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Shimano XT SM-RT81 Rotor

Shimano developed the Center Lock disc rotor and hub system, and riders love it for it's ease of use, quick removal and installation, and solid-feeling spline interface. Designed for XT-level disc brakes, the RT81 Center Lock Rotor can be used with any Shimano disc braking system. A significant advantage for XT disc brakes comes from the XT IceTech disc rotors. The RT81 is the Center Lock variant of the temperature-reducing IceTech RT86 6-bolt rotor. This technology is actually quite simple, even if the engineering and manufacturing requirements are not. The principle of a cooler rotor is that heat reduction at the rotor prevents overall heat build-up, maintaining stopper power without fade, increases pad life, and protects the seals and moving parts of the disc caliper from overheating. All measurable, tangible benefits.

Shimano constructs IceTech rotors using an aluminum core, bonded on both sides to steel. The steel provides the strength and hardness of the braking surfaces, while the aluminum core releases heat build-up from the steel. Aluminum cannot hold heat the way steel can, making it a perfect way to moderate the heat that comes from the friction of braking. Additionally, aluminum is lighter, dropping the overall rotor weight. The steel-aluminum rotor is pinned via an arm system (number of arms varies with rotor size) to a sculpted aluminum spider, which is machined for the Center Lock spline and lockring mounting system. The cut-outs and shaping of the rotor itself are designed to provide excellent brake pad purchase, while shedding moisture, mud, and excess edge heat during use.

As with most Shimano products, the disc rotors are designed for optimal use with the overall braking system. Use of the finned Shimano IceTech brake pads maximizes temperature management, preventing excess heat build-up in the pad-caliper interface as well. With both the rotor shapes and pad fin design, air flow is the greatest asset for cooling. Overall, you know if you are running an XT set-up, you have a well engineered system that not only allows you to achieve high performance, but won't cost you a fortune. IceTech works, and if you are running Center Lock, the RT81 is the way to go.


  • IceTech equipped disc rotors designed for all levels of mountain bike use
  • 3 layer construction dissipates heat more efficiently than full steel versions
  • Aluminum core is sandwiched by steel plates, aluminum releases heat build-up
  • Center Lock interface via machined aluminum spider, pinned to outer braking ring
  • Rotor is directional, install as specified
  • Optimal results with Shimano IceTech finned hydraulic disc brake pads
  • Rotor, with Center Lock lockring for standard hub set-ups
  • Sizes: 140mm, 160mm, 180mm
  • Weight: 122 grams (160mm)