My experience
daniell said:
How does an 8 speed crank differ from a 9 speed crank? Are the chainrings narrower, or is the spacing between them less?
Also, when comparing a 9 speed chain with an 8 speed chain, is there a difference in the width where the chain fits inside?
Thanks
IME with using a 9-speed crankset (Deore) w/ an 8s chain, I had massive problems with chainsuck, even with the drivetrain cleaned/lubed and the chainrings relatively new. It was on a Klein Attitude hardtail, which has pretty short chainstays, so it's possible that that combination led to the problems I had. When I put a 9s chain on (using an 8s cassette), the problem went away. Shifting was pretty much the same with the 9s chain on the 8s speed cassette.
This was back when I defiantly resisted switching to 9s, believing that 8s was more durable. I finally gave up on that notion and use only 9s offroad. Durability doesn't seem to be any different than 8s, so I'm convinced the supposed durability of 8s over 9s is largely a myth.
You really should ask questions like this on MTBR, they'll have better answers/experiences to share

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