Originally Posted by
Looigi
If weight is a disadvantage up hill and an advantage down hill, there exists a slope between those two where the light and heavy rider would go the same speed for the same power output. (Mean value theorem...sort of).
That slope would be "0" I think, or close to 0 if you factor in a larger frontal area.
If we consider the squared resistance at higher downhill speeds we see that the lighter rider with the same power always has an advantage in velocity over the circuit if uphills and downhills are symmetrical.
to add: since the rolling resistance is negligible at higher speeds I think the difference due to weight alone is negligible on flats. Other things being equal though the larger guy usually has more power giving him the advantage.