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I need to replace the middle chainring on my M770 crankset. I can get hold of an M760 32T chainring locally. I know there are issues fitting M770 chainrings to M760 cranksets as the rings need a bit of dremelling to fit onto the shoulders of the cranks, but is there an issue the other way around? I think the M770 cranks don't have a shoulder for the middle ring, so any chainring should fit, but I read a comment somewhere amongst various Google searches that suggested the M770 ring was thicker so would require extra spacers for proper chainline (can't see it making much difference to be honest).
I'm inclined to think it will be fine as I'm pretty sure I have a Middleburn chainring on there at the minute, rather than the original Shimano, but cannot be sure as I'm not at home.
I could be patient and investigate when I get home, but I thought I'd open it up to the STW masses to see if anyone has experience of this issue.
Have run an SLX 36t middle on my 770 now on a stronglight 34t there have been no issues with either of these rings.
Just checked and neither of my 770 cranks ( 9 and 10 speed) have a shoulder, see no reason why it wouldn't fit.