The shimano dura ace cs 9000 11 speed cassette is an incredibly light weight and rigid high end road bike cassette that produces incredibly fast accurate and reliable shifts even in the trickiest of riding conditions with a rigid carbon and alloy carrier the shimano dura ace 9000 cassette is able to produce even under the most demanding gear changes and when combined with the hyperglide ev sprockets which uses contoured shift gates the shifting performance is incredibly smooth even