The 9 tooth cog lets you step down one chainring size while keeping the same top end gearing and provides not only better ground clearance, but an overall lighter drivetrain.
e*thirteen Helix R Cassette - 12-Speed Works flawlessly with Shimano and SRAM drivetrains, including electronic shift systems CNC optimized for light weight and wide range Helix R is durable and serviceable, with replaceable gear clusters Engineered with improved durability of 2 part steel and aluminum assembly XD driver compatible 12-Speed, 9-45t, Gray Weighs only 319g while offering a 500% gear ratio Color: Gray Cassette Body Type: SRAM XD 11/12 Speed , SRAM XDR Drivetrain Speeds: 12 Defined Color: Gray , Silver Cassette Cogs: 9-11-13-15-17-19-22-25-28-32-38-45 Weight: 319 Range: 9-45 9-50t,12-Speed, 9-50t, Nickel/Gray Color: Nickel/Gray Cassette Body Type: SRAM XD 11/12 Speed Drivetrain Speeds: 12 Defined Color: Silver Cassette Cogs: 9- 11- 13- 15- 17- 20- 23- 27- 31- 36- 42- 50 Weight: 345 Range: 9-50 12-Speed, 9-50t, Intergalactic PVD finish for improved durability Color: Intergalactic Cassette Body Type: SRAM XD 11/12 Speed , SRAM XDR Drivetrain Speeds: 12 Defined Color: Blue , Silver Cassette Cogs: 9, 11, 13, 15, 17, 20, 23, 27, 31, 36, 42, 50 Weight: 375 Range: 9-50 12-Speed, 9-50t, Bronze Color: Bronze Cassette Body Type: SRAM XD 11/12 Speed , SRAM XDR Drivetrain Speeds: 12 Defined Color: Brown , Silver Cassette Cogs: 9, 11, 13, 15, 17, 20, 23, 27, 31, 36, 42, 50 Weight: 375 Range: 9-50 12-Speed, 9-50t, Bronze.The e*thirteen Helix R 12-speed cassette is an upgrade to any SRAMâ„¢ Eagle or Shimanoâ„¢ drivetrain, and offers more range than other cassette options.