Problem with Stronglight rings on Shimano 5750 cranks

[yelfordrover]

Replaced worn Shimano rings with Stronglight on a 5750 compact. Now have the issue of chain rubbing the inner face of the 50 ring when in the 34 and on the 12,13 &14. I expected the rub in the 12 but not the 13 & 14. With the original Shimano rings there was only rub in the 12. I suspect the Shimano outer was a bit wider so that it was positioned further out (and more out of the way). Can anyone suggest a solution?

[Brucey]

If you don't use the correct outside chainring, you might get away with using thin washers to space the rings further apart. Be warned though; if you overdo it the chain may tend to sit on top of the smaller chainring, but without actually meshing with it.

Suitable spacer washers are fitted as standard to some shimano chainsets and the washers are available as spare parts.

cheers

[fastpedaller]

I don't understand how this issue has occurred though (unless the outer ring is larger than before), because however thick the outer ring is, it wouldn't be any closer to the inner ring .... would it?

[531colin]

If the Stronglight pick-up pins are bigger than the Shimano ones, that could do it.
Also the teeth are not as thick as the rest of the chainring, they are machined down a bit, so the teeth on the inner ring can be in a different place relative to the spider on 2 different brands of chainring......all assuming the crankset has gone back in exactly the same place as it was.........

[Brucey]

I don't understand how this issue has occurred though (unless the outer ring is larger than before), because however thick the outer ring is, it wouldn't be any closer to the inner ring .... would it?

I have heard of this sort of problem before, and IIRC the outer chainring is effectively slightly dished outwards vs a standard one on some shimano compact chainsets. I think that the issue is so devious that even some other shimano chainrings won't work right for similar reasons.

cheers

[fastpedaller]

Ah - I see (confucious he say )

[yelfordrover]

Thanks for the replies.
Looking at the original Shimano 50 ring, it does seem that the inner side is "fatter" & that the teeth are therefore more out-board. The original inner looks more traditional. I have tried a pair of Sram rings on the 5750 crank & have the same interference as the Stronglight rings. Shall look into getting some spacers but am aware of the floating chain syndrome!