Carbon fiber quality control

[notsew]

That’s a question Philip W. Coats, an attorney in San Diego, set out to answer when he represented a client whose front fork shattered. Coats obtained documents from the Chinese manufacturer (a settlement agreement forbids him from naming the company). Using a Mandarin translator, he found that the factory had no standards on how carbon fiber is produced. No rules restricted how thick it should be or how much impact it needed to absorb in a collision, Coats said.

Yikes! Maybe carbon fiber bikes are going to explode after all! One would hope this isn't coming from a majjor manufacturer. But who knows. I'll keep trying to buy my carbon bikes from the French and Italian.

https://www.outsideonline.com/231181...dents-lawsuits

[Veloo]

When my 2005 Giant TCR C2 reached 7 years old, I'd ride it and wonder: is thing gonna explode on me at any time?

[drewskey]

I too have often wondered just how long carbon frames are 'good for.'

I've replaced 2 frames (BB shell and rear dropout cracks) and 1 fork (delam in steerer) due to carbon failures in the past 8 years.

If your're interested in all thing carbon fiber testing and failure, a great follow on YouTube/Instagram is Luescher.
https://www.youtube.com/channel/UCY9...4lLOHpb_zbIedQ

[bicycletricycle]

I think stringent QC practices could add a lot of value to a brand. Especially if they cut apart a lot of competitors bikes to show how other companies aren't. I think Canyon X-rays all of their forks which is great.

For example- a lot of lugged frames have a problem with getting the glue viscosity/fit tolerance correct and end up pushing a lot of the glue out of the lug leaving large dry areas. I have talked to someone who does this operation at a boutique builder and they have no way to inspect the joint afterwards even though they know the whole joint is not getting an even coat of glue. I have also seen this problem in almost every carbon lug joint that has been cut apart (trek, time, look, etc..)

[Mark McM]

There's a lot of carbon fiber used in aerospace/aviation. Aircraft are probably subject to far more extremes of conditions and usage than the average bike frame. And yet, carbon fiber is considered reliable enough for airliners that will be in service for decades. Whats different in bicycles? Is there simply poorer quality control and inspection in bicycles? I guess that wouldn't be entirely surprising, given the relative cost differences between aircraft components and bike components.

[David Tollefson]

Originally Posted by Mark McM

There's a lot of carbon fiber used in aerospace/aviation. Aircraft are probably subject to far more extremes of conditions and usage than the average bike frame. And yet, carbon fiber is considered reliable enough for airliners that will be in service for decades. Whats different in bicycles? Is there simply poorer quality control and inspection in bicycles? I guess that wouldn't be entirely surprising, given the relative cost differences between aircraft components and bike components.

QC is tight in the aircraft industry. It's amazing what these suppliers try to get away with even when you ARE watching them like hawks... I shudder to think of what they do when no one is looking. The reason why I will never buy Chinese open mold... anything.

[notsew]

Originally Posted by Mark McM

There's a lot of carbon fiber used in aerospace/aviation. Aircraft are probably subject to far more extremes of conditions and usage than the average bike frame. And yet, carbon fiber is considered reliable enough for airliners that will be in service for decades. Whats different in bicycles? Is there simply poorer quality control and inspection in bicycles? I guess that wouldn't be entirely surprising, given the relative cost differences between aircraft components and bike components.

Yeah, I think that's the point. I certainly don't think that CF is inherently weak or prone to failure. Quite the opposite. I've seen enough large objects hit with boats to recognize the strength of laminated fibers, but bike manufacturers are trying to make light, cheap things. Light, cheap or durable. Pick two.

[buddybikes]

If you are worrying about the frame, worry first about your carbon wheels and handlebars!


ENVY made in Utah tubes in my FF is comfortable for me.

[bikinchris]

Some companies have very stringent quality control standards and require each frame to be certified by X-ray before they will buy it.
Many people who are buying cheap knock off parts are taking their life in their hands. I will NOT mount no name or knock off parts on a bike. My shop insurance will not allow that kind of exposure. I have taken some off, like handlebars that cracked on the first ride after the owner put them on.

[DuddyJ]

Is this a surprise though? If you cut corners you're gonna have problems later down the line. China is focused on how many plies they can lay and parts they can deliver.

Honestly X-rays aren't the best way to see defects in carbon fiber, it takes way too long to get the results of other NDE methods. Better off with some type of ultrasonic inspection.

[Salty]

Originally Posted by drewskey

I too have often wondered just how long carbon frames are 'good for.'

I've replaced 2 frames (BB shell and rear dropout cracks) and 1 fork (delam in steerer) due to carbon failures in the past 8 years.

If your're interested in all thing carbon fiber testing and failure, a great follow on YouTube/Instagram is Luescher.
https://www.youtube.com/channel/UCY9...4lLOHpb_zbIedQ

I was going to post the same link. Some very interesting videos.

[dem]

I ran into a guy who worked for a china company that builds parts for several of the big names - nearly all of them don't build their own small parts (stems/bars/etc.) even if they build their frames or rims or whatever in-house.

The short answer is: doing NDS (non-destructive testing) on carbon would be very very expensive. A wing for an airplane is an entirely different situation.

They basically take a sample occasionally and destructively test it. If it is good, the batch is good.

The reality is carbon fiber is very very tough, even with flaws, voids, sloppy lay-up etc. The amount of JRA (Just Riding Along, non-crash) carbon fiber catastrophic failure is almost nil.

Crash? All bets are off. I'd never ride a crashed carbon fiber handlebar (and I ride generic carbon frames & rims.)

Outside of the french guys (Time, Look) all carbon fiber is pretty generically crappy in the volume domain. But again, does it matter? Doesn't appear to.

[oldpotatoe]

Originally Posted by notsew

Yikes! Maybe carbon fiber bikes are going to explode after all! One would hope this isn't coming from a majjor manufacturer. But who knows. I'll keep trying to buy my carbon bikes from the French and Italian.

https://www.outsideonline.com/231181...dents-lawsuits

Anybody 'in the industry', like product managers, who use 'offshore' manufacturing(factories not owned by the manufacturer..but do work for scads of companies) have stories like the one above. They need to be monitored frequently, their product needs to be QCed thoroughly and constantly.

[Devotion]

Is there an accepted “industry standard” for shelf life of a carbon fiber frame and fork?
I recall hearing years ago that it’s about 10 years...though I’ve never seen that actually stated anywhere...
It’s my understanding that UV can eventually cause some breakdown of the resins/epoxies that hold everything together. Again, just heresay.

[CAAD]

I can say i just grab my supersix evo off the wall and just ride it. I'm good about maintenance and keeping it clean so it get regular inspections. I still see plenty of old trek carbon frames coming into the shop, still going strong.