The Shimano R9100 11-Speed Cassette is part of the brand new R9100 Dura Ace range. Replacing the 9000 as Shimano s flagship groupset, the R9100 offers improved weight, exciting new features and superior performance. The R9100 is a super lightweight HG-EV cassette with a ridged carbon and alloy carrier to provide excellent shifting even under the most demanding gear changes, Hyperglide EV sprockets with a computer designed tooth configuration and contoured shift gates to ensure crisp and smooth shifting even under load and a close ratio gearing to allow for a more efficient use of energy through finer cadence control. The sprockets are all extensively cut away and drilled to reduce weight, the largest of which are mounted on lightweight alloy and carbon carriers and constructed from titanium to further reduce weight and increase rigidity without sacrificing strength. The R9100 has an alloy cassette lockring and features a nickel-plated finish for hard wearing resistance to corrosion. If