Shimano Dura-Ace Track BB-7710 Bottom Bracket is NJS (Keirin) certified. This splined bottom bracket is available only in English threading and uses a sealed cartridge bearing system with steel cups. 109.5mm spindle length.
CARTRIDGE BOTTOM BRACKET SET
DURA-ACE TRACK, BB-7710,
SPLINED TYPE AXLE,
BSA 68-109.5MM,
NJS-TYPE