Shimano SM-RT64 rotors offer secure and easy set-up with the proven Centre-Lock mounting system. Precision cut stainless steel braking surface improves pad clearing in muddy conditions while aiding cooling underhigh load Rotor contact surface has been developed for excellent pad clearing and cooling which increases pad performance and life Alloy spider supports rotor surface increasing rigidity and reducing weight Comes complete with steel lockring Average weight for 160 mm rotor with lockring is 153 grams