My peddling stops being effective around 106-108. But there's a BF racer (Carpe Diem? from Connecticut?) who has a blog. My recollection is he was around 245 and ruing that he couldn't hit higher rates that he used to be able to achieve. His words in his blog seem quite believable, and I've read at least one other BF rider claim over 250 IIRC (fixed gear downhill), but I can't even fathom the possibility.