Shimano chainring doesn't fit – Help please.

Sorry for possibly the most boring post of the day.

I’m servicing a mates bike, including replacing all chainrings.
I purchased a Deore M532 32-t 4 bolt middle ring but it doesn’t quite fit on the exisitng hollowtech crank arms. It’s as if the tabs containng the bolt holes are slightly too long and won’t fit into the recesses on the arms.

Of course, I chucked the old rings before ensuring proper replacement so now can’t compare. The small and big ring fits fine just the middle ring doesn’t.

Any help gratefully received!

Thanks

Topper

Yep some rings have longer tabs and won’t fit without a bit of gentle modification. Got a dremel or angle grinder?

Check the small ring fits over the BB shell too.

There’s often a bit of shaping on shimano rings that needs a touch of filing to fit

Thanks for the feedback guys. Is this a quality control issue for Shimano rather than there being different size specs on Shimano chain rings?.

Thanks

Topper

I think there have been a lot of revisions on the crank design over the years meaning that some are not quite the same as others. I’ve had rings from shops that have been in stock for a while too… same BCD just meant for different cranks.

If memory serves me correctly, I think the difference occurred when they brought out 9 speed, probably to prevent people mixing them with 8 speed rings.

No, not a QC issue. The cranks do vary between each model and variant.

Shimano do it so ppl have to buy the offical version of the rings, as bike shops won’t tend to file chainrings to fit. There’s no harm in filing the tabs back though, been doing it for years, & yet to have issue due to the adjustment

I too , have had to make the Dremel mod on more than one occasion. Other than everything working fine, nothing else happened .