dangerous situation and ignore the fact that your gap is getting shorter. Not at all! But because you are then aware of the slowing down you no longer have a built-in delay of any meaningful duration that will get in the way of your reacting to what the vehicle ahead of you does next. If it decides to stop, so will you. If it continues to decelerate as it had been doing, so will you. It's just that you did not remain in lock-step synchrony with that leading car's behavior and as a result, neither did all the vehicles behind you.

When the vehicle ahead of you begins to accerate, so should you - but NOT AS QUICKLY! Allow your gap to get wider than you would normally want and close it up, later, when traffic is moving smoothly again.

In essence, if you refuse to behave in lock-step synchrony with traffic ahead of you, you have introduced a shock absorber into the flow of traffic. The more drivers who act like you do, that is, the more shock absorbers there are in the system, the smoother will be traffic flow for all and that translates into fewer - BY FAR - rear-enders.

So I made a case for vehicles that are all moving at about the same speed, but the biggest payoff of this methodology is when they are moving (or not) at vastly different speeds.

Consider driving on surface streets and you notice that traffic ahead of you has stopped for a red light. I suggest that you begin slowing down LONG before you get up close to the vehicle ahead of you (and then MUST stop yourself) and GRADUALLY approach that vehicle as you eat up time. In some (often many) cases you will find that the light has turned green and vehicles ahead of you have begun to move before you have had to stop yourself so that you then merely continue on your way accelerating as necessary to regain or attain a 2-second gap.

Again you have acted as a shock absorber. Again all the traffic behind you has smoothed out. And again your odds of being rear-ended has been diminished by your actions.

Lest it has not occurred to you, this is a specific recommended behavior for you when group riding!

(I hasten to add that your gasoline mileage has improved and your brake pads will last longer.)

Copyright 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 241-260 - 242: Controlling your Rear Brake in an EmergencyJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=8610Tips 241-260 Thu, 21 Aug 2008 11:33:28 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=8610 Controlling your Rear Brake
In an Emergency

By: James R. Davis

I have maintained that the most dangerous control on your motorcycle is your rear brake lever. That, because it is so easy to misuse in an emergency - to use it in an overly aggressive manner - and cause a rear wheel lock, skid, and possibly even a high-side. Even the most skillful rider, in a panic, can stomp on that pedal.

If you agree with me, then perhaps you would be interested in a braking technique that I personally employ and that has prevented me from making serious mistakes in some pretty dicey situations.

Like most of you, when I emergency brake I always use both front and rear brakes.

I think we all understand the need to squeeze hard, then harder, then harder still when emergency braking with the front brake.

Since the rear brake is so dangerous, in my opinion, it takes a bit of counter effort to make it work properly for me. That is, I begin by applying a reasonable amount of rear brake pedal pressure (when the rear brake can handle it because weight transfer has not yet happened), then I moderate that pedal pressure by EXTENDING my calf muscles. That causes my entire foot to rotate (effectively raising the toes but it feels like pushing your heel down) - note that I do NOT mean simply raising the toes!

In order to press harder on the rear brake pedal while extending the calf muscles I have to literally push down with my upper leg muscles and cause my KNEE to go down - a very hard task, indeed, and one that takes a very deliberate effort. And, recall that you do NOT want to increase rear brake pedal pressure after the initial reasonable pressure - instead, you want to MODERATE (make less of) that pressure so that you do not lock the rear brake as weight transfer is occurring.

The extending of the calf muscle feels like you are trying to release the brake pressure entirely, but ANY movement of your knee towards the brake pedal offsets that release. And so the net feeling is of conflict! You feel like you are fighting yourself - and the rear brake pedal - which is just fine as far as I'm concerned because that is exactly what I want to happen. I want to fight my urge to jump on that pedal in an emergency.

Now most of you are thinking to yourself, "But in an emergency I do what I have practiced. I don't think about new/different techniques in an emergency situation. So how likely is it that I would be able to adopt this new technique when panic strikes?"

Here's the shocker, folks: I ALWAYS do this when applying the rear brake. Despite what I earlier said about beginning by applying modest braking pressure, in fact, I ALWAYS BEGIN using the rear brake by pushing my heel into the floorboard/peg and THEN adjust the amount of pressure I put on the pedal. In other words, that is the technique I ALWAYS use with the rear brake, not just in an emergency. Muscle memory works, just as you thought it does. With practice this becomes THE way you use the rear brake.

Note, too, that I have adjusted the rear brake pedal such that I need to make a deliberate effort to cause any rear brake action. I do not want the mere fact that my toes are resting on the brake pedal to be causing some braking action.

Copyright 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 241-260 - 241: Friction ZoneJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=8432Tips 241-260 Sun, 03 Aug 2008 07:11:48 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=8432 Friction Zone
You must MASTER this control!

By: James R. Davis

The friction zone is that part of the clutch lever travel from where the clutch just starts to engage until it is fully engaged. In the picture below it is the range between 3 and 4.

If you constantly stall or have awkward/erratic (jumpy) starts when you operate the clutch lever then the problem is that you are releasing the clutch lever too quickly - more to the point, you are failing to hesitate while in the friction zone (between 3 and 4 in the diagram) as the engine speed and rear wheel speed synchronize before easing that lever all the way out.

Phrases like "release the clutch lever" or "ease out the clutch" do NOT mean that you are to release that clutch lever all the way out! I know, somebody should have told you that when you were learning to ride, but they didn't.

Those phrases really meant that you were to ease out the clutch lever UNTIL you reach the friction zone and then you are to HESITATE there until the engine and the rear wheel speeds synchronize. THEN, you ease the clutch lever all the way out.

If you are starting from a dead stop this is particularly important as the rear wheel is turning at zero rpm while the engine is turning at more than 1,000 rpm.

Nothing that you can do with the clutch lever while it is outside of the 3-4 range makes any difference whatever to the motorcycle. You can move it quickly or slowly, in small or large increments, and the clutch lever outside of the range of 3-4 does nothing.

So it makes sense for you to become INTIMATELY familiar with that zone. As the clutch lever can save your life, can get you OUT of most control problems with your motorcycle, you MUST MASTER its usage before you begin testing your skills with any other motorcycle control.

Copyright 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 221-240 - 240: Control is an Optical Illusion ...James R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=7429Tips 221-240 Mon, 05 May 2008 11:53:17 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=7429 Control is an Optical Illusion ...
Without Experience

By: James R. Davis

For those of you who are new to riding and have managed to successfully acquire a few months and perhaps a couple of thousand miles of experience, you have probably wondered just how much more you need before you can get a newer, bigger, bike. My advice: back off.

You are essentially a newbie. MANY new riders are offended when they are described as newbies.

Wrong attitude.

Newbie simply means that you have yet to experience MOST of the events and incidents from which you WILL learn how to control your motorcycle, and yourself. Therefore, a newbie is a rider who is untested and is easily found to be riding over his head because he doesn't, yet, know better. He is quite likely to THINK that he knows what he is doing because he is 'still standing' when, in fact, he is delusional as to his knowledge base - without experience that knowledge base is purely theoretical. (These people are quick to offer advice to other new riders as they honestly want to help but that advice often turns out to be absolutely wrong, or is so nuanced -- unbeknown to the person giving that advice - that it turns out to be dangerous to the recipient.)

How does a newbie cease to be a newbie?

He/she experiences riding and most of those incidents - and survives.

When a brand new rider goes out on the street for the first time he is usually rather frightened. GOOD! There are lots of reasons to be terrified out there. Besides having to spend precious mental energy and time dealing with the fundamentals - most of which are NOT, yet, learned beyond superficially - they must re-learn the behaviors of the drivers of other vehicles because those behaviors are NOT the same as they used to be when confronted as a driver of a big, easily visible, automobile. And, after much getting used to those new behaviors and having developed a new regard for defensive riding, the new rider begins to experience some of those incidents from which he matures his skills and confidence.

But it takes NO SKILL, whatever, to ride a motorcycle at highway speeds. NONE. You are along for the ride. The bike steers a straight line all by itself. The bike does not fall down by itself. The engine will keep running without a second thought on your part.

Which means that unless you are confronted by one of those incidents (say, a car in front of you that does a panic stop), you are not developing responses and skills that you will sooner or later need.

And in a short time frame of, say, 6 months, you will not have developed tried and true responses and skills sufficient to assure yourself that WHATEVER HAPPENS, whatever the environment throws at you, no matter how the bike behaves itself, or doesn't, you will respond appropriately and survive the experience.

In short, you will, with limited experience, come to believe that because you haven't died yet, you must be pretty good with your machine and come to believe that you are 'always (or pretty much) in control' of the bike. And that leads you to think about maybe getting a larger bike.

Those incidents cannot be 'practiced for' without having had similar incidents behind you. This time it is having to deal with some water on the roadway. Next time it will be having to cross a low-water bridge with standing water on it, invisible sludge at the bottom. The time after that it will be 36 degrees out there and that water will not look like it's frozen. Then you will find yourself 50 miles from home when it starts to hail. That stops and the ground seems to dry up, but in a curve you ride over some leaves and your rear-end squirts to the side a bit.

Believe me, those incidents happen almost every ride. And after a year or two you will have overcome most of them. After 40 years of riding I found myself carrying a passenger (Cash) in the fast lane of a freeway going about 70 mph when a LARGE cardboard box presented itself in my lane! I tried to swerve around it but that box just blew into my new line of travel. I was going to hit it, no doubt about it. EXPERIENCE told me 'NO BRAKES!!!!!' so I squeezed just the clutch lever, hit the box and rolled over it without incident instead of ending up eating asphalt.

As to a new, larger bike ... you will be starting all over again! FROM THE BEGINNING! Or you will have to find out that controlling the motorcycle is only part of the drill. You also have to learn how to control yourself.

Slow down in your quest for having 'arrived' as a motorcyclist. Treat being a newbie as a learning experience that everybody goes through and only some actually appreciate. Do it right and you will cease to be a newbie some time in the future - at least most of the time that you ride.

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 221-240 - 239: Just Do It!James R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=7195Tips 221-240 Sat, 12 Apr 2008 09:03:15 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=7195 Just Do It!
ALL riders have those moments of doubt

By: James R. Davis

I was reflecting on an experience I had during my first MSF class (nearly 20 years ago) and remembered something that made a real difference for me - a time when I was not at all convinced that my (unfamiliar bike) would safely make an abrupt 90 degree turn at slow speed without dumping me to the ground.

As a long term rider I didn't REALLY believe that the bike couldn't make it, it was something far more subtle than that. I was convinced that *I* couldn't make it. I mean, with HUNDREDS OF THOUSANDS of miles of riding behind me before I got to the class, those miles were virtually all at highway speeds. Certainly at counter-steering speeds. I had been guilty of duck-walking my bike at very slow speeds as I turned the bike into a parking space, for example, and hadn't given it a moments thought as it seemed like a perfectly rational way to handle the bike at very slow speeds.

Then I attended this class (of beginners) and I thought, "this is going to be boring!", yet I wanted to learn whatever there was to learn by being there. So one of the earliest exercises they had us do was to make a sharp left or right turn through a set of right angled lines with our feet to remain on the pegs.

And, to my surprise, all of the newbies seemed to manage the exercise without any trouble (I figured they simply didn't know that they couldn't easily do that!)

Then it was my turn. I approached the first turn at the right speed and began to turn the handlebars. But, of course, the bike seemed sluggish and possibly 'fighting me'. I was going to go wide on my first effort! And that was when the Eureka! moment occurred.

I figured I could handle a slow speed drop if it came to that, but I'd be damned if I was going to demonstrate that I couldn't make a simple slow speed turn like the rest of them. So at that point I merely said to myself, "JUST DO IT!" (I confess, I actually used a two word expletive) and I turned the handlebars aggressively IN THE DIRECTION I WANTED TO GO (and prepared for the fall) - and damn if the bike didn't do exactly what I'd told it to do and make that turn just like everybody else.

It was then that I realized that the bike wasn't fighting me, I had been fighting myself. I had let personal doubt get in the way of controlling the bike. And that was when I decided that I needed to get control of MYSELF as well as the bike in order to ride it safely.

And for 20 years that has remained my mantra - get control, and keep it!

But there was that other lesson, wasn't there? If there comes a time when you KNOW the bike can do something but you are not at all sure that you can, then it may well be time to simply say "Just do it!" to yourself and prepare for the worst. And be surprised far more often than not, that the worst was purely in your head. Soon thereafter you will have gained a new skill or at least gotten over a mental block.

Don't be surprised if you get in the habit of continuing to say that to yourself every time the same situation presents itself. There was a mental block for some reason and all you are doing is overcoming it.

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 221-240 - 238: Mental ModelsJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=7082Tips 221-240 Thu, 27 Mar 2008 13:06:58 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=7082 Mental Models
The 'Close To Home' one needs to be built

By: James R. Davis

In virtually all of the other safety articles I have written you will note that I have focused on some aspect of controlling the motorcycle or its dynamics. Though this articles may seem to you to not fit that mold, I invite you to reconsider because when I talk of control I include controlling yourself.

Putting your mind into the right 'gear set' is a fundamentally important part of safe riding.

When you are riding local streets you must scan for potential threats coming at you from your side. You must consider the possibility that someone will run a stop light or sign at an intersection. You must allow for the possibility of pedestrian or domestic animals entering the roadway ahead of you or from in front of the parked car you are about to pass. You need to consider such things as cars backing out of driveways, how long a light ahead of you has been green (is it 'stale'), whether or not it is a school day and what time of day it is in order to recognize whether or not you are traveling too fast for a school zone. And you need to evaluate each and every left and right turn you are going to make for road surface quality and obstructions, proper speed, traffic signs, proper sight lines, and the often unpredictable driving behavior of others as you 'negotiate' right-of-way. You can also expect to have to make an occasional start or stop on a steep hill. In other words, you must adopt a mental model of your environment that is specifically designed to best let you deal with situational awareness issues. Call that your 'local streets model'.

An obviously contrasting model needs to be activated the moment you enter a freeway and begin riding at highway speeds. Now you need to consider erratic lane-changing behavior, on- and off-ramp merging threats, the possibility of having to make an emergency stop or rapid slowdown from high speed, tailgating drivers talking on cell-phones, and lane selection strategies to position yourself properly for upcoming road changes or exits. But you need not spend much effort or attention looking for pedestrians or domestic animals, or people pulling out of driveways, and you do not have to deal with 90 degree right or left turns and stop lights or oncoming traffic with left turn signals. In other words, you need to adopt a very different mental model in order to deal with the realities you will be confronted with on those freeways. Call this model your 'freeway model'.

My guess is that you can see where this is going. When you are riding on country roads you will need to switch mental maps to one that includes an awareness of the need to watch out for deer, or slow moving tractors, or poor pavement, or cars that have pulled off the road ahead of you who decide to make a U-turn just as you approach them. You need to have adopted the 'country road model' in your mind or those threats are not anticipated properly.

Riding in the dark requires a variation of each of those mental models just as riding in the rain requires yet other variations.

What is common to all of the models is that they are selected based on known threat potentials. That is, you use them to increase your odds in dealing with the threats that tend to be unique to the situation you place yourself into. And with experience you don't even have to decide which model to use - when your engine speed changes from one pattern to another, your subconscious switches those models for you appropriately. That is one reason you seek experience - call it practice.

But my riding partner, Cash, alerted me to one mental model that I had not realized we both have and which I had not thought of until she did so. Call it the 'close to home model'. This one is NOT automatically activated unless you are aware of it.

You see, statistics are very clear about this - most motorcycle accidents occur relatively close to home. And whether you go out on a hundred mile ride, or a two thousand mile tour, or a fifty mile day ride, before you get home you must get 'close to home' first.

And when you do you are more tired, more fatigued, than when you left. You probably have encountered and dealt with half a dozen 'close calls' or instances of crazy driver behavior or any of the other threats mentioned above, and survived them. And now the road is familiar and you have a tendency to unwind and settle into the familiar. And that leads to making mistakes when the unexpected happens.

