Shimano UN55 Bottom Bracket

The BB is also durable, hard-wearing sealed cartridge bottom bracket with square tapered spindle fitting. Tech Info: Please note - The first two numbers in our options (eg. "68" 70 or "73") relate to how wide your bike's bottom bracket shell is in millimetres.

The other three ...The BB is also durable, hard-wearing sealed cartridge bottom bracket with square tapered spindle fitting. Tech Info: Please note - The first two numbers in our options (eg. "68" 70 or "73") relate to how wide your bike's bottom bracket shell is in millimetres.

The other three numbers (eg. 118) relate to how long your current bottom brackets spindle (axle) is in millimetres. The 68 and 73mm sizes are the "English thread" type, the 70mm size is the "Italian thread" type - please measure your bike's bottom bracket shell width to confirm which size you need.