Shimano UN55 English SQUARE-JIS 73x113mm Bottom Bracket
- 25% more durable than UN54 with alloy left hand cup
- Traditional square JIS 2-degree taper crank-arm interface
- Offered in either English (BC1.37 x 24tpi - RH/LH) or Italian (M36 x 24tpi - RH/RH) threads