Shimano ultegra 6500 9 speed road cassette similar to the dura ace the five largest sprockets are mounted on two light seperate alloy carriers that reduce weight and increase sprocket stiffness featureshigh performance 9 speed cassettehyperglide sprockets have a computer designed tooth configuration with contoured shift gates resulting in a crisp smooth shift even under loadclose ratio gearing allows a more efficient use of energy through finer cadence controltwo largest sprockets are mounted