A rugged but inexpensive bicycle frame comprises a tubular head post welded to the flattened forward end of a relatively large diameter tubular crossbar. The rear end of the crossbar is flattened laterally and provided with a concave rear edge. A tubular rear fork has a rounded bridge portion which is fitted to the crossbar rear edge so that the nominal plane of the rear fork is perpendicular to the headpost. Welds permanently connect the front and rear ends of the crossbar to the headpost and rear fork bridge portion respectively. There are openings in the top and bottom walls of the crossbar just forward of the rear end thereof for receiving a tubular seat post so that the lower end of set seat post extends appreciably below the crossbar. Welds permanently connect the seat post to the crossbar. A short tube is welded to the lower end of the seat post to support the pedal crank.
A joint assembly adjusts the height of a bicycle saddle and includes an elongated seat tube member, a joint member made of a carbon-fiber composite material, a seat post, and a hoop member. The joint member has an upper connecting portion, a lower connecting portion, and a longitudinal receiving chamber formed through the joint member from the upper connecting portion to the lower connecting portion. The upper connecting portion has a plurality of open-ended slots formed therethrough. Each adjacent pair of the open-ended slots define a flexible plate therebetween. The seat tube member is inserted fittingly into the receiving chamber and has a plurality of open-ended slots aligned with the open-ended slots of the joint member, and a shoulder portion which abuts against the bottom surface of the lower connecting portion of the joint member. The seat post extends downward from the bicycle saddle to engage movably the seat tube member. The hoop member is sleeved on the upper connecting portion of the joint member so as to lock the seat post on the joint member.
A bicycle frame constructed of a composite material and formed of an integral, one-piece unit having a W-SHAPED geometry when viewed from each side thereof.
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.
