BB91-42A Press Fit Bottom Bracket (new in box)

The Shimano SM-BB91-42A is a professional XTR-level press-fit bottom bracket designed for HollowTech II MTB cranksets. The cups are constructed from a fiber-reinforced polymer, which significantly reduces the potential for creaking and prevents damage to high-end frames.

This maintenance-free assembly features advanced sealing to keep out water and grit, ensuring smooth rotation in the worst trail conditions. It is compatible with both 89.5mm and 92mm shell widths, utilizing a 42mm cup diameter for a secure and easy press-fit installation.