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52 or 55 mm chainline (shimano) cranks for the Aeris9? Both should work on paper with a boost spaced hub but I've never managed to work out whether there is any real reason to use one over the other? Wider q factor doesn't bother me. I can't find anything on the Bird product page.
Ta,
S
I can check what version of XT they have fitted to mine when I get home tomorrow if it helps.
Dan from Bird has posted 52mm for boost and 55mm for super boost in relation to the AM9 if that helps
If 52 gives chainstay/chainring clearance, that’s what I’d go with as it gives a better chainline.
OK, ta. Trying to find 165mm cranks as I'm having a devil of a time with root/rock pedal smashes. The only in stock slx options seem to be the 55 mm version.
You could try phoning Bird, they supplied 165 XT's on my build.
I have some SLX FC-7120 165mm (55mm) which have done 20 miles, still have the box (no chainring).
If you get stuck DM me.
I'd go 52mm.
I’ve got those slx 7120 165mm cranks for 55mm chainline on my aether9. They just have a longer spindle and two more spacers than the 7100 52mm chainline version.
I fitted them with one spacer from the drive side on the nds to move the chainline back in to 52mm.
And Q Factor jumps from 172mm with 7100 to 178mm ( the two 3mm spacers and a longer axle) with the 7120 - if that bothers you.
Personally, despite what the manufacturers say, I think 55mm chainline on 148mm boost is rubbish unless you've got decently long chainstays.
I'd default to 52mm. That said, for my riding I'm happy to run a 30t chain ring which helps with chainstay clearance, obviously.
Thanks all, I'm running a 30t ring so no issues with clearance. Will wait for 52 mm sets to come back into stock