Shimano UN55 Bottom Bracket
Best durable drivetrain component for reliable bicycle maintenance and upgrades.
A reliable, sealed cartridge unit that serves as the gold standard for square-taper drivetrains. It offers exceptional durability and weather resistance, making it the ideal choice for commuters and vintage restorations that need to keep spinning smoothly for years.
$29.99
at
The Cellar LLC (shopLightspeed)
More BB-UN options
Who it's for
- Everyday riders seeking dependable, long-lasting performance without frequent maintenance.
- Budget-conscious cyclists needing a quality replacement or upgrade for their bike.
- Commuters and casual riders who prefer a "set it and forget it" component.
Who should skip it
- Performance-oriented cyclists and weight-weenies prioritizing minimal bike mass.
- Riders upgrading to modern drivetrain components or high-performance cranksets.
- Competitive racers and powerful sprinters demanding maximum power transfer efficiency.
Performance breakdown
Bearing Longevity
Sealed cartridge design keeps grit out for thousands of trouble-free miles.
Installation Ease
Standard threading makes swapping this unit a straightforward, tool-friendly task.
Weight Efficiency
Hollow spindle shaves grams without sacrificing the necessary structural integrity.
Compatibility Range
English threading and JIS taper fit almost any classic commuter frame.
Drivetrain Stiffness
Provides a solid, flex-free platform for efficient power transfer while pedaling.
Weather Resistance
Robust seals effectively protect internal components from rain and road spray.
Key Specs
Spindle Type
Square Taper
Thread Type
English
Compatibility
JIS Square-Taper Cranksets
Spindle
Hollow
Standard
BSA Threaded
Know before you buy
Still have a question?
Ask Metto anything about the Shimano UN55 Bottom Bracket before you decide.