Re: "brittle" vs. non-ductile

A Muzi wrote:
frkrygow@xxxxxxxxx wrote:
On Sep 6, 11:57 pm, jim beam <spamvor...@xxxxxxxxxxxxxxx> wrote:
Peter Cole wrote:
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." ?
simply pay attention big guy.

We all know it's pointless to argue with "jim beam," but since others
are reading: I think the advice he gives below is practically useless
for most people.

1. the bike comes with an owners manual outlining inspection and
warnings.

In America, warnings are attached to every consumer device. Our
society is perpetually crying "Wolf!" and most people are no longer
believing the warnings. I believe we've reached a point where the
warnings serve only as legal ammunition in a court action.

Any consumer actually reading his CF bike's manual would have to
distinguish whether the CF inspection warnings are any more serious
than statements like "Always check the tightness of every bolt before
any ride" and "Never ride any bicycle at night." Most will assume all
such warnings are legal smokescreens.

2. ask advice on this forum from people that are familiar with the
material and its failures.

:-) Trouble is, some poor sucker might believe advice from "jim
beam"!

3. ask bike shop owners that are familiar with the material and its
failures.

Correct me if I'm wrong (Andy? Mike? Sheldon?), but I don't think
all bike shop owners get extensive training in evaluating CF damage.
I've been in bike shops where the kid on duty couldn't operate a quick
release properly! No, he wasn't the owner, but how does the average
consumer tell the difference?

I don't think the typical American sport cyclist has any idea about
the true advantages and disadvantages of CF. IMO, he has no
understanding deeper than "Lance used this. It's 30 grams lighter and
it looks cool. Buycycling gave it 7 chainrings. It's going to
finally let me beat Fred up that hill."

And I think it's a bad idea to whittle the practical factor of safety
down to the point where the typical American sport cyclist has to
pretend to be a CF-certified airframe mechanic. It's like designing
the next Mazda Miata with an all-composite suspension system, and
hoping nobody ever hits a curb.

Right.

fud.



Yes, we can sometimes spot damage. But we are clear that our inability to see damage

but you can hear it. just like you wouldn't stand on a plank that made cracking noises under your weight, don't ride carbon that does the same.


is not an imprimatur of soundness. When in doubt post-crash we suggest replacement. Some riders do, some do not.

if no damage was evident, and it was silent, i wouldn't replace. indeed, i haven't replaced my carbon fork after the wheel-smashing incident. works fine - still no evidence of problem.



Chicago Trib last Sunday says Boeing is 'developing' i.e., doesn't yet have, test equipment to nondestructively spot anomalies and/or damage in composite materials for the Dreamliner. Boeing spokesman pointedly noted that rapping a structural member with a quarter, the previous standard test, is no longer considered sufficient to establish airworthiness.

i think the f.a.a. is going to be the best judge of this, not fudsters on r.b.t or the chic trib.
.

Relevant Pages

  • Re: Trek Pilot vs Dawes Audax
    ... wall thicknesses and frame ... the (all carbon) frame and forks back to the makers for damage ... Damage to carbon composite structures very often cannot be ...
    (uk.rec.cycling)
  • Re: Road bike crash damage
    ... tell if my carbon forks and handlebars are structurally damaged, ... quoting the damage to the bike has included the carbon fork and handlebars ... although they show no cosmetic signs of damage. ...
    (rec.bicycles.tech)
  • Re: "brittle" vs. non-ductile
    ... warnings are attached to every consumer device. ... Any consumer actually reading his CF bike's manual would have to ... all bike shop owners get extensive training in evaluating CF damage. ... we can sometimes spot damage. ...
    (rec.bicycles.tech)
  • Re: CHOOSING A FORK
    ... manufactuer nowadays are as safe as steel forks of about 20 years ago. ... The difference between steel and two phase carbon fiber & resin as a structural material is the failure mode. ... It is true that carbon fiber structural members show less outward indication of damage than do steel structural members. ... it's an old look, one of their first carbon forks, and tests, as described elsewhere in this thread, without trouble. ...
    (rec.bicycles.tech)
  • Re: "brittle" vs. non-ductile
    ... warnings are attached to every consumer device. ... I don't think the typical American sport cyclist has any idea about ... we can sometimes spot damage. ...
    (rec.bicycles.tech)
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