Running a wheelset with Center Lock hubs when the rotor you want is only offered in 6-bolt is a common enough mismatch that Shimano makes a dedicated fix for it. The Shimano SM-RTAD05 Disc Rotor Adapter converts a Center Lock hub interface into a standard 6-bolt mounting pattern, so you can run conventional 6-bolt rotors on Shimano hubs or any Center Lock–compatible hub from DT Swiss, Zipp, Reserve, or others. One adapter covers one hub, so a full bike conversion takes two.

Installation uses the same external-spline lockring tool you'd use for a standard Center Lock rotor or a Hollowtech II bottom bracket cup, which most riders already own or can borrow from Excel's service department. The adapter slides onto the hub splines, the 6-bolt rotor bolts to the adapter face, and the included lockring torques the whole assembly down as a unit. An anti-loosen plate keeps everything from backing off under repeated hard braking — worth having when you've added an extra interface between hub and rotor.

One compatibility note to flag before you order: the SM-RTAD05 does not work with 2-piece rotors that use an aluminum spider carrier, which includes Shimano's own RT86 (XT) and RT76 (SLX) 6-bolt rotors. The center carrier on those rotors interferes with the adapter body. Standard 1-piece steel 6-bolt rotors from Shimano, SRAM, Hope, Galfer, TRP, and Magura all seat correctly. The adapter accommodates 160mm, 180mm, and 203mm rotor sizes, covering road, gravel, cross-country, trail, and enduro applications.