BB-7700 has a 22mm splined, hollow spindle; fits FC-7700/FC-7703/FC-6500/FC-6503/FC-5500/FC-5501/FC-5503/FC-5504 cranks * Use TL-UN74 (TL6028) installation tool * Track BB-7710 has a 22mm, splined, hoow spindle, cartridge beaRingsand steel lockring