Square Profile Nipple Driver

The square-profile internal spoke nipple is the workshop-friendly alternative to slot-head and Torx nipples. The square recess is shallow enough to engage cleanly even when the nipple is slightly recessed in the rim's spoke hole, and the four-corner contact distributes torque without the round-out risk that a slot-head can present under high build torque.

The 1751/2Q is the dedicated driver for the 3.2 mm square-profile internal nipple; a common size on aero and deep-section rims, where the internal nipple geometry needs to clear the spoke hole and seat well into the rim's spoke bed. The driver's 80 mm shank reaches through standard double-wall and most deep-section aero rims; the 6.5 mm outer diameter of the shank clears most spoke holes without binding.

A knurled handle gives the grip its working comfort, particularly when spoke tension is high and the nipple is harder to turn against the spoke's pull. Build sessions on deep-section aero wheels with square nipples are where this tool earns its space on the bench.

Compatibility

• Nipples: 3.2 mm square-profile internal spoke nipples.
• Rims: standard double-wall and most deep-section aero (up to about 60 mm depth).
• Wheels: aero road wheels with internal-nipple builds; most modern deep-section wheelsets that use square-profile nipples.

Specs

• Engagement: 3.2 mm square tip.
• Shank length: 80 mm (clears most deep-section aero rims).
• Shank diameter: 6.5 mm outer diameter (clears most spoke holes).
• Handle: knurled grip for workshop comfort under high spoke tension.

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 square-profile nipple is one of the smarter manufacturing decisions in modern wheelbuilding; easier to engage cleanly, harder to round out, friendlier to the workshop. The 1751/2Q is the driver that pairs with that nipple geometry; a generic flathead screwdriver will engage briefly and then strip the recess, and a slotted driver will not engage at all.

Pro tip from our mechanics

When the nipple recess is recessed below the rim's outer face (common on internally-spoked aero wheels), the 80 mm shank length of the 1751/2Q is the difference between a clean engagement and a half-engagement that strips the recess. If a shorter driver makes contact but won't fully seat, the engagement is partial and the round-out is one or two turns away. Reach for the 1751/2Q or the Speed Nipple Bit 2.5mm before applying torque. The full wheel-building workflow is in How to true a bike wheel →