Abstract: A bicycle having forwardly and rearwardly extendible guide wheels and a pivotably mounted lateral outrigger wheel to allow use of the vehicle as a bicycle on a solid roadway or a velocipede on railroad tracks. The forward and rearward guide wheels adjust laterally to accommodate a wide range of rail sizes and the outrigger wheel adjusts laterally to accommodate normal rail spacings. With the appurtenant wheels folded to an inoperative position, the vehicle may be effectively operated as a normal bicycle.