Cash tells me that whenever she gets within five miles of home she switches her mental gears and perspectives. She convinces herself that she has "only FIFTY MILES to go" instead of "only FIVE MILES to go" in order to remind herself and enable the right mental model to remain vigilant, because like all of us, she knows that she cannot enjoy tomorrow's ride if she doesn't survive today's ride.

Build your mental models with experience, shift them as often as your situation changes, and create and use a "Close to home model".

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 221-240 - 237: Witnesses are GoldenCash Anthonyhttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=7033Tips 221-240 Fri, 21 Mar 2008 09:50:21 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=7033 Witnesses are Golden
Especially if they're reliable

By: Cash anthony

Let's say that you observe an accident occur, or you are one of the first on scene after the fact. You wish to help, but someone else is attending to the victim(s) and directing traffic around the scene. A policeman arrives and takes over. What then?

You may be able to gather valuable information as a witness that should be reported or conveyed to the people involved, either now or later. Either way, you can take steps now to make sure it's useful and reliable. Eye-witness accounts of sudden events can be confused, strange sights can be over-emphasized, details can be forgotten by the parties involved. But your particular information may be just what's needed to sort it all out.

For various reasons, a law enforcement officer on the scene may not seem to want your report or will be too busy to take down the details. If this is the case, you should consider coming forward later. That is, if you want to accept the benefits of living in a civilized world and consider yourself a decent human being, then you should also take steps to notice, record and offer information that would help establish what happened, before you leave the scene. You can track down the person to give it to, afterwards.

Even if you are shocked and upset, you can probably remember to get at least some of what will help out later. It seems to be the natural response these days to pull out a cell phone and take a picture, and in many cases, that's a great response.

If nothing else, even without a camera phone, you can call your own number on your cell phone (repeatedly if necessary) and dictate a message to yourself with the information. You can tell what you saw of the event ("The red car ran the light"), what other people are saying, what's the most likely way it happened. You can note what the police are saying, and who they are (for instance, in Houston we have something like 36 different police organizations that could respond).

This kind of 'on the spot reporting' may end up being critical information later, and it can help a terribly injured person end up with enough resources to live out a much better life. Or it can prevent an innocent person from being burdened with the cost of supporting someone for life who actually was the person at fault.

A person who is willing to record his or her immediate perceptions of an accident is absolutely golden, in terms of the search for truth.

So, if you are a witness, I would urge you to get as much of this as you can:

The official accident report number
The names, agency and officer numbers of the investigating police

The names of the drivers involved (and any other pertinent info you can gather about the vehicles: License plate numbers, make, model, year of the cars/bikes/trucks, general description of damage, cell phone photos of cars, drivers, and environment)

Exact record (others talk into your phone) or your best recollection of what the persons involved say

Exact names of roads, address numbers and landmarks where the accident occurred

Time of day when you made your observations - give time and also give a reference (I arrived at 10:12 and I saw the accident, I arrived at 10:12 and it looked to be seconds afterwards, the vehicles were still steaming and no one was moving, etc., I came on the scene well after the police)

A general description of what you saw and what you think, using your common sense, probably happened. Try to keep a calm attitude, and don't let your emotions dictate who was right or wrong.

After the immediate needs of the injured or affected persons are dealt with, a witness who has recorded this info will be able to track down the names and contact information of the parties. If you have enough of those facts and come forward, you may literally save someone's life after the accident.

You don't know how? Well, do you have any idea what happens to people who have to come back from life-threatening injuries, or situations that cause permanent loss of function, without money for treatment? Do you know how many give up if they have no one to help them get what they deserve for long-term care? People really do 'get away with murder,' even though they didn't intend that to be the result of their carelessness. They didn't think, and no one saw -- or admitted they did.

Even if the police do not seem to want your statement, there's no doubt that one or both of the parties involved will see you as a real resource later, no matter "which side" your facts appear to be support. A fast settlement or an end to false hopes is better than dragging an impossible case out.

You will also provide an invaluable service to those who are trying to figure out exactly what happened for safety reasons, and what would help prevent another such incident. That's a lot of incentive to come forward and say what you saw, I believe.

I don't think there's a lot of legitimacy in ducking out and avoiding the small commitment of time that it takes to be a witness, assuming that you are in a position to stop and have decided your own safety won't be threatened if you do. Fewer than 20% of court cases actually go to trial, so the most a witness usually has to do is to make a couple of telephone calls, or to answer some questions at an appointed time and place (not in court).

I think most of us, if we put ourselves in the position of someone who has been hurt in an accident, would be extremely grateful to someone who comes forward.

It may not be 'heroic' -- some people may just expect it, without realizing that it can require courage (and human nature sometimes disappoints) -- but it really is the decent thing to do. If you can't save a life, you can still make the aftermath of an accident much more fair, and perhaps you will have insights that will cause a change of environment or conditions which could save many more lives later on.

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org
]]>Tips 221-240 - 236: Gods or Demons?Cash Anthonyhttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=6878Tips 221-240 Tue, 26 Feb 2008 19:51:45 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=6878 Gods or Demons?
Which voices should you pay attention to?

By: Cash Anthony

When a rider is new at the sport of motorcycling, advice seems to come from all directions. It comes in overwhelming quantity and detail about subjects the newbie never heard of, concerning problems he can’t even imagine yet.

He or she may have a friend or family member who once owned a motorcycle and who decides to be the authority, or the rider may join a club to find other riders whose advice is reliable. But is it?

And like other information in today’s complex world, it’s easy to reach a point where you want to put your hands over your ears and shout, “Stop! Information overload!”

From the point of view of someone who has had to learn to expand her point of view to include far more technical and engineering-related knowledge than she ever dreamed, this problem is one of the best reasons to take a structured training course right off the bat. You will get information in tiny units and overall, only a limited amount (in the big picture), but it will come in fairly manageable chunks.

In structured training programs, you have people who have watched many, many riders learn to operate a motorcycle under their supervision, and they’ve been trained to coach beginners through the basics. If you don’t understand something at that basic level, you can indeed call for a time-out and ask for clarification. And you have a live human being there who should be able to answer your question and give you at least a brief explanation, enough to get you through the immediate situation or to help you figure out to improve that skill because they have watched you personally, knowing what to look for.

After that basic instruction, most riders are on their own. This is when a rider’s judgment and purpose for taking up motorcycling comes into play: after basic training, who do you listen to? Is it possible to find a good mentor? Must you learn everything else by yourself?

If you want to learn more about your particular bike and others of its marque, you’ll probably seek out a brand-related club and go to a few meetings. Some of these meetings may not be your cup of tea, offering nothing about what you want to learn and a social setting that is not friendly or comfortable for you.

But some clubs are full of sharp people with a great deal of experience on the very bike you ride, and you would do well to listen to their stories if they have had problems in common. (“With that model, your bike will turn over but it won’t start. And you may get a big boom when the ignition boot blows off. Expect it several times a month – just put it back on.”) And they can show you how, or tell you who to call.

If you bought your bike to commute, you'll pre-drive the route for your daily travel a time or two in your car, looking with ‘new eyes’ at signs, signals, road conditions and traffic threats, before your first ride to work on your motorcycle. Then you’ll talk to other riders at your office about commuting: where to park, what to do with your bike in bad weather, protective gear you can wear over a suit.

If you just want to ride around town with a few buddies on the weekend, your route may be undetermined, but you know at the end of the trip, you plan to hang with your friends and kick tires. You’ll definitely get advice from them, but can you believe it? How much of it?

Maybe you ought to take a good look at those buddies with the same ‘new eyes’ and listen to them with ‘new ears’ before you ride off with them. There’s a lot of foolishness out there. A guy you admire, one who looks like a Motorcycle God today, may lose his luster when you take a closer, more rational look.

Are your riding buddies relatives or old friends? Are you prone to try to one-up them, to impress them, to compete under any condition or situation, whenever one of them throws a dare? Do you think they’re experts because they’ve been riding a few years, or because they ride a bigger bike than yours? Do you tend to listen to the guy who has the biggest mouth, because everyone else does?

“It’s easier just to go along with him -- nobody wants to get in his face,” or “He’s not as good as he thinks, but nobody wants to hurt his feelings. Just ride your own ride. But keep your head up around him on the road!” I’ve heard those very comments about members of groups I used to ride with, and I’ve observed some riders with nasty tempers, even old brain injuries, and on lots of drugs. People notice, but people don’t always act as if they did. Will you have the presence of mind to say “No thanks, I’ll ride alone” when you find yourself on the road with one of these people who claims to know it all? In other words, will you “question authority”?

Wear a helmet? “Nobody else in the group does, it’s proven to be more dangerous than riding without one.” Wear long sleeves, even leathers, on a hot day? “My brother said he got a heat stroke riding in leather. Man, take it off!” Er, okay. A group of peers can sound like authorities if you forget to be skeptical.

In “Predictably Irrational: The Hidden Forces that Shape Our Decisions,” Dan Ariely, an MIT professor, discusses why people do irrational things (like take a dare or listen to stupid advice or ignore warning signs in other people). Human beings make decisions against their own self-interest every day, and it’s very hard to convince them to do otherwise once it becomes a habit of mind. Faced with certain options, they will consistently make the wrong choice, according to Ariely. They will have a rationale, but it’s a devilish one that makes no sense when you really look at it hard, unless you’re willing to accept a certain logic to illogic.

“Our irrational behaviors are neither random nor senseless – they are systematic,” he says. “We all make the same types of mistakes over and over.” We’re so attached to some of them that we can’t even recognize that they are errors, despite the results.

For example, researchers asked people to estimate what proportion of African nations were members of the U.N. This sounds like a pretty neutral test question, right?

They discovered that they could influence the answer those subjects gave just by spinning a “Wheel of Fortune” in front of them to generate a random number. When it was a big number, the estimates were big. Small number, small estimate. How rational a creature is this we’re talking about?

More to the point of acting against self-interest, two Ph.D. students at Duke put together a research project using the school’s passion for basketball. Some fans had won tickets to a Blue Devils game through a lottery. Other fans who had failed to win them were asked the maximum they would pay to buy them from the winners, and the winners were asked the minimum they would accept to give theirs up.

From a rational perspective, both groups should have thought about the opportunity the same way: a few would strike deals with each other. But this wasn’t the case.

The people who had won the tickets were willing to sell them only if they could get, on average, twenty-four hundred dollars. The ones who wanted to buy them were willing to offer only one hundred seventy-five dollars. Not a single ticket holder would sell for a price that a non-ticket holder would pay. One said he wouldn’t sell at any price.

These examples may seem far afield from motorcycle safety, but they show that human beings are programmed to take shortcuts in their thinking at times, and sometimes those shortcuts result in decisions that simply don’t make sense in terms of protecting themselves. The results may be unfortunate because shortcuts don’t work every time.

When you’re a rider, this desire to avoid making an effort can include giving other people authority to influence your behavior -- and change your life. It can mean surrendering your common sense – not listening to your own ‘inner voice’ – or failing to challenge your inner voice when it’s talking nonsense. It can mean developing sloppy habits or making assumptions, even though you’ve been warned not to do that.

We’ve heard from a few riders who read a tip here and then got the opposite advice from a buddy. And sometimes what we’ve heard was, “Boy, did I find out which one of you was right!” after the fact. This may fall in the category of experimenting with two hypotheses, but unless you’re in a controlled environment, those experiments are best taken in tiny, baby steps when you’re involved in a hazardous sport. (If you’re on a closed track, take your best shot, if that’s how you want to teach yourself.)

It seems to me that before you decide to try some stunt that your latest Motorcycle God is doing – or claims to have done -- you might give a thought to the notion that you could have an inner Demon urging you to do something you already know isn’t very smart. If in doubt, STOP! Then bring it to a forum of riders who have demonstrated good judgment and a safety consciousness, like the one you’re trying to acquire.

In the marketplace of ideas and information, it’s finally up to you to decide what to believe. Still, you don’t have to learn everything you need to know by trial-and-error, especially when an error on the road can cost so much. Question authority. Try to gain an understanding of the facts for yourself, and use the collective wisdom of other riders. A forum is a good place to start. If it’s stupid, you’ll probably find out soon enough here.

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org]]>Tips 221-240 - 235: Fastest Possible Right Turn on Public StreetsJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=6858Tips 221-240 Sat, 23 Feb 2008 17:21:34 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=6858 Fastest Possible Right Turn
on Public Streets

By: James R. Davis

Some people wonder why slow-speed parking lot practice exercises are meaningful given that they usually travel at much faster speeds when they are riding their bikes.

Let me share with you an example that might shed some light on this question.

A young man who was relatively inexperienced with motorcycle riding decided to make a 90 degree right turn from one street onto another. He was traveling at a speed substantially in excess of 35 MPH, but he claimed that he was certain that he could 'make it' if he just slowed down to 35 MPH before he gave it a try. Needless to say, he didn't.

So why not? Was it just a matter of skill?

Well, consider these facts:

The width of a standard lane in the United States is approximately 12 feet.
In order to make the fastest turn you must select a path that provides the largest turn radius.
Thus, you will want to carve a path from the outer edge of the approach lane, into as close as possible to the curb as your apex, then out to the outer edge of the new lane.
The largest radius possible is approximately 40 feet in this scenario.
If you don't drag any hard parts of the motorcycle along the way then your limit is determined by the amount of traction available. (on good streets with good tires that could be upwards of .9G's of centrifugal force.)

Here is a diagram to put it all in perspective:

Observe that the fastest possible speed through that turn is about 23 MPH. That is about as fast as you ever go while doing parking lot practice.

In order to make a tighter turn than that you MUST go slower. When you are practicing making U-turns you usually do it at about 10 MPH, no? 35 MPH is FAST! Making that turn at 35 MPH is an impossible task for the most experienced motorcyclist in the world, let alone a newbie.

For those of you who would like to check out other scenarios, here is a model that will do the calculations for you:

Lean angle and speed calculator

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 221-240 - 234: Wide Open Throttle PreventionJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=6818Tips 221-240 Sun, 17 Feb 2008 09:21:51 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=6818 Wide Open Throttle Prevention
Reduce training deaths!

By: James R. Davis

In reviewing the many deaths and near fatalities that have occurred during student training over the past seven years I cannot help but recognize that common to virtually all of them is the phenomenon where the student has cranked his throttle 'wide open' then freezes at the controls as the motorcycle accelerates out of control until it runs into something.

The MSF and others seem to think this is the result of those students having positioned their right hands on the throttle in a 'wrist up' posture such that when they reach for the brake they actually increase their acceleration because the wrist is brought down as their fingers reach for the brake lever.

I am of the opinion that the real problem precedes all of that and would like to explain what I think can be done to dramatically reduce such tragic incidents during student training.

In a totally unfamiliar venue including a training facility, motorcycles, instructors and students, all of which are 'unknowns', students are familiarized with the controls on a motorcycle in a classroom and then on (or near) the range. As to the throttle, they are told to 'make a quarter turn' of it and, later, told to 'turn it all the way' - this, apparently to provide them the experience of the full range of travel available. That is all well and good but it fails to follow through and educate those students about reality and practical limits.

Not having any other frame of reference, these students have just been 'taught' that the normal range of throttle usage is between a 1/4 turn and full turn of that control. Nonsense!

In more than 40 years of riding I cannot remember a single time when I cranked the throttle 'all the way' from a dead stop, and very, very few times when I did so other than gradually - as in when I needed to pass a vehicle with minimum time riding in an oncoming lane.

Furthermore, a 1/4 turn of the throttle has always been a substantial event for me. The VAST MAJORITY of time when I change the throttle in order to change speed it is by using the smallest amount of movement possible. 99+% of the time when riding I am attempting to maintain my speed, regardless of road grade, and the smallest amount of throttle turn possible is more than adequate to do just that.

Surely you have noticed that relatively new riders are the only ones who race their engines as they start out from a dead stop - that is, who crank their throttles far more than necessary in order to increase engine speed as they ease out the clutch. What you noticed is that these people have failed, at least so far, to learn proper friction zone management technique and they rely on a racing engine to give them the confidence they need that their bike won't stall on them during launch. Embarrassment usually tones down their right wrist behavior over time and forces them to learn how to manage their friction zones better if they tend to ride with other bikers.

