My motobecane 50v (78') varies, up hill no more than 28 max (usually 20-25), on flat ground about 30-33 mph, and downhill i actually hit 50 mph, I really don't think that was good for the bike so I only did it twice, once because I was just playing and the second time was with my friend behind me (in his car) so I could prove the bike would go that fast.- most hills (downhill) I try to take about 35mph (what I beleive to be as the optimal speed via anything).