Originally Posted by
AdamDZ
It allows you to identify the bottom bracket. Then you get a tool for that bottom bracket. If your BB is Octalink then you get the Octalink tool, if your BB is ISIS then youo get ISIS tool, etc.
For road bikes, Octalink, ISIS and Shimano's cartridge square taper bottom brackets the same tool (Park's BBT-22 or BBT-32)
External cup bottom brackets (most all Shimano Hollowtech II, SRAM, Campy, FSA, etc.) use Park's BBT-19 or BBT-9
Campy's lower line cartridge bb's use Park's BBT-4
Campy's higher line cartridge bottom brackets (Centaur and up) use Park's BBT-5 which also fits Campy cassette lockrings.