Originally Posted by
Brian Ratliff
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.
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.