I was discussing this with a friend: Say you are doing a tailwhip on a bike (bike spins around pivot at headtube) Simpify this by looking at it as a bar pivoted at one end, with a wheel mounted to the bar with the radius in the direction of the bar. We want to spin this around the pivot in the direction of the wheels axle. (The wheel is spinning, but I am not sure if this makes any difference?) Now, if we make the wheel's radius smaller, does the force required to spin the wheel/bar around the pivot decrease? The "back edge" of the wheel is closer to the pivot, so less torque is needed to turn it around the pivot, but the "front edge" of the wheel is further from it, so more torque is needed to turn it around the pivot? However, can the wheel not be though of a point mass, positioned at the axle? In this case, provided the wheel's mass does not change, the radius of the wheel is independent? Thanks.