To follow on from a previous thread, looking to set the comuter up as 1×9, however bit of dilemma with regard to the chain rings. It’s an inbred frame with slx cranks, I’d like to run a 40t chain ring. The 40t won’t fit in the middle ring, as it will foul the chain stays, running in the outer position means an extreme chain line when it’s ‘big on big’ gear. I’m thinking of juggling the bottom bracket spacers around ie one on the drive side with two on the non drive side to move the chain ring further inboard in order to improve the chainline a bit. Anyone else done this?

I run 40t front ring in middle ring pos on a 456, on 9sp xt cranks. Just fits

Bit of fiddling with spacers won’t do any harm

Maybe, but it’ll mean your pedals aren’t even on each side. One more in than normal, one more out. Granted only 2.5mm difference, could maybe get away with 3 on the non driveside and 5mm out on each pedal

If it wont fit and you cant go to the biggest that will fit (38t? 36t??) Id be tempted to run it in the outside position and accept extra drag in big-big. You’d likely need some sort of inner/upper chain device at least though? Like an N-gear jumpstop if itll reach that far out?