I am unable to convince the heavies in my cycling group of this (possibly because I'm wrong) but here goes: being heavier does not make you descend faster. If you are 10% heavier (say) then there is 10% more gravitational force between you and the earth - but the thing is this is *exactly* offset by there being 10% more inertia for this force to overcome. .

There are fifty million demonstrations of this, none of which has overcome the popular misconception. Here is a neat old one: http://video.google.co.uk/videoplay?...91572259784994 - it doesn't work on earth because feathers are frightened of the earth. This is how come birds can fly.