Cassette lockrings and certain centerlock rotor lockrings share the same splined interface, which means one tool handles both jobs. The Park Tool FR-5.2GT fits that 12-spline pattern found on Shimano, SRAM, and most other cassette lockrings, plus it works on Shimano centerlock disc rotor lockrings that use the internal spline design. The "GT" in the name refers to the guide pin on the face of the tool—that pin drops into one of the lockring notches to keep the tool centered and engaged while you're putting torque on it.

Without that guide pin, cassette tools have a tendency to skip out of the lockring splines under heavy force, which usually means scraped knuckles and damaged lockring teeth. The pin solves that problem by physically indexing into the lockring, so the tool stays put even when you're breaking loose a lockring that's been torqued to spec and ridden for a few thousand miles. It's a small addition that makes a real difference when you're working on a bike that's seen some weather and road grime.

The FR-5.2GT fits in a standard 24mm hex wrench or adjustable wrench, or you can chuck it in a bench vise and rotate the wheel to break the lockring loose. Park Tool also makes a handle specifically for their remover tools if you prefer a dedicated setup. The through-hole in the center allows the tool to sit flush on lockrings even when the quick release skewer or thru-axle is still in place, which speeds up the job when you're just swapping cassettes between wheels.... Read More