What Our Gearhead® Experts Are Saying: "I switched to the RT-CL900 rotors for my endurance road and gravel setups, and the difference was immediate. They run whisper-quiet—even when soaked—and stay cool on long, steep descents. The two-piece design manages heat beautifully, and installation is seamless thanks to the included lockring."When we’re dropping into high-speed descents or threading through technical switchbacks, we rely on the Shimano RT-CL900 Disc Brake Rotor to keep our braking predictable and noise-free. Designed for consistent stopping power, this rotor excels in both road and gravel applications, especially where heat management is key. With a robust two-piece design and innovative heat-dissipating paint, Shimano delivers on both quiet operation and thermal control. Even under sustained braking, the RT-CL900 remains cool and composed, ensuring every squeeze of the lever results in smooth, powerful deceleration. Add in the Center Lock mounting and a lockring that comes in the box, and it’s a clean upgrade for any performance build.