That small piece of metal can render a bike unrideable, and sometimes a repacement is impossible to find.

There are standards for headsets, bottom brackets, brake mounting points, OLD and dropouts, etc, that frame manufacturers follow. Are there no standards for the hanger shape, so people can easily find a replacement and keep riding their lovely bikes?

  • 10
    The great thing about standards - there are so many to choose from.
    – David D
    Commented Jun 21, 2023 at 15:43
  • 2
    Unfortunately there is no standard committee or anything. Nobody to really push a standard. Usually you have one bike manufacturer or component manufacturer start doing one thing and then others copy it – more or less. But still no clearly defined dimensions, no clearly defined tolerances.
    – Michael
    Commented Jun 21, 2023 at 15:50
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    The obligatory XKCD: xkcd.com/927
    – MaplePanda
    Commented Jun 21, 2023 at 19:11
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    I'm not sure I'd agree with the statement "standards for headsets, bottom brackets, brake mounting points, OLD and dropouts, etc,". I mean, yes there are common sizes, but that hasn't stopped companies from introducing new ones.
    – Andrew
    Commented Jun 21, 2023 at 22:07

1 Answer 1


SRAM introduced the Universal Derailleur Hanger, which is a standard design. I'm not sure how much of a industry-standard it is right now but many bike brands and frame manufacturers have started to sell UDH-compatible frames and bike models, for example Canyon.

Note: As far as I know, this has only been adopted in the MTB world, you can check compatible bikes/brands here: https://bikefinder.sram.com/universal-derailleur-hanger-bikes

  • 3
    The Escape Colletive speculates that the UDH will make its way onto at least some road bikes.
    – Weiwen Ng
    Commented Jun 21, 2023 at 13:58
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    @WeiwenNg Yeah, I see no reason why we should move on like this. That being said, the only road bike I've seen in SRAMs listing is the Enve MOG, if we count gravel.
    – DoNuT
    Commented Jun 21, 2023 at 14:01
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    Small addition: SRAM has introduced this year a MTB derailleur that doesn't not require a hanger at all (XX Eagle, mounted directly on the axle).
    – Rеnаud
    Commented Jun 22, 2023 at 6:51
  • Yes, but it is UDH-compatible, so you just mount the XX Eagle RD directly onto a UDH frame. One of the special features of the Eagle Transmission is a derailleur hanger-free mounting of the electronic rear derailleur, which is mounted instead of the UDH universal derailleur hanger.
    – DoNuT
    Commented Jun 22, 2023 at 6:57

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