Just fitted one with new chain and cassette and getting lot of chain suck. Suspect I’ve got it the wrong way round (I’ve got it with engraved side on inside)

Is it directional and if so which way round?

Thanks

Chain ramps on the inside.

yes it is directional.

no chain ramps on a granny but the teeth are profiled.

Stamping should be on the inside and the little lug on the inner circumference should line up with the crank arm. As should all the little lugs (or sometimes dowel on the large) on the other chainrings so all the shift points match up.

errmmm its the right way round but I actually think the chain is catching on the middle chainring – it’s one of those ones with large black lumps on it (good description that)

think I’ve got a compatibility issue – was getting with previous inner ring as well and thought that was worn, but guess not?

The middle chainring sounds like one of the newer style ones introduced on 9 speed SLX and 9 speed XT from M770 onwards (and now on 10 speed from Deore up).

What cranks are you running? Older cranks are designed for rings without the black plastic bit so the ring sits too far towards the granny – ie not exactly in the middle of a 3 ring set up.

Or your chainline is messed up. Do you have the correct BB spacers?

and is your front derailleur at the right angle?

thanks Andy – that sounds like it. They are old style XT Hollowtech cranks – the first external BB ones (8 / 9 years old). Ring is new so I guess it is the type you are talkng about

so looks like I have 2 good grannies and the wrong middle ring!

think I’ll just lob a deore steel one on it!

Sounds like your cranks are M760s then.
You could probably shim the inner ring out a bit from the crank to bodge it.

You should be able to modify the chainring to get it to fit. I got a set of M760 cranks off ebay with the latter rings and need to do likewise.

You can modify the crank lugs but I prefer sorting the ring out if possible.

yup they are 760’s

did think of the shimming idea – don’t see why that shouldn’t work

I think my outer ring is new SLX too, so if I put a different middle ring on, I guess the outer and middle may foul as well?

Andy – modify how?

Guess you could file / grind a bit of the black plastic off?

thanks

I think Andy is talking about the mounting points on the spider needing to be filed down to accommodate slightly deeper tabs on the rings. Not sure its relevant to your (different) issue.

Just had a look at the cranks I have and if you look at the lugs on the cranks that the middle and outer ring bolt to they have a lip just in from the bolt holes that the normal chainring would sit on to centre it.

You either need to file down the lips OR, if you can, file down the black plastic (glass fibre on SLX, carbon fibre on XT) so it no longer hits the tabs.

ermm right definitely got m660 chainrings on XT 760 cranks. Live and learn eh

I have shimmed the inner out with some washers and it works but there is quite a big gap – only had thickish washers, so I’m not totally comfortable with it…….. suspect it works as my front shifter isn’t indexed (bar end shifter on a drop bar fargo)

think I’ll try to file down the black plastic a bit, or thinner washers. Or would a deore middle ring work with the slx outer and inner?

thanks again

Deore middle will work.

Just don’t get the new 10 speed deore one as it’s like the one you have 😀

Personally I would make the nice SLX one fit as they do shift nicer.

tried thinner washers – seems okay!

thanks for your help