Unior 16-Notch Closed External Bottom Bracket Wrench
This is Unior’s closed-style 16-notch bottom bracket wrench for modern external bearing crank systems.
It’s a shop-grade hand tool used for installing and removing common threaded external bottom brackets—and it also doubles as a wrench for external-style Centerlock rotor lockrings.
Key Functional Details
- 16-notch closed wrench design
- Installs and removes external threaded bottom brackets
- Also fits external-profile Centerlock rotor lockrings
- Made from Unior premium flex plus carbon steel
- Chrome plated for corrosion resistance
- Includes small auxiliary wrench for Shimano Hollowtech II plastic preload caps
- Magnet embedded in handle stores the small wrench when not in use
Compatibility & Technical Notes
- Compatible with Shimano Hollowtech II bottom brackets
- Compatible with SRAM / Truvativ GXP and DUB threaded external BBs
- Compatible with Race Face, FSA, Campagnolo Ultra-Torque and Power Torque threaded systems
- Fits external-style Centerlock rotor lockrings (not internal cassette-style lockrings)
- For threaded external cups only — NOT for press-fit bottom brackets
- Manual hand tool — not designed for impact drivers
Service / Ownership Context
This is a proper workshop wrench meant for regular drivetrain service. It provides better engagement than thin stamped tools and reduces the risk of slipping or damaging BB cups.
Fit & Use Signals
- Good Fit: Home mechanics and shops servicing Shimano-style external bottom brackets and external Centerlock rotors.
- Not A Fit: Press-fit BB systems, internal Centerlock lockrings, or riders looking for a compact trailside tool.
This is the standard shop-style external BB wrench. Way better engagement than cheap stamped tools.
Biggest customer mistake: trying to use this on press-fit bottom brackets. Won’t help. Also people buy this when their rotor actually uses an internal cassette-style lockring — always check first.
Closed design matters. Keeps the tool square on the cup so you don’t round alloy BBs.
The little plastic-cap wrench is for Shimano preload caps only. That’s not for tightening crank bolts — just for bearing preload.
Common service scenario: customer cross-threaded a BB with a cheap tool. This prevents that if used correctly.
Failure points are almost always user error: wrong BB standard, cheater bars bending things, or trying to impact it.
Who this is really for: anyone regularly installing Hollowtech II / GXP / external threaded BBs.
Who should avoid: press-fit users and casual riders who never touch drivetrains.
Mechanic advice: always grease BB threads, start by hand, torque to spec. If a BB is seized, soak first — don’t just reef on it.