Shimano Dura-Ace R9100 Hollowtech II English Bottom Bracket

The Shimano Dura-Ace R9100 bottom bracket is the English-threaded bearing unit for Hollowtech II cranksets at the top of Shimano's road lineup. Designed for frames with 68mm or 73mm BSA-threaded shells, it provides smooth, low-friction rotation built to Dura-Ace standards. Preload adjustment is handled externally, making installation and fine-tuning straightforward with a standard bottom bracket wrench. Compatible with Dura-Ace and Ultegra Hollowtech II cranksets.