Nipple Driver

When building a wheel from components, the order of operations matters. Lace the wheel, seat the nipples through the rim, thread the spokes into the nipples (a few turns each), then drive every nipple to the same starting depth before any tension goes on the build. That last step; the “same starting depth” pass; is what the 1751/2 Nipple Driver does.

The tool's tip has a small nub machined into the end that engages the nipple's outer face. As you drive the nipple onto the spoke, the nub controls how far the nipple goes; the nub stops every nipple at the same depth on its spoke, giving the same thread engagement across the wheel. That's the starting point for the tensioning pass.

Starting with all nipples at the same depth matters because uneven starting depths translate directly to uneven final tension. If half the wheel's nipples start 1 mm deeper on their spoke threads than the other half, half the spokes will run shorter than the rest at any given tension reading; the wheel will be impossible to dish without giving up tension balance, or impossible to balance without giving up dish. The 1751/2 closes that variability at the build's starting point.

A knurled handle gives good grip during the rapid in-out motion of seating nipples across 32 spokes in succession.

Compatibility

• Nipples: slot-head internal spoke nipples (the standard).
• Wheels: any standard nipple geometry; the 1751/2 is the depth-control tool, not a wrench.
• Companion tools: pair with a spoke wrench in the matching size for the tensioning pass.

Specs

• Tip: depth-control nub machined into the slotted blade; 1.2 × 1.3 mm tip profile.
• Handle: knurled for grip.
• Length: 171 mm overall; 71 mm working section on a Ø 6.5 mm shaft; weight 160 g.

Built in Zreče, Slovenia

Unior has been forging hand tools in Zreče since 1919, and sponsors professional road and mountain-bike race teams. The Nipple Driver is one of the small workshop tools that separates a methodical wheelbuilder from an improvising one: it's an extra two minutes per wheel that costs five minutes of search-and-fix work at the tensioning pass. Workshops that do this step routinely have noticeably more consistent wheels coming off their benches.

Pro tip from our mechanics

Drive every nipple in a single direction around the wheel; clockwise if you're right-handed, counter-clockwise if you're left-handed. The rhythm becomes muscle memory after the first wheel, and you stop missing nipples or double-driving them. The depth-control nub does the work; your job is to apply it consistently. The full wheel-building workflow is in How to true a bike wheel →

FAQ

What does a nipple driver do in a wheel build? It handles the pre-tension pass. After lacing, you spin each nipple onto its spoke with the driver; a machined nub in the tip stops every nipple at the same depth on the spoke, so the whole wheel starts the tensioning pass from an even baseline.

How does the depth-control nub work? The nub sits in the center of the slotted tip and sets how far each nipple threads onto its spoke — drive until the nub stops the nipple, then move to the next spoke. Because the stop point is identical on every spoke, all the nipples end up at the same thread depth.

Which spoke nipples does the 1751/2 fit? Standard slot-head internal spoke nipples — the slotted blade with its 1.2 × 1.3 mm tip profile drives the screwdriver slot in the nipple head. For inverted square-drive nipples, Unior makes a separate driver, the 1751/2Q.

How big is the 1751/2, and how is it finished? 171 mm long overall with a 71 mm working section on a 6.5 mm offset shaft, weighing 160 g. The tool is trivalent chrome plated and, like all Unior hand tools, carries a lifetime warranty.