Patent ID: 7156764

Claim:
A drive sprocket for a bicycle crankset, said drive sprocket comprising: a toothed ring, the ring comprising teeth having one pitch in correspondence with one chain pitch, the ring being divided into a plurality of segments, the segments being borne by a frame, the frame being rotationally movable about a crankset axle, each said segment being movable with respect to the frame in a plane perpendicular to the crankset axle between a low position and a high position in which each said segment is further distant from the crankset axle, thereby defining a small diameter state and a large diameter state of the sprocket, a system for transferring each said segment from one of said low and high positions to another of said low and high positions, and an indexing mechanism to control the system for transferring said segments, wherein each said segment is floatingly mounted with respect to the frame, and wherein said system for transferring each said segment between said low and high positions transfers each said segment in guided movement along a trajectory with respect to the frame, said trajectory of movement having a radial component and a tangent component, said tangent component being greater than zero.