You may have noticed that it is harder to balance on the wheels of a bicycle if you are moving slowly than if you are pedaling more quickly. This is because a rolling wheel has a tendency to remain upright on its own, by virtue of its spinning. This force is called precession. Precession is the force that causes a gyroscope (shown right) to overcome the force of gravity and to circle instead of falling.
Have you ever rolled a tire down a hill and watched it stay upright all (or most of) the way down? This is another example of precession.
