Shimano BB-UN300 Bottom Bracket
Product Details
The Shimano BB-UN300 Square Spindle Bottom Bracket provides dependable performance for JIS square-taper cranksets, ensuring smooth pedaling and precise drivetrain alignment. Designed for BSA/English threaded frames, it delivers proven compatibility with multiple spindle length options to achieve optimal chainline and efficient power transfer.
Engineered for a 68 mm BSA/English threaded shell, the BB-UN300 features a hollow spindle construction that reduces weight while maintaining long-term durability for reliable daily riding. This bottom bracket allows precise adjustment to optimize shifting performance and drivetrain efficiency with JIS square-taper cranksets. Straightforward installation makes it ideal for both new builds and replacements, proving that a fundamental component can deliver consistent, trouble-free performance at the heart of every drivetrain.
Key Features
- BSA/English Threading Compatibility – Designed specifically for 68 mm shell width with reliable 1.37" threading for secure, long-lasting installation
- Hollow Spindle Construction – Lightweight design maintains durability while ensuring smooth power transfer and efficient pedaling performance
| Component | Specification |
|---|---|
| Spindle Interface Type | Square Taper JIS |
| BB Shell Width (mm) | 68 |
| Bottom Bracket Shell I.D. | 1.37 |
| Spindle Length | 113 |
| Defined Color | Black |
| BB/Frame Interface | English |
| Crankarm Fixing Bolts | Sold Separately |
| Spindle | Hollow |