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You can the entire collection of Safety Tip articles in a 33 Megabyte PDF Portfolio

 All Forums
 Motorcycle Safety
 Contrary Opinions
 Tip 31 - Do bikes out-brake cars?
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Robsalvv
Male Standard Member
205 Posts


Melbourne, Vic
Australia

Kawasaki

ZX9R

Posted - 05/23/2018 :  10:37 PM                       Like

https://www.msgroup.org/Tip.aspx?Num=031 is a worthy tip which also includes this sentence:

"I think most of you know that your motorcycles can stop more quickly than can an automobile. Indeed, a professional motorcycle racer can obtain a 1g deceleration rate, or more, on his motorcycle. (1g deceleration is 32 fpsps.)"

I'm not sure I'm posting up a contrary opinion, but this seems to be an appropriate forum to post it in all the same.

Do I take the above sentence in a strictly literal sense based of the words as laid out and take away from it that generally cars stop faster than bikes, but a bike ***CAN*** outbrake a car (in that this is a sometimes thing, they have the ability to outbrake cars presumably if certain conditions are in play), or is it saying in a general sense that bikes generally outbrake cars?

If it's the latter, then perhaps this is opening the door to a contrary opinion based on the conventional wisdom that with four tyres with bigger contact patches, brakes with usually bigger discs/bigger brake pads/better heat dissipation, a greater available traction as a result of a tyre's generally higher weight loading and less weight transfer due to lower CoM so that all tyres remain more effective than on a motorcycle, a car should theoretically and in a general sense out brake a bike.

??

I did a bit of a search of the site to see whether msgroup comes down on one side or the other of this "argument" but it seems to be mostly on the bike's side with a little ambivalence towards the car side.

The rest of the web seems mostly on the car side with a situational / conditional "it depends" additional run of discussion describing where a bike would outbrake a car.

I've seen comparisons that show that tricked up cars outbrake tricked up bikes all day every day, particularly with aerodynamic effects advantaging a car, but what about in the general sense out on suburban roads with average car tyres and OEM brakes and pads?? Is this a topic where we can be more definitive on which vehicle type can stop faster? Can we say one way or the other whether a car should generally be considered to be able to outbrake a bike?


Appreciate your thoughts.

Cheers



Edited by - Robsalvv on 05/24/2018 2:28 AM

scottrnelson
Advanced Member
6899 Posts
[Mentor]


Meridian, ID
USA

Honda

XR650L

Posted - 05/24/2018 :  7:08 AM
A quick internet search shows very few actual facts on the subject. It's easy enough to just measure the distances. Based on many years of reading car magazines, I think you can learn much more from a 70 mph to 0 stop than one from 60 mph. The stops from 60 always seem to be within just a few feet of each other, like around 124 feet or something. Those from 70 usually have a bigger range, like between 150 and 180 feet (again, my recollection, not necessarily the actual numbers).

I was able to find one test that measured braking, back in 1996, of a Dodge Viper vs a Yamaha 1000. The Yamaha stopped from 70 mph in 154 feet. The Viper took 18 feet longer. But they complained about the brakes on the Viper in multiple places in the article.

Article: https://www.caranddriver.com/compar...strip-page-2

With an average driver against an average rider on the street, I, personally, would expect the car to do better. Especially with anti-lock brakes. I definitely don't count on being able to stop in a shorter distance than a car and instead do everything that I can to avoid needing anywhere near maximum braking.
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DataDan
Advanced Member
541 Posts
[Mentor]


Central Coast, CA
USA

Yamaha

FJR1300

Posted - 05/24/2018 :  2:03 PM
My table of stopping distance from Motorcycle Consumer News road tests (which I maintained through 2015) shows an average distance of 121.7ft 60mph-0 or .99g for 500 some bikes tested over the past 20 years.

Here's a Motor Trend article about exceptionally short stopping distances for high-end sports cars: Fast Brake: 20 Best 60 to 0 Distances Recorded by Motor Trend. Spoiler: Number 1, a Corvette, recorded a 1.3g stop (90ft from 60mph).

That's sort of beside the point, though, since what we worry about day-to-day is the braking of Honda Civics and Ford F150s, etc. etc., which aren't nearly that good. There used to be a few tables of road test results easily accessible on the web, but they're not coming up today. ISTR that your basic mid-size sedan was in the .90g neighborhood, or 130ft 60mph-0.

The reason test results are not coming up (easily) in internet searches today is that news is dominated by poor braking performance by a Tesla Model 3, which caused Consumer Reports to withhold a recommendation. My hunch is that this is totally a software issue, not braking or tires.
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DataDan
Advanced Member
541 Posts
[Mentor]


Central Coast, CA
USA

Yamaha

FJR1300

Posted - 05/30/2018 :  9:01 PM
Regarding the Tesla braking issue raised by Consumer Reports. It was fixed with a software patch:


In an email to CR, a Tesla spokeswoman said that the company had improved the software for the Model 3's antilock braking system to adapt to variations in how the brakes might be used and to respond to different environmental conditions.

In CR's initial review of the Model 3, testers noted that the EV's 152 feet to stop from 60 mph was 7 feet longer than a Ford F-150 pickup's stopping distance, and 25 feet longer than Teslas own Model X SUVs. In retesting after the software update was downloaded, the sedan stopped in 133 feet from 60 mph, an improvement of 19 feet.

The new shorter distance is typical for a compact luxury car and matches the 133 feet that Tesla claims its own testing found, using the same tires as those on our Model 3.



For info, stopping distance from 60mph of 133ft is average decel of 29ft/s^2 or .90g.
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rkfire
Advanced Member
1700 Posts


Stratford, CT
USA

Suzuki

Bandit

Posted - 06/09/2018 :  7:16 AM   Join poster on Facebook as Friend  
It seems to me, looking at magazine tests both cars and bikes, there is the great performing of both. Then the poor performing of both. Then the average performing, which is the majority.

The best of the best in both 2 and 4 wheelers, the cars win.

The average in both 2 and 4, are comparable.

Same with the worst, if you count a couple 3 wheelers with the bikes.

I think the bottom line is, you want a safe distance following traffic, and you do what's necessary to rid yourself of a tailgator.

I think motorcycles used to have the advantage of grippy tires, but now a days the cars getting equivalent.

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Baggsy
Male Advanced Member
725 Posts
[Mentor]


Ottawa, Ontario
Canada

Suzuki

09 Wee

Posted - 06/21/2018 :  7:15 PM
I try to assume that anything in front of me can out brake me,
anything behind me cannot, and act accordingly.
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