Originally Posted by fmw
Weight isn't the issue for descending on a bicycle. Air resistance is.
I'm going to have to disagree with you here. Big riders with huge frontal areas creating more air resistance are able to descend (coast) noticably faster than lighter/skinny aero riders. I understand even a slight air resistance can slow down a light weight rider. I know aerodynamics come into play at a certain point here but I think weight plays a major role when descending. Of course when you put these two riders on a mountain top on the Moon they'll both descend at the same rate.
One reason why tandems quickly pick up some frightening speeds on descents.