Shimano asymmetric compatibility

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  • Hello,

    I'm wondering wether older 4 bolts / 110 BCD chainrings (like Ultegra 6800 for instance) would fit a GRX crankset. BCD is the same, what about the asymmetric design ?
    Would like to widen the choice for big rings beyond the couple GRX specific ones available.

    Thanks !

  • Thanks @Chaley will try to ask my question more clearly :)
    The document you shared shows a Shimano 4 bolts 110 BCD Asymmetric type of pattern : do you know if this is the same for all 4 bolts, 110BCD asymetric Shimano cranksets ? Would an Ultegra 6800 ring (4 bolts, 110 BCD asymetric) fit a GRX crankset in this respect ?
    Thanks

  • Mr vs ms I think the shimano chainring terms your after

    Ta specialises and a bunch of other people make aftermarket rings foe slightly less than the probably obsolete shimano ones

  • Thanks @BrickMan, sorry my english is limited and i didn't understand your first sentence (Mr / Ms). Can you please rephrase it ? Thanks.

  • Even if the holes are placed exactly the same the chainrings are shaped to fit only in 6800, you may need to file it to make it fit. Also, the small chainring on GRX it's not 110 bcd, it's smaller,so you wouldn't be able to use a pair and probably it will shift pretty badly. And it would look like ass.
    Anyways, 48t is plenty for anything up to 70kph, and probably a lot more useful than a 53 for the average cyclist

  • 'MR'
    'MS'
    'MA'
    'MB'
    etc there are loads of these
    Are the terms shimano use for those 4 bolt road chainring type, it means only some of them work with other inner + outer as a matched pair otherwise they don't shift very well.
    Check Shimano tech docs and I also find SJS cycles website is good for explaining about chainrings, we run a shop but sometimes end up referencing a few places like SJS for a sanity check on whats what.

  • Thanks @Netakure my idea was basically to make a 40-30 (yeah i know but it's relevant for my riding on 9 speeds), so with a road 40 as GRX doesn't offer this size (30 inner exists as GRX so shoulnd't be a problem). Seems i'll turn to good old TA as the cheapest + lightest option for unusual pairing. Thanks @BrickMan didn't know about these "marks", makes sense as brands would rather sell new rings that maintain compatibility unfortunately.

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Shimano asymmetric compatibility

Posted by Avatar for CoconutCrab @CoconutCrab

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