I ride mostly with guys who out weigh me by quite a bit and on descents I can pedal my heart out in my biggest ring (52 on front, 11 on back) and they can still beat me down the hill without pedaling, so I believe weight does factor in quite a bit. On our last ride we were going down a pretty steep section and DH and our other buddy were doing 53+ MPH and I was at 47MPH.