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Integrated Braking Systems
A marginal benefit that can save your life

By: James R. Davis



If, when you apply your rear brake, your motorcycle also applies front braking for you, then you have some form of 'integrated braking.' In the case of the Honda GoldWing, there are two front disc brakes and one rear disc brake. One of the front brakes is independently controlled by the front brake lever while the other front brake and the rear brake are both activated by the rear brake pedal.

Some people do not understand why integrated braking exists and are of the opinion that they are unsafe. There are some who actually disable (or want to) this function and tie the two front brakes together so that they are both activated at the same time and exclusively by the front brake lever.

The reason they do this is NOT in order to increase the amount of braking force they can employ on the front wheel, but in order to prevent using any front brake force at all under certain braking conditions. In other words, they want the ability to selectively use either their front or rear brakes, or both. This, because they fear that integrated braking increases the odds that on slippery roadways they will lock the front wheel with the resulting dumping of their bike.

This is a common concern by those that have had no experience with integrated braking systems, but is, in my opinion, an exaggerated concern.

Let's get something out of the way right up front - there is NEVER a time to aggressively use your REAR brake. IT is the most dangerous control on your motorcycle because it is so easy to abuse.

Under severe braking weight transfer results in far more load on the front tire than on the rear one. What that means is that it takes far less braking force to lock the rear wheel. Let's say, for arguments sake, that 70 percent of the bike's weight is on the front tire and 30 percent on the back one during a severe braking event, and let's also assume that your bike weights 1,000 pounds with you on it. In this case if you applied about 300 pounds of braking force to the rear wheel it would be close to sliding.

Your integrated braking system (at least in the case of a GoldWing) is setup up such that when you apply 300 pounds to the rear brake something between 200 and 250 pounds of braking force is applied to one of your front brakes. (This is because the size of the piston in the integrated front brake is smaller than the piston in either of the other two brakes as well as the pistons in the master cylinders.) Since there is 700 pounds of load on the front tire, it is clear that the integrated braking system cannot cause the front wheel to lock by itself. On the other hand, if you didn't use the front brake lever at all in this condition, you have applied only a total of less than 550 pounds of braking force (300 + up to 250) and that is not enough to have caused a weight shift resulting in 70% being on the front tire. In other words, you had to use the front brake as well in order to be in a 'severe braking' condition.

Let me review for a second: Braking causes a weight transfer towards the front. If you do not lock the rear brake, you CANNOT lock the front brake unless you also aggressively use the front brake lever. So, if you lock the front wheel you do so with the front brake lever, not the rear one.

If you agree that it is NEVER appropriate to aggressively use the rear brake, it becomes only marginally important when stopping aggressively. (Though that margin could be the difference between life and death.)

So, integrated braking should be viewed as providing an added safety margin when you need to stop aggressively. Whether the surface is dry or wet, the relationship between the two integrated brakes is the same and what has been said so far remains true.

What if, however, you overuse the front brake while using less rear brake than would cause the rear wheel to lock? Then it is entirely possible to lock the front wheel. This possibility is apparently what concerns inexperienced users the most.

I assume, because virtually all motorcycle riders know better, that you do not employ 'severe braking' while your bike is leaned over in a curve. That is, you straighten the bike up before you grab the binders. If that is the case, then what is the consequence of locking the front brake? A slide that you can abort by simply releasing some of the front brake pressure.

Since your SPINNING rear wheel provides gyroscopic stability for the majority of your motorcycle, (meaning you have not locked the rear wheel, just the front one), then your sliding front tire will not immediately dump you to the ground as it would if it were sliding in a turn. In other words, you have time to release the front brake to recover.

Most people, once they learn that the rear brake must never be used aggressively, are far better off having integrated braking than not because of the marginal increase in stopping power it provides.

But there is a time when they can get in the way. If you are driving at slow speeds on slippery surfaces (such as on a gravel covered parking lot), then the combination of both front brakes being used can cause the front wheel to lock easily. That is, since we are not talking about 'severe braking', then there is minimal weight on the front tire at this time and it is easier to lock that wheel.

If going in a straight line you can save the situation by simply releasing the front brake, just as before. But when you are driving on a parking lot it is not unthinkable that you are making a turn or two, and if you lock that front wheel when it is not dead center, you will dump the bike.

So, should you disconnect the integrated brakes to prevent a parking lot dump? NO! Just don't use your front brake lever in this case. As we discussed, your rear brake lever always applies more braking force to your rear brake than it does to the integrated front brake. If you do not lock the rear wheel with it, you will not lock the front wheel either.

Finally, it is NOT true that just because you have integrated braking it is impossible to apply rear-wheel braking without getting some front-wheel braking. How so? Just use engine braking rather than your rear-brake pedal.

Copyright © 1992 - 2019 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.)

     
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