Yes, well of course all mechanics are based on the principle of the lever, which is the fundamental unit in mechanics and the lever is quite simply a means of altering the power available in the component. If you want to drive... if you have a wheel driving a component and you want to speed up the rotation of the component, then you make it smaller, which is exactly the same thing as making the driving wheel bigger. The end result is that you always divide the long end of the lever by the short end of the lever, and that gives you the lever ratio, and all mechanics are based on that lever ratio. It's not always obvious to see it, but it's there in the mechanism. Even the wheel is based on the lever, and in fact the bit of the wheel that's on the ground doesn't move, it's the rest of the wheel that's moving. You could only be sure if you took the rim off and rode on the spokes and each spoke would be stationary till it was lifted off the ground by the following spoke, and the lever ratio is the distance between the hub and the ground and the hub of the top of the wheel gives you the ratio, which is 50/50... 1:1.