The Krampus is the bike that started it all -- the plus-size movement that is. The Krampus features Surly's Gnot-Boost rear hub spacing of 145mm; compatible with Boost 148 x 12mm thru-axle, 142 x 12mm thru-axle and 135mm quick-release hubs. - 100% Surly 4130 CroMoly steel frame and fork; double-butted main triangle and 44mm headtube - New tube-set uses the same trumpet tubes found on 2017 Karate Monkey frame - Gnot-Boost adjustable rear dropouts - Internal dropper seatpost routing - 30.9mm seat tube - Designed to fit up to 29 x 3.0" tires