I have a trek 3700 hardtail that I want to replace the fork on. It came witha 63mm rst fork that can handle rough streets but that is about it. I've been looking at the bike geometries on trek's website and I've been trying to figure out how much travel my new fork can have. my geometry only comes with a max of an 80mm fork through trek, but the next one up only changes the head angle by half a degree and barely at all on the offset...point is, how do I know how much travel I can have. I'm thinking about getting a u-turn fork so that if I get a full suspension frame later on this summer I can just dial up the travel. thanks!