Open 16 Notch External Bottom Bracket Wrench

The 1609/2HOBBY-US is the home-mechanic version of our 1609/2BI-US 16 Notch BB Wrench. The pattern is the same; the engagement is the same; the difference is an open-cup design rather than a closed cup, and a price point that fits a home toolkit rather than a workshop wall.

For most home BB jobs, the open pattern is what the work calls for. The closed-cup 1609/2BI-US matters on benches that see hundreds of BB services a year, where the additional cup material adds a margin against tool wear. On the home bench that sees a BB service once a season, the open version delivers the same job for less.

How it's used

Mount the wrench so all 16 notches mesh with the BB cup's outer face. Press home before applying torque. Drive side is reverse threaded on Shimano-pattern external BBs (loosens clockwise); non-drive side is normally threaded.

Apply force slowly. The most common home-mechanic mistake on a BB removal is jerking torque on a cup that hasn't been fully seated by the wrench. The cup notches round, the wrench splines round, and the next BB service requires both a new cup and a new wrench.

Compatibility

• Shimano Hollowtech II road and MTB external BBs
• SRAM GXP and DUB external BBs
• Campagnolo road, FSA Mega Exo, Chris King, Race Face Cinch, and other 16-notch external BBs
• Most 16-notch BB designs across the current market
• Compatible with Shimano Centerlock disc-rotor lockrings on thru-axle hubs (15 mm and 20 mm) that use the external-spline pattern

Specs

• Material: premium flex plus carbon steel
• Surface finish: chrome-plated to ISO 1456:2009
• Handle length: ~200 mm
• Notch pattern: 16-notch external, open-cup design

Built in Zreče

Unior has been forging hand tools in Zreče since 1919, and is the official technical partner of multiple World Tour and downhill teams. The 1609/2HOBBY-US is the same precision-machined notch pattern as the workshop 1609/2BI-US; the price difference comes from the open-cup geometry, not from cutting tolerances on the splines.

Pro tip from our mechanics

If the BB cup won't release with steady pressure, the issue is almost always corrosion at the cup-to-shell interface, not torque. Apply a penetrating fluid at the thread interface, wait fifteen minutes, then try again. A cup that's been seized in place for years often releases on the second try after a soak; one that won't release on the first try usually responds to patience rather than to an impact pull.

For the home-mechanic BB service walkthrough including the order of operations and the torque specs for reinstall: Replace or clean your bottom bracket →.