Shimano has been hard at work refining their Flagship group so that it virtually disappears under the rider with more intuitive controls. Part of this rider-tuned philosophy led to an 11-speed rear cassette with improved ratios so that you can always be in the perfect gear. Best of all is you get an extra gear for only a couple grams more.
Engineers at Shimano were able to add an extra cog with virtually no difference in weight with special materials and construction. The largest two cogs are made of titanium fixed to an alloy carrier. Here comes the interesting part. The next three cogs are also titanium but fixed to a carbon fiber carrier for extreme low weight and high strength. The last six cogs are loose and made of hardened steel.
Durability is the same as the excellent CS-7900 to perhaps better considering the matching CN-9000 chain can be expected to last 20% longer thanks to its PTFE coating. This coating along optimized chain width allows shifting on the CS-9000 cassette to be smoother and quieter than ever. Weight is 166 grams for the 11-23 size and 191 grams for the 11-28 size.
Only fits rear wheels designed to be 11-speed Shimano compatible