What is the difference between a Cartridge bottom bracket (BB) and a Semi-cartridge BB?
Cartridge BBs are standard these days on better quality bicycles. The cartridge BB consists of a single unit (apart from a loosely attached cup), that is screwed into the BB shell of the frame. No adjustment is necessary. Normally cartridge BBs are not serviceable, and must be replaced at the end of their life. The semi-cartridge BB is a hybrid, somewhere between a traditional cup and cone BB and a cartridge BB. Parts are enclosed in a cartridge but the bearings still need to be adjusted before securing the lockring.
