Originally Posted by OldNick
Isn there not a 1/2? E = 1/2 m v^2.
However the same formula applies to everything on the bike. Why should the tyre of a bike, which rotates only as fast as the bike is travelling, and accelerates under the same rules, be _3 or more _ times as inertial?
To put something like a wheel and tire into rolling motion, you are moving it in a transverse direction along with the rest of the bike, but it also requires energy to accelerate the the wheel and tire. There is motion in more than just the direction of the bike.