So, during control familiarization indoctrination it seems entirely reasonable that instructors should point out that 'normal' throttle usage involves making the smallest possible change in throttle position AND TO HAVE THE STUDENTS DEMONSTRATE TO THEMSELVES THAT BEHAVIOR. Indeed, while out on the range on their motorcycles the students should have an exercise which does nothing more than have the students take ONE LAP of the range and purposely change their speeds ONLY ONE MPH UP AND DOWN throughout that lap. (If they have a tachometer on their bike it would be even better to have them change their engine speed, both up and down, by no more than 500 RPM and note that as 'normal' throttle behavior.) They MUST be exposed to NORMAL behavior on the range, in my opinion.

Now when in that class and on the range we have all heard an instructor say, often with nauseating repetition "wrist down"! The students and instructors know that with a wrist up position, if they reach for the brake lever they will automatically INCREASE engine speed. Yet I wonder why it is that nobody has explained to the instructors and those students why they find themselves having to deal with a wrist up position more than once?

Riding with your wrist down is AWKWARD. The proper riding posture is to have the hand level with the forearm - wrist 'neutral'. But the instructors insist that the students are to ride 'wrist down'. So, human beings are fast studies and quickly learn that if they start out wrist down and anticipate that they are going to have to accelerate (bring their wrists even farther 'down'), they preemptively adjust their grip to accommodate that movement. That is, they creep their grips into a more wrist up position in order to be comfortable when they accelerate. Again, the problem is that they have been 'taught' that to accelerate they will 'normally' use between a 1/4 and full throttle crank. If instruction can be modified to accentuate the least possible throttle movement model I propose, then these fast learning students will have far less of a tendency to creep up into wrist high position prior to performing their range exercises.

And that means that when something goes wrong on the range (usually something no more dangerous than a student winding up his engine more than he really wanted to), that mistake will likely be a smaller problem than it would have been had the student been 'wired' from the get-go to use large throttle movements, and in the event that he simply freezes at his controls, his rate of acceleration will be modest instead of 'wide open throttle' aimed at the building next to the range.

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 221-240 - 233: Slow-speed Counter-steering?James R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=6710Tips 221-240 Tue, 29 Jan 2008 10:20:20 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=6710 Slow-speed Counter-steering?
Absolutely NOT!

By: James R. Davis

A series of videos are being run on YouTube that appears to provide very reasonable descriptions of how a motorcycle steers at slow speeds - until you get down to the reality of it.

Here, for example, is one such video. (A YouTube video can disappear at any time.)

Those of you who have read my stuff know that I maintain that the ONLY way to steer a motorcycle at normal riding speeds, indeed at any speed over about 6 MPH, is via counter-steering. I also maintain that the ONLY way to steer a motorcycle going at very slow speeds is via direct steering.

Yet this video makes a very compelling case that counter-steering can be accomplished at very slow speeds. It is wrong.

The fundamental mistake in his presentation is his definition of counter-steering. He maintains that it is the process whereby when you turn the handlebars in one direction the motorcycle will lean in the other direction and therefore move in that other direction. It sounds pretty good, but it is actually a definition crafted to support his contention rather than fact.

The fact is that counter-steering, or direct steering, results in a change of direction, not lean. A change of direction results in a lean, a lean does not result in a change of direction.

The result of that video being watched by members of my board is that several of them became convinced that counter-steering works at any speed and they used that video to 'prove it'.

In fact what that video demonstrates is what some of us call 'the dip maneuver' which is no more, nor less, than direct steering in one direction followed by direct steering in the opposite direction (at very slow speeds) or by counter-steering in one direction followed by counter-steering in the opposite direction at higher speeds.

I constructed some graphics to make this clear. In summary, I challenge the 'counter-steering characterization as follows:

The video is an example of what has been described on my board as doing a 'dip' at slow speed. It is SIMILAR to counter-steering in terms of results, but it is actually direct steering in one direction followed immediately by direct steering in the opposite direction.

It is NOT necessary to do a 'dip' before actually steering at slow speeds while at higher speeds there is nothing optional about steering - you MUST use counter-steering and CANNOT use direct steer.

What a dip does is cause a lean of the bike without you having to lean your body in support of the turn. You can simply turn the handlebars (direct steer) at slow speed to accomplish the same thing as you use your body to maintain bike balance. This is what virtually everybody actually does.

A dip at the start of a slow speed turn provides one valuable advantage over simply direct steering: it allows you to start your turn on a tighter radius. That is, it gets you leaned over sooner in the turn. In essence, it allows you to begin the turn from farther outside of the radius as the dip forces you to track wide to begin with.

There is no argument that centrifugal force exists at very slow speeds - but it is trivial as compared to at normal riding speeds. For that reason while you are making very slow speed turns you CANNOT simply maintain the counter-steer pressure and expect to move in any direction other than that pointed to by the front wheel. The announcer on that video makes it clear that 'doing it wrong' can make the bike fall over. What he means is that if you maintain a 'counter-steer pressure' at very slow speeds, unless you immediately DIRECT STEER in the direction you want to go you will fall down as gravity will have its way with you.

This video demonstrates the dip, not counter-steering, despite what the announcer calls it.

Maybe a picture or two will make 'the dip' more obvious.

Let's say that your motorcycle can, at best, do a 360 degree turn at, say, 10 MPH, that has a 20 foot radius.

You wish to demonstrate the bike's ability (and yours) so you layout the target as shown above with some chalk. It turns out, however, that you find it impossible to keep your wheels inside the chalk marks all the way around the target.

Why is that? Because your bike doesn't change from a straight line into a full tight turn instantly. For some period of time, the transition period, you are carving a decreasing radius turn. The part of the turn shown in red is that transition period.

What that means is that it is IMPOSSIBLE to start the 20 foot radius turn anywhere on the circumference of the circle.

In other words, you MUST start that turn outside the circle some distance.

An alternative is to do 'the dip' from any point on the circumference of the circle.

A member of the board then said he was confused and asked if the dip was actually a steer/steer maneuver then it wasn't really counter-steering at all, was it?

My response: Nope. If it were counter-steering, then you would make ONE steering input to accomplish the turn, not two.

Of potentially more practical interest was a question that wondered why a person had to lean in order to get the bike to lean at very low speeds.

I put a couple of drawings together to give you a better idea of why the bike leans in the direction you turn it at very slow speeds. I am not an artist so these are crude.

Note that while moving in a straight line the front tire's contact patch is at point B.

Then notice what happens to that contact patch when you are in a turn. Here I have exaggerated the turn to a full 90 degrees. Note that the contact patch is now very close to point C' - it has moved forward stretching out the length of the wheelbase. Notice, too, that the front-end of the motorcycle has FALLEN!

So we already know that as we turn the front-end of the motorcycle gets lower - and there is some momentum in that move that helps the bike fall toward the inside of the turn.

What you cannot see easily from the diagrams, but which should be entirely obvious to you, is that the front-end is no longer in-line with the rest of the bike - it is to the inside of the turn. Thus, the CG of the bike has moved toward the inside of the turn. Gravity, assisted by the momentum of the front-end lowering, tries to make the bike fall in that direction.

Thus, the simple act of turning your handlebars to the left (at very slow speeds) results in the bike wanting to fall to the left. That creates a lean angle. Only your body 'language' can then control the fall if you do not change speed.

When the MSF says 'lean' they mean 'turn the handlebars and you will lean'.

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)
]]>Tips 221-240 - 232: Starting from a dead stop on a hillJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=6580Tips 221-240 Sun, 30 Dec 2007 21:30:42 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=6580 Starting from a dead stop on a hill
It's not which brake to use, it's managing the friction zone
By: James R. Davis

Those of us who have been riding for awhile just assume that anybody who rides can start their bikes from a dead stop while they are on an incline - say at a traffic stop. It turns out that many riders have a great deal of trouble handling that situation, even very experienced riders.

Here is the apparent issue: Should you use your front brake or your rear brake to hold your bike in place as you ease out the clutch lever and roll on some throttle?

Now what difference would your choice of brakes make in that situation? Surely either one by itself would hold the bike in place until you got some power to the rear tire, right?

Well, yes, that's true. But take it from the newbies perspective. The MSF has drilled into their heads that they are to have their right foot on the brake and their left foot on the ground when they stop. So, for those people it would seem natural to continue to use the rear brake. But for people like myself, who have learned that a rider of a bike should put BOTH feet on the ground when they stop, the natural action would be to use their front brake.

Still, we have not seen a problem regardless of your choice of brakes, so what is the real issue here?

A new rider on my board recently confessed that he was paranoid that when starting from a dead stop while on an incline he might give the bike too much gas and end up shooting across that intersection much faster than he wants to go, or that traffic would allow.

Some members of the board focused their assistance (advice) on how to use the front brake and throttle at the same time. Others focused their advice on always easing the clutch lever out instead of 'popping' it. But the real problem was that this newbie apparently thought that when he eased the clutch lever out it was supposed to be ALL THE WAY OUT.

Indeed, several months ago I had occasion to spend a little parking lot practice time with a long time Harley Davidson rider who absolutely refused to agree that he should be riding WITHIN his 'friction zone' while doing slow speed maneuvers. His father had taught him to drive/ride and he remembered the advice he received from that man. "Son, your clutch belongs all the way in or all the way out, not in-between, so that you don't wear it out." So this 'idea' that when you ease out your clutch lever you should hesitate and maintain a position within the friction zone just simply failed to register for him as a reasonable way to behave on a bike.

But when you consider the problem of starting your bike from a dead stop while you are on an incline you immediately see why the friction zone is EXACTLY where you should start that ride. You ease the clutch lever out until you just feel power to the rear wheel and increase throttle modestly as you MAINTAIN that clutch lever position (within the friction zone) and ease off your brake(s). When you are certain that you are in control of your motorcycle and it is moving again with your feet up on the pegs, you THEN ease the clutch lever all the way out.

So though the issue at first looked like which brake to use, and how to coordinate the clutch lever and throttle at the same time, it turns out that it really didn't matter which brake you used and that the real issue was how to use the clutch lever. When our newbie heard this advice lights went off - a EUREKA! moment had occurred for him.

I've said it a thousand times before, but it's worth saying again. Low speed control is primarily a function of your left hand. It's called, managing your friction zone.

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 221-240 - 231: Advisory 'SPEED LIMIT' SignsJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=6182Tips 221-240 Wed, 26 Sep 2007 09:32:54 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=6182 Advisory 'SPEED LIMIT' Signs
What they are and what they mean

By: James R. Davis

When a roadway has signage on it that includes the words 'SPEED LIMIT', those signs represent the maximum speed that you may legally drive on that roadway. Despite some lost causes who have tried to argue in court that since it didn't use the word 'Maximum', it could also mean that it was a minimum speed expected, the courts have ruled that these signs represent maximum speed limits.

Did you know that if the words 'SPEED LIMIT' does not appear on those signs then they are NOT speed limits at all? They are known as 'speed advisory signs' and represent the maximum speed at which you are assumed to be able to safely travel on that roadway - that is, with essentially ZERO risk of having an accident caused by that speed. (In other words, as a result of losing traction.)

There may be an exception here or there but in virtually every state across the country you will not be cited for exceeding the speed limit if you are traveling faster than that posted speed unless it is otherwise unsafe to do so (for example: rain, construction, fog, congestion).

I recently had the privilege of explaining this distinction in a court of law to the jury. I was retained as an expert witness in a civil suit involving two motorcyclists who suffered serious injuries while riding at about 3:00 AM one morning on a county road that was posted with a 65 MPH SPEED LIMIT sign. As they approached a relatively tight right turning curve they saw a sign on the roadway that said: "35 M.P.H." - an advisory speed limit sign that warned them about the upcoming turn.

Let me take a tangent here and explain that I was literally shocked by what BOTH attorneys (the defendant's and the plaintiff's) thought those signs meant. The defendant's attorney claimed (outside the presence of the jury) that there was essentially no difference between the two signs I showed above - that both represented a maximum speed limit. The plaintiff's attorney knew differently and was quick to point out the distinction in the courtroom in front of the jury. Unfortunately, he had not the slightest idea what an advisory speed limit sign actually meant and caused trouble for his client by exaggerating his 'understanding' of the distinction in front of that jury.

Both attorneys, by the way, admitted that their clients had been speeding at the time of the accident - at somewhere between 70 and 85 MPH. So this was NOT a case about speeding. It was a civil case about who was liable to pay for the damages resulting from the accident they had.

In any event, let's deal with what those advisory signs mean and why they exist.

Almost 80 years ago, in about 1930, when cars (and motorcycles) were far less capable than they are today, it was recognized that states had an obligation to construct and maintain roadways that were essentially safe to drive upon. It was further recognized that despite the otherwise safe speeds you could drive on those roadways when they were essentially straight lines, some curves simply had to be constructed which could not be driven on safely at the speeds the roadway was otherwise designed to support. So, the states agreed to provide warnings - signs that advised of upcoming danger. These 'caution-warning-danger' signs were invariably associated with tight turns.

But how did they determine what speed to post on those signs? Some turns were tighter than others, after all.

Engineers collaborated with automobile manufacturers and tire manufacturers and determined that automobiles could be expected to safely travel on any road of 'normal quality' provided that they did not experience more than about .2g's of centrifugal force while making a turn. This was well below the traction capabilities of tires at the time. Better rubber compounds and better roadway surfaces since then have made their assumptions even more conservative as time went on.

So, test vehicles equipped with a swinging weight (a metal ball) inside them were constructed with an indicator of the angle that weight made relative to vertical. In other words, if a particular curve was ridden at 35 MPH the weight would be seen to lean, say, 15 degrees away from vertical because of centrifugal force.

It turns out that when the weight angle was between 10 degrees and 14 degrees then the vehicle was experiencing a sideways acceleration of very close to .2g's.

So, advisory speeds were established, rounded to the nearest 5 MPH, at whatever speed caused that weight to lean about 12 degrees. That, it happens, is the same lean angle your motorcycle adopts when riding that curve at that speed.

You've heard it before but I want you to really understand this: You, as the rider of a motorcycle, can ONLY determine its speed and direction of travel. The lean angle you and your motorcycle adopt in a curve is NOT set by you! It is absolutely and entirely determined by your speed and the radius of the turn you are riding. The faster you take that turn, or the tighter that turn is, the greater your lean angle will be. That's the law! (physics).

So those advisory speed limit signs specify a speed that you can virtually guarantee is safe for you to ride that turn at. It is merely a 'caution-warning-danger' signal, not a speed limit. (Note that at least one state finds no difference between a speed limit sign and an advisory speed sign and can successfully ticket you for exceeding the posted speed on that sign - the vast majority of states, however, recognize the difference.)

But if an advisory speed limit is posted at 35 MPH, how fast can you actually ride through that turn with relative safety?

Interesting question. The plaintiff's attorney ruined his credibility in front of the jury by bragging that as a motorcyclist himself he 'knows' that with enough skill and good equipment he could 'easily' handle any curve at twice the speed posted on an advisory - for example, he could easily take the turn in question that was posted with a 35 MPH advisory sign at 70 MPH. Indeed, he said, "I could do that with my car." (He was attempting to discredit me as an expert witness at the time.)

I showed the jury the truth of the matter. (Note that the following models presume that the roadway is flat - has no bank angle. The higher the bank angle, the LOWER the lateral acceleration and, thus, the higher you speed at which you can travel on it without losing traction.)

For example, a curve with a radius of 375 feet taken at 35 MPH:

Notice that the motorcycle would have a lean angle of 12 degrees which means that it would be experiencing centrifugal force (lateral acceleration) of about .22g's. In other words, that roadway would have a 35 MPH advisory sign posted on it even though the rest of the roadway was posted at 65 MPH.

Now see what happens to those numbers when you take that same curve at double the speed - 70 MPH.

The bike lean angle has increased to about 41 degrees which means it is experiencing centrifugal force (lateral acceleration) of about .87g's.

