Cassette lockrings and certain bottom bracket cups share the same splined interface, which means one tool handles both jobs. The Park Tool FR-5.2 fits the 12-spline pattern used on Shimano, SRAM, and SunRace cassette lockrings, plus Shimano external bearing bottom bracket cups like those in the Hollowtech II system. If you're building up a home workshop or restocking a shop tool board, this is the splined tool that gets grabbed most often.

The FR-5.2 features a 23mm body diameter that clears the axle on thru-axle hubs without interference. Earlier versions of this tool required a separate thru-axle adapter, but the current design works with both quick-release and thru-axle setups straight out of the package. The tool steel construction handles the torque required to break loose lockrings that have been installed at factory spec or over-tightened by previous mechanics.

One detail worth noting: this tool provides the splined interface only. You'll need a wrench or adjustable spanner to actually turn it—a 23mm cone wrench works, or an adjustable wrench if you're not concerned about marking up the flats. Some mechanics prefer using a 3/8-inch drive with Park's FR-5.2G variant that includes a guide pin, but the standard FR-5.2 handles the job when paired with proper technique. Hold the tool firmly into the lockring as you turn to prevent the splines from skipping.... Read More