xdrmusclex

There is alot of talk that CF frames will explode or detonate and kill everybody in the immediate vicinity, is there any evidence that this actually happens, i dont seem to see any pictures or real reports of any of these catastrophes.

asmallsol

BOOOOOM.....

No what really happens when CF breaks is individual strands exceed their fracture strength, and will snap. The load that the individual strand carried is then transfered by the matrix to surrounding strands. Because of the nonisotropic nature of CFRP, the prorogation of the crack will not follow a set path like metals, and will cause a very random fracture pattern.

roadfix

What happens in many cases is you end up in the ER.

Quijibo187

no.

asmallsol

Not really. When CF fails, it looses like 99% of its structural integrity, but since not all the strands will fail, it will stay in one piece. I have seen some soft-tail mountain bikes fail (a semi-full suspension MTB that uses flex of the chain stays (typically CF) to pivot instead of hinges.) and when they fail, it was still semi (used extremely loosely) rideable, similar in the respect that a flat tire is still rideable on a big descent.

steaktaco

Can you then assume, if you find a hairline crack that is straight (rather than the randomness you described), that it is just a scratch in the clear coat? Or does the resin crack straight until the fiber underneath completely fractures?

Also: when carbon does fail, can you really stab yourself with jagged edges? The one time I've seen a seatpost fail, it was pulverized; looked almost like cloth at the edges.

roadfix

I was more or less referring to a sudden fork failure. I should have made that clear.

asmallsol

You can impaile yourself with just about anything given the right circumstances, but many broken carbon things I have seen (hockey sticks) fail, but stay in one piece. Basically how you describe as almost a stiff cloth were it snapped at. As for the hair line cracks, its probably the clear coat, not the resin that are cracking up but there is no way to really tell unless you put it under a Keyance or some other type of optical microscope.

rockabilly808

do they explode? ever heard of hiroshima? the government wants you to think it was atomic weapon. but in reality it was a prototype american aircraft made of carbon fiber that happened to be flying over the city when the CF failed, massively, boom, lash city gone. and that is the truth.

on a serious note what happens is the individual fibers break

timmyquest

This is a recently uncovered photo taken by Treks R&D department. It is the result of crashing an '08 Madone frame into a wall at 17mph

carpediemracing 

Carbon fiber is sort of like a cross between coal and glass. I've cut myself on carbon shards when I got too curious about a broken fork (roof rack + low hanging branch + 50 mph). Looks like when you get a magnet in steel filings - except the little spikes don't move when you touch them.

In car races they blow the shards off the course else everyone will flat. Those spikes are really sharp.

In "safety carbon" (I made up that term) they layer it with kevlar, the same way car glass is plastic with glass. The kevlar becomes flexy cloth, helping retain the carbon shards. In fact, kevlar is so resistant to tearing that it's used in some bike locks - you can't rip it using a jack or whatever, you actually have to use scissors to cut it. The kevlar in carbon fiber helps prevent panel disintegration (like on a race car).

cdr

tzracer

Anisotopic (and anisotropy) is way funner to say.

Treefox

04jtb

what happens when you give it too much power in a high gear...

Crash716

My CF frame actually had a crack in it and it looked like a hairline crack. the frame basically failed but did not destruct. Don't assume that straight "scratches" in carbon frames are clear coat...i did that for 3 weeks on my frame and then found another "scratch" in the frame only to flex it and actually see the frame separating....all this after just finishing a crit race sprint.....i have never seen a CF frame just explode unless it was from blunt force trauma...usually it cracks and gets weak and you fall over, but it doesn't send shards of CF into the atmosphere.

jonathanrules

damn. i've got a scratch in the clearcoat. luckily it really doesn't penetrate past it

bigreen505

I bought a bunch of Trek overrun tubing from the company that makes it for a non-bike project. I would guess this is what is used for head tubes, top tubes, seat tubes, not down tubes. We were only testing compressive strength in a press. It breaks. I remember it being pretty uneventful. That stuff is crazy strong.

xdrmusclex

ok, so we all agree the big boom theory is a load?

timmyquest

The "theory" you're referring to is a sarcastic joke that stems from threads like this...

BHBiker

HOLY SCIENCE FICTION BATMAN!!!! do you really believe that craparoonie boom boom explode krakakoom expression they use with CF? Boy o boy....CF cracks so if yo are doing 60kph while your carbon frameset decides to fail...you end up with an explosion...exploded lips, skull and bones....Thats what the boom is all about....so go get yourself an eBay carbon bike that is used "only 500kms"....he he he he he

Aren't all eBay bikes used only for 500kms or even less because its only gathering dust in the shed????

CHEERS!

steaktaco

A pile-up kinda looks like a mushroom. Sometimes.

Machka 

It cracks.

If it is your seatpost, your weight might hold it in place, and you might not even notice it at first.

If it is your forks, you could end up doing a face plant.

No one has ever (seriously) said that CF explodes. Several people have translated posts by people like me who say that CF shatters (because it fragments like glass) to mean explodes. Very different words.

Also the term "catastrophic" has been used to describe what happens to CF when it cracks/shatters. That use of "catastrophic" simply means that it happens quite suddenly ... it doesn't gradually twist, bend, or break like other materials might. And the suddenness with which CF can crack/shatter is potentially dangerous ... like if, for example, you were riding down a hill and your forks shattered. This happened to an acquaintence of mind ... he did the face plant I mentioned above, and was hospitalized. Although he was fairly seriously injured, he lived.

spry

We have never interviewed a CF failure/explosion survivor so it is safe to assume that the fatality rate is quite high.
What,you want to die in front of the television on your recliner?

kensuf

A tear in the fabric of time and space occurs and you wind up in an alternate universe.

operator

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