The seemingly simple two-wheeled machine that takes us from home to work, or from a picnic back to the car uses momentum, force and friction to get you where you need to be. Like everything in life, friction is both your friend and your enemy - where it occurs, and how much you have of it can mean the difference between a smooth ride and a jarring crash.
To understand how the friction rider works, we first need to look at the forces acting on a motorcycle in a straight line. Weight points down, and normal (which is always perpendicular to the bike's motion) points inward. These two forces cancel each other out, and the centripetal force is equal to the sum of the normal and weight.
But when the bike moves into a circle, the forces change. Normal still points down, but it is now not opposite the weight. This means that the net force is the weight, and it must be balanced by something that is not accelerating tangentially to the circle. Friction is that something, and it cancels out the weight's acceleration to maintain the same speed.
In the real world, there are other forces that can interfere with friction, such as aerodynamic drag and direct friction (which is caused by wind hitting the rider's outer skin). But these are secondary concerns. If you are able to master the concept of the friction zone, you will be able to use it every time you ride your motorcycle: from stopping at a stop sign, to shifting gears and moving off the line.
