I Coulda Been a Contenda

Several years ago, I needed to improvise a tool to work on some cartridge bearing hubs -- if you press on the inner race of the cartridge you will ruin it. I came up with a good idea and sent it in as a submission to a mechanic tip contest held by The Third Hand/Loose Screws (a mail-order bike part and tool biz). I never heard squat back -- I'm pretty sure they took my idea and made TENS of dollars with it, but I still like them anyway. Moreover, I still like my idea. Here it is:

While overhauling a cartridge bearing hubset, I realized that I didn’t have a tool for installing the new cartridges. Wanting to press the new cartridges in (rather than hammer them in), I needed a tool that would to guide along the hub’s axle while only contacting the outer race of the new cartridge (a la Specialized’s cartridge installation tool that looks like a cartridge with a protruding outer race). Lo and behold, the old cartridge slipped perfectly into the backside of a 1” headset locknut, making a unit that would satisfy both criteria. It worked like a dream as the axle locknuts drove the new bearings into the hub shell.


I then wondered what cartridges the other size locknuts might accommodate and made a table with the locknut inner diameters, various common cartridge bearings and their outer diameters, whether a certain locknut will accommodate the bearing. A little machining (of the locknut’s inner diameter) is usually required for a fit, but using an aluminum locknut makes that an easy task. This tool is cheap and will last a long time, so press on and roll smoothly!