Rear suspension for bicycles

Claim 1

A bicycle frame comprising: a main frame having a bottom bracket defining a crank axis; a plurality of chain wheels of differing diameters connected to said bottom bracket for rotation about said crank axis; a pair of lower arm members which each have a front end portion and a rear end portion, the front end portion of each of the pair of lower arm members being pivotally connected to the main frame at a pivot point for pivoting about a first pivot axis located above the horizon of the crank axis; a pair of upper arm members which each have an upper end portion and a lower end portion, the lower end portion of each upper arm member receiving a rear wheel axle at a hub point located on a hub axis, the lower end portion of each upper arm member being pivotally connected to the rear end portion of a respective one of the pair of lower arm members for pivoting about a second pivot axis spaced below the hub axis, a plurality of sprockets of differing diameters mounted on said hub axis; a shock absorber for limiting a path of movement of the upper end portions of the upper arm members and for limiting an extent of movement of the upper end portions of the upper arm members, said shock absorber being connected to the upper end portions of the upper arm members and being pivotally connected to the main frame, said shock absorber providing effectively all resilient resistance to movement of said upper portions of said upper arm members.