"Steer" - To direct the course of.

When your motorcycle is stable in any course, whether in a straight line or in a curve, it is your rear wheel that is primarily responsible for maintaining that course and stability. Indeed, it's the job of your front wheel to DESTABILIZE the bike in order to change course. That is, your front wheel changes course, your rear wheel maintains it.

How is that possible? Well, I suppose it is easiest to think of in terms of influence. A spinning rear wheel provides gyroscopic stability to over 80% of your motorcycle (including yourself) because it is directly connected via its axle/swing-arm to the frame of the motorcycle. The front-end is only indirectly influenced by the spinning rear wheel.

When a motorcycle is stable it will maintain its current course until an outside influence or steering input to the front-end results in destabilizing it and a new course is sought that will once again result in a stable motorcycle.

Proof that the rear wheel is directing the course of your motorcycle is easy to come by. Watch any motorcycle that is performing a 'wheelie'. Whether it is going in a straight line or it is in a curve, the motorcycle will continue that course even while the front wheel is off the ground.

The significance of this otherwise esoteric bit of insight should be to cause you to rethink about locking your brakes. For example, it should now no longer be a surprise that if (while going straight) you lock your rear brake and cause a skid that the motorcycle does not simply drag the rear tire along in a straight line - the majority of the motorcycle is deprived of the stabilizing effect of a spinning rear tire and it will try to fall over to one side or the other. On the other hand, if you lock your front brake (while going straight) and cause the front tire to begin to skid, there is every reason to believe that (so long as the rear wheel continues to spin with some speed and you leave the front wheel pointing straight ahead) the bike will continue to stand tall and track straight while you correct the problem (by releasing the front brake lever.)

Indeed, so long as there is meaningful speed and you are moving in a straight line, locking the front brake (for a brief time) is less dangerous than locking the rear brake. Obviously you do not want to lock either brake, ever, but it will happen. Further, we all know that we should not aggressively use either brake while the bike is leaned over in a curve. But now you should know that it is NEVER reasonable to aggressively use the rear brake, and why.

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