Shimano XT SM-RT81 Center Lock Disc Brake Rotor (180mm);

Shimano's XT-level centerlock rotor uses Ice Technology and a deeper disc area to manage heat better than an all-steel rotor. Ice-Tech construction consists of an aluminum core sandwiched between steel exteriors to provide better heat dissipation. The rotor is then joined to an aluminum carrier which further improves heat dissipation and also helps the rotor resist bending. The result is reduced brake fade for more consistent braking, especially on long descents. These rotors are compatible with centerlock hubs only. An HB20 lockring is required for 15 and 20mm thru-axle hubs, which is sold separately.