Shimano Tiagra/Sora HG50 9-speed cassette.It's a sad fact of life, your moving components on your bike will need to be replaced eventually. When your cassette wears out, it will start to prematurely wear out your chain. If you put new chains on it, the chains will wear out much quicker. The Shimano Tiagra/Sora HG50 9-Speed Cassette is a lightweight cassette for 9-speed drivetrains. It works on Shimano and SRAM freehub bodies.FeaturesMust use 9-speed chainReduced cog spacing: 9-speed is the same overall width as 8-speedItem SpecificationsColorSilverDrivetrain SpacingShimano/SRAM 9Cassette Body TypeShimano 9 | Shimano Tiagra/Sora Hg50 9 SPD Cassette 12-25T, 9 Speed