Broken frame

[carbonazza]

Patrick, that is very interesting. It is already dark here.
I'll post better pictures tomorrow morning.

[RS VR6]

Good stuff Patrick. The general bike buying public really has no idea what goes into the production of a carbon frame...including me. You just have to take the word of the manufacturers on how the frame is made. If you buy a $3k frame...you just have to assume that the materials and research you expect are actually in the frame.

I'm real curious to see a Specialized (or any big brand) frame cross sectioned and compared to a well known open mold (non bootleg) China frame. Done by a third party with no brand bias.

[Patrick C.]

Again, I'm no expert in composite failure modes, but nothing I've seen would stop me from riding my Chiner frame.  There is a lot of info out on the web, but it can be tough to sift through and find anything relevant.  It may be describing a completely different process than making bike frames, but this paper has a few pictures of broken test bars- http://www.scielo.br/scielo.php?pid=S1516-14392005000100016&script=sci_arttext  - the loading method has a big influence on what the fracture looks like as well as the layup. Particularly interesting (to me, anyway) was the conclusion-
"In general, the flexural and shear tests showed that the matrix type caused greater influence on the mechanical properties than the carbon fabric arrangement type. The F584/PW and F584/8HS laminates showed the highest flexural strength values than the F155 epoxy ones. This behavior is attributed to the higher toughness of the F584 matrix, which was modified with a thermoplastic"

Which makes sense, since the fiber is so much stronger than the matrix the overall strength depends on how well it holds together.  I guess instead of talking about the carbon fiber the bike companies should talk about their new toughened epoxy resin, but that doesn't impress people like "Ultra Super High Modulus Carbon Fiber".

[carbonazza]

Here are some close up pictures of the bits.




A plastic bag remained inside the frame. Probably the ones used to compress the wall against the mold.









The rock hit between 3 - 4

[cmh]

A plastic bag remained inside the frame. Probably the ones used to compress the wall against the mold.

Uh, huh, yeah, right, sure. Nice way to try to explain how your stash got all the way down there. Upside, it's probably still good. 

(and yes, that probably is remnants of the compression bag but I like my story better)

[Patrick C.]

Thanks for posting the pics, but you probably gave the gram counters an aneurysm seeing that bag left in there.  Probably an extra 10 g in there, or more if you count all the tubes 

I'll ask some coworkers about the pics, but based on the description of the crash I still think it performed as expected. 

[carbonazza]

@cmh, I'm afraid we are all part of a global opium traffic and should all get our frame inspected

@Patrick, so we finally found where the famous "frame weight: XXXX g  +/- 50g"  comes from.
It depends on the quantity of plastic bag left in the frame   

It is the only place( the other seat stay being intact... ) where I saw a plastic piece, and it must be stuck in an irregularity inside, as I couldn't pull it out.

[RS VR6]

Sucks that the bladder is left in like that. I've seen pictures of China carbon wheels with the bladder left in. How much more work is it to pull them out...or is it that once the part is molded...the bladder can't be pulled out? 

I have a Cervelo and a set of Zipp wheels...I hope that there are no plastic bags left in them. 

[Vipassana]

Do we really care if the plastic bag bladder is left in? It weights basically nothing.  Its presence has no performance degradation.  It will never be seen in normal use.  It might actually serve to help damp noise reverberation.

I also fail to see where/how you're supposed to reliably pull it out from after assembly?    You cannot from the dropout end.  And getting it out through that coming seat stay junction on the 256 has to be damn near impossible.

I see it as a non-issue and I bet it occurs on frames routinely, Chinese design or not.

[RS VR6]

On the Chiner frame...not really...but on the more expensive stuff yes.

If I pay an "X" amount for a high end product...I'd be pretty irritated to find leftover production tools left inside my frame.

To each their own.

[325racer]

On the Chiner frame...not really...but on the more expensive stuff yes.

If I pay an "X" amount for a high end product...I'd be pretty irritated to find leftover production tools left inside my frame.

To each their own.

But if you're in a situation such as this where the only way you know a bag was left inside is to break your frame.  Will you ever know if a Bag was left?

[RS VR6]

How about I put it this way. I don't like the idea of production tools being left inside my frame. Is that easier to accept?

[bruto]

How do you like the idea of non-structural foam adding weight to your XX crank arms?

[Cnasta]

Although the weight can be neglected, I'm also quite shocked about plastic being left inside. I don't think it supposed to be there Could be true that big brands have the same from time-to-time, but this is the first time I ever saw it... Apart from the weight, thinking about condensation as well although with carbon, that doesn't matter anyway. Just doesn't seem right

How about the rest of the frame, does it look ok (hard to tell from the photo's, but carbon seems pretty dense with now delamination issues on the inside). That is nice to see

[bruto]

It may just be impossible to extract the bladder from some of the tubes as they're closed
bladder in a rim is just sloppy QA, because there're plenty of spoke holes, but seatstay may not have any after leaving the mold (depending on whether it's made separately or the frame is monoqoque)