Bottom brackets
Shimano Shimano BB-UN300 Bottom Bracket
BSA 68 mm · 122.5 mm spindle
Compatibility: reviewed
Known specifications can be used by the compatibility engine.
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Catalog trust
Evidence and freshness
Technical-source dates and retailer offer checks are separate. A retailer check does not validate compatibility.
Report a correction- Technical review
- Jul 29, 2026
- Compatibility review
- Reviewed Jul 29, 2026
Approved technical sources
- Shimano bottom bracket specificationsManufacturerSource checked Jul 29, 2026Evidence reviewed Jul 29, 2026
- Shimano crankset and bottom bracket compatibility C-449ManufacturerSource checked Jul 29, 2026Evidence reviewed Jul 29, 2026
- Shimano current MTB component ordering catalogManufacturerSource checked Jul 29, 2026Evidence reviewed Jul 29, 2026
- Shimano current drivetrain compatibility tablesManufacturerSource checked Jul 29, 2026Evidence reviewed Jul 29, 2026
Technical data
Specifications
- Supported BB shells
- BSA-68
- Supported crank spindles
- Square Taper
- Spindle length
- 122.5 mm
- Front drivetrain groups
- Shimano Acera Altus 3x8, Shimano Tourney Tx 3x8