Shimano Ultegra R8101 12 Speed Cassette - SilverShimano Ultegra R8101 12 Speed Cassette Silver Shimanos Ultegra R8101 12 Speed Cassette provides amazing shifting under pressure, with the Hyperglide+ design moving the chain between ratios flawlessly whenever called upon. By offering 12 sprockets, Shimano has been able to reduce the jumps between gears so that it is easier to stay in the cadence sweet spot for greater efficiency and less fatigue. The combination of steel sprockets and an alloy