Quote Originally Posted by Triskeliongirl View Post
Rotating weight means weight that is related to movement, i.e. wheels, tires, crank set, pedals.
To be more specific, rotating weight is the product of mass and distance from the center of rotation. On a wheel, the axle is not rotating mass. The hub flanges are, but they are so close to the center of rotation that they have little rotating weight. Likewise the cassette. The rim and tire constitute most of the rotating weight. A crank and pedals do rotate, but the radius is not very large.

For you folks who are taking or have taken calculus, try integrating r*M over a crankset (assume uniform density from r=0 to r=R) or over a wheel (assume all weight is either in the hub (r=~0) or in the rim r=~R). This exercise may make you want to use a compact crankset and 650C wheels (if rotating weight were the only concern). I'm getting an r-cubed dependence in the crankset and an r-squared dependence in the wheel. Can anyone confirm or deny my solution of the simplified problem?