All of the necessary components for a 12-speed drivetrain were present. However, I was confused by the SunRace CSM901 WA1 12-speed cassette, which weighed 597g. It seemed too heavy.
I looked for a lighter, yet affordable, alternative suitable for the [Shimano] HG freehub body. I bought a used SunRace CSM903 WA1 12-speed cassette.
The CSM903 is very similar to the CSM901: its sprockets are 11-13-15-17-19-21-24-28-33-39-45-51 (teeth) too.
The main difference is that the CSM903 has three aluminum A7075 sprockets (39, 45, and 51 teeth) instead of the CSM901's single 51-tooth sprocket. So the SunRace CSM903 WA1 weighs just 498g. This is an attractive weight for a 12-speed cassette.
See also related notes:
- SunRace CSM901 WA1 12-speed 11-51T cassette (2025-10-25)
- Shimano RD-M8100-SGS (Deore XT): 12-speed rear derailleur (2025-10-17)
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