Flat = 36 mph.
Down a hill Ive gotten 52 mph (on a Giant Yukon with semi slicks, LOLOLOL), couldve pushed it but I was quite scared. Ive heard that if you maintain speeds like that the bearing in your freewheel can melt and seize up causing a lockup. That would SUCK!!!!
EDIT: This is all on concrete. On the trail my top speed comes in around 3 mph.
