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Video: CF failure

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Video: CF failure

Old 09-16-19, 04:19 PM
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bruce19
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Video: CF failure

https://www.youtube.com/watch?v=NQJU...od6KOUTZhHwTt8
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Old 09-16-19, 04:32 PM
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Yup- that further confirmed it's never fun to see crashes. Solo crashes included.
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Old 09-16-19, 05:22 PM
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That was scary seeing that thing come apart in his hands.
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Old 09-16-19, 06:08 PM
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That has to be frightening. I suppose it can be said he was lucky it did not happen on a high speed descent. Several years ago a man from the Boston area had a carbon fork failure and he died. I check my bike, not on a schedule but frequently as I wipe it down with a damp cloth. This is the equivalent of a pilot doing a walk around of the airplane. Once I found a broken spoke while cleaning up.
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Old 09-16-19, 06:19 PM
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The importance of a torque wrench can not be understated
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Old 09-16-19, 06:57 PM
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I think this video proves that everyone who rides a carbon fiber bike will die someday.
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Old 09-16-19, 09:33 PM
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Originally Posted by Seattle Forrest View Post
I think this video proves that everyone who rides a carbon fiber bike will die someday.
That's a true statement there. Who needs rim or disc brakes when you got a handlebar braking system! That might be the next big thing in cycling. Let the debate begin.

On a serious note, super props to the rider. It finally breaks for good and he jams what's left onto the front wheel and nearly comes away crash free. Never did panic, either. Wow.
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Old 09-17-19, 05:08 AM
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Originally Posted by Seattle Forrest View Post
I think this video proves that everyone who rides a carbon fiber bike will die someday.
I must be immortal....I'm riding steel.
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Old 09-17-19, 07:01 AM
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always use steerer compression plug that goes the full length of the stem clamp.
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Old 09-17-19, 07:04 AM
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It's like his trying to tame a spooked horse. "Whooooa, Whoooooa there big fella! Easy, easy, calm down."
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Old 09-17-19, 07:36 AM
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Would be interested into finding the cause of this. Over-tighten components? Existing unknown damages?

CF is 5 to 10x stronger than steel - it might just be a manufacturer defect.
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Old 09-17-19, 08:47 AM
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If you drill down in the comments section, Lanterne Rouge confirms he got feedback from the rider or team and there was no previous crash with that bike. With a pro team it's unlikely to have been an issue with faulty adjustments or not using a torque wrench.

That pretty much leaves manufacturing defect. Another commenter claimed to have visited a famous marque's assembly plant that spot checked only one in 50 frames made by contractors elsewhere.

If I were with a pro team I'd expect every component to have been inspected before racing. That may not eliminate mishaps like this but it sure couldn't hurt.

And that guy's reflexes are amazing. He had the presence of mind to unclip his right foot for balance while his bike was assploding and he was looking directly at the video camera person. And apparently wasn't too seriously injured and plans to race again in a few days.

I can barely remember to unclip at stop signs.
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Old 09-17-19, 09:14 AM
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Originally Posted by Seattle Forrest View Post
I think this video proves that everyone who rides a carbon fiber bike will die someday.
Exactly why I ride ti. I plan to live forever.
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Old 09-17-19, 09:20 AM
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Originally Posted by canklecat View Post
If you drill down in the comments section, Lanterne Rouge confirms he got feedback from the rider or team and there was no previous crash with that bike. With a pro team it's unlikely to have been an issue with faulty adjustments or not using a torque wrench.

That pretty much leaves manufacturing defect. Another commenter claimed to have visited a famous marque's assembly plant that spot checked only one in 50 frames made by contractors elsewhere.

If I were with a pro team I'd expect every component to have been inspected before racing. That may not eliminate mishaps like this but it sure couldn't hurt.
Or simply the nature of the material.
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Old 09-17-19, 09:48 AM
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Originally Posted by indyfabz View Post
Exactly why I ride ti. I plan to live forever.
Unfortunately a vast majority of Ti bikes delivered use carbon forks.
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Old 09-17-19, 10:11 AM
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That was an interesting video -- and it led me to watch "Carbon Fiber -- The Truth" by an Australian guy interviewing a carbon expert who came out of Boeing and now does bike repair. He had a lot of interesting things to say.