The coefficient of friction of that roadway and the tires on your motorcycle is almost certainly about .8 which means that if you tried that curve at 70 MPH you would have lost traction and washed out before reaching 70 MPH!!!

So, you've heard, just as that attorney stated, that a skillful rider could take any curve at twice the speed posted on an advisory sign and now you know that is NOT TRUE.

If you think that the knowledge, or lack thereof, of those two attorneys is a serious concern given the nature of the trial they were engaged in, then you will be absolutely dumbfounded by what the other expert witness had to say about that curve. She is a very talented motorcycle racer who also happens to be a certified MSF RiderCoach.

In a deposition prior to the trial she was asked if it was possible to safely ride a motorcycle on that curve at speeds greater than 35 MPH. She responded that it was certainly possible to do so. When asked if she could safely ride that curve at 50 MPH, again she responded that she could do so. She added that it was merely a matter of skill and technique.

"Really?" said the attorney. "Then could you safely drive that curve at, say, 100 MPH?" She said that she could do so. "Well, could you safely drive that curve at 150 MPH?" Again, she said that she could.

Her credibility as an expert witness became ZERO. (At 150 MPH her bike would be leaning over at 77 degrees and she would be experiencing about 4.5g's of centrifugal force - well beyond the abilities of ANY motorcycle regardless of skill or technique.)

You can, with almost no risk of losing control, take a curve posted with a 35 MPH advisory sign at 50 MPH assuming no other safety issues. I do it routinely and so, probably, do you. But take heed that listening to an 'old salt' tell you that you could 'safely' handle any curve at twice it's advisory speed will with virtual certainty result in your crashing that bike of yours!

Then there are other things that the 'old salt' will tell you that makes a lot of sense in the right situation but which can also result in your eating asphalt. For example, getting into the habit of always taking curves using a 'late apex' approach. NUTS! By definition, a late apex method involves delaying the start of your actual turn and then using a GREATER lean angle (meaning a tighter radius) than you would use normally at the beginning of the curve and opening it up (lessening the lean angle) as you get to the apex. In other words, using a late apex method while at the same time trying to press speed limits is a test of concepts that is DANGEROUS. Late apex turning is, in my opinion, generally safer than a single lean angle turn, but NOT when getting near speed limits.

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 221-240 - 230: Learning to 'Threshold brake'James R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=5873Tips 221-240 Fri, 10 Aug 2007 23:24:05 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=5873 Learning to 'Threshold brake'
Requires great care!

By: James R. Davis

You know that you get the best braking performance by getting as close to skidding as possible without skidding. This is called 'threshold braking'. You also know that if you skid the front tire you are almost certainly going to crash, at least if you are not traveling in a straight line. So clearly practicing in an effort to learn how to achieve the best possible braking performance involves some danger and should not be done casually or by riders who are new to their bikes.

Learning threshold braking needs to be done with great care.

It doesn't matter if you are traveling at 60 MPH or 30 MPH, you can threshold brake. So it makes no sense to practice this skill at more than 30 MPH. Further, it makes no sense to try to learn threshold braking while also using both brakes. You learn this skill using ONLY the front brake. Once it is mastered you can then move on to learning how to use the rear brake at the same time.

NOTE: If you bike can do a stoppie (like most sport bikes), then if the Coefficient of Friction between your tires and the roadway surface is high enough you CANNOT threshold brake - that is, if the Coefficient of Friction is high enough, then you will do a stoppie before reaching the point where the front tire will skid.

Let me make a few points here that you should UNDERSTAND before you begin this kind of practice:

A tire skids when you attempt to decelerate (or accelerate) it at a rate greater than the Coefficient of Friction available.
The Coefficient of Friction between your tire and concrete is USUALLY higher than that of asphalt.
The TEXTURE of the roadway changes the Coefficient of Friction (i.e., Rougher texture = higher CofF). In other words, you CANNOT stop as quickly on smooth concrete as you can on highway concrete.
The MOISTURE content of the roadway changes the Coefficient of Friction.

What all of that means is that you CANNOT rely only on muscle memory to acquire this skill. That is, the 'feel' of the braking effort is not enough feedback to let you know that you are close to skidding. Fortunately, there is another form of feedback available to you - the sound of the tire as it gets close to skidding.

You need to ease into the threshold zone (meaning you use small increments of added braking pressure on the front brake lever) until you can actually hear the front tire begin to 'sing' to you as imminent traction loss occurs. NO FURTHER than that.

Obviously you only practice this skill while vertical and traveling in a straight line so that if you exceed that threshold and the tire begins to actually skid you can release the brake lever and recover. The entire purpose of practicing this is to learn to feel and hear when you are approaching the threshold.

While the front tire is 'singing' it is leaving a light 'skid mark'. It will not be a dashed line. It will be rather faint, not dark.

A dashed skid mark can result from the use of ABS. It, too, uses threshold braking but instead of holding the braking pressure as close to skidding as possible it releases then reapplies the brake causing the dashed 'imminent skid mark'.

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 221-240 - 229: ConspicuityJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=5834Tips 221-240 Sun, 05 Aug 2007 14:23:39 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=5834 Conspicuity
Don't give them the excuse

By: James R. Davis

We have all heard and lament that car drivers inevitably argue that they didn't see the motorcycle before the collision occurred. Certain that the real problem is that they were otherwise busy talking on their cell phones or simply not paying attention, we do not credit that excuse other than with a "Yeah, sure". But what if it's true?

Most motorcyclists have heard the word 'conspicuity'. It means conspicuousness or obviousness. It is a ten-dollar word that turns off most people who hear it, but there is substance behind it. It certainly helps your ability to be seen if you are conspicuous or obvious, though that person on the cell phone still might not notice you, and even if they do, they may not be able to recognize what they are seeing.

When you hear the word 'conspicuity' you probably think 'light colored clothes'. Yep, that can certainly help - when the sun is shining. But I suggest that at night you are FAR better off having reflective strips of some kind on your jacket/helmet/motorcycle than if you are wearing a light colored jacket as opposed to black. Those reflective strips or patches should be across your upper back and on your shoulders (facing to either side) for best effect.

And why is it that we tend to think of the person who is ahead of us needing to see us more than the person behind or from the side? The truth is, it doesn't matter where 'they' are, they MUST be able to see you and recognize you for what you are.

Curiously, despite the natural desire to be seen by drivers coming toward us, when motorcyclists think about adding some lights to their rigs they think about rear facing lights first. They add bigger, brighter, brake lights and even modulated lights to aid those who are behind them. I say curiously because most threats to a motorcyclist are in front of your motorcycle, not behind.

Many years ago the railroad industry determined that the most conspicuous lighting arrangement, and safest, was to have a triangle of forward facing lights, the largest, brightest light at the top and two slightly smaller/dimmer lights mounted horizontally below it. This configuration had benefits that might not be immediately obvious. Most notably, when a train is moving toward you the two bottom lights appear to get farther apart. Thus, you not only recognize the lights as coming from a train, but you can tell if it is moving toward you, and you can even estimate at what speed.

A motorcycle can have exactly the same lighting advantage. If you mount running lights below your headlight you have created that magic triangle. When seen from the front you no longer look like a far distant car. Since nobody expects to see a train coming toward them on a public road, you are recognized for being 'something else' - indeed, almost certainly a motorcycle.

Unlike modulating brake lights, I am absolutely against modulating headlights. They are distracting and easily confused as being from an emergency vehicle of some kind. They may be illegal in many states if setup incorrectly. They are also, like magnets, strongly attracting to your eyes which increases, in my opinion, the chance that an oncoming vehicle driver will target fixate on them. That, I assume you agree, is not your intention at all.

As to drivers behind you ... you are well advised to remember that engine braking does NOT turn on your brake lights. If you roll off your throttle while someone is following you you should either lightly use your brakes as well, or simply double tap your front brake lever to give them notice of your change of speed.

Don't give them the excuse. Insure that they see you.

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 221-240 - 228: Visual Conflict of InterestJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=5811Tips 221-240 Wed, 01 Aug 2007 10:31:34 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=5811 Visual Conflict of Interest
Especially when Accelerating

By: James R. Davis

There are times when your eyes show you what you expect to see and other times when they show you something else entirely. This tip attempts to demonstrate why you need your mind to be 'in the present', and why you need to actively interpret what you see instead of believing what your eyes are telling you.

For most of your riding history you have trained yourself to respond to visual input with almost 'reaction' speeds, to not delay responding in any way because at highway speeds you cover a lot of ground in very short order. Delays (internal debates about what you should do) can result in unthinkably harsh consequences.

Take as a real world example of this the fact that many of us, certainly myself included, cover our front brake lever whenever we are riding at faster than parking lot speeds. We know that it takes, on average, about one full second to recognize an unexpected threat and to decide to react to it, and then it takes additional time to begin doing something - like reaching for and squeezing that brake lever. We cover the front brake lever because that will shave off at least 1/10th of a second of reaction time and, as a consequence, it effectively provides us additional stopping distance between our motorcycle and that threat. Indeed, 1/10th of a second at 60 MPH provides us a life saving extra NINE FEET of stopping distance.

We train ourselves to REACT as quickly as possible to that visual input. We also use the time from the moment we start to squeeze that brake lever to decide how hard to squeeze it. That little decision is made AFTER we begin doing something about the threat, not before. Humans are damned smart after all.

So what could possibly be wrong with that scenario? Not a thing when you are travelling at highway speeds - it is a life saving learned behavior.

So then what is the purpose of this article? Well, you are not always traveling at highway speeds when you notice a threat and at very slow speeds, particularly if you are accelerating, your visual input can lie to you.

Consider ... you are stopped behind a vehicle which is also stopped at a signalled intersection with a red light. The light turns green and both you and the vehicle ahead of you begin to move. That is, you are both accelerating.

What your eyes show you is that the car ahead of you is pulling away from you - the gap between you and it is widening. But what your mind is telling you is that you have rolled on your throttle and your body is telling you that you are accelerating. So far, so good. But going back to your mind for a moment, your experience is such that you EXPECT the gap between you and the vehicle ahead of you to be getting smaller OR YOU ARE LOSING THE RACE! That, in turn, causes you to roll on the throttle even farther.

The two second rule remains just as valid at 5 MPH as it is at 60 MPH. When you were stopped at the light you were very close (relatively) to the back of the vehicle ahead of you. As both vehicles begin accelerating the gap between them MUST WIDEN in order to provide that two seconds worth of space. But your mind, if it is not 'in the present', if you are simply going through the motions without active thoughts controlling your behavior, expects the gap to get smaller. You are not a 'loser' of races, after all.

So, there is a time when both your eyes and your mind misinterpret a widening gap and prior experience causes you to INAPPROPRIATELY respond by rolling on even more throttle. But that is essentially no big deal, not particularly dangerous. It becomes dangerous when that vehicle then unexpectedly hits its brakes! Then your eyes are in a conflict of interest position. They show that the distance between you and the vehicle you are following is narrowing - just as you expected because you have rolled on that throttle. And instead of REACTING as quickly as possible to avoid the collision, a delay occurs as your mind gets out of racing mode and into survival mode. Covering the front brake lever saves you 1/10th of a second when you need it, which is significant if you have distance to stop, but you have, by rolling on that throttle, eliminated (shortened) the gap - there isn't two seconds of space there as there should be, and you end up biting the rear-end of that vehicle with your front wheel - and the pain begins.

Get and maintain that two second following distance IMMEDIATELY, especially when starting from a dead stop.

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 221-240 - 227: Guns Aren't Dangerous, You AreJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=5516Tips 221-240 Wed, 27 Jun 2007 07:17:58 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=5516 Guns Aren't Dangerous
You are

By: James R. Davis

Guns?

Well, Okay, motorcycles. Sometimes a point can be made with an analogy.

At a recent outing at a pistol target range the instructor made an interesting point. He said that "Though we are going to have some fun today, that is NOT the highest priority here. Today you are going to learn how to handle a weapon SAFELY, and PROFICIENTLY. And when you know those things and demonstrate that knowledge EVERY TIME you touch a hand gun, THEN you can focus on having some fun with that weapon."

Some people would tell you that if you want to have fun you will not enjoy riding motorcycles with me. They would probably be correct. In the very same way that the target range instructor would not be someone you would find being fun to associate with if all you wanted to do was go out into the woods and squeeze off a few rounds, and when you are at his range you WANT him to be a 'safety Nazi', you can be sure that I am exactly that whenever I am near a motorcycle with its engine running.

'Fun' is an earned reward, to my way of thinking, and is NOT the primary justification for riding motorcycles. When you are ALWAYS in control of your motorcycle, are ALWAYS in control of yourself, understand situational awareness and management, wear reasonable protective gear, and have maintained your motorcycle with professional care, then you are, in my opinion, entitled to have 'fun'. Otherwise you are playing and having 'danger', 'thrills', 'excitement', and 'close calls' - or 'accidents'.

Please hear this simple truth: When you play with a gun and are not doing so safely or with proficiency, someone is likely to die or get seriously hurt. But that should be as nothing to you when you recognize that when you play with a motorcycle and are not doing so safely or with proficiency, unlike as with a gun, the person that is likely to die or get seriously injured is YOU.

By the way, don't be too concerned about having fun when you are riding with me. You will. Because unless you do so safely and with proficiency, I won't be riding with you at all.

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)
]]>Tips 221-240 - 226: "I laid it down" is a crockJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=5460Tips 221-240 Wed, 20 Jun 2007 10:43:40 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=5460 "I laid it down" is a crock
(More charitably, it is an excuse.)

By: James R. Davis

I recently had a message posted on my board from a long-time rider which said the following:

quote:
I laid it down one time on purpose.
I was entering a green light intersection about 30mph when I saw what turned out to be a drunk driver entering on my right intending to run his red light.
I ran thru 3 options in my head:
1) If I keep going he will T-bone me;
2) If I try and stop I will T-bone him;
3) Lay it down and hit him with both of my wheels and the whole bike between me and his car.

I took Option 3, destroyed my helmet on his A-pillar, destroyed his left front fender/wheel/ door, landed on my tailbone after flying over his car. Bottom line: totaled Harley, totaled Plymouth, totaled Bell helmet, cracked tailbone, opened up head, 10 days on a board in the hospital.
I never ride without a helmet now.

His 'logic' was reasonable, though badly flawed, but worse by far it sounded like a recommendation to others to consider doing the same thing. On balance, it was a crock of ...

This is the kind of story that a newbie must learn to filter and dismiss instead of believing. It is especially difficult for them given the 'story' includes a rational and obvious bit of good advice (to always wear a helmet).

His 'option 2' was the ONLY viable and certainly the safest choice he could have made. If you are going to crash you want to do it at the slowest possible speed and that happens only if you use an emergency braking maneuver. By 'maneuver' I mean that you squeeze the front brake hard, then harder, then harder still without locking up the brake, and by using the rear brake modestly and then with less and less pressure so that it, too, does not lock up. And it means that you keep your head and eyes pointing straight ahead, the bike pointing straight ahead, and you lean forward to lower the bike's center of gravity.

Let's look at the whole idea of 'laying it down'. Do you wonder where a person learns how to lay a bike down on purpose? I mean, I have never heard of a class, certainly not an MSF class, that teaches a rider how to do that. Yet, it seems, this rider knew just how to do it in an emergency situation. Isn't that fantastic?

Let's suppose that you really did want to lay down a bike while it's moving at highway speeds. Which control would you use? There is no 'lay down' button on your motorcycle so it must be one or more of the other controls. Since this rider wants to end up with his wheels hitting the car ahead of him, my guess is that the bike has to be made to turn 90 degrees from its direction of travel. The only controls that you have to change direction are the handlebar itself. And, at highway speeds, you have no choice but to use counter-steering. So, it must be that you use counter-steering to lay a bike down. But my experience has taught me that when you change direction you actually move in a different direction. If this rider merely pressed hard on, say, his left grip, then his motorcycle would have moved dramatically to the left, not just swiveled in place within his lane of traffic and switched the front end of the bike from pointing dead ahead to pointing directly to the left.

