bottom bracket
Crank spindle bearing assembly
The bottom bracket is the bearing assembly at the base of a bicycle frame where the crankset attaches, allowing the pedals and chainring to rotate smoothly.
It sits in the bottom bracket shell—the cylindrical housing at the junction of the down tube, seat tube, and chainstays.
Various standards exist: threaded, press-fit, and others that mechanics love to debate.
- frameSupporting outer structure
- axleShaft for wheel rotation
- spindleRotating rod for thread
- pedalFoot-operated lever
- chainringBicycle's front sprocket
creaking · shell · crankset · bearing · BSA · threads · press · torque · crank arm · chainstay · cup · press fit · grease · cartridge · bicycle · watts · stiffness · derailleur
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