Currently running a single ring on an xt double.

I need some new cranks (shorter).

Do I buy another double or go with a triple? Thinking a triple might give me a slightly better chain like if I run the ring on the middle ring position?

You could just keep the double & move a bottom bracket spacer across to the drive side to get the alignment.

yes. get the triple.

Triple with ring in the middle ring pos. job jobbed.

If you have to buy a new set of cranks then triple would be better. How much shorter do your cranks need to be? Thinner pedals could be a different option? Superstar deltas are 14mm as opposed to say an old v12 at 25mm?

Do single cranksets have the same chainline as a outer ring of a double?

Ah but running on the middle section of a triple will look shite. the ring should blend in seamlessly not look a bodge. Buy a single chainset.

Thanks. I already have thin pedals and i’m thinking of going from 175 to 165 cranks.

Never had a single ring specific crank, whats out there, I’m guessing Zee and Saint? But owt else.

If you have to buy a new set of cranks then triple would be better. How much shorter do your cranks need to be? Thinner pedals could be a different option? Superstar deltas are 14mm as opposed to say an old v12 at 25mm?

Thinner pedals would make no difference, just a lower saddle height.