Shimano XT M770 Hollowtech II crankset maximizes stiffness while keeping weight to a minimum. It features a precision two-piece construction for perfect chainline and chainwheel alignment and a carbon/steel composite middle ring for better shifting. This also increased service life, and smoothly delivers power to the cassette. Increased stiffness and improved shifting performance Outboard bearings maximize stability and stiffness Steel/carbon composite construction and middle gear doubles durability Thicker and stiffer 44T ring. Crank Arm Material/Finish: Aluminum/Anodized Spider Arm Material/Finish: Aluminum/Anodized Outer Ring Material/Finish: Aluminum/twice Anodized Middle Ring Material/Finish: Steel + Composite/Plated Inner Ring Material/Finish: Aluminum/Anodized Weight(claimed): 850g