You don't think the force exerted on the carbon fiber is at least as great while flying a X ton plane? Being afraid of a material is ridiculous. do we need to find the Trials guy on the carbon bike and rims?

as shown with the cannondale bike.. if you hit something hard, things will break. Not to mention that just because it breaks in multiple places they all happened in the crash. Once one tube goes the support structure is gone and other things will fail. If someone takes your leg out and you fall down and break your arm.. your broken arm wasn't caused by the person kicking you.. it was a separate condition.

if you're hitting another person or a car at high speed the bike is the last thing i'd be worried about.

In the immortal words of Del Grifith, "That'll buff right out."

Now that I look at it, the headtube did snap off at the TT-HT-DT junction, like it did on the Bianchi and Specialized, but the fact that it also snapped in the middle of the TT and at the DT-BB junction is something else.

Why do people insist on comparing carbon bike frames to aircraft? Just because the two are both called "carbon fiber" in the popular press doesn't mean they have much in common. At the very least, the layup of the material (you know, the variable which determines the strength of the part), is completely different. The resin is probably different. The stresses and the margins of safety of the design are different as well.

Bike frames, in general, are not made to withstand loading from a frontal collision. Because the frame broke after a collision doesn't, by itself, mean there is anything intrinsically wrong with the frame.

irrelevant.

You're missing the point. Bikes have wheels. So do planes. So the two are very similar.

And I can fly on my bike.

It looks kind of like the tubes fractured where the cable stops are riveted. The holes from the rivets will create a stress concentration right there. Stress will also want to concentrate at the interface between the "rigid" cable stop and the "soft" carbon tube.

Also, as you know, there are different ways of building carbon frames. Some lead to the weakest area being at the tube joints, some in the middle of the tube or where lugs and tubes are joined.

Um, hello? The plane was invented by bicycle mechanics! Duh.

Maybe America's cup catamaran's would be a better comparison? probably more similar layup and resins there. either way it takes quite a lot of force to break it

re: bolded
exactly, but people like surgeonstone say they won't use a carbon bike because they break in a crash.

Why would this be a better comparison?

more tubular shapes than airplanes? between the pontoons, mast, boom, hydrofoils... i'm guessing the layups are more similar.

I was shocked when this guy's bike didn't explode saturday.... :rolleyes:
https://fbcdn-sphotos-e-a.akamaihd.n...02771996_o.jpg

Both get wet if you put them in a lake. You need to try harder to keep up.

Ok, this is the road forum so commuting issues aren't really what I think about. They make carbon recumbants and mountain bikes too.

Carbon bikes are supposed to absorb vibration etc better than aluminum. maybe less than steel. that is why they use it for forks, seatstays, seatposts, stems, bars even on aluminum bikes.

The picture of the CAAD involved the CAAD hitting other riders from behind so it was a head on impact like the OP.

And the CAAD appears to be broken and/or bent in similar places as the OP's bike.

Just using that pic as an example indicating these incidents are not CF specific.

*yawwwwwwwn* not my fault you want carbon to be stiffer than aluminum but less stiff than aluminum. perhaps you should think about it more.

i didn't say anything about head on collisions since no bike is built to handle that.

"Their" who need a babysitter?

I try not to hit things head on. That being said, the Chinese have a long history of putting junk into everything they make. They've even been caught putting plaster and asbestos in the pills they sell as medicine. By the way, have you seen Pepcid AC on drugstore shelves in the last few years? Not the cardboard little pills but the bottles. I haven't been able to find it for three years. I asked the pharmacist and he just fell silent. I smell a cover up. The bike frame in question is probably made from tin and pig iron.

you're clueless

When you're as smart as I am you don't need clues. You just know, you know? :thumb:

That was what I thought was odd, too.

That's a good point about the cable stops but the effect those stops have on the structural integrity of the frame should be very small. No data on this just spitballing based on failures I've seen in the past.

This looks like tube to tube construction which is why the failure at the junctions doesn't raise an eyebrow.

The fact that the impact happened at 35km and caused such catastrophic failures in multiple place suggests to me that it is a resin issue. Polyester resins are much cheaper and more brittle than resins used in more expensive frames.

Another thing to consider is the fact that the Chinese market is now flooded with locally produced prepreg that is compatible to T300 as opposed to the T-700 that is pretty much a benchmark for contemporary frames. I can't recall the tonnage of T-300 off hand but it is much lower than that of T-700.

All speculation on my part but possible explanations as to why this frame ate it so badly in a crash that shouldn't have ended its existence.

Too small of a data set to come to any conclusions, but if we are going to speculate at least use the available data in the thread and some basic logic. You have two pictures on this thread to compare -- the OP and the CAAD. Some observations: Both were head on collisions. Based upon the ride where the CAAD accident happened both were at very similar speeds. One was carbon into a motorcycle. One was aluminum into another rider. Aluminum doesn't use resin.

Now look at and compare the stress and breaking points in the two pictures.

Carbon Frame: Break in the TT about four to six inches from the head tube.
CAAD: Break in the TT about four to six inches from the head tube.

Carbon Frame: Break in the TT about four to six inches from the seat tube.
CAAD:Break in the TT at the seat tube.

Carbon Frame: Break in the DT where it connects to head tube.
CAAD: Bend, but no break, in the DT about three to four inches from the head tube.

Carbon Frame: Break in the DT where it connects to BB.
CAAD: Break in the DT where it connects to the BB.

There seems to be a problem in this thread distinguishing between correlation and causation. An unbranded frame broke to pieces in a crash in no way equates to it broke to pieces because it was an unbranded frame. In fact if that was some sort of hypothesis that was being tested the evidence in this thread that is most comparable, the CAAD picture, directly contradicts that idea. Think of how ridiculous it would be to suggest a CAAD frame broke to pieces in a crash, therefore it broke to pieces because it was a CAAD.

"All speculation on my part but possible explanations as to why this frame ate it so badly in a crash that shouldn't have ended its existence." (my emphasis). Why shouldn't it have ended its existence? That assumption seems not only baseless but in direct contradiction to all of the other pictures in this thread. The starting point should be the cause of the "asplosion" was direct force applied to the front of the bicycle in an amount and at angles the frame wasn't designed to handle and that most frames, even CAAD frames, are not designed to handle.

don't forget humble.

I suspect you own a Chinese grey market frame, am I right? In any case, speculation one way doesn't offset speculation in another.

I think the word you are looking for here is "experience". There are people (particularly BDop) on these forums who have seen a lot of different things. In the absence of data, I would be hesitant to discard their observations lightly, particularly if all I had to offer in return is other observations. Nobody knows if the frame build is scary or not. But observations can only add to what we know, it cannot be used to refute or cancel other observations. Remember the fable about the three blind men trying to describe an elephant? Each blind man is observing a piece of the overall picture; all the observations add but none can cancel or refute.

BDop has a lot of relatively inside knowledge about the bicycle component world, including frame manufacture. The stuff about the resins and quality of prepreg which tend to be used by off-market Chinese frames is knowledge which is not easily found outside the industry. I wouldn't discard it so lightly.