Bottom Brackets

- American style BB for older 3-piece cranks - American BB for 3-piece cranksets - Fits 68mm American frames - Steel construction - Weight: 517 grams - Shell: 68mm - Interface: 24 tpi - Spindle Type: SQR JIS - Cup Material: Steel

- Fits 3-piece crank set - Includes right and left cup, lockring and bearings - English type - Shell: 68/73mm - Cup Material: Steel - Weight: 123 grams

- With plastic washers - Shell: 8mm Allen head axle bolt

- One-piece bottom bracket cup set - Bearings included - Shell: 68mm - Spindle Type: OPC - Cup Material: Steel - Weight: 265 grams

- Forged steel body - Alloy cups - Chromoly spindle - Sealed bearings - Interface: English - Spindle Type: Square Taper JIS - Weight: 290-300 grams

Shimano's BB-UN55 Square Spindle Bottom Brackets are the unofficial standard for English-threaded cartridge bottom brackets. Quality, value, and durability come together to keep you cranking for many, many miles. - Fits JIS Square-Taper Cranksets - Hollow spindle - Crankarm fixing bolts not included

Shimano's Ultegra bottom bracket uses Pro Tour-proven technology for lighter weight and super smooth spinning, while still maintaining the same level of durability and stiffness. It's available in English, Italian, or Press Fit models.