> The point is that to rely only on visual inspection for CFRP damage is
> foolish, since
> 1. as you say, people don't know what to look for or
> 2. don't wanna look; but also
> 3. damage is likely to be sub-surface and CANNOT BE eyeballed, yet it's
> there.
Why do you insist that damage to carbon fiber cannot be seen? If that were
true, there'd be quite a few bikes still on the road that came in for crash
inspection, where we SAW damage to the tube. It's not uncommon to find an
area where the frame has a moderately-sized but hard-to-spot (unless you're
looking for it) crack. Usually it looks like a mild wrinkle in the tube. We
have seen such damage long after the crash happened (and after many
additional miles had been ridden), so it's not the case that a damaged
carbon tube allways instantaneously and catastrophically fails.
I should add that, if we don't find any visual damage, the next two steps
are to tap the tube with a coin and listen for any "dead" or buzzing areas,
and to squeeze the tubes by hand, feeling for any soft spots. The key to
successfully finding such things is to know how it crashed, and then figure
out where it may have been damaged.
> It's also quite stupid to rely on any noise that CFRP may make when it
> gets damaged. CFRP failure is catastrophic, and depending on the
> component, the loud crack is the last thing you hear before things go not
> so nice. If it's on a component like a handlebar, seatpost or fork, hope
> you have good health cover.
I think I covered most of that in the prior paragraph, but beyond that
should point out that all materials used in forks, stems & handlebars are
known to have catastrophically fail at times. I've gone through three stems
myself; one titanium & two aluminum. I've also broken aluminum seatposts.
All sudden, "catastrophic" failures that gave, to the best of my knowledge
at the time, no prior warning.
> If people want to use CFRP on bikes, fine and well, but it will do them
> good to be aware of the pitfalls.
It will do them good to be aware of the limitations of *any* bicycle
component, regardless of material. Common sense prevails (or should
prevail). If it seems like the crash was bad enough to cause you to think
"Wow, how could it possibly have survived that intact?", you should consider
that it may not have.
To me, the main "danger" posed by use of carbon fiber in frames & forks etc
is that the expense of replacement is such that people may be willing to
take risks and make assumptions that are dangerous.
--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
Redwood City & Los Altos, CA USA
"Jambo" <
[email protected]> wrote in message
news:
[email protected]...
>
> "Mike Jacoubowsky" <[email protected]> wrote in message
> news:[email protected]...
>>> Then how (if there are "warning signs") could there be:
>>> "a lot of people out there riding on damaged (broken) carbon frames &
>>> forks that aren't aware of it." ?
>>
>> Because, as pointed out previously, people either don't know what to look
>> for, or don't want to look for it (wishful thinking, wanting to believe
>> everything's OK since the bike can be ridden) or a combination of the
>> two.
>>
>> The statement is factual. That it's difficult for some to comprehend is
>> obvious, but that doesn't change that it's true.
>
> The point is that to rely only on visual inspection for CFRP damage is
> foolish, since
> 1. as you say, people don't know what to look for or
> 2. don't wanna look; but also
> 3. damage is likely to be sub-surface and CANNOT BE eyeballed, yet it's
> there.
>
> It's also quite stupid to rely on any noise that CFRP may make when it
> gets damaged. CFRP failure is catastrophic, and depending on the
> component, the loud crack is the last thing you hear before things go not
> so nice. If it's on a component like a handlebar, seatpost or fork, hope
> you have good health cover.
>
> If people want to use CFRP on bikes, fine and well, but it will do them
> good to be aware of the pitfalls.
>