Ideally when going 1×10 or 1×11 you get a crank designed for a single chainring, maybe a triple so that your chain is always in the middle.
But what if you’re on a double chainset, doesn’t that knock the chainline off? Do you shift the BB over with the spacers to bring the chainline back towards the frame? Or just leave it as is?

I asked a similar question mate.

I’m using an old Stylo triple with an Absolute Black oval mounted behind the bikesfor the outer ring.

Chain line is biased toward the small sprockets for sure and was thinking about using the 3mm spacer on the nds to pull the crank set over, (Gxp bb). That said, as pointed out by someone on here,3mm won’t make a huge difference on the 11 spd cassette to chainset, chainline anyway.

Going to finish build and see how it rides.

Mines inline with about the 4 sprocket up from small from memory.

I believe I’m correct in saying that a 1×11 chainline wants to be 50mm, so measure away and adjust accordingly.

I’ve read on here that someone was experiencing uneven chain wheel wear on the inside face of the teeth with their 1×11 set up with a specific single ring crank, mentioning that the angle of the chain in the lower and especially lowest gear looked too severe. This would make me think that perhaps 50mm is too much. Typically a single ring on a triple crank set will give between 46 – 48mm.

Shorter chain stays would also affect the chain angle too, from longer chain stays but I don’t know if any account needs to be taken for that in terms of chainline. Perhaps someone like Brant maybe able to offer some insight on that question?

I moved the BB spacer from the DS to the NDS, and added a 2mm spacer, which moved it in 4.5mm altogether and that works fine on an XT M785 double chain set.

10 & 11 speed rear mech are designed to be used 1* & 2* aren’t they? if so, is there any reason a double should be any more of an issue than a single set-up?

@ ade9933 – I’m not sure I understand your question about the rear mech and its influence on chainline, unless I’m being really slow on the uptake.

Hiya – I’m just saying that the 11 on the rear mech should ‘just work’ with a 1* on a double front chainset because they are designed to work with a 2*11 anyway so therefore the chain line should be just the same as setting up 1& 11 as for 2*11.

any clearer?