5.5mm Hex Nipple Driver

Some modern wheelsets; many aero road builds in particular; use internal spoke nipples with a 5.5 mm hex recess instead of the standard slot, square, or Torx geometries. The 629TBI is the dedicated driver for that 5.5 mm hex recess.

The tool has a 125 mm shank, long enough to reach the nipples on the deepest aero rims commonly in service (50, 60, even 70 mm deep-section rims). A shorter driver bottoms out against the outer rim before the hex tip reaches the nipple recess; the 125 mm length closes that gap.

The three-component handle is the workshop-comfort decision. A driver used through a full wheel-build session; 32 nipples driven through engagement, depth-set, and tension; gets used hundreds of times. The handle's grip needs to stay comfortable across that volume.

Compatibility

• Nipples: 5.5 mm hex-recess internal spoke nipples.
• Rims: any rim profile up to and including 70+ mm deep-section aero builds (the 125 mm shank reaches through deep rims that other drivers don't).
• Wheels: most modern aero road wheelsets with hex-recess nipples.

Specs

• Engagement: 5.5 mm hex tip.
• Shank length: 125 mm (clears deep-section aero rims).
• Handle: three-component, sized for workshop comfort.

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. The 5.5 mm hex nipple has been a Mavic and DT Swiss preference for some of their premium aero wheels, and other manufacturers have adopted similar geometries for their own deep-section builds. The 629TBI is the Unior-built driver that matches the published nipple recess; a generic 5.5 mm hex driver won't have the deep-rim shank length, and a standard nipple driver doesn't engage hex recesses.

Pro tip from our mechanics

When servicing an unfamiliar wheelset, check the nipple recess geometry before reaching for any driver. A 5.5 mm hex recess looks superficially like a small square recess; a 5.5 mm hex driver in a square nipple will turn the nipple briefly before rounding it off. The recess geometry is visible from the rim side once the tire is off; if it's a hex (six sides), use the 629TBI; if it's a square, the Square Profile Nipple Driver 1751/2Q is the right tool. The full wheel-building workflow is in How to true a bike wheel →