Speaking of carbon fiber failures

This came in to our shop today. Customer said the bike simultaneously snapped in four places (chain and staystays) when he stood up on a 10% grade. First time I have ever seen anything like this; customer said it was JRA and I don’t know the history of the bike.

On a positive note for internal cables; they sort of held the rear end together! :grinning:

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that’s bizarre. it’s hard to understand how all 4 members would break at the same time.


Looks like a “replica” frame–is it? Kind of a cheesy post, though, without any real information other than “he said…”…not sure of the point. “JRA”? Japan Racing Association?

it’s got what looks like a UCI approved sticker on the seat tube? why do you think it’s a replica frame?

JRA = just riding along, or “I didn’t do anything bad”


JRA = Just Riding Around or Just Riding Along

I just wanted to share because I have been working at shops for a while and had never seen anything like this. There is likely more than meets the eye but as I said, I don’t know the history of the bike so all I have is the customer’s word.

It is not a replica frame.


I saw a TT chainstay break when a rider pushed out of the start gate with max. effort. He crashed when the DS chainstay snapped. Nothing else broke. This is weird. I agree there’s likely more to the story.


Thanks for the clarification on “JRA”–which clearly would NOT explain this frame damage–which begs the question of the missing info, without which, one could speculate to the moon, but have no real sense of what happened, or why–thus, don’t get the purpose of the post, other than to suggest that carbon frames can get damaged from accidents and abuse (as can steel, aluminum, even the idolized titanium…)…

Wouldn’t have necessarily broken at the same time, despite it seeming to do so.

You could imagine a scenario where one chainstay has failed, but failure is not known to the rider.

The rider then rides bike with failed chainstay up a 10% grade, stands up and kicks. Second chainstay fails. Bike is now supported by seatstays only.

At this point with zero chainstays in play, both the seatstays snap off like twigs.

To a rider this would seem like it all failed at the same time, because the process of the chainstay snapping and then seatstay snapping might happen in under a second.

You can imagine variations on that scenario but it would seem likely that one chainstay was compromised or failed, which led to the chain reaction of events that made it seem like the back of the bike fell off in one fell swoop


The members of a carbon frame, even the seat stays, are pretty strong. They don’t just snap without a lot of force. I don’t believe they’d break like twigs when the chainstays broke. I especially don’t believe the 2nd seatstay would instantly snap when the 1st one broke. They are really strong, they don’t break that easily.


I guess we can agree to disagree on that, perhaps you can test stomping on the pedals up a 10% grade with no chainstays?

Also noting that the timing between one chainstay going and the second chainstay failing could be pretty significant, it doesn’t necessarily happen in the same ride. But once you pop that second chainstay, I can’t envisage the seat stays hanging around too long if you’re putting power down.

From the looks the bike doesn’t look fastidiously maintained, in my experience you find things that are wrong with your bike when you clean them… hence I clean my bikes regularly :rofl:

Would be cool for Raoul to comment for sure.


Have a look at some of the videos of testing carbon frames to destruction on YuTube. They don’t just break like a twig. They cop a lot before they fail.

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Link me a video that applies to this situation?

technically under power, the chain will pull the seat stays forward under tension, counteracting the tendency for them to bend backwards under rider weight. applying power would likely help, not hinder.

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The profiles of the breaks appear to support the idea that there was downward force on the frame while the bike was upright. Hard to fathom that occurring from JRA - one chainstay yes, but all four points? It is a Canyon who have a poor QA record (I have a Canyon TT rig), but even so this is pretty low probably as a manufacturing fault in all four spots.

I’m dubious on the customer story…unless your customer is Robert Förstemann.
Agree with the comments re: some sort of downward force perpendicular to the stays.

Mounted on a roof rack (front wheel off) and driven into something perhaps?


Reminds me of @James_Huang’s blog (JRA with the angry Asian) ^^ No way that legit Canyon frame broke like this without a hit (maybe the user was unaware of the hit but still).

One more thing: please don’t use “replica” for “counterfeit”.


that’s not a carbon failure, that’s a comedy of errors.

Customer wanted an Aethos, but the wife wouldn’t let him.


As I said before, it was too bizarre a failure, likes of which I have never seen before, so I thought I would share.

I currently have three MTBs and one gravel bike all of which have carbon fiber frames (and all except one have carbon wheels and cockpits) so I do not have an anti carbon fiber agenda or anything :slightly_smiling_face:


Zero chance that was JRA and zero chance it was a compounding of failures. That is simply not how carbon fails.

Does the owner have a hitch rack in their car? My guess is that, if they do, they either backed into something or got hit from the rear.

Why did they bring it into your shop? Canyon doesn’t have dealers so I think they have to deal directly with Canyon for a warranty claim.