But if the bike actually moved away from the track he was riding in, and aggressively so, then wouldn't that actually be a panic swerve? And if a panic swerve COULD be performed such that you would miss the collision altogether, why wouldn't you simply do that instead of going further and ending up on the ground?

The fact is that if you could use a panic swerve to avoid an accident you would do so instead of 'laying it down'. This rider already claimed that that was not an option because it was not listed.

In order to end up on the ground your tires have to lose traction. That happens, as you know, if you overuse your brakes. Skid marks are clear indicators when that happens. And the brake that is easiest to overuse is attached to the rear wheel. Its at least a coincidence that when you skid the rear tire your bike's rear end tends to yaw to one side or the other, particularly if you are also using the front brake. And the result can easily be that the rear tire, not the front one, is what slides out from under you while you tend to stay in the same lane you were traveling in at the time. Surely it is more likely that in order to 'lay a bike down' you use the rear brake instead of counter-steering.

But if you skid your tires you no longer are getting maximum stopping power from your brakes. Instead, you have reduced your rate of deceleration by about 25% from what it was just prior to the start of the skid.

Now I don't know about you but if I had my preferences I would want to be slowing as quickly as possible when faced with a crash and that means I would not want my tires to skid at all.

But what if you could increase your rate of deceleration by sliding on the side of your motorcycle instead of on its tires? Well, the problem with that is that steel (and plastic) have less friction when scrubbing against asphalt than does the rubber of its tires. So that a sliding motorcycle which is on its side instead of on its tires will slow even less quickly than if you simply skid your tires.

You know what I'm saying ... 'laying down' a motorcycle is NOT a deliberate event on the street. Instead, it is an after-the-event explanation, an excuse, of what happened which is designed to save face. In short, it is BS.

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 221-240 - 225: Newbie Attending Rider TrainingJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=5358Tips 221-240 Mon, 04 Jun 2007 16:53:59 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=5358 Newbie Attending Rider Training
Preparation and other considerations

By: James R. Davis

This one is for those of you who are new (or are returning) to motorcycling and have decided, because of GREAT judgement, to attend either a state sponsored Rider Training class or a Harley-Davidson Rider's Edge version of the same class.

You will be well advised to prepare for your days on the range.

Get plenty of rest the night before.
Be HEALTHY - not on medications!
Eat and drink a breakfast before going to the class.
Dress appropriately.
- Over the ankle Boots.
- Full fingered gloves.
- Long sleeved shirt.
- Sturdy full-length pants.
- Eye protection (shatter resistant glasses or goggles).
Lots of bottled water.
Helmet ...
- Bring your own if you have one - DOT approved!
- The class will USUALLY provide one if you don't have your own.

The above is a MINIMUM list. If you want to protect yourself properly then you will, regardless of whether or not it is cold, hot or even raining, wear a sturdy (preferably leather) jacket as well.

And if it is raining you will probably want to bring at least a modest amount of foul weather gear (a rain suit). By the way, count yourself VERY FORTUNATE if it is raining while you are out on the range because you will learn that you can EASILY control a motorcycle in the rain and that it has almost as much traction when riding on wet roads as dry roads. When you graduate you will have knowledge and skills and experience that will awe other beginners, but more importantly, will assure you that you can control your motorcycle even in the rain.

Incidentally, most experienced riders will not start a ride if it is raining but will have no problem completing one if the rain starts after their ride begins.

Finally, a word about helmets ... and hygiene. Yes, you can use helmets provided by the class for people who do not have their own. BUT, you should NOT expect that they will fit properly, you should NOT expect that they will be full-face, and YOU SHOULD NOT EXPECT THAT THEY WILL BE CLEAN!! In other words, you should bring a skull cap with you (about $10 silk hair cover) and a spray bottle of disinfectant! Indeed, if I had to rely on a borrowed helmet for the class I would bring, instead of a skull cap, a balaclava (also about $10 silk full head and neck cover, like a ski mask, with a wide eye opening, available at almost any motorcycle dealership.)

Whether you wear a skull cap or balaclava or not your head will sweat when you wear a helmet for any meaningful amount of time. You can wash a skull cap and balaclava but you cannot wash a helmet. Enough said?

Oh, and if you have a choice between a state sponsored MSF and the H-D Rider's Edge class, take the state sponsored class. The Rider's Edge class has been shown to be THIRTY-FIVE TIMES MORE DANGEROUS!

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 221-240 - 224: Rider Education ala MSF is NOT About Safety!James R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=5299Tips 221-240 Sat, 26 May 2007 09:41:00 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=5299 Rider Education ala MSF...
... is NOT About Safety!

By: James R. Davis

To be sure, the MSF's BRC curriculum used in almost all state sponsored motorcycle training classes and Harley-Davidson's Rider's Edge classes contains some safety information. But it would be a mistake to think that the purpose of that training or even the passing of the class by students results in safer motorcycle riding by those students.

It has been shown that graduates of the class do have a better safety record for a short period of time following the class, but no study has ever concluded that graduates of the MSF curriculum are safer riders other than in the short-term. Still, any improvement in the accident statistics is generally worth having, but then again, I wonder if that is true at any price? Here we will discuss the seamier side of Rider Education in an effort to understand that price.

Many of you are aware that over the years I have become increasingly antagonistic towards the MSF and their riding curriculum. It's time that you understood why that has been happening and what the fundamental issues are that I have with the MSF.

First, let me repeat what I have often said about the MSF: it is a WORLD-CLASS organization that provides a WORLD-CLASS fundamental training curriculum for motorcyclists.

That said, it's time to dispel some myths and focus your attention on priorities.

The current MSF basic rider curriculum (BRC) is NOT a course that can be called a motorcycle SAFETY oriented class. It's purpose is to teach you the fundamentals about how to ride a motorcycle, not how to do it safely. Even that 'purpose' is not exactly top priority for the MSF. Instead, the primary objective of providing a fundamental 'how to ride' curriculum is to provide an increasingly large set of motorcycle buyers and, not incidentally, to insulate the motorcycle manufacturers from legal claims by riders who are injured or killed while riding their motorcycles.

In the almost 35 years that the MSF has been providing motorcycle training curriculum there have been slightly more than 3 million students attend those classes. One would think that if safety was the paramount objective of that training, deaths and injuries would have fallen during that time. Some statistics show that to have been the case, not on an absolute basis, but on a relative basis. Kudos are in order for that accomplishment and it would not be fair to suggest it was the result of anything other than that training. But one would also assume that deaths and severe injuries that occurred DURING motorcycle training would also have fallen either absolutely or relatively. NOT TRUE!

During the first 28 years of their existence the MSF was responsible for training more than 1.6 million students using what was called the MRC:RSS (Riding and Street Strategies) curriculum and during that time there was exactly ONE DEATH during that training. Then the MSF changed its curriculum and renamed it the BRC (Basic Riding Course); they dumbed it down, made it easier and more fun, so they say. Since that change (until 12/07) no fewer than EIGHT students and ONE instructor were killed or suffered a near fatal accident using the new and 'improved' curriculum. That means the new curriculum is no less than EIGHT TIMES more dangerous than the older MRC:RSS curriculum. That is NOT supportive of a belief that the MSF is focused on teaching motorcycle safety.

But there is more. Not only was the curriculum changed, so was the acceptable size of the motorcycles that could be used in the BRC training. With the adoption of the BRC curriculum training providers could use 500 cc motorcycles for their rank beginner students to learn on. Oh, and they also changed the requirements for the size of the training range upon which training could occur. They can now occur on 'compact' ranges that, not coincidentally, happen to be readily available on adjacent motorcycle dealership properties. Oh, and let's not forget that one of those motorcycle manufacturers, Harley-Davidson, happens to have rejoined the ranks of MSF sponsoring (owner) manufacturers, designed, just by chance, an entry level motorcycle called the Buell Blast (500 cc's, of course), and created a sub organization within itself that teaches a class called the Rider's Edge on ranges adjacent to their dealerships, using the new MSF BRC curriculum. (Let me add that up for you, while the BRC is 8 times more dangerous than the original RSS, the Rider's Edge classes, using the BRC, have been shown to be THIRTY-FIVE TIMES MORE DANGEROUS than state sponsored BRC classes! The Rider's Edge classes have graduated 100,000 students and 'only a few' of the other students died or nearly did. Indeed, 5 (possibly 6) of the 9 deaths or near-fatalities occurred during a Rider's Edge class. In other words, 1 in 20,000 Rider's Edge students die or nearly do while 3 or 4 students have died in state sponsored MSF BRC classes which is close to 1 in 700,000 students!

One begins to wonder if safety is, after all, what motivates the MSF. Indeed, with the intimate relationship between MSF and the motorcycle manufacturers (they are, like Harley-Davidson, the stockholders of the MSF), it seems clear that profit is more likely to be higher on their priority list than is safety. But you know that the MSF is a 'non-profit' organization. (I will speak directly to that bit of misdirection of fact later.) Still, if the MSF could, by providing motorcycle training result in lowering of motorcycle manufacturer liabilities, that would be a 'good thing' from their stockholder's point of view. Even better, if they could cause an increase in sales of motorcycles, 'everybody' would be happier, no?

A lawsuit against, for example, Harley-Davidson, which claims that "they sold or allowed to be sold a motorcycle to a person who they knew or should have known was not capable of handling that machine without serious risk of injury or death" falls on judicial deaf ears when it can be shown that the buyer of that motorcycle SUCCESSFULLY completed a BRC class (whether state sponsored or Rider's Edge.) The liability has been shifted away from the manufacturer to either the training provider or the rider himself.

But to go even farther, a lawsuit against, either Harley-Davidson or the MSF itself which claims that "they provided insufficient training to assure that the rider would have been able to handle their motorcycle without serious risk of injury or death" also falls on judicial deaf ears when the state has provided a motorcycle endorsement on that rider's license which, in effect, says that the state agrees that the rider has sufficient knowledge and skills to safely ride a motorcycle.

Then there is the little matter of the MSF suing Team Oregon because they (the MSF) allege, Team Oregon's curriculum (BRT, not BRC) includes material for which the MSF holds copyrights on. Little known is that they (MSF) offered to drop that suit if the state would agree to provide motorcycle license test waivers to graduates of the BRC classes, whether state sponsored or not. In other words, if the state would provide graduates of the Harley-Davidson Rider's Edge class those waivers.

You see, that motorcycle endorsement puts another layer of liability insulation between the manufacturer and the rider. In essence, if you get a motorcycle operator endorsement on your drivers license, as a result of passing your states' sponsored MSF BRC class, liability then falls on YOUR shoulders. Kiss good bye your ability to sue Harley-Davidson, or Honda, or any other of the STOCKHOLDERS of the Motorcycle Safety Foundation. (Yes, that non-profit organization is a CORPORATION (501 (c)) OWNED by the manufacturers of motorcycles.) And lest you forget an economic fundamental, corporations are REQUIRED to do those things that enhance their bottom line (either currently or in the future) and they CANNOT do those things that damage their bottom line, such as public services, safety training, save-the-earth from global warming campaigns, or anything else.

Let's get that straight immediately. Motorcycle manufactures CANNOT, for example, DONATE MONEY OR INVEST IN an organization such as the MSF in order to promote safety. They may ONLY do so if, as a result, they can enhance the performance of their corporation's bottom line.

Then there is the issue of why the MSF's BRC curriculum has been dumbed down. THEY claim it was in order to make the course EASIER and more FUN. In fact, it was to result in more student who PASS the course and, thus, insulate the manufacturers from that liability we talked about earlier. The same can be said of why they now encourage their Rider Coaches to IGNORE minor errors early in the class. And, not incidentally, they shifted liability from the MSF to the Rider Coaches!!!!

So, in summary, taking the MSF is profoundly important for the new or returning rider as it DOES teach them the fundamentals of HOW TO RIDE. It is a mistake to believe that taking the MSF course teaches how to ride SAFELY or that being an MSF graduate reduces your odds of having an accident except in the short term.

No less an authority than Harry Hurt (author of the famous Hurt study) agrees with this point of view. In a recent article published in MCN (Motorcycle Consumer News) by Wendy Moon (a member of this board), he is quoted extensively on the subject. You may read an extract of Mr. Hurt's comments on Wendy Moon's blog here. (Scroll down to the May 24, 2007 posting at 9:53 AM.)

So if the MSF is in business to promote motorcycle sales and to reduce liabilities for those motorcycle manufactures, does that mean that they have assumed some of those liabilities? Not hardly. Indeed, the MSF has essentially insulated itself absolutely from liabilities and shifted them almost entirely onto the backs of the students. Almost? Well, they also have shifted some liabilities onto the backs of motorcycle Instructors/Rider Coaches. During the last few years the MSF created a new 'liability waiver document' which not only specifies the words DEATH and SEVERE INJURY (in boldface) as expected outcomes of the classes, it does so twice! And it removes MSF altogether from any accountability or responsibility for the course and, thus, puts all that liability on the course provider and instructors.

Rider Coaches are NOT MSF employees. They are contractors of the class provider (possibly employees of the dealership that provides Rider's Edge classes), but NEVER MSF employees.

When an accident happens during a class, the instructor must fill out a report of the incident. Among other questions they must answer is one that asks if this was the first incident that student experienced during the class and, if not, a description of prior incidents. Now, please, who do you think is self incriminating by answering 'No' to the first question and who do you think then has liability should they explain why it is that they allowed that student to continue in the class? MSF? Certainly not. The provider? Possibly, if that provider has written instructions to the instructor that MANDATES that he/she allow minor errors or incidents to be ignored. And, oh yeah, that is exactly what the BRC does have their INSTRUCTORS do - ignore minor errors. Once an error becomes an accident, however, there certainly is a lot of room to argue about the judgment of the instructor for deciding that earlier 'incidents' were minor enough to allow the student to continue. No?

[Speaking of liabilities ... I am NOT an attorney and the above is in no way legal advice. It is my opinion. I will add, however, that if I was required to answer that question after an accident in one of my classes I would seek the opinion of an attorney before I did so!]

In summary,

The MSF BRC is not as safe as the curriculum that it replaced.
Students are dying at an INCREASED rate during training.
The classes are designed, in particular the H-D Rider's Edge class, to sell more motorcycles, not increase safety.
Liability has been removed from motorcycle manufactures and the MSF and transferred onto the backs of students and instructors.

It appears to me that motorcycle rider training is about something entirely different than safety.

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)
]]>Tips 221-240 - 223: Chains are not trouble freeJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=5191Tips 221-240 Wed, 09 May 2007 12:28:22 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=5191 Chains
Efficient but NOT Trouble Free

By: James R. Davis

There are some major reasons why some motorcycles drive the rear wheel with a chain or belt instead of a shaft. Most important of those reasons is that chains are far more efficient than shafts - indeed, as much as 25% more power is delivered to the rear wheel with a chain than with a shaft. Secondarily, they are much lighter than shafts.

On the other hand, they require constant maintenance and despite that maintenance they wear out and must be replaced. That is, wear is NORMAL.

It is often said that chains 'stretch'. Not true. They wear. The result of that wear is that they get longer - that is, the distance between the roller bearings increases because the pins and housings holding them together wear.

The transmission on your motorcycle is directly connected to and rotates a drive sprocket. The chain meshes with the teeth of that sprocket and the teeth of a driven sprocket which is attached to the rear wheel. A new chain almost perfectly meshes with those teeth. That is, the teeth of the sprockets are the same distance apart as are the chain links.

Here you see a 15 tooth drive sprocket with a properly fitting chain around it.

And here you see that same sprocket with a worn chain. Note that you can see that the links of the chain fit tightly at the top but are progressively unseated the farther around (counter-clockwise) it moves. As a result, the trailing edge of the sprocket teeth receive unusual wear as indicated in red.

A modest amount of sprocket teeth wear is not significant but unless you correct (tighten or replace) that chain the wear can quickly become a major problem as first the edge of those teeth wear more, then the tips of the teeth are worn off. Soon thereafter the sprocket will 'jump' links or teeth will break off altogether, or more likely, the chain will bind while a link is atop a tooth and simply break.

