Quoting Chuck Schmidt:
>Craig Sandvik wrote:
>>
>> I always wondered if the classic "campy crack"
>> in the web could grow all the way into the arm.
>> Now you know:
http://www-tec.open.ac.uk/
> Quote from the web site:
> "This was a high quality component that had very
> high load cycles but was in excellent apparent
> condition until the final fracture that
> unseated the rider in heavy city traffic."
The cross section shows the darker oxidized area,
where the crack was before the arm broke through.
The crack reached the label on the front of the arm
before the break. Ergo, it was not in "excellent
apparent condition" to an eye that knows what to
look for. If you read the rest of the
description, they also say "The crack progressed
slowly through the crank arm (dark area) until
the remaining fragment was incapable of supporting
the bending moment generated by the force on the
pedal and the crank arm fractured rapidly."
> In 25+ years of daily participation in the
> bike scene in Southern California I have never
> seen nor heard about a Campagnolo crank failing
> in this manner.
I doubted it was possible for the web crack to grow into the arm, since the arm's cross section is so greater. The other break pictures I've seen have been lower on the arm or in the pedal eye.
One reassuring thing: all of the pics I've seen show that the crack should have been noticeable before the final break.
-- Craig Sandvik Berkeley, CA CC w/ list replies is ok (I'm Web only)
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