Surly Krampus Frameset - 29" Steel Chester Copperpot Small. The Krampus is the bike that started it all — the plus-size movement that is. For 2017 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.