Originally Posted by
steelbikeguy
it's a bit off-topic, but it's not just CF forks that can suddenly snap. I've had a recumbent fork where the aluminum fork blade broke. This was not unheard of for this fork, and the general hypothesis was that the attachment of the little loop that the disk brake cable fastened to might have affected the heat treatment of the fork blade.
Since the break occured right where the upper weld holdng the cable retainer attached, even without looking at the fractured material I'd say that pretty damning circumstantial evience of the cause. Weakened the material, possibly created a stress riser with some of the original material removed?
I've done a small amount of failure analysis over the years. Here's a good picture and explanation of what to look for in a stress fracture:
