The Shimano Deore XT FC-M8120 12 Speed Chainset uses forged HollowTech II aluminium cranks that offer unrivalled strength-to-weight ratio. These Shimano Deore XT chainsets have a lightweight construction for external super smooth bottom bracket bearings. Shimano Deore XT FC-M8120 12 Speed Chainset Features For use with 12-speed transmission systems 36/26T chainring combination Super boost 51.8 mm chain line for use with 148 mm rear axle width Stiffness and strength increased with advanced design due to wider spaced bearings and oversized axle 70 degree spider arm for optimal rigidity For use with 12-speed HG+ MTB chains only We recommend that the bottom bracket is initially installed by a bike shop to ensure perfect bottom bracket facing and fit