He's pretty critical of the bike industry's carbon fiber manufacturing processes in general, but rides carbon bikes himself. He says carbon clinchers are a design intended for aluminum, and he only rides carbon tubulars.

One of his main points: Compared to aerospace, carbon fiber in cycling is sloppier in the layup with far less quality control and inspection, allowing defects like air bubbles and wrinkles to go to market.

Also, carbon fiber repair has to be done with knowledge of the layup stiffnesses, orientations and carbon grades and match the original design of the bike.

He uses a specialized ultrasound system to see if carbon is solid. He says visual inspection doesn't cut the mustard, and you don't see him tapping any quarters on a frame. As much as he strips away a lot of marketing stuff, his diagnosis of potentially risky carbon could be maybe where he does a little voodoo of his own. It would have been great to see him show how ultrasound detects a layup problem and then have him tear into it and fix it. I'd have loved to see, for example, how a carbon steerer that is at risk of failure presents differently from a sound steerer.

He says that the compression plug is absolutely a structural element and keeps a steerer supported against the clamping force of a stem. He calibrates his torque wrenches.
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Old 09-17-19, 10:13 AM
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(one moment while I locate my Highly Speculative Failure Analysis Pocket Protector...there it is)

Notice in the video that the bars are rocking up and down well before the separation. That suggests that the crack began at the rear of the steering tube, between the stem and the headset.

Since the stem clamps at the rear, and the crack appears to have started at the rear, it's plausible that the stem clamp damaged the steering tube. My guess is a sharp edge on the inside of the stem clamp.

Also notice that the stem had no spacers underneath, so the stem was resting directly on the fairly rigid headset. With this configuration, it's easy to visualize some front-to-back rocking movement of the stem as the bars bounce up and down. This rocking motion might allow a sharp edge on the stem to cut carbon fibers at the rear of the steering tube.
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Old 09-17-19, 10:15 AM
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This just confirms my bias!
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Old 09-17-19, 10:21 AM
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Originally Posted by indyfabz View Post
Exactly why I ride ti. I plan to live forever.
except ti bike brands nowadays loves to put a carbon fork on their ti frame
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Old 09-17-19, 10:26 AM
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Originally Posted by ljsense View Post
That was an interesting video -- and it led me to watch "Carbon Fiber -- The Truth" by an Australian guy interviewing a carbon expert who came out of Boeing and now does bike repair. He had a lot of interesting things to say.

He's pretty critical of the bike industry's carbon fiber manufacturing processes in general, but rides carbon bikes himself. He says carbon clinchers are a design intended for aluminum, and he only rides carbon tubulars.

One of his main points: Compared to aerospace, carbon fiber in cycling is sloppier in the layup with far less quality control and inspection, allowing defects like air bubbles and wrinkles to go to market.

Also, carbon fiber repair has to be done with knowledge of the layup stiffnesses, orientations and carbon grades and match the original design of the bike.

He uses a specialized ultrasound system to see if carbon is solid. He says visual inspection doesn't cut the mustard, and you don't see him tapping any quarters on a frame. As much as he strips away a lot of marketing stuff, his diagnosis of potentially risky carbon could be maybe where he does a little voodoo of his own. It would have been great to see him show how ultrasound detects a layup problem and then have him tear into it and fix it. I'd have loved to see, for example, how a carbon steerer that is at risk of failure presents differently from a sound steerer.

He says that the compression plug is absolutely a structural element and keeps a steerer supported against the clamping force of a stem. He calibrates his torque wrenches.
Interesting read! Not surprised at all to see that the quality of CF in the aerospace industry is better in terms of quality than the CF used in sports or other ''less dangerous'' sectors. In fact, it is logical.

I guess that guy was just unlucky. The probabilities of this happening are most likely slim to none (1x out of 10 000 or 100 000?).

