The Shimano Dura Ace BB-R9100 Bottom Bracket shares the same performance enhancing features as the previous 9000-series bottom bracket, using small diameter bearings to shave weight, reshaping the cones for better durability, and improving the seals to reduce friction while maintaining the same water and debris resistance.
Available in English-threaded 68 mm shell and Italian-threaded 70 mm shell-width versions. Includes TL-FC24 adapter for use with standard external bottom bracket tools designed for 44 mm OD cups. Compatible with the 24 mm spindles found on Hollowtech II cranks. Claimed weight is 65 g.
A guide to bottom bracket standards.