Last week I put the triple chainrings back on my cranks as I’ve converted the bike back to geared from SS.

It looked like this (not my crank);

and all appeared well.

I very rarely use the granny ring and on the two occasions I ended up selecting it (because I thought I was in the big ring at the front not the middle) yesterday the chain fell between the middle and granny rings and jammed.

I’m confused. The middle looks like it’s in the right place (pins facing inwards), the granny looks right – writing inwards, bolts in the recesses in the rings.

So what have I done wrong?

Front mech adjustment ?

M760 or M770? (that picture has m770 rings)
Older M760’s have a strange spacing that maybe to blame?
As per a comment from Middleburn when I asked why they had a specific 760 ring “Shimano changed the shoulder that the ring sits on to from 90mm to 88mm and the chain line is 0.6mm closer towards the outer ring.”

That said, I’ve since given up on Middleburns (double the price without double the life) and use deores without issue, so have you fitted the inner ring the right way round? (Deores have a cut out on one side IIRC, really dunno if this would be enough to affect the chainline)

[embarrassed cough]

I’d fitted some XTR rings from the crank rings box which have a different spacing for the granny ring.

😳
[/embarassed cough]

thanks for the suggestion 🙂