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Cup-and-Cone Bearing
Traditional bicycle ball bearings use cup-shaped races and cone-shaped races, with the bearing balls rolling between them. They come in pairs, either with two cones on the inside, held between two cups, or, with two cups on the inside and two cones at the outside.
In a conventional threaded bottom bracket, the cones are part of the bottom bracket axle, and the cups thread into the bottom bracket shell of the frame. The left cup is adjustable, to permit the bearing to be fine tuned. It has a lock ring to secure the adjustment. The right cup is the "fixed cup", usually having a flange that bumps against the edge of the bottom bracket shell when it is screwed all the way in. In the case of hubs and pedals, the cups are part of the hub shell or pedal body, and the cones attach to the axle. One or both of the cones is adjustable, and usually has a locknut and a keyed washer to secure it.
