Shimano CS 6600 Wide 10 Speed Cassette. The Shimano CS 6600 Wide 10 speed cassette is specifically designed to meet the demands of junior category racing cyclists that must adhere to gear restrictions during competition. These cassette ratios, with their larger than normal smallest cogs, are designed to be paired with standard sized road double chainrings typically a 5339T combination to meet the gear restrictions. Note that in modern day frames with carbon fiber tubing, using a cassette with the smallest cog size of 13 through 16 teeth may not be compatible with the chain stays andor seat stays. Also, due to compromises in shifting performance, Shimano recommends that these cassettes only be utilized with a double chainring crankset, not a triple crankset.