Originally Posted by vadimivich

This kind of makes me laugh that you posted this, because you can't see the answer right in front of your nose. The reason the model that Mark McM posted on the WW forum works is because he is also calculating the benefit of the inertial forces that a heavier wheel is effected by. The same thing with a flywheel - they stay at speed once you spin them up ... the energy from the original spin up isn't wasted, it's just delivered across a longer time frame. Same thing with a bicycle wheel - a heavier wheel actually has reverse benefits from a lighter one in that it requires more effort from friction to slow it down. In all practicality, for bicycle purposes that means that rotating mass is a zero sum game - bearing smoothness matters far more, since it's where friction is being applied. All in all, a 15 pound bike will go the same speed with the same power and gearing no matter how the weight is distributed.

That doesn't mean that lighter rims don't offer benefits when quick accelerations are required (say, field sprints or explosive moves on a climb) and heavier rims probably are actually superior in disciplines like time trials where accelerations are kept to a minimum and constant delivery of power is the goal.