# US 4,398,740 A · Chain drive for a bicycle > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,398,740 A - Document ID: US4398740A - Status: Granted - Kind: A - Application number: 06/328,124 - Filed: 1981-12-07 - Granted: 1983-08-16 - Earliest claimed: 1981-12-07 - Inventors: Victor L. Clem - Web page: https://patentgrep.com/patent/US4398740A ## CPC - B62M 9/02: of unchangeable ratio - B62M: RIDER PROPULSION OF WHEELED VEHICLES OR SLEDGES; POWERED PROPULSION OF SLEDGES OR {SINGLE-TRACK} CYCLES; TRANSMISSIONS SPECIALLY ADAPTED FOR SUCH VEHICLES (arrangements or mounting of transmissions in vehicles in general B60K; transmission elements per se F16) ## Abstract A chain drive for use on a bicycle having a conventional frame and wheels. The chain drive comprises a wheel hub mounted for rotation on the frame. The opposite end portions of the hub are disposed on opposite sides of the frame, respectively. Two sprocket devices are mounted on the opposite end portions, respectively, of the hub for imparting rotation thereto. A pedal operated crank is also mounted for rotation on the frame, and includes two coaxial sprockets secured to the opposite ends of the crankshaft. The crank sprockets are axially spaced, parallel and disposed on the opposite sides, respectively, of the frame. The two sprocket devices and the two crank sprockets are radially aligned, respectively, one sprocket device being associated with one crank sprocket. Two chains are mounted on the aligned sprocket devices and crank sprockets, respectively, for driving the wheel hub by means of the crank. ## Claims ### Claim 1 A double drive wheel hub assembly for a bicycle comprising a wheel hub having opposite end portions, two sprocket devices mounted on said opposite end portions, respectively, for imparting rotation in a common direction to said hub, said sprocket devices being free wheeling relative to said hub when the latter is rotating in one direction but are drivingly engageable therewith when rotated in the same direction at a rate faster than said hub, said two sprocket devices being commonly threadedly coaxially secured to said hub end portions, respectively, means threaded oppositely on one of said end portions for further retaining the adjacent sprocket device on the same end portion, the threading of said means and the other sprocket device being in a tightening direction when said sprocket device is rotated at said faster rate. ### Claim 2 (depends on 1) The hub assembly of claim 1 wherein said means includes a threaded reduced diameter distal end portion on the wheel hub which defines a radial shoulder with the adjacent end portion of the wheel hub, and a lock ring threaded onto said distal end portion and engageable with said shoulder thereby to further retain the adjacent sprocket device on said wheel hub. ### Claim 3 (depends on 2) The hub assembly of claim 2 wherein the threading of said sprocket devices on said end portions, respectively, is right-hand and the threading of said lock ring is left-hand. ### Claim 4 (depends on 3) The hub assembly of claim 3 wherein said opposite end portions onto which said sprocket devices is threaded are of equal diameter. ### Claim 5 (depends on 1) The hub assembly of claim 1 wherein said means includes a threaded reduced diameter distal end portion on the wheel hub, and a lock ring threaded onto said distal end portion to further retain the adjacent sprocket device on said wheel hub. ### Claim 6 For use in a bicycle having a frame and wheels, a pedal operated chain drive comprising a wheel hub mounted for rotation on said frame, said hub having opposite end portions on opposite sides, respectively, of said frame, two sprocket devices mounted on said opposite end portions, respectively, for imparting rotation in a common direction to said hub; a pedal operated crank mounted for rotation on said frame, two coaxial sprockets secured to said crank for rotation therewith, said crank sprockets being axially spaced, parallel and disposed on opposite sides, respectively, of said frame; said two sprocket devices and said two crank sprockets being radially aligned, respectively, one sprocket device with one crank sprocket; and two chains on said aligned sprocket devices and crank sprockets, respectively, for imparting rotational drive from said crank to said wheel hub; said sprocket devices being free wheeling relative to said wheel hub when the bicycle is coasting forwardly but are drivingly engagable therewith when rotated in a foward direction at a rate faster than said wheel hub; said crank including a common shaft rotatably mounted on said frame, said crank sprockets being secured to the opposite ends, respectively, of said shaft such that said two chains lie in parallel planes, respectively, on opposite sides of said frame; said two sprocket devices being alike, said two crank sprockets being alike, and said two chains being alike, said sprocket devices, said crank sprockets and said two chains being symmetrically arranged on opposite sides of said frame and with respect to said wheel hub and crank; said two sprocket devices being commonly threadedly coaxially secured to said wheel hub end portions, respectively, means threaded oppositely on one of said end portions for further retaining the adjacent sprocket device on the same end portion, the threading of said means and the other sprocket device being in a tightening direction when forward driving force is imparted to said wheel hub. ### Claim 7 (depends on 6) The chain drive of claim 6 wherein said means includes a threaded reduced diameter distal end portion on the wheel hub which defines a radial shoulder with the adjacent end portion of the wheel hub, and a lock ring threaded onto said distal end portion and engageable with said shoulder thereby to further retain the adjacent sprocket device on said wheel hub.