Interesting concept that actually was a thing to get more gears with 1/8" width chains. Your Choice of a NOS 22t, 19t, & 16t ( 22t cog is the base with threading, smaller cogs can be removed from the cassette with a chain whip ) or Used 28t, 22t, & 13t has double threaded inner that all cogs can be removed from inner or Used 24t, missing 2 cogs has double threaded inner that all cogs can be removed.
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