Four-sided spoke wrenches grab more of the nipple than standard two-sided designs, which means less chance of rounding off flats when you're chasing a stubborn wobble. The Park Tool SW-40 fits 3.2mm nipple flats—the size you'll find on most Shimano, DT Swiss, and Mavic factory wheels, plus a wide range of aftermarket builds using standard brass or alloy nipples.

The four-sided engagement distributes torque across more surface area, so you can apply real force without the wrench slipping off and chewing up the nipple corners. That matters most on wheels that have seen some miles, where corrosion and road grime have made the nipples tighter than they were when new. The plastic handle gives you something to grip beyond the wrench body itself, making it easier to apply controlled pressure without your fingers cramping up halfway through a truing session.

Size matters here more than people realize. A 3.2mm wrench on a 3.23mm nipple will feel sloppy and round things off. A 3.2mm wrench on a 3.2mm nipple seats fully and turns cleanly. If you're not sure what size your wheels need, check the spoke nipple packaging or manufacturer specs before ordering. Park Tool makes the SW-40 series in multiple sizes for exactly this reason—one size doesn't fit all, despite what the universal spoke wrenches claim.... Read More