Driven by a cutting-edge, single-ring carbon crank arms and seamless component integration, the SRAM XO-1 Carbon Crank Arms deliver flawless chain management and faster, more precise shifting. But the relationship between X01 components goes far beyond fitment. From the X-HORIZON rear derailleur with TYPE 2 technology to the super wide range 11-speed 10-42T cassette, each component is designed to function synergistically with the others, achieving what no other 1X drivetrain has before. Innovative tooth profile alternates thickness by inner and outer links, providing maximum chain control with no need for a chain catcher. Chainring and bottom bracket sold separately. 520 grams includes bolts.