Originally Posted by
SoSmellyAir
So, you think, for example, that a 9-speed chain would work with a 12-speed crankset? I am not disagreeing, I just don't know; I had thought that the gap between chain rings in a 2x crankset is somewhat dependent on the chain.
I also don't know. But higher speed systems have everything thinner (and thus less durable, given the same material quality). So an older system like a 9 chain on 12 cogs and chainrings, I think the wider outside width of the 9 chain may be a problem on a 12 cassette with noise and possible unintended upshifts, and the wider inside diameter may be a problem on a 12 chainring as it may be less stable, may want to twist slightly.