I now have a complete original SRAM GX 11 speed group with an 11-42 cassette and a 30 tooth chainring. I'd like to upgrade it by replacing my cassette with a new 11-50 (11 speed) and also a new chainring, probably 28 tooth.

Someone knows if exists a compatible cassette with these specifics? I've found this http://www.sunrace.com/en/products/detail/csmx80 but it is not said the compatibility.

  • Welcome to the site! I doubt that SRAM tests 3rd party cassettes with its own products, so you'd better look for compatibility claims at the Sunrace source. In general, look for derailleur capacity claims for the derailleur you plan to use. Additionally, to clear the largest 50t cog a hanger extension is often needed, such as e.g. Goatlink Feb 4, 2019 at 20:53

1 Answer 1


The max sprocket size for a GX 1x11 derailleur is 42 teeth, so an 11-50 cassette is not compatible.

See https://www.sram.com/sram/mountain/products/gx-1x11-x-horizon-rear-derailleur.

A derailleur hanger extension allows running a larger sprocket than the derailleur is specced for, but I don't know if that will work in your specific case.

Rear derailleurs don't care what size the chainring is, but it looks like the min chainring size on the GX crank is 30 teeth. https://www.sram.com/sram/mountain/products/gx-1000-1x-x-sync-crankset.

Really you are already at the lowest limit of gear ratios for this drivetrain.

  • Ok, do you also know if I can put a 28 or 26 T front crown?
    – Landau
    Jan 31, 2019 at 19:45
  • @Landau see update Jan 31, 2019 at 20:00
  • I think that 30T is just the smaller crown produced by Sram but I think I can put another one from another brand
    – Landau
    Feb 1, 2019 at 12:09
  • I used a 11-46 Sunrace cassette on a GX 1x11 derailleur without problems. Haven't tried with 11-50 cassette. Feb 2, 2019 at 12:50
  • @Landau, you'll need to find out what the bolt center diameter of the crank is, that is the limiting factor. Feb 2, 2019 at 12:55

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