Abstract

A generally hollow bicycle frame of resin impregnated fibrous material having a main tubular beam and cross tubular portions as required by single seat and dual seat bicycle frames. At the rearmost end of the main tubular beam is a cross tubular portion providing an upstanding seat support post and a downstanding pedal support post, and having a rearwardly and downwardly extending V-shaped rear wheel support member affixed to the seat support upwardly of the main tubular beam. For the dual seat frame, an additional cross tubular portion is provided intermediate the ends of the main beam, providing an upstanding front seat support and a downstanding front pedal support post. The frame is constructed of an innermost shell of fibrous material impregnated in synthetic resin and an outer layer of similar material. The junctions of the seat and pedal support post with the main tubular beam portion are strengthened by the main beam innermost shell extending continously, unbrokenly, through the junction. The innermost shells are constructed using male mandrels removed after vacuum bag cure of the shells. Subsequently, the innermost shell components are bonded together and overwrapped and overlaid with the outermost layer, serving thereafter as a mandrel for vacuum bag cure of the outermost layer, bonding it integrally to the innermost shells.