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I am converting my merida silex from fsa omega bcd 120/90 bcd 2x9 to a 1x9 drivetrain. I am keeping the cranks and bottom bracket and trying to only change the rings.

There are not many 120 bcd narrow wide chain rings on the market. I have found a 'stone' chainring from China which is usually for sram 120 bcd. Is this likely to fit my 120 bcd fsa cranks?

Links FSA https://www.bikeinn.com/bike/fsa-omega-pro-120-bcd-chainring/137172323/p

Stone https://m.aliexpress.com/i/32959164753.html?gatewayAdapt=Pc2Msite

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The FSA 120mm chainrings are an asymmetric bolt circle that is totally unique to the several (maybe only one?) FSA models they come on. It is a standard they made up fairly recently still, and why or what they were thinking is not clear. The chainrings for it are bad quality. Nothing else is compatible. The SRAM 120mm rings are symmetrical.

FSA has made up a couple weirdo chainring standards in recent years that outside support doesn't exist for yet. They're all on a lot of bikes. There is some chance that a third party maker will step in, the situation seems primed for it, but I don't believe it's happened yet. Until then, if you can't get by with the replacement rings FSA offers, you need a different crank.

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  • That is a shame! I will likely convert it back to 2x
    – Tom Vine
    Oct 14, 2021 at 18:14
  • @TomVine The upshot is a pretty large number of those cranks have been sold OEM the past few years (the FSA Tempo Adventure too, which also uses its own weirdo BCD), and the chainrings really do have lifespan issues. I think there will probably be an aftermarket solution sooner or later. Oct 14, 2021 at 19:10

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