I figured 80mm would be a good starting point, and I know that there are TONS of options out there as far as different brake setups, headsets and whatnot. Like I said, I'll replace whatever needs to be replaced as I go along. Right now I just want to get as much technical info on the bike as possible so I can start shopping for parts without dissassemble the bike and measuring it by hand. There's got to be a website or something out there that has that info. I might try contacting customer service at Trek to and see what they have to say.