Stylish and strong a forged aluminium b knuckle improves stiffness while the x9 styling exudes sram39s commitment to quality x9 is now available in three cage sizes sram x9 9 speed rear derailleur features technology 11 actuation ratio and direct route technology for lighter effort shifting speeds 98 material aluminium alloy composite cages short cage option only compatibility sram 11 shifters triggers and twisters available cage lenghts long medium aluminium