"Andrew Thorne" wrote in message
...
Be careful of the scratches - anything more than a superficial surface
scrape can easily lead to failure in a carbon frame.

Just a quick question for those who may actually have data: Is this true?
It's
one I've heard many times over the years, but the only broken carbon
frames
I've ever seen were the first generation OCLV that would break if you
looked at
them cross-eyed.

Sooooo, is this "deep scratches cause carbon frames to break" just an old
spouse's tale?

-Andrew

Mind you I'm not schooled on carbon bike frames in specific, but I do deal
regularly with carbon fibre industrial components. The danger of component
failure (or in this case, frame failure) comes from the depth of the damage.
What some people might call a scratch others would call a gouge. Most
carbon components built up for strength are composed of layers of carbon
fibre "cloth" weave, stacked in different directions. An individual carbon
fibre is strong only in one direction, so you need lots going in different
directions to make something that can withstand load.

Anything deep enough to break a significant number of individual fibres in
the weave weakens the frame at that point, making it more likely to break
under sudden load. If the scratched part is still stronger than the weakest
area designed into the frame under that specific load, then no harm, no
foul.

However, if the damage is deep enough to make that area the new weakest
point in the frame under any particular load, then the clock is ticking, so
to speak.

Hope that helped.

-Chuck W