Bottom bracket: The bearing system the pedals (and cranks) rotate about. Consists of a spindle to which the crankset is hooked up and also the bearings by themselves. There exists a bearing area over the spindle, and on Just about every from the cups that thread into your frame. Rim: https://minibikeengines37814.mybuzzblog.com/14742952/considerations-to-know-about-bike-parts-pedal