In order to properly tension your chain you must realize a couple of simple facts. For example, the tension on your chain changes based on how far the rear suspension is extended. Remember the 'swing arm'? If you use only the rear brake while stopping that arm tends to straighten out which, in turn, lengthens the wheelbase. So, adding weight to your motorcycle in the form of a passenger, or bottoming out your suspension by riding over speed bumps for example, or merely using just your rear brake puts a great deal of tension on your chain.

Here is what your chain and sprockets look like at the midpoint of your suspension travel.

Notice that the top segment of your chain is the most tensioned - it is what conveys power to your rear wheel. The bottom segment of the chain sags and is least tensioned.

But when that swing arm straightens out the chain then looks like this.

It should be clear, in other words, that there MUST be some slack in your chain when you adjust its tension. In fact, if your chain tension mimics the diagrams I showed above, that chain is still too tight! There should ALWAYS be some slack in the chain, even with a passenger aboard or going over speed bumps.

So how do you tell if you have enough? With the bike sitting on its wheels, top chain segment tensed, you can merely lift the center of the bottom segment (with the tip of your boot, for example) and eyeball at least 1 inch of movement. If there is more than 2 inches of play, that chain is probably too loose. If there is less than 3/4 inch of movement, it is too tight.

I mentioned tightening the chain. That only camouflages the actual wear of the chain and sprockets for a time. Tightening the chain is accomplished by adjusting the location of the rear wheel axle away from the drive sprocket, taking up slack in the chain. Of course the chain itself is not being shortened - the wear continues to exist.

Modest wear is typically caused by road grit and/or rust. But if the sprockets start to wear then metal filings (dust) collect in the chain lubrication and QUICKLY begins to accelerate that wear. A sprocket can wear all its teeth down to nubs in a matter of only a couple of thousand miles as a result.

Chains must be kept lubricated and that means virtually every couple of hundred miles of riding should be ended with the application of a chain lube. Note that it makes a lot of sense to do that while the chain is still warm. There are those who argue that putting a lubricant on chains only encourages the accumulation of road grit and that, in turn, hastens wear. My opinion is that lack of lubrication results in faster wear, and rust. Some argue that it is easier to simply let the chain wear, adjusting for proper length as needed, and then replacing the chain (and usually the sprockets at the same time) than it is to mess with routine maintenance. Again, my opinion is that routine maintenance is a safety requirement and it saves you money at the same time.

The proper tension on the chain is achieved by adjusting the rear axle's distance from the drive sprocket, as I indicated earlier. Make sure that both ends of the axle are moved the same distance so that the rear wheel remains in-line with the front wheel, and maybe more importantly, the sprockets remain in alignment. Proper tension exists when you can lift the center of the bottom edge of the chain about one inch, but not much more. If you have too much tension (less than 3/4 inch, for example), wear become rapid and you also wear out axle bearings. Too little tension and you risk the chain coming off the sprockets altogether and that can be highly dangerous!

When replacing the chain you will want to also replace the sprockets at the same time if there are obvious signs of wear on their teeth. Replacing the sprockets at the same time as the chain is more expensive than replacing just the chain, but substantially less expensive than replacing them individually. You typically can purchase either aluminum or steel sprockets. The aluminum ones are lighter, often more expensive than steel, and they wear much faster than do the steel sprockets. On the other hand, because they are lighter you gain a meaningful amount of power at the rear wheel by using them as the inertia involved in rotating the lighter sprockets is substantially less. Steel sprockets usually never need to be replaced as they simply do not wear like aluminum sprockets do.

Here you see an old and badly worn aluminum rear sprocket and its replacement steel sprocket. The wear on the aluminum sprocket was primarily caused by an alignment problem between the front and rear sprockets rather than a worn chain.

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 221-240 - 222: Moving from Scooters to MotorcyclesJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=5155Tips 221-240 Thu, 03 May 2007 11:42:13 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=5155 Moving from Scooters to Motorcycles
Gaining a new safety feature!

By: James R. Davis

Look around you and you will find that there are a lot more scooters on the road than there used to be. And if you look closely you will see that many of those scooters are no longer small, underpowered, fit-only-for-a-short-commute machines. There are maxi-scooters out there that can easily handle a 400 mile freeway trip, safely and with comfort.

And where do you think the owners of those maxi-scooters will go when they outgrow them? To motorcycles, of course. And many scooter owners are doing just that.

I have recently been involved in training an experienced scooter rider how to handle the Buell Blast that she just purchased. She had already attended a Harley-Davidson Rider's Edge class and passed it, so she certainly knew all the fundamentals. With several thousand miles of riding experience on her scooter, the idea of riding her new motorcycle in traffic was not a serious issue for her. But she was NOT confident - indeed, she was almost paralyzed with fear, that she might make a mistake with the clutch while shifting. Like virtually all scooters, her's had been an automatic.

I bring that to your attention because it is my experience that people who have scooter experience seem invariably to look upon having to deal with a clutch and standard transmission as the principal issue holding them back from buying a motorcycle, even if they have experience driving a standard transmission car.

For some reason none of these people seem to think of having a clutch as being a safety advantage. I do, but then again I tend to look at everything about riding motorcycles in safety terms.

Here are a few things to think about for anybody who is considering a move up from a scooter to a motorcycle or who are entirely new to motorcycles.

The two controls on a motorcycle which tend to save lives are the clutch lever and the front brake.
The two controls on a motorcycle which tend to cost lives are the throttle and the rear brake.
You should MASTER the ones that tend to save lives before learning the subtleties and limits of the two that tend to cost lives.
In order to REGAIN control of a motorcycle that is out of control (because of a popped clutch, for example), you must SQUEEZE BOTH LEVERS - immediately, instinctively, without any lost time thinking about it!
With an automatic transmission you CAN apply max throttle and max braking at the same time - you CANNOT disconnect the engine from the rear wheel.
with a motorcycle you can also apply both full throttle and full brakes, but you can ALSO totally disconnect the engine from the rear wheel via the clutch lever.

CONTROL of your motorcycle is your principal obligation as a rider, no matter what conditions you find yourself in, no matter the weather, no matter what condition the bike is in, indeed, no matter what condition *YOU* are in. But in the real world things happen and on rare occasions you can lose control. You can pop a clutch (release the clutch lever too quickly). You can roll on a fistful of throttle without realizing how powerful a new bike is. And, as a result, your obligation as a rider is to REGAIN CONTROL of that bike.

Unfortunately, the MSF curriculum for motorcycle training only teaches you how to get and maintain control. They lack, utterly, even a mention of how to REGAIN control if control is lost. The result of that is that motorcyclists tend to FREEZE at their controls and merely hang on - and sometimes die as a result.

Since 2001 there have been SEVEN deaths and three near-fatal accidents during MSF or Rider's Edge classes because of this (as of 12/07). In all cases the student popped his/her clutch and grabbed a handful of throttle, then FROZE as their motorcycles raced with a wide open throttle into a building, a fence, a curb or once into an instructor (killing him instead of the student). In fact, though not part of a motorcycle training class, an experienced Harley-Davidson dealership employee in Houston, Texas, took a customer's Hayabusa super-bike out onto that dealership's Rider's Edge range and did the exact same thing - he popped the clutch, grabbed a handful of throttle, and FROZE at the controls as the bike raced OUT OF CONTROL into a wooden stage just off the range, and died as a result.

In EVERY ONE OF THOSE ELEVEN SITUATIONS the motorcycle had a functional clutch lever that was ignored. By simply squeezing both the clutch lever and the front brake lever they could have REGAINED CONTROL of their out of control motorcycles - and lived as a result.

People freeze in a panic situation because they have not been taught, and therefore don't know, what else to do. Sure sounds like an addition to the MSF's curriculum is called for - a How To REGAIN Control module, at the very least.

The clutch lever is, without any question in my mind, a SAFETY FEATURE on a motorcycle, not a problem that will have to be dealt with. Mastering the use of that lever can save your life. Scooters don't have that feature. But, on the other hand, they are easier to ride and have lots more cargo carrying capacity and space than do most motorcycles.

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 221-240 - 221: Performance is all about TORQUE, not HPJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=4634Tips 221-240 Thu, 12 Apr 2007 18:02:58 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=4634 Performance is all about TORQUE
(Not HP)

By: James R. Davis

I am constantly amazed at how gullible, or at least willing to be misled, people are when it comes to their transportation. Consider that all automobile manufactures and most, if not all, motorcycle manufacturers, use Horsepower ratings in their ads. Now why is that, do you suppose? Is it because the buyers believe that horsepower is the magic number that boils all the rest down to irrelevance and tells you just what kind of performance your vehicle is capable of?

I would argue that performance is all about torque and has nothing whatever to do with horsepower. I know, I've just stepped into an age old argument. But I'm going to demonstrate my position here so that the argument can go away.

First, I'd like to talk about electricity - something you all know more about than you realize. I want to talk about Volts, Watts, and Amps. Then I'll relate this story to the engine in your motorcycle.

Every outlet in your house has 110 Volts of FORCE sitting there and waiting to be used. But unless you plug something into that outlet that force is not being used to do any work. And because there is no work being done, NO POWER is being consumed. Power? Yep, it's called Watts. Watts is a measurement of how much work is being done over time. Work? Yep, like lighting your house is the work being done when you use 110 Volts of force to push electrons across the filament on a light bulb. A 60 Watt bulb is far brighter than a 30 watt bulb because twice as much current (amps) is being pushed across its filament. More work is being done.

So what does any of that have to do with a motorcycle? Well, it will help you get over the belief that horsepower is what does work for you, for one thing. You see, horsepower is like Watts - it is merely a measurement of how much work is being done over time. But it doesn't cause that work to be done any more than it causes a light bulb to shine. It takes a FORCE to do work. In the case of electricity, that force is measured in and known as Volts. In the case of a motorcycle, the force that does work is known as TORQUE and is measured in units of foot-pounds.

I used the word 'Work' above. It means MOVEMENT resulting from a force. In the case of electricity, it is the amount of electrons moving through your wires and that filament. If there is no movement, then there is no work being performed. Even though the force remains available to do work, if you turn the light switch off the Volts CANNOT DO WORK.

Similarly, Torque (not horsepower) is a force that tries to cause movement. Unlike Volts, however, Torque always tries to cause a rotating movement.

Look at this lug wrench and you will see what I'm getting at.

Torque is measured in foot-pounds. If that wrench was exactly one foot long and it was connected to the hub of your rear wheel, and you stood on the end of it, you would be producing 180 foot pounds (usually written ft./lbs.) of torque. (Assuming, of course, that you weigh 180 pounds.)

If the resistance to movement of that rear wheel happens to be greater than 180 ft./lbs., it would be the same as volts trying to light a bulb with the switch turned off. NO WORK would be accomplished. But if the resistance is not that great then the torque you are applying to that wheel's hub will cause it to ROTATE. In that case, work would be accomplished - and, by the way, ONLY in that case would there be ANY horsepower because horsepower is merely a measurement, like Watts, of work being done.

Can you have horsepower without rotation? Of course. A rocket engine accomplishes work - it involves a force (not torque) that causes movement. Thus, horsepower. But in the case of your motorcycle, virtually all work accomplished is in the form of rotation and that REQUIRES the force called Torque.

About the only linear movement involved in motorcycling is piston motion (up and down) and the movement of your motorcycle along the roadway. In order to translate the up and down motion of your engine's pistons into the movement of your bike across the roadway it is converted to rotations. First, the piston motion becomes a rotation of the engine's crank shaft. That, in turn, rotates gears that rotate yet other gears within your transmission, which causes a drive shaft or chain or belt to rotate your rear wheel. As you already know, rotation is caused by torque, not horsepower.

So what does HP have to do with speed? AS it is only a measurement of how much work is being done over time, HP tells you how fast your motorcycle can go. That is, all the forces that try to move your motorcycle must overcome all the forces that try to stop your motorcycle from moving. Thus, when wind forces and other drag forces add up to the amount of torque you can deliver to your rear wheel, you have reached your top speed. But what HP does NOT tell you is how quickly you can get to that top speed.

Changing speed is called acceleration. The ONLY thing that causes acceleration is FORCE acting on a mass. In other words, your acceleration is determined by how much torque you can produce, not HP.

But surely HP is directly related to torque, right? Of course. HP is calculated as a function of torque and engine RPM. So, if either torque or RPM increases, so does HP. But the relationship is NOT linear! Torque can decrease while RPM increases and the resulting HP can continue to increase. Let's look at a dynamometer chart and see the relationships for clarity.

This chart shows two runs on the dynamometer for the same bike (one is red and the other is blue). The top two lines are Torque and the bottom two are HP.

Notice that the torque curve increases with increases in RPM, flattens out between 3,500 and 4,000 RPM, then decreases at even higher RPM. On the other hand, HP increases as RPM increases.

In fact what you are seeing is that HP is merely a calculated number. It is the torque times the RPM divided by 5252. Note that the HP curve ALWAYS crosses the torque curve at exactly 5252 RPM. In other words, HP is ALWAYS greater than torque at RPM greater than 5252. Notice also that the maximum torque occurs between 3,500 and 4,000 RPM while the maximum HP occurs at around 5,500 RPM. Thus, torque and HP are directly related, but absolutely not linearly.

So?

So performance of a motorcycle is typically measured in how fast you can cover a certain distance (such as a quarter mile). It is tempting to say that the bike that is going the fastest from a dead stop within that 1/4 mile is the highest performing of the two bikes but, in fact, regardless of the maximum speeds reached by those bikes at the end of that distance, it is the bike that crosses the line first that wins.

Why isn't it always true that the bike going the fastest at the end of the race the one that crosses the finish line first? Because they will have different rates of acceleration. The bike that can accelerate the fastest is virtually always the winner.

And you know from experience that the lower the gear you are in, the greater will be your rate of acceleration. That is, if you are in first gear, you can change speeds (accelerate) much more 'easily' (quickly) than you can in fifth or sixth gear. Further, you know that there is a 'sweet spot on your engine's performance where you get the absolute best acceleration as compared to any other RPM.

From the chart above you should recognize that that 'sweet spot' occurs between 3,500 and 4,000 RPM, which as we have already seen is far below where you have maximum HP. In fact, if you look closely at the torque curve you will note that it *IS* the acceleration curve.

Let me make that perfectly clear for you. Let's say that your bike's speed is 35 MPH when the bike is in first gear and the engine is making 3,500 RPM. If you opened the throttle all the way then you could VERY QUICKLY accelerate to 40 MPH because you have max torque available to you there. On the other hand, if your bike was moving at 55 MPH while in first gear and the engine was turning at 5,500 RPM, even though your engine is putting out more HP there than at any other engine speed, it would take you longer to get to 60 MPH than it took you to accelerate from 35 to 40 MPH. That, because you have LESS torque at 5,500 RPM than you do at 3,500 RPM.

Now if you shift gears from first to second your engine RPM will decrease if you continue moving at the same speed. And, as we noted earlier, no matter what the RPM is in second gear, you CANNOT accelerate (normally) as quickly in second gear as you could in first gear. What that is telling you is that your gears act as multipliers of torque. What determines how fast you can accelerate is the amount of torque that reaches your rear wheel and that is determined by your gear ratios. So, for example, if your first gear ratio is 3.5:1 while it is 1:1 in sixth gear, then you can accelerate three and one half times faster in first gear than you can in sixth.

Did you notice that I said that your gears are a torque multiplier, not a HP multiplier? HP is a measurement of what your engine can do in terms of work over time. Torque (a force) is what does work, not HP. Your gears and your engine's ability to develop torque are what determines performance, not HP.

So there remains one more persistent myth (actually a misunderstanding) that needs to be dealt with here before you get the big picture. Many people will tell you that the way to get the fastest speed out of your motorcycle is to always shift at the highest RPM in each gear, not at the highest point of the torque curve. And because there is more HP at the higher RPM points than at the highest torque points, those people believe that performance is clearly HP related instead of torque related.

