I just bought a Specialized HR Pro Disc the other day and have decided that I don't care for the fork that came on it.. I'm a very light rider (130 lbs) and don't do much hardcore offroad riding. The bike comes with a Marzocchi MZ Comp 100mm fork that weighs 5.2 lbs. The SID Race weighs 2.87, which is a HUGE weight savings over the Marzocchi. I don't feel like I need 100 mm of travel and would like to shave some weight off the bike. Would stepping down from 100mm of travel to 80mm of travel effect the geometry negatively in any way? If so, would it be a big problem or something I could deal with? I do also realize that I would be moving from an elastomer fork to an air fork. I do mostly commuting/urban riding. Would an air fork offer any benefits for this type of riding?