Rear wheel suspension for a bicycle and bicycle equipped therewith

Abstract

A suspension assembly that is formed of an essentially horizontal swing arm which is pivotally attached at one end to the underside of a bicycle frame by a pair of short links and which carries the rear wheel at an opposite end. The geometry of the suspension assembly is designed to produce a substantially straight line trajectory of the rear wheel in an upward and rearward direction at an angle that is preferably 20.degree.-30.degree. with respect to a vertical line through the wheel axis of rotation to increase traction, making the acceleration forces apply an upward vertical force component to the frame, and a downward component to the frame under braking, independent of wheel position, that reduces rear frame lift (pitch). Furthermore, to obtain a constant pedal 'feel,' the suspension geometry is also designed so that the maximum vertical height movement of the pedal crank axis of rotation can be kept to less than 5% of the vertical wheel travel (e.g., a 0.25' crank axis height increase for a 4' vertical wheel travel). The suspension is designed to attach to a standard frame leaving room for mounting of the derailleur between the frame and the rear wheel. In a particularly preferred form, the swing arm assembly is provided with a tubular derailleur mount and an upper tube to which the rear wheel brake assembly can be mounted.