I always though that the belt cogs use the same thread as a normal cog, and that they need also a lock ring.
That would be the case with the threaded belt pulleys, but I'm pretty sure the District Carbon uses a splined pulley on a cassette rotor.
@gbj_tester started
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That would be the case with the threaded belt pulleys, but I'm pretty sure the District Carbon uses a splined pulley on a cassette rotor.