The Shimano Dura Ace CS-7900 cassette provides you with a wealth of gearing options unlike any previous generation of Dura Ace. You get an unprecedented 8 different ratios to choose from -- 11-21, 11-23, 11-25, 11-27, 11-28, 12-23, 12-25, and 12-27. The low 6 cogs are steel, and the high 4 cogs... read more

The bottom 4 cogs on the Dura-Ace 10-Speed cassette are made from titanium -- unlike the 2 (or sometimes 3, depending on ratio) you got in the 9-speed era. These Ti cogs get an improved surface treatment to give them a 30% increase in wear. They are compatible with all 8 and 9-speed Shimano hubs.... read more

Thanks to its use of thin sprockets and spacers, the Ultegra CS-6600 cassette's 10-cog stack is no thicker than the CS-6500 9-speed version. This is a versatile cassette -- it's fully compatible with a Dura Ace 7800 10-speed drivetrain. It's also compatible with any Shimano 9-speed generation... read more