The chainring teeth have been developed to work in conjunction with the CN7900 and CN6700 chains for increased contact to provide greater efficiency and improved power transfer. Industry leading HollowTech II cold forged hollow crank arms have been evolved to increase rigidity, reduce weight and improve strength. A wide range of chainring options and crank arm lengths are available to meet the needs of all riders and racing disciplines. This chainset has been optimized to work with the HollowTech II 68/70mm integrated bottom bracket which uses a wider bearing placement and larger axle diameter for increased stiffness and efficiency. The seal design has minimal bearing interface ensuring smooth rolling and increased durability, please note that the bottom bracket is not included in this package.