Lockring tools look simple until you realize how many standards exist. External bottom bracket cups, cassette lockrings, centerlock rotor lockrings, and disc brake rotor lockrings all use splined interfaces, but the spline counts and diameters vary enough that one tool rarely covers everything. The Park Tool LRT-4 handles the specific case of external bottom bracket cups that use a 16-notch interface—the pattern found on SRAM DUB and Race Face Cinch systems, among others.

The tool features a 16-notch engagement pattern with a 41mm inner diameter, which matches the external cup interface on these bottom bracket systems. A 3/8" hex fitting on the back lets you drive it with a ratchet or breaker bar, giving you the leverage needed to break loose cups that have been torqued to spec or seized from corrosion. The steel construction handles the loads involved without flexing or rounding off the engagement surfaces.

External bottom brackets thread into the frame's shell from the outside, which means the cups sit exposed to road spray, pressure washer overspray, and general contamination. That exposure leads to corrosion between cup and frame, and breaking that bond requires a tool that engages fully and transfers force without slipping. The LRT-4's notch pattern seats into the cup's splines completely, distributing the load across all sixteen contact points rather than concentrating stress on a few.... Read More