Abstract

A rear suspension system for a two wheel cycle such as a bicycle or motorcycle having a main frame which includes a rearwardly or downwardly inclined down tube. A vertically pivotable rear frame assembly includes a pair of swing arms which extend rearwardly from pivotal connections on the main frame. Rear wheel fitments are carried by the swing arms. A pair of elongated flexible tubelike or rodlike chain stays extend forwardly from the rear fitments at a fixed angle relative to the swing arms. A tubular shock absorber assembly is supported on the down tube and has a spring urging a coupler portion thereof in a forward and upward direction. A bell crank assembly, pivotally connected to the underside of the frame, connects the chain stays to the coupler portion of the shock absorber assembly. Upward impacts on the rear wheel are reacted on the main frame as a downward and rearward force with a largely downward force component so pitching motion at the rear end of the main frame is minimized when moving over ground or highway irregularities or rough terrain encountered in off road riding. In one embodiment, the shock absorber assembly is supported on the forward side of the down tube; in another embodiment, the shock absorber assembly is inside an open rear ended down tube.