Ok, here's the deal. Building an AM bike and want to use the new 10 spd. Shimano shifters and cassette with 9 speed cranks. 9 spd XT cranks are a little cheaper and come with a 22 tooth small ring( 10 spd.have 24T ). I'm sure it will work but, I want my new bike tight. Set it and forget it. Anybody know how much narrower the 10 spd chain is compared to 9 spd. Will this even be an issue or am I being a dumba$$ for asking?