Though they are correct, more or less, about where to shift gears, it is not for the reasons they think. The reason you would want to shift at higher RPM points instead of at the highest torque point is that even though the engine torque is LOWER at, say, 5,500 RPM than 4,000 RPM, the torque at the rear wheel will be higher there in the lower gear than it will be after the shift, even if the new engine speed in the higher gear is closer to the max torque provided by the engine.

This is a very hard concept to understand but the following charts should help.

The left side of the chart shows the motorcycle's torque curve in first gear (which has a ratio of 3.5:1) while the right side shows it in second gear which has a ratio of 2.4:1. Observe that while the engine max torque is just over 80 ft./lbs. at about 4,000 RPM, because of the multiplying effect of the transmission gears it puts just over 280 ft./lbs. at the rear wheel. Notice also that even though the torque at the rear wheel DECREASES as the engine speed increases from 3,500 to 6,000 RPM, it is always higher than what it would be at the rear wheel after you up shift.

If the gear ratios were closer together than shown then there could be a time where the torque at the rear wheel was greater after the shift than before. So, the trick to maximize speed through your gears is to always shift at the point where the torque at the rear wheel is exactly the same after the shift as before.

Thus, shifting at 5,000 RPM would result in losing the acceleration causing torque shown in red, while shifting at 6,000 RPM results in no such loss. On the other hand, if the gearing was tighter, shifting at 6,000 RPM would have been a bit too late as had you shifted earlier the torque at the rear wheel would have been exactly the same before and after the shift. This should put to bed the argument that you should shift at the highest RPM in order to maximize speed!

Even though it 'looks like' shifting at max HP or max RPM results in max overall acceleration, since acceleration is EXCLUSIVELY about torque, not HP, you now know that in truth, the way you max acceleration is to shift at the points where torque at the rear wheel is equal before and after the shift, and that is determined by the torque curve and the gear ratios.

A couple of more thoughts for you to consider on the subject ...

You RARELY, if ever, get to use the max HP of your engine unless you are into racing while you FREQUENTLY get to use (and enjoy) the maximum torque developed by that engine. Surely you should want to maximize what you use instead of a number?

When you use your maximum HP you are wearing out your engine quickly while when you use your maximum torque you are extending the life of that engine as it relates to normal wear and tear. An important thought, no?

Advertisers and salesmen who insist on talking about how much HP an engine can make simply are playing to a dumbed down audience. HP is easier as a concept than is torque. But now you are an informed owner/buyer. You want to know about torque, not HP, thank you very much.

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 201-220 - 220: Cruise ControlJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=4994Tips 201-220 Sun, 08 Apr 2007 12:59:51 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=4994 Cruise Control
NEVER if the road is wet!

By: James R. Davis

You may have cruise control on your bike and you may think it's God's gift when you are out on a long ride and your right hand begins to cramp. But you should pay attention to this bit of advice: NEVER use cruise control if the road is wet!

If your bike's speed sensor obtains its information from the front wheel and the ground is slippery, your engine can begin to race aggressively as that control tries to increase your speed. That, of course, spins the rear tire. You have lost control!

And if that's not bad enough, once you pass beyond that wet spot and regain traction with your rear tire you can then be literally thrown off your bike, at least accelerated big time, when it does so.

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 201-220 - 219: 'Traction Pie' - Dumbness PersonifiedJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=4950Tips 201-220 Fri, 30 Mar 2007 08:47:03 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=4950 'Traction Pie'
Dumbness Personified

By: James R. Davis

According to the MSF our tires provide only so much traction and that if you exceed that amount your tire breaks loose (you skid or slide). That's true.

They also presented to all students a 'visualization' of this in the form of a 'Traction Pie'. Below is a chart that is close to what that visualization looks like. Note that it is NOT *THEIR* chart as I am mindful that the MSF likes to sue people for copyright infringement and they seem to think that anything they say in their curriculum is 'intellectual property' and has great worth - not true.

The idea, according to the MSF, is that the circle represents the amount of traction a tire provides. They go on to suggest that there are FOUR 'pieces' of that circle (pie), the sum of which is the total pie: Acceleration force, Braking force, Cornering force, and Reserve (unused). The Assertion by the MSF is that if any 'piece' of that pie is Reserve, then you are not skidding/sliding. Fair enough, but that is not the same as saying you are not in trouble.

Well, if you were a fourth grader, I suppose, you might buy that and that is the fundamental problem with the analogy - it is a dumbed down concept that is easy to grasp, but is wrong and virtually useless. For example, instead of having FOUR 'pieces' that pie can have ONE, TWO or THREE 'pieces', and NEVER FOUR. If the tire is motionless, there is only one 'piece' (Reserve.) If moving in a straight line, there are AT MOST two 'pieces' (Acceleration OR Braking, and Reserve - if any.) And if moving in other than a straight line there are AT MOST three 'pieces' (Acceleration OR Braking, Cornering, and Reserve - if any.) So we already know that the visualization is mis-representing.

At least in the figure I drew for you above I have attempted to show you that the piece of the pie shown as 'A' is EITHER Acceleration force OR Braking force. In other words, the pie can have no more than three pieces. Nothing earth shattering about that mis-representation, but please bear with me as we next try to determine anything of value from the MSF's 'Traction Pie' concept.

Let's first look at the circle itself. The MSF would have you believe that it represents the traction provided by a tire. Fine. But there are no numbers associated with that circle so we must conclude that it represents 100% of that traction. And how much is that? I mean it is a finite number, right? Let's be charitable and say that *YOUR* tire can provide enough traction so that it supports 1.0g of force (Acceleration, Braking, Cornering.) So, I suppose, and the students will as well, that the circle would represent 1.0g. That is, the 'pieces' of the pie, when added together will amount to 1.0g.

There is a problem already. The amount of traction your tire provides is NOT independent of the roadway surface. If that tire is in the air, for example, it supports ZERO Acceleration, Braking and Cornering forces - thus, I suppose, that means there is only one 'piece' of that pie - Reserve. And since there is a Reserve 'piece' of that pie, the MSF would claim that you are not in trouble. If your tire is in the air you are NOT then in control and that, to me, means that you ARE in trouble.

But let's say that the tire is on the ground and moving. How much traction does it provide? I assure you that it does NOT provide 1.0g worth unless the coefficient of friction between that tire and the roadway is 1.0. In other words, that circle actually represents the coefficient of friction available (sometimes called the 'drag factor'.)

So let's pretend that all the students know that and that the drag factor happens to be 1.0. Is the visualization then right? No.

What would the diagram look like if the tire was moving in a straight line, that the drag factor was 1.0, and it was braking at a rate of 0.5g's?

Would you agree that this is a fair representation of that scenario using the MSF's 'Traction Pie' visualization?

Well, I'll not quibble here except to say that almost everybody would because they will be dealing with a false assumption, but for practical purposes I will agree that it is fair in that it shows that a good deal of Reserve exists and the tire is not skidding or sliding.

But let's change the scenario and say that we are looking at the 'Traction Pie' for a tire and that in addition to supporting a 0.5g braking force is also supporting a 0.5g Cornering force. Again, total traction supported by the tire is 1.0. Is, then, this diagram fair and correct? Since there is no Reserve 'piece' of the pie left, is this tire about to skid or slide?

The answer to those questions is a decided NO! Though it shows the assumptions made using the concepts earlier explained, it totally misrepresents reality. The tire in this example is nowhere close to a skid or a slide - there remains a Reserve of about 0.3g's of force that it can support.

And now you see the fundamental problem with the MSF's 'Traction Pie' visualization - it does not convey reality even in concept form and students have absolutely no way of understanding the actual dynamics of traction from it. A correct and fair 'Traction Pie' chart using the information provided would be:

How is this possible? Simple. Braking and Acceleration forces are ORTHOGONAL (Perpendicular) to cornering forces.

So that, according to Pythagoreas, instead of the total force being the sum of those forces, it is the Square root of the sum of the squares. Thus, the amount of traction used in the example is NOT 1.0. Instead, it is 0.7. That leaves 0.3 in Reserve.

Forces are always directional. That is, they are VECTORED quantities. In order for the 'Traction Pie' to represent reality, therefore, it would have to be a vector diagram. In that case, instead of the area of the circle representing total traction available, it must be that the RADIUS of that circle does that. In other words, if you were to apply line segments from the center of the circle of a length equal to the amount of force being described, and the DIRECTION of those line segments representing the vector, it would have much greater utility (and accuracy.)

Our current example would be represented this way:

It would be clear that since the vectored total forces line did not go beyond the edge of the circle that the tire was not about to skid or slide.

And if we then increased one of those forces from 0.5g's to, say, 0.9g's, the resulting diagram would look like this and a skid or slide would already have happened!

Please pay attention to what was just said. The MSF teachings have left virtually every graduate of their classes with the absolute belief that if you are in a turn you must NOT use your brakes without first standing your bike upright. What you just saw is how preposterous that belief actually is. Unless your bike is leaned over at close to 45 degrees and, therefore, taking nearly 1.0 full g's of lateral (cornering) force, you have the ability to use somewhat more braking force than you think without exceeding the traction limits of your tires. How much?

Well, let's look at a normal and reasonable example. You are traveling at 50 MPH in a curve that has a radius of 335 feet. As a result, your bike is leaned over at an angle of 27 degrees and you are experiencing lateral acceleration of 0.5g's. How hard can you brake in that case without exceeding the traction your tire's provide?

Again assuming that your tires (and the roadway) support 1.0g's of force before skidding or sliding, then you can apply as much as 0.87g's of braking force. That is a WORLD-CLASS BRAKING EFFORT before a slide will occur! Most riders cannot get a deceleration rate of more than about 0.80g's, even in a panic stop! (I should point out that though you will not slide in this scenario, you WILL widen your turn - perhaps a great deal!)

Here is the output of a model I created that shows this scenario for you. Note the 'Maximum Deceleration Rate' line near the bottom.

Now, please pay attention! The model shows a maximum deceleration rate that is higher than real! That, because until I modify it to include the effects of weight transfer in the calculation of that maximum for each tire, it shows a result for an imaginary vehicle having only a single tire - thus, without weight transfer effects.

Now if you REALLY wanted to reflect some reality with the 'Traction Pie' diagram and teach some valuable information along with showing a visualization, you might want to tell the students that the 'Traction Pie' is not really a circle at all. It is more like an oblong. That's right, some tires provide greater Braking/Acceleration traction then they do Cornering traction:

While others, perhaps those you want to put on your sport bikes for example, provide better Cornering traction than they do Braking/Acceleration traction:

But, hey, all of that defies the dumbed down approach - designed to 'make learning easier and more fun', so don't hold your breath.

See Spot. See Spot run.

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 201-220 - 218: ALL Riders Are RetreadsJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=4922Tips 201-220 Sat, 24 Mar 2007 11:10:57 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=4922 ALL Riders Are Retreads
(If they have ridden a motorcycle at least twice)

By: James R. Davis

Much has been made about the fact that many long term riders have at one time or another given up their riding in order to pursue their careers, raise a family, or for some other reason, then come back to the sport.

These riders, it is suggested, are far more likely to be represented in motorcycle accident and death statistics than are those who ride with a continuous history of doing so.

My reaction to those claims is: prove it. Do so without using anecdotal evidence such as "I knew a guy who was a 'returning rider' who was killed just last year." So? Have you not heard of other guys who died last year who had a continuous riding history?

But more to the point, there is no such thing as a rider who has had a 'continuous riding history'. Some people ride every weekend. That means they have taken a break from motorcycle riding for at least five days every week for some time. Others, far more in fact, live in climates where they must put aside motorcycle riding for at least three months in a row every year. Some, like me, have ridden motorcycles for more than 43 years and had at least one spell in four decades where he did not put his butt on a motorcycle saddle for a couple of years. We are all, in a word, retreads.

Which of the above, then, would you consider a rider with a 'continuous riding history'? If you don't touch a motorcycle for five days, are your skills on the sixth day as good as they were before those five days? If you do not ride for three months in a row, then when you finally do get up on your motorcycle are your skills undiminished from before? It is only academic to go on and ask if my skills after a couple of years of being away from the sport were as good as they were before taking my hiatus - we all know that they were not.

Three more significant questions have to be asked about these con-continuous riding history riders before you can begin to draw conclusions about how likely they are to become involved in a motorcycle accident:

Relative to how long they were away from the sport, how long did it take them to become as skilled as they were before they left?
How long had they been riding since they took their sabbatical?
What changes have occurred DURING that sabbatical?

If you have taken a one week sabbatical, my guess is that you have lost virtually none of your skills and, thus, it takes essentially no time to 'regain' them. It might take you a week of riding to recover the skill level you had prior to leaving riding this past winter. It might take you a month or more to recover skills lost from a multi-year 'vacation'.

So, it would seem to me that if the answer to the second question - 'How long has it been since you took your sabbatical?' - has been longer than those recovery times, it is no longer relevant that a sabbatical was taken at all - in particular as to your odds of having an accident.

But, then there is that third question - 'What changed?' Well, if what changed is the bike - your previous bike was a Honda 350 and the one you have now is a Ducati Monster, for example, all bets are off. You are no different than a new rider the first time you take that baby out on the street. Granted you don't have to learn such things as what a friction zone is and how to use it properly, but you do have to learn how it feels and functions on that new bike. If what has changed is that you used to ride dirt bikes and now you expect to do some slab pounding, you are essentially a new rider again - regardless of how many years of prior experience you had or how well your skills used to be honed. Let me be very clear about that ... if you rode a motorcycle TEN MINUTES AGO, then got onto an unfamiliar bike, you are a retread at that point!

In essence what I am trying to get at here is that we - ALL of us - have non-continuous riding experience. NONE of us can afford to have a smug attitude that goes something like: 'Because I've been riding for years without an accident and because my skills are at least as good as anybody else's out there, I will not become an accident statistic like those retreads' - because we are ALL retreads to one degree or another.

My overall opinion is that older men and women who return to motorcycling after any length of time away from the sport need to take the time they need to recover their skills, and after that period of time they are no longer more likely than any other riders to have an accident.

[Further, relative to fatality statistics, the older of these people DIE more often than younger riders with the same experience and skill levels for one fundamental reason - they break more easily.]

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 201-220 - 217: Your Motorcycle CANNOT Fall DownJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=4911Tips 201-220 Thu, 22 Mar 2007 19:58:26 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=4911 Your Motorcycle CANNOT Fall Down
(At any speed greater than 10 MPH)

By: James R. Davis

I have recently received a number of E-mails from new riders asking me to help them figure out how to deal with the fear they feel while riding at highway speeds and having to lean their bikes during turns. Invariably they tell me that they can't take those turns as fast as other riders do because they are afraid to lean the bikes enough to allow them to do so.

Despite the fact that their comments include all the information they need to know about their problem, they honestly don't get it. (That is, they know that if they do not go as fast as others do they will not lean their bikes as far as those others do either.)

So, here is a brief and possibly eye-opening response to those people and to those of you who are experiencing the same problem.

When you are moving at a speed in excess of about 10 MPH on your motorcycle, so long as you keep your tires on the ground, you CANNOT FALL DOWN. It is IMPOSSIBLE!

Balance is only required by you as a rider at speeds so slow that counter-steering doesn't work. Above that speed, not only is steering virtually effortless, it is the only thing that you CAN control about your motorcycle other than its speed. You are along just for the ride when traveling at speeds in excess of 10 MPH.

Your motorcycle does not have a brain and it does not, therefore, decide to do what you want it to, or not. Instead, it is just a dumb machine that ALWAYS follows the laws (of physics), even if you don't.

And, you do NOT decide what the bike's lean angle will be when you are in a turn - the bike does that for you automatically, as a result of following those laws of physics.

The amount of centrifugal force generated in a turn is determined, exactly, and invariably, as a function of the square of your speed and the radius of the turn you are in. The greater the speed or the shorter that radius is, the steeper that lean angle will be. When the amount of centrifugal force is exactly equal to the force of gravity (discounting any effect that a side wind might have), the bike will be leaned over at exactly 45 degrees. Less centrifugal force, because gravity is constant, results in a smaller lean angle while if it is greater than gravity the lean angle will be greater than 45 degrees. *YOU* control the amount of centrifugal force by changing speed or by changing the radius of the turn you are in.

