The reference gauge that calibrates the Unior Pro Truing Stand V2 (the matte-black-finish revision available from June 2022 forward). A flat steel reference plate that seats into the truing stand's caliper arms and lets the mechanic align the calipers to a known-zero centerline, restoring the symmetry the stand needs to read wheel dish and lateral true correctly. A truing stand is only as accurate as its calipers' centerline. Over hundreds of wheel builds, the calipers can drift off-center by a fraction of a millimeter; enough that a wheel built true to the stand reads as off-center on a frame, or a wheel built dished to the spec rides untrue. The calibration tool is the periodic-service item that resets the centerline: install the gauge, verify both calipers seat against it equally, adjust if not. A five-minute service that restores the stand's accuracy across the next dozens of wheel builds. Match the tool to your stand version The 1689.1 is specific to the Pro Truing Stand V2 (black finish, June 2022 onward). The V1 stand (black and chrome finish, pre-2022) uses a different calibration tool; part number 629229. Verify your stand's revision before ordering: the V2 gauge will not fit the V1 caliper arms cleanly, and using the wrong tool gives a false-center reading. How to tell the version: V1 has a chrome upper assembly above a black base; V2 is matte black throughout. The serial label on the stand base also identifies the revision. Specs For: Unior Pro Truing Stand V2 (black finish, June 2022 onward) Material: machined steel reference plate Function: zero-the-centerline calibration on truing-stand caliper arms Article: 1689.1 SKU: 629288 Built in Zreče, Slovenia Unior has been forging hand tools in Zreče since 1919, and sponsors professional road and mountain-bike race teams. The Pro Truing Stand family is the wheel-building backbone of Unior's wheelbuilding category; the calibration tool is the workshop-discipline item that keeps the stand reading true year after year, the same way a torque wrench needs periodic calibration to stay within spec. Pro tip from our mechanics Calibrate at the start of a wheel-build session, not after. A drifted calibration shows up as wheels that read true on the stand but ride untrue in the frame; by the time you discover the drift, you've built three wheels that need correction. Five minutes of calibration at the start of the session saves the rebuild time downstream. For the broader picture on wheel-truing technique, including when the lateral and radial readings tell you something different about the wheel: Fix disc brake rub → (covers rotor truing, with the same caliper-alignment principles that apply to wheel truing).
