Round Spoke Wrench

One tool, seven nipple sizes. The 1631/5 is the round multi-size spoke wrench, drop-forged from a single billet and cut to the most common spoke-nipple dimensions in the cycling world: 3.3, 3.45, 3.7, 4.0, 4.4, 5.0, and 5.5 mm.

For a traveling mechanic, a touring rider, or a bike-shop owner who sees a variety of wheelsets through the day, this is the spoke wrench that lives in the seat bag or on the bench. It doesn't replace a dedicated four-flat Professional Spoke Wrench 3.3mm or 3.45mm for high-volume building (those have plastic-dipped handles and dedicated sizing), but it does what those can't: cover the rare 3.7 mm, 5.0 mm, and 5.5 mm sizes you'll encounter on older European wheelsets and some house-brand bikes, all from a tool the size of a small biscuit.

The drop-forged construction is the load-bearing decision here. A spoke wrench whose contact faces are stamped will round under high-torque truing; the 1631/5's faces are forged into a billet of steel before being machined to size, so the grain runs parallel to the working surface and the tool stays true through years of bench work. The 1631/5 is the wrench we hand to a mechanic on their first day and tell them to take with them when they move on.

Compatibility

• Spoke nipple sizes: 3.3, 3.45, 3.7, 4.0, 4.4, 5.0, and 5.5 mm.
• Engagement: round / four-flat for the standard sizes.
• Works on standard internal-spoke and external-spoke nipple geometries.
• Fits most modern wheelsets and a wide range of older European builds.

Specs

• Material: drop-forged steel billet, machined to size at each working face.
• Seven nipple sizes on a single tool body.
• Compact for a saddlebag, tool roll, or workbench drawer.

Built in Zreče, Slovenia

Unior has been forging hand tools in Zreče since 1919, and is the official technical partner of multiple World Tour and downhill teams. Drop-forging at Unior is one of the construction processes that distinguishes the cycling-tools line; the same grain-aligned-steel principle that makes the Chain Breaking Pliers 1640/1DP hold up under repeated chain-rivet loads makes the 1631/5 hold up under years of spoke-wrench use without rounding.

Pro tip from our mechanics

Always test the nipple fit before you load the wrench. The 1631/5's seven sizes are tight tolerances, and a nipple at the upper end of its tolerance band can be a near-fit on a slightly-too-large slot. Slide the wrench onto the nipple, twist gently with no torque on it; if the wrench rocks at all, step down one size. A loose fit will round a nipple, and a rounded nipple is the kind of problem that ends a building session. The rest of the wheel-truing workflow is in How to true a bike wheel →