So, for example, if when you are riding at 45 MPH on a particular curve your lean angle might be 30 degrees and when you speed up to 55 MPH on that same curve that lean angle might be 35 degrees. That is the angle at which the force of gravity which is trying to pull you down is exactly offset by the centrifugal force being generated.

Why should that matter to you? Because not only is it impossible for that lean angle to be less than the one determined by the laws of physics as I just described, but because it CANNOT BE GREATER THAN THAT - in other words, IT CANNOT FALL OVER!

In order for the bike to fall over that lean angle would have to increase to well over 45 degrees at which point your pegs would scrape HARD and that, in turn, would lift your tires off the ground (which is why, then, you fall down.) But we already know that the lean angle CANNOT BE GREATER than the angle at which the centrifugal force and gravity are equally offsetting each other. In order to reach a 45 degree angle or more you have to deliberately increase your speed or shorten the radius of the turn.

Let me be very clear about the above. *YOU* can decide only the direction and the speed of travel of your motorcycle. Those things, in turn, determine what the lean angle of your bike is - not you. Once you have reached a lean angle of, say, 40 degrees, if you do not increase your speed or shorten the radius of the turn, your motorcycle MUST maintain that lean angle - neither less than nor greater than that angle. So it CANNOT FALL DOWN.

The same is true at any lean angle. So long as your tires maintain traction and you are not dragging any parts of the bike, you CANNOT FALL DOWN.

There is something to be said about following the law, no?

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 201-220 - 216: Downshifting During Emergency BrakingJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=4897Tips 201-220 Sun, 18 Mar 2007 12:11:26 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=4897 Downshifting During Emergency Braking
(MSF teaches an Unsafe practice)

By: James R. Davis

The MSF insists that you downshift while braking in their range exercises. Indeed, if you fail to do that your performance is reduced in the class.

The logic for this, they explain, is so that you end up in first gear when you come to a complete stop so that, if you need to then quickly start moving again, you can do so without loss of time.

This is simply specious thinking, in my opinion. It suggests, for example, that either you are always in second gear when you begin braking or that you are to downshift several times while braking, even in an emergency situation.

But there is an even more obvious flaw in that argument. The technique they teach is to downshift at the start of your braking effort. In other words, you are encouraged to take the time when you are moving at your fastest speed in order to save time when you are not moving at all - after you have come to a complete stop. (You would think that if you don't let out the clutch lever during multiple downshifts you will not have lost any time. Untrue. The reason is not because of engine braking conflicts. It's because of the distraction that interferes with braking skill performance.)

Most of you have heard my arguments for covering your front brake any time you are moving faster than you can run. In essence, my argument is that by covering your front brake lever you save yourself about 1/10th of a second in reaction time or, at 60 MPH, about NINE FEET of stopping distance as compared to not covering that lever.

Note, please, that again we are talking about saving time when the motorcycle is moving at its highest velocity. So, advice by the MSF to downshift at the start of your braking effort is tantamount to advocating that you give away braking time while the motorcycle is moving at its highest velocity.

There is, of course, another even more important reason that you should NOT downshift while emergency braking. It takes mental effort and focus away from what may well be a life saving concentration on controlling your motorcycle during an emergency braking maneuver - a distraction when you simply cannot afford any distractions.

It is my opinion that downshifting while braking CAN be safely done during any normal gradual stopping maneuver but should NOT be done in an emergency stop effort. The MSF training is misdirected and counter-productive to the extent that it fails to differentiate between those kinds of maneuvers and it leads to longer stopping distance and greater time to stop during an emergency situation.

Studies have convincingly shown that in order to stop in the shortest possible distance and the shortest possible time you must disengage the clutch fully at the time you begin to brake.

Here, for example, is a chart that demonstrates the effect that clutch usage had on 77 emergency braking stops performed by professional riders performed and documented by the Federation Motorcycliste Du Quebec in 2004:

You see that the greatest deceleration rate, fstest time and shortest distance all were the result of fully disengaging the clutch lever at the start of an emergency stop effort.

Get into the habit of downshifting AFTER YOU HAVE COME TO A COMPLETE STOP.

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 201-220 - 215: CB or Helmet to Helmet Intercom?James R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=4850Tips 201-220 Sat, 10 Mar 2007 10:07:04 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=4850 CB or Helmet to Helmet Intercom?
Safety perspective

By: James R. Davis

Cash and I did a short ride a couple of days ago and while out on the road I had the pleasure of chatting with a couple of truckers using my CB.

I told them that I could only get a range of about a mile using the CB on my motorcycle and asked what kind of range they get with their rigs. Typically, the responses said, 'a couple of miles'. But then a BIG BOOMING response came in from a trucker who obviously had an illegally amplified CB rig and he said that he easily gets five miles.

That's when I realized that there are riders (motorcyclists) out there who seem to think that the only difference between CB's and helmet to helmet chat devices is cost. ??? (I mean, by definition you are not restricted to chatting with only one person when you have a CB.)

But that is certainly not the biggest difference between those choices. Your potential audience using a CB is vastly larger than one, and the majority of those you can talk to are in one way or another professional drivers when you use a CB.

You cannot imagine how good it feels when you are 1,000 miles away from home on a road you've never been on before trying to find a particular exit and you simply change your CB to channel 19, key it and say: "Any drivers out there who can give me some local information"? (They ALL call themselves 'driver' - a term of respect between them.) If you are within range, you are almost certain to get a friendly "What do you need to know? Come back." And shortly after that you will no longer be lost.

Remember what I said in the beginning? There are drivers out there who can handle ranges of five miles! That's five times what most motorcyclists can handle. Indeed, the area covered by a CB that can transmit 5 miles is close to 78.5 square miles while one that can transmit only 1 miles is only 3.1 square miles, so you could say that the more powerful rig is 25 times more powerful. However you are on a road that is pretty straight and receivers will almost certainly be on that road - either ahead of you or behind, so it is, from a PRACTICAL point of view, 'only' five times more powerful.

Since getting local information is not all you can do with your CB, you might want to consider the value of these things that you will hear by just listening on your CB:

'Smokey westbound at mile post 260'

'Debris in the fast lane westbound at mile post 260'

'Drivers, you might want to take the loop around I-10 as there is a major jam eastbound near the Galleria'

'Driver of that red Mack eastbound near mile post 185, you got your ears on? You are shedding rubber on your left side.'

Sure, you will hear a lot of colorful - really nasty - stuff as well. They are not all 'good guys', but they ARE all professional drivers and you can learn a lot from just listening.

Well, you can unless you saved a few bucks and opted for a helmet to helmet intercom rig.

FRS (Family Radio Service) rigs were introduced in 1998, I believe, and have both technical as well as range advantages over CB. They will become, in my opinion, the preferred rig for motorcyclists in time but for now what you need is to be able to reach the widest possible audience and that means the CB remains the best traveling solution until the FRS gains popularity.

Copyright © 1992 - 2010 by The Master Strategy Group, all rights reserved.
http://www.msgroup.org

(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 201-220 - 214: How to Save it if you do a StoppieJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=4682Tips 201-220 Fri, 02 Feb 2007 23:07:23 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=4682 How to Save it if you do a Stoppie
EASE OFF YOUR BRAKE!

By: James R. Davis

There is absolutely no chance that I would teach anybody to perform a Stoppie with his motorcycle and no rational, mature, mortal human being should intentionally try to do one. But because you might be riding an unfamiliar bike, or because of incredibly poor skills, or even because of trying too hard to master emergency braking technique, you just might find yourself sitting in your saddle when the rear-end of the motorcycle lifts its rear tire off the ground.

Must you end up in that case being thrown over the handlebars and landing face first on the asphalt? Absolutely not!

Let me emphasize some concepts here. A Stoppie is NOT when your rear tire comes off the ground - that happens with some regularity, from being overly aggressive with your REAR brake (your rear shock contracts and lifts the rear tire off the ground) or when riding over bumps on the pavement. Rather, a Stoppie is the result of being overly aggressive with your FRONT brake and causing so much weight transfer to occur that the resulting weight on the rear wheel becomes negative. That is, your bike's rear-end lifts into the air and drags that rear tire off the ground with it.

Some motorcycles simply cannot, under normal conditions, perform a Stoppie. GoldWings and most Harley-Davidsons, for example. Sport bikes, on the other hand, are quite prone to doing Stoppies.

Why? The ratio of the height of the bike's CG as compared to its wheelbase determines how efficiently weight transfer will occur for any given deceleration rate. A GoldWing's Weight Transfer ratio is usually very close to 1:2 (50%) while a sport bike, because of their relatively short wheelbase, will have a Weight Transfer ratio closer to 55%.

What that ratio does is determine how much weight transfers from the rear wheel of the bike to the front during deceleration. Suppose that the combined weight of the bike and rider is 1,000 pounds and it is distributed 55% on the rear wheel and 45% on the front wheel when the bike is not in motion. If that bike decelerated at a rate of 1g (32.2 ft/sec/sec) and had a Weight Transfer ratio of 50%, then 50% of 1,000 pounds would move from the rear tire to the front tire. As there was 550 pounds on the rear tire when the bike was not moving, when 500 pounds are removed from it there is still 50 pounds of weight holding that rear tire on the ground. Now if your rate of deceleration were only .5gs, then you would have transferred only 275 pounds of weight, but if you managed to attain a 1.1g rate you would transfer 605 pounds and the rear end weight would be negative. A Stoppie would occur. HOWEVER, the traction of your front tire is almost never sufficient to support a 1.1g rate of deceleration without skidding. So BEFORE a Stoppie would occur you would wash out the front-end. That's true for the GoldWing and HD, typically.

But in the case of a sport bike with a combined weight of 600 pounds, distributed 50% on the rear wheel and 50% on the front, then at rest there is 300 pounds of weight on the rear tire. If you were to brake (decelerate) at the rate of 1g on that bike, and if it had a Weight Transfer ratio of 55%, then 330 pounds (55% of 600) would be removed from the rear tire and moved to the front one which would make the weight on the rear tire a total of MINUS 30 pounds. THAT is doing a Stoppie. In fact, the weight transferred from the rear wheel to the front on a sport bike is usually sufficient to cause a Stoppie when you reach a deceleration rate of about .95g's. Because your front tire has sufficient traction to not skid at .95g's, a sport bike will do a Stoppie BEFORE it can do a front tire skid - usually.

The following graphic depicts a GoldWing at normal posture (in the background) and doing a Stoppie in the foreground. The same is true for any motorcycle - that is, what you will observe in the graphic is that the CG rises and the wheelbase shortens when the rear tire comes off the ground:

What that means is that because the height of the CG grew and the wheelbase shortened, the Weight Transfer ratio INCREASED! Indeed, the higher the rear wheel gets, the higher (more efficient) that ratio gets and, thus, the MORE WEIGHT is moved from the rear to the front wheel.

I trust that you now see where this is leading. IF YOU DO NOTHING when your Stoppie begins, YOU WILL GO OVER THE HANDLEBARS!!!! You MUST reduce your braking effort in order to stop (or reverse) the weight transfer increase.

What that means, in turn, is that the maximum rate of deceleration you can achieve with a sport bike is that rate at which a Stoppie occurs while a bike that cannot normally do a Stoppie can stop more quickly - even without skidding its front tire.

I have mentioned a number of times that GoldWings and most Harley-Davidsons cannot NORMALLY do a Stoppie and explained why. But if you happen to be 6'6" tall and weight 300 pounds, when you get on the saddle of your scoot you will have changed the Weight Transfer ratio meaningfully. You will have raised the CG! Just like sport bikes, it is the Weight Transfer ratio that determines how much weight gets transferred at any given rate of deceleration and you will have brought that ratio above normal. In other words, you had better not grab a handful of brake!!! (But if you do, immediately release it and you will not get thrown over those bars.)

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(James R. Davis is a recognized expert witness in the fields of Motorcycle Safety/Dynamics.)]]>Tips 201-220 - 213: Emergency Braking Practice SpeedJames R. Davishttp://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=4637Tips 201-220 Wed, 24 Jan 2007 04:55:02 -0500http://www.msgroup.org/forums/mtt/topic.asp?TOPIC_ID=4637 Emergency Braking Practice Speed
30 MPH is as realistic as is 60 MPH

By: James R. Davis

A very interesting question was asked by a new rider on my site: How fast should I be going when I practice emergency braking?

I suppose that many of you, like me, average speeds in excess of 60 MPH while we are riding and I also suppose that you might believe it is necessary, therefore, to practice emergency braking at a similar speed in order to make it 'realistic'.

Absolutely NOT!

Despite how fast a motorcycle can theoretically decelerate (very near 1g, or 32 ftpsps), *YOU* and your bike are more likely to be able to stop at a rate no faster than about 29 ftpsps or 20 MPH/Sec. That's about .9g's and beyond the ability of probably 90% of even the most experienced of riders.

Why is that important to know? Well, the fundamental risk to you as a motorcyclist when doing emergency braking is that you will lock your brakes and fall down. Locking your brakes, alone, is not particularly dangerous, but doing so almost always results in losing the balance of your bike and shortly thereafter its 'footing' - i.e., you dump the bike.

Another thing about the ability of well over 90% of even experienced riders is how short a time they can balance a bike. If your bike is at a dead stop, how long do you think you can keep your feet on the pegs before you must put a foot down to save the bike from falling over? For the vast majority of us it would be about 1 second.

If it takes longer than 1 second for you to stop a moving bike, in other words, then you cannot rely on balance alone to keep you from dumping that bike if you make the mistake of too aggressively using your brakes and locking it(them).

In fact, when you lock your brakes it takes some time before the bike ceases to be vertical - because of a slide (to the side) of a tire or other steering input. Only then must you try to correct the problem using your sense of balance. So, if you lock your brakes, perhaps 1/2 second later the bike is no longer vertical and about 1 second later you are on your side.

Let's put all of that into a coherent picture.

If you are close to maximum efficiency with your brakes, and use both of them, when moving at 20 MPH, you should be able to come to a complete stop in approximately 1 second. If you are too aggressive with your rear brake and lock it, then it will take you slightly longer than 1 second to come to a complete stop. But so long as it does not take you 1 1/2 seconds to come to that stop you will do so while still on your wheels. Any longer and you will likely come to a stop with the bike on its side because it will have fallen over.

The objective of emergency braking practice is to find how close you can come to a skid without actually causing a skid - that is, without locking a brake. So, in order of likely outcomes, during practice you will neither brake at the theoretical limits of the bike's ability nor will you lock your brakes, you will lock your rear brake only, you will lock both brakes (a very unlikely event while practicing), you will brake at the bike's limit. If you lock only your rear brake then you are likely to fall over if it takes longer than 1 1/2 seconds to come to a stop.

At 20 MPH, in other words, there is almost no chance of falling over before you come to a complete stop (and even if you do you will collide with the pavement going approximately zero MPH.) At 25 MPH you have reached a speed at which making a mistake in your braking (too aggressively using the rear brake and locking it) can result in you ending up falling over before you have come to a complete stop.

At 30 MPH you are tempting fate. Meaning, it is now dangerous for you to make a braking mistake.

Thereafter, meaning at any higher speed, the danger to you increases.

So, doing emergency braking practice at speeds up to 25 MPH is essentially without serious risk to you, and doing those practice sessions at 30 MPH is REALISTIC in the sense that you are clearly at risk if you do it wrong. But doing those practice sessions at any speeds higher than 30 MPH is both unnecessarily dangerous and no more realistic than if you do them at 30 MPH.

By the way, the reason that the MSF 'got away' with having their students do a rear brake locked skid to a stop exercise was that they did not allow their students to do so at speeds greater than 20 MPH. No deaths occurred and very few dropped bikes - and those drops occurred at about zero MPH. (AGGRESSIVE USE OF THE REAR BRAKE IS NEVER 'REASONABLE' OR SAFE and the MSF has finally learned that having students do it was irresponsible so they no longer do.)