Everything seems to be going 10 speed at the moment. According to Singletrack’s piece on 2012 Deore kit, even that’s moving to a 10×3 setup. Sooner or later I guess that you won’t be able to buy decent 9 speed kit.

I’ve got a perfectly decent 9 speed XT crankset that I’d rather keep, it’s Octalink but running on a 50mm chainline. Could I use a 10 speed cassette, chain, rear mech. and shifter with a 9 speed chainset? Singletrack’s article talks about a directional 10 speed chain but not whether it’s narrower than a 9 speed one (there was some compatibility between 8 and 9 speed kit).

If the chainset’s a no goer, could I change to 10 speed rings or would it be simpler (if more expensive) simply to upgrade the whole drivetrain?

I’ve had no issues with 9 speed SLX chainset and 10 speed SRAM chain.

Yep it’ll work fine, may not be quite as smooth as 10 speed rings, but it’ll work.

Excellent, so 3×10 on a 50mm chainline 9 speed chainset should work. I’m sure that 9 speed is just fine but I guess that at some point availability of spares is going to force my hand.