Bottom Brackets

- Simple and reliable square taper bottom bracket - Replaces both BB-UN26 and BB-UN55 - Sealed cartridge bearings - Cr-Mo axle - For bicycles equipped with a chain case, select BB-UN300-K - For E-type front derailleur compatibility, choose BB-UN300-E - Fixing bolts not included; Shimano FC-E6000 bolts suggested

- Tiagra-level Hollowtech II bottom bracket - Compatible with all road Hollowtech II cranks

Shimano's Dura-Ace Bottom Bracket is perfect for Shimano's Dura-Ace crankset. It features durable composite construction, super-smooth sealed bearings and a plastic sleeve for additional protection.