A 650b fixie …yes and 700 or 26. From Traitor Cycles.
668 represents the outer wheel diameter with tire that the bike is designed around to maintain proper geometry, bb height and have no toe overlap. Our idea was to let the rider decide which wheel size was right for them while still allowing some flexibility in going larger or smaller. 668mm just happens to be the outside diameter of a 26 x 2.1” wheel, a 650b x 42mm and a 700c x 23mm wheel. With 668mm wheel we were able to keep the chainstays short, 375mm slammed, to give it a lively feel that is effortless to get off the ground. For the 700c purist the frame will fit up to a 700c x 38mm tire with plenty of room but there can be toe overlap on the smaller size depending on the crank you use.