Looking for a Shimano Deore XT RT-MT800 Rotor? Meet the RT-CL800
If you’ve recently tried to find a replacement Shimano Deor XT RT-MT800 rotor, you’ve probably noticed it’s getting hard to find. Shimano has effectively discontinued it and replaced it with the RT-CL800. The trouble is that when you look up the new rotor, Shimano lists it under Ultegra and GRX alongside Deore XT, and a lot of our customers understandably assume it’s a road or gravel rotor that won’t suit their mountain bike. We get this question often enough that we thought we’d put together a quick post to clear things up.
Same Rotor Tier, New Name
Most of the confusion comes down to Shimano’s model codes. Under the old naming, the “MT” in RT-MT800 stood for mountain, which made it easy to assume it was an MTB-specific part. With the new rotors, Shimano switched to “CL”, which simply stands for Center Lock, the mounting standard. It says nothing about what kind of bike the rotor is meant for. The RT-CL800 occupies exactly the same spot in Shimano’s lineup that the RT-MT800 did, it’s the XT grade Center Lock rotor, it just happens to share that grade with Ultegra and GRX.
What most riders don’t realize is that the RT-MT800 was already doing the same thing. Despite the “MT” in its name, it was sold as an XT, Ultegra and GRX rotor, and plenty of them ended up on road and gravel bikes. Nothing about the shared branding is actually new. Shimano has just stopped tying the rotor’s name to one type of bike.
Straight From Shimano
If you want confirmation from the source, Shimano’s disc brake caliper and rotor compatibility chart lists the RT-CL800 as compatible with their full range of mountain bike calipers, including XTR, Deore XT, SLX and Deore, in the same rows where the RT-MT800 appears. As far as Shimano is concerned, the two rotors do the same job on the same brakes.
The size range tells the same story. The RT-CL800 is available in 140 mm, 160 mm, 180 mm and 203 mm. Nobody runs a 203 mm rotor on a road bike, that’s a size for trail, enduro and e-MTB riders. Shimano built one rotor to cover everything from a road or gravel bike’s 140 mm rear to a long-travel bike’s 203 mm front.
What’s Different About the RT-CL800?
Think of it as a refinement rather than a whole new design. It still uses Shimano’s ICE TECHNOLOGIES FREEZA construction, the stainless steel and aluminum sandwich with the exposed cooling fins that made the RT-MT800 such a good performer on long descents. The main change is a redesigned aluminum carrier with a stiffer arm shape, which Shimano says reduces heat deformation. In practice, that means less of the rubbing and noise you can get from a hot rotor partway down a long descent. Pad compatibility hasn’t changed either, so whether you run resin or metal pads, they’ll work just as they did before.