Eccentric bottom bracket assembly
AssigneeTrek Bicycle Corporation
InventorsTravis Braun, Andrew Krautbauer, Michael Leighton
Life of this patent
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Abstract
A bottom bracket assembly of a bicycle that cooperates in an eccentric or off-center manner with a bottom bracket shell of a bicycle frame. The eccentric bottom bracket assembly has a cylindrical insert with an off-centered opening for receiving a spindle that connects to cranks of the crankset. Rotating the cylindrical insert repositions the off-centered opening relative to at least the longitudinal direction of the bicycle and thus can be used to adjust the tension in the flexible drive member of the bicycle. A worm gear arrangement provides controlled manipulation of the position of the insert relative to the bicycle frame.
Claims16
A drive system for a bicycle, comprising:
- a crankset that includes a set of pedals;
- a first sprocket connected to the crankset and rotatable with revolution of the set of pedals;
- a second sprocket adapted to drive a wheel of the bicycle;
- a flexible drive member extending between the first and the second sprockets;
- an eccentric bottom bracket assembly that is engaged with the crankset, the eccentric bottom bracket assembly including an outer shell having an inner surface and defining an opening;
- a worm wheel positioned in the opening and connected to the eccentric bottom bracket assembly, wherein the crankset is offset from a center of the worm wheel;
- and
- a worm engaged with the worm wheel such that rotation of the worm manipulates a position of the crankset relative to the outer shell thereby adjusting tension in the flexible drive member;
- wherein the worm wheel includes a removable curvilinear track that is fastened to the circumference of the worm wheel, the worm wheel includes a cylindrical body having an outer surface with a groove formed therein;
- the track lies in the groove that is engaged with the worm;
- and the track comprises a plurality of notches formed radially through the track.
An eccentric bottom bracket assembly for use with a bicycle frame, comprising:
- a cylindrical insert having an off-centered opening adapted to receive a shaft connected to a pair of cranks of a bicycle crankset;
- and
- a worm gear arrangement operatively engaged with the cylindrical insert to rotate the cylindrical insert;
- wherein:
- the cylindrical insert has an outer surface and a channel formed in the outer surface,
- the worm gear arrangement includes a removable track that lies in the channel and is fastened to the channel of the cylindrical insert, and the track comprises a plurality of notches formed radially through the track.
A method of adjusting tension of a flexible drive member of a bicycle drive train, comprising:
- rotating a worm that is engaged with a worm wheel to manipulate a position of an axis of rotation of a crankset relative to a bicycle frame;
- wherein the worm wheel includes a cylindrical body having an off-centered opening formed therein and wherein the off-centered opening is adapted to receive a spindle attached to the crankset, the cylindrical body has an outer surface and a channel formed in the outer surface,
- wherein the worm wheel includes a removable track fastened in the channel to the cylindrical body, and wherein rotating the worm causes the removable track to crawl along the threaded shaft to rotate the cylindrical body relative to the worm, and the track comprises a plurality of notches formed radially through the track.
Dependencies are inferred from the claim text.