The sram x9 9 speed rear derailleur stylish and strong a forged aluminium b knuckle improves stiffness while the x9 styling exudes sram39s commitment to quality from steep endless climbs to hair raising technical descents x9 is engineered to handle whatever comes your way smooth precise shifting helps you cover more ground faster the lightweight stiff and always reliable crankset lets you maintain your momentum through the rough stuff whether yoursquore sprinting for the finish