If you've ever tried to install a Center Lock rotor on a thru-axle hub and discovered your cassette lockring tool won't fit through the axle opening, you've run into the problem this part solves. The Shimano HB-M8010 Center Lock Disc Rotor Lockring uses outer serrations rather than internal splines, so a 16-notch external bottom bracket tool engages the outside face of the ring to torque it down. That single change makes it compatible with hubs running 12mm, 15mm, or 20mm thru-axles, where the standard internal-spline lockring simply doesn't work.

The aluminum lockring threads into the hub body the same way any Center Lock ring does, clamping the splined rotor carrier against the hub face. Shimano specifies 40 Nm of torque for installation, which is enough to keep the rotor secure without stressing the hub threads. Fits front and rear applications across XTR M9000-series, XT M8000/M8010, and any Center Lock hub built around a 12/15/20mm axle standard.

One installation note worth flagging before you order: on some road and gravel forks, the outer profile of this lockring sits close enough to the fork leg that clearance can be tight. Center Lock rotors on thru-axle road bikes usually work fine with the internal-spline version paired with a cassette tool, so this outer-serration ring is primarily the answer for mountain hubs, deeper hub flanges, or any setup where the axle blocks tool access. Check fork clearance at the hub before committing to this style on a drop-bar build.... Read More