this builds on a question i asked a few weeks ago... if my bike has 135 rear spacing, i've been told that i can get a hub designed for 120 and space it out if the axle is long enough... easy. if it's not long enough i can change out the axle for a longer one? is this easy? are axles pretty much all the same or what do i need to watch out for? i've taken apart my surly hub before to replace the bearings, so i know HOW to do it, provided i have the right parts.