I just purchased a Quest and would like to know what I have. Is it a Q100 or a 559 a V2,V3?
Q559 and Q451 refer to the wheel sizes the Quest was originally sold with, 559 of course being 26", and 451 being 20". The Q was intended to be packable in an airline-legal suitcase, with the 451 wheels and a short chainstay. If the Q was sold with 559 wheels, it had a longer chainstay to accommodate them. The color for all production Quests is a burnt orange, with some differences in decals.
V1 and V2 had a suspended fork, and could be ordered with either wheel size. V3 went to a non-suspended fork, and was sold only with the 559 wheels and longer chainstay (unless you custom-ordered). My Q (originally 451, since modified) is a V2, purchased in May 2014, right as they were making the transition to the V3.
Q
X100 is the follow-on to the Quest. Came in dark blue, dark green, or black. Frame is very similar to the Quest. 26" wheels. No idea what "X100" means, if anything.
Click on the "507" in my signature if you'd like to see how I modified mine over the years.