Theory American Bottom Bracket to Mid bearing kit
Best durable upgrade for reliable bicycle drivetrain performance.
Upgrade your BMX's American bottom bracket to run modern 19mm, 22mm, or 24mm spindles. This kit offers sealed bearings for improved durability and a smoother ride, perfect for transitioning from older crank systems.
$34.95
at
Stacked BMX Shop
Who it's for
- Riders wanting to upgrade their vintage or BMX bike's drivetrain
- Cyclists seeking better power transfer and a more efficient ride
- Budget-conscious enthusiasts preserving classic frames with modern components
Who should skip it
- DIY mechanics without specific bottom bracket installation experience
- Performance-focused riders prioritizing minimal weight and ultimate simplicity
- Aggressive riders demanding maximum long-term durability from their components
Performance breakdown
Upgrade Versatility
Seamlessly adapts older American shells to modern, high-performance crank standards.
Bearing Durability
Sealed construction significantly outlasts traditional unsealed American bottom bracket setups.
Installation Ease
Requires a press tool, but simplifies the transition to three-piece cranks.
Spindle Compatibility
Covers the three most common spindle sizes for maximum crank flexibility.
Build Quality
Robust aluminum construction ensures a secure, wobble-free fit under heavy load.
Maintenance Simplicity
Serviceable bearings allow for easy cleaning and long-term performance upkeep.
Key Specs
Bottom Bracket Standard
American to Mid
Spindle Compatibility
19mm, 22mm, 24mm
Bearing Type
Sealed
Material
Aluminum
Serviceable Bearings
Yes
Included Components
Bearings, Spacers
Know before you buy
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Ask Metto anything about the Theory American Bottom Bracket to Mid bearing kit before you decide.