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 external bottom brackets
• SRAM and Truvativ external bottom brackets
• Campagnolo Ultra-Torque and Power Torque, Race Face, FSA, and Chris King 16-notch external bottom brackets
• This open 1609/2HOBBY-US is not the closed-ring 1609/2BI-US workshop wrench; that article has a double-component handle and includes a crank-cap tool
• Also fits the external Centerlock disc nut and other disc-brake rotor lockrings with 16 external notches

Specs

• Material: premium flex plus carbon steel
• Surface finish: trivalent chrome plated according to ISO 1456:2009
• Handle length: 310 mm. Thickness (A): 3 mm. Radius (R): 1.5 mm. Weight: 270 g
• Notch pattern: 16-notch external, open-jaw design. Jaw diameters D1 21.35 mm and D2 22.5 mm

Built in Zreče

Unior has been forging hand tools in Zreče since 1919, and sponsors professional road and mountain-bike race 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 →.

FAQ

What cups does the 1609/2HOBBY-US fit? Unior names Shimano Hollowtech II, Campagnolo Ultra-Torque and Power Torque, Race Face, FSA, SRAM, Truvativ and Chris King, plus other 16-notch external cups. It is not an 8-notch, BSA30, T47 or press-fit tool.

How is this different from the 1609/2BI-US? This article is the open HOBBY wrench: 310 mm long, 270 g, no included crank-cap tool, listed in Home kit 2.0. The 1609/2BI-US is a closed ring (350 mm, 333 g) with a double-component handle and an included wrench for Shimano plastic crank bolts. Do not mix the two spec tables.

Does it turn a Centerlock rotor lockring? Yes, when the lockring is the external 16-notch pattern. Unior says the 1609/2HOBBY also fits the external Centerlock disc nut and other disc-brake rotor nuts with 16 external notches. Unior does not publish a 15 mm or 20 mm thru-axle limit for this wrench.

What are the official dimensions? Code 624935. Jaw diameters D1 21.35 mm and D2 22.5 mm, length 310 mm, thickness 3 mm, radius 1.5 mm, weight 270 g. Material is premium flex plus carbon steel; the finish is trivalent chrome plated to ISO 1456:2009. Dimensions are in millimetres and may vary in tolerance.