Originally Posted by canklecat View Post
If you drill down in the comments section, Lanterne Rouge confirms he got feedback from the rider or team and there was no previous crash with that bike. With a pro team it's unlikely to have been an issue with faulty adjustments or not using a torque wrench.

That pretty much leaves manufacturing defect. Another commenter claimed to have visited a famous marque's assembly plant that spot checked only one in 50 frames made by contractors elsewhere.

If I were with a pro team I'd expect every component to have been inspected before racing. That may not eliminate mishaps like this but it sure couldn't hurt.

And that guy's reflexes are amazing. He had the presence of mind to unclip his right foot for balance while his bike was assploding and he was looking directly at the video camera person. And apparently wasn't too seriously injured and plans to race again in a few days.

I can barely remember to unclip at stop signs
.
this ^^

Last edited by eduskator; 09-17-19 at 10:31 AM.
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Old 09-17-19, 10:41 AM
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Originally Posted by eduskator View Post
Interesting read! Not surprised at all to see that aerospace CF is better in terms of quality than Bicycle CF. It is very logical.

Guess that guy was just unlucky. The probabilities of this happening are most likely slim to none (1x out of 10 000 or 100 000?).
Yeah, I agree -- there are a ton of carbon bikes out there in the world. The guy I mentioned on YouTube is compelling because he says some of this freak of nature accident stuff can be predicted.

All that I wished for in terms of more information looks like it's on his YouTube channel -- it's Luescher Teknik. He does a video with a Specialized Venge fork and shows its voids along the steer tube, both by using his ultrasound machine, and also with the old school tapping -- but he uses a small thing I'm going to call a tuning hammer.

He has another video where he talks about paint cracks and how they may or may not be anything to worry about.

It's difficult to watch his videos and not come away with apprehensions about carbon fiber, which really should be the opposite of his message. Carbon is a great material to use in cycling, and he builds his own bikes from it. Aircraft that use carbon fiber have much longer maintenance intervals than aluminum. It's a great material, he says. But the way he shows problems in manufacturing or use (such as crushing steer tubes with stem bolts) is kind of a horror show.

His business, of course, rests on selling the idea of having carbon professionally inspected, and if necessary, repaired.
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Old 09-17-19, 10:42 AM
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It'll be interesting to hear what comes out of that, but 100% first thought was incorrect install of a stem to the steering tube on a carbon steerer tube. In other words, the insert too short or misplaced or over/under torqued the insert or the stem.
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Old 09-17-19, 10:46 AM
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Originally Posted by ljsense View Post
Yeah, I agree -- there are a ton of carbon bikes out there in the world. The guy I mentioned on YouTube is compelling because he says some of this freak of nature accident stuff can be predicted.

All that I wished for in terms of more information looks like it's on his YouTube channel -- it's Luescher Teknik. He does a video with a Specialized Venge fork and shows its voids along the steer tube, both by using his ultrasound machine, and also with the old school tapping -- but he uses a small thing I'm going to call a tuning hammer.

He has another video where he talks about paint cracks and how they may or may not be anything to worry about.

It's difficult to watch his videos and not come away with apprehensions about carbon fiber, which really should be the opposite of his message. Carbon is a great material to use in cycling, and he builds his own bikes from it. Aircraft that use carbon fiber have much longer maintenance intervals than aluminum. It's a great material, he says. But the way he shows problems in manufacturing or use (such as crushing steer tubes with stem bolts) is kind of a horror show.

His business, of course, rests on selling the idea of having carbon professionally inspected, and if necessary, repaired.
Proper maintenance is always the key! I didn't understand at first why it was so important to respect the torque specs and now I do. It's a lot easier to damage CF components than the steel ones.
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Old 09-17-19, 10:50 AM
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Originally Posted by Chi_Z View Post
except ti bike brands nowadays loves to put a carbon fork on their ti frame
That's why I change my fork after every ride.
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Old 09-17-19, 10:52 AM
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Originally Posted by indyfabz View Post
Exactly why I ride ti. I plan to live forever.
Gonna Live Forever. Thanks for the earworm.

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