Originally Posted by
mschwett
yes, and the force which acts/depends on mass is gravity, so the root cause of moving downhill at all is gravity! that was my initial and subsequent point, despite being well aware that the rate of acceleration from gravity is not dependent on mass. i remember that much physics
with dramatically reduced gravity but similar aerodynamic friction (say inside a habitat on the moon), the result would be different.
In practical terms, the actual variables involved here are mass, air resistance and rolling resistance. Of those variables, mass is the most important when comparing riders on similar bikes.
Tandems are a good example of this. Roughly double the mass of a single rider, but with almost equal air resistance. With twice the momentum and potential energy, tandems reach a much higher terminal speed.