The frame thru axel hole/dropout cracked while using my wahoo kickr trainer.

  1. Is this crack dangerous?

  2. If it is, what can I do?

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  • 2
    An experienced carbon frame builder might be able to glue in a new dropout.
    – Michael
    Jan 26, 2021 at 18:58
  • 1
    Does the crack exist on the other side too? It might be a deep gouge rather than a crack through.
    – Criggie
    Jan 26, 2021 at 19:48
  • 1
    Rule 12 applies. You now have your n+1 trainer queen. ;-) Jan 27, 2021 at 10:37
  • You can walk... Jan 27, 2021 at 12:37

2 Answers 2


A crack, unfortunately, is a crack. That’s dangerous no matter what the material. You could contact Allied to see if you have any options in terms of warranty. However, if you didn’t secure the bike properly, I would guess that they’d offer a discounted frame at most. You could find a carbon repair shop, e.g. Calfee and Ruckus Composites are two well known ones in the US, and there may be others local to you. From one price list I remember seeing, dropout repair was more expensive than tube repair, so I’m not sure what the most economical option is. However, that can most certainly be repaired.

  • 1
    If OP gets a replacement, then carbon might not be the best material for a dedicated trainer bike. Aluminium would be absolutely fine, as would steel.
    – Criggie
    Jan 27, 2021 at 7:26
  • 1
    @Criggie Well, sweat doesn't corrode or rust a carbon fiber frame... Jan 27, 2021 at 10:34
  • To both of you, sweat will facilitate galvanic corrosion anywhere you have aluminum inserts, e.g. cage bosses. However, I believe sweat issues could apply to steel and aluminum as well, in addition to aluminum-carbon interfaces.
    – Weiwen Ng
    Jan 27, 2021 at 14:15
  • 1
    @Criggie A steel frame might be the best choice. Aluminum will fatigue, especially on a trainer where the side-to-side forces are abnormally high. Light weight or whatever doesn't matter on a trainer either.
    – MaplePanda
    Jan 28, 2021 at 1:05
  • @WeiwenNg sweat will facilitate galvanic corrosion anywhere you have aluminum inserts, e.g. cage bosses But those are replaceable. When sweat corrodes away the cable stop in your aluminum frame for the internally-routed brake cable, you're stuck with doing something like running a full-length cable housing tie-wrapped to the frame. Jan 28, 2021 at 11:21
  1. Yes it's dangerous.
  2. Contact Allied.

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