I share what I was taught at police motor school, and it is what I pass on in class.
This is all based on the results of extensive LAPD motor accident investigations.
Take a typical riding scenario riding along at 50mph on a "Two Wheeled In Line Articulated Vehicle", fancy words for motorcycle. You have "two wheels", they travel straight when they are "in line", and there is "articulation, or movement" at the handlebars. We the rider, or "the load", sit behind the bars, somewhere just in front of the rear wheel.
As the bike moves along at 50mph:
The front and rear wheel are in alignment.
Both wheels are rolling forward at the same speed
Now for whatever reason, a deer runs out, someone turns across your path of travel, whatever reason, you have to BRAKE. As you apply BOTH brakes, the front end dives down and becomes heavier as weight transfers forward, and the rear end becomes lighter and comes up. As a result, the rear has a higher propensity to lock up, because it is becoming lighter and has less tire contact and less traction. If you have ever locked up a rear wheel, chances are you may have felt is slide to the side. It can slide either to the left or the right, but for the sake of this explanation let's say it slides to the right.
So now the bike is moving along and......
The front wheel is rolling along at 50mph and pointed straight
The rear wheel is NOT rolling at all (0mph), and is pointed off to the side as the rear end slides around.
Picture in your head ONE motorcycle and each wheel is pointed in a different direction. The front is straight and rolling forward, and the rear, which has slid to the right and is OUT OF alignment with the front wheel is NOT rolling at all. We the load are sitting in front of the rear wheel, so our body is out of alignment with the front end too.
Now their studies have shown that when you release the rear brake, that rear tire suddenly gains immediate traction and starts rolling, and goes from 0mph - 50mph in half a heart beat. And it travels in the direction it is pointing in,...... out of alignment with the front wheel and off to the side. This action can violently snap the whole rear end of the bike to the right using the steering stem as a hinge, and throw the rider off the bike to the right and over the bars (High Side). Sometimes what happens to inexperienced riders, is that when they hear that rear tire screeeeching, and they feel the rear end sliding around, they do on their bike what they do in their car, which is release the FOOT BRAKE PEDAL (remember in a car ALL we have is ONE brake pedal) which causes the above described high side. That is why on a non-ABS equipped bike they advocate keeping the rear brake locked. The other mistake some riders make is that they relase the brake before the bike stops. They lock it up and go 50-40-30-20-10mph and then release and are STILL thrown. Now I know there are instances where the locked rear end can come back around in line with the front end and riders have managed to release the rear brake at that one moment when the bike is back in alignment. And yes, while that CAN happen, I would not count on it happening at that moment.
So what can we do while the rear end is locked up and is sliding around? USE THE FRONT BRAKE, because it is the ONLY braking system we have left. Apply a good progressive squeeze until the bike stops. Hold onto the front end, keep your head and eyes up, and use that front brake to stop. If you lock up the front end, release, regain control of the front, and reapply with a firm progressive squeeze. Keep that rear locked up. And remember as long as you have control of the front end, you can still steer the bike even with the rear locked. It may not be as much control but it may be enough to get you out of harms way.
Having said all that, there are situations where you can release the rear brake, and that is low traction surfaces. Dirt bike riders often intentionally lock up the rear to "bring it around", then "gun it" to complete the slide. But that is in soft forgiving dirt while riding a lighter motorcycle. On clean, hard, high traction pavement with a heavy Harley, keep it locked up. On the street you may be able to get away with it on a wet road, but not on dry. On dry hard surfaces, when released, that rear wheel will bite into the road and that immediate traction may launch you.
Now I'm sure there are thousands of scenarios of "what coulds" out there, but this is what I was taught, this is what I practice, and this is what I pass on to others.
Mark
Author
Topic: Things amateurs don't like.... (Read 6961 times)