"brittle" vs. non-ductile



Jay Beattie wrote:
>
> Jambo wrote:
> >
> > If people want to use CFRP on bikes, fine and well, but it will do them good
> > to be aware of the pitfalls.

>
> Why is Boeing making planes out of this stuff? Are they using
> something different than we see in bikes?


Yes. They are using fanatical (and fantastically expensive) quality
control and ongoing scheduled inspection.

Chalo
 
> 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.
>
 
"Jay Beattie" <[email protected]> wrote in message
news:[email protected]...
> On Sep 6, 5:55 pm, "Jambo" <[email protected]> wrote:
>> 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.

>
> Why is Boeing making planes out of this stuff? Are they using
> something different than we see in bikes? -- Jay Beattie.


CFRP is good for planes because its strength to weight ratio is better than
Al alloys, it has higher fatigue limits, and since its desirable properties
can be made directional (i.e. it's anisotropic), a component can be made
thinner with CFRP than if metal alloys are used. However, all aircraft
manufacturers using CFRP invest heavily in continual, regular
non-destructive inspection and damage assessment techniques. Why? It's
long been recognized that CFRPs can get significantly damaged without any
visible clues (i.e. sub-surface damage), due to low velocity impacts
perpendicular to the duty loads, e.g. a dropped hammer on a composite wing
skin, or a blow to a composite panel. Once significantly damaged, failure
is catastrophic.

In terms of numbers, as in my other posts:
1. in the elastic range, CFRPs have similar stress/strain characteristics as
Al alloys (ratio around 0.4 - 0.5). This means that what can dent an Al
alloy can also damage a CFRP, but the latter may not exhibit visible clues
2. in the plastic range, where deformations are permanent, CFRPs have
elongation to failure of about 1.4 %, whereas Al alloys typically have 25%.
This means that once the load has exceeded the elastic limit, CFRP will fail
catastrophically compared to Al.

So, Boeing makes plane components out of this stuff, but it also spends a
lot of money in making sure the stuff is always ok to fly, by more rigorous
non-eyeball inspections compared with Al alloys.
 
"Mike Jacoubowsky" <[email protected]> wrote in message
news:[email protected]...
>> 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),


I didn't say all damage to carbon components cannot be seen; but many types
of damage are not visible. Delamination is almost always not visible, and
any deformations where fibers have broken but the plastic matrix hasn't
plastically deformed (such as bumps). All damage aren't caused by crashes
where things become visible externally: I can overtorque a clamp on a carbon
handlebar, or overload my seatpost and not notice anything until it fails.

> so it's not the case that a damaged carbon tube allways instantaneously
> and catastrophically fails.


Sure, it depends on where the damage is, as I've also indicated before.
However, you've only mentioned frames - a cracked BB weld may take a while
to grow to noticeable size, but I've seen many CF handlebars and seatposts
fail catastrophically with almost no warning.

> 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.


Your method may work for some damage, but not for all. I wouldn't ride a
crashed bike that has only been checked by your coin tap and squeeze tube
technique, and I wouldn't recommend anyone do so either: there are many
types of serious CF damage that are undetectable by these techniques.
Google the topic of NDI and carbon composites.

>> 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.


Of course, no one said that the other side is consequently true: that Al
alloys do not fail catastrophically. The fact is that CF will fail much
more readily after plastic deformation than Al, by a magnitude percent.

>> 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.


Except that "common sense" isn't really all that common. Some may argue
that if it doesn't look damaged, doesn't feel damaged, then it must be ok -
common sense to the uninitiated.

> 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.


That may be a factor, but the main danger is the failures experienced by
those who use CF in high-injury likelihood components such as stems,
handlebars, seatposts - as I've indicated before, check out the pictures and
stories at mtbr.com for examples.
 
Luke wrote:
> In article <[email protected]>, jim beam
> <[email protected]> wrote:
>
>> Luke wrote:
>>> In article <[email protected]>, jim beam
>>> <[email protected]> wrote:
>>>
>>>> Luke wrote:
>>>>> On Mon, 03 Sep 2007 14:32:04 -0700, jim beam
>>>>> <[email protected]> wrote:
>>>>>
>>>>>> eh? the privilege of arguing against me lies with /you/ big guy, not me
>>>>>> - so feel free to go ahead and present your own information. whenever
>>>>>> you're ready...
>>>>> "privilege of arguing against me"?! Consider me truly debased at
>>>>> receiving such a distinction! LOL!
>>>>>
>>>>> My intent was not to argue, it was to know more. Up thread you wrote
>>>>> that in your experience CF failure is preceded by much 'audible
>>>>> warning'. Will you be more specific?
>>>> i think you should d.a.g.s. first.
>>> A quick search of rbt archives, key words "jim beam carbon failure"
>>> yielded 397 results. A quick scan -- I don't have the time to wade
>>> through the whole list

>> and i do???

>
> Evidently not. So consult your memory, it's much quicker.
>
>>> -- reveals many rancorous threads;

>> that is not relevant to an innocent question.
>>

> True. No need to have inserted it.
>
>>> is there an
>>> example among the results comprising a detailed description of a carbon
>>> component failing you?

>> the answers are out there.

>
> You have them, pass them along.
>
>> bottom line, i smell "agenda" in this question, and it has nothing to do
>> with curiosity about materials.

>
> Lotta aromas circulating...I detect overtones of bull feces in your
> evasiveness.


which is exactly where you were intending to go from the start, hence my
original comment. present your own work - i'm not going to do your
arguing for you.
 
Tim McNamara wrote:
> In article <[email protected]>,
> Peter Cole <[email protected]> wrote:
>
>> Luke wrote:
>>> In article <[email protected]>, jim
>>> beam
>>>> bottom line, i smell "agenda" in this question, and it has nothing
>>>> to do with curiosity about materials.
>>> Lotta aromas circulating...I detect overtones of bull feces in your
>>> evasiveness.

>> You're learning why arguing with this guy is pointless.

>
> Except for the rather sad entertainment factor of watching him flail
> about yet again, clueless as to why his arguments sink like stones and
> retreating into puerile name calling. He's probably entertained, too,
> since he can go on with it for weeks and weeks at a time.


timmy, you're a retard.
 
Peter Cole wrote:
> Luke wrote:
>> In article <[email protected]>, jim beam

>
>>> bottom line, i smell "agenda" in this question, and it has nothing to
>>> do with curiosity about materials.

>>
>> Lotta aromas circulating...I detect overtones of bull feces in your
>> evasiveness.

>
> You're learning why arguing with this guy is pointless.


but you don't argue. you merely make up some gainsay position, try to
justify it with ********, then continue to repeat yourself in the hope
that repetition will obliterate the real facts. "cfrp is brittle -
except for when it's not". what a crock.
 
Jambo wrote:
> "Mike Jacoubowsky" <[email protected]> wrote in message
> news:[email protected]...
>>> 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),

>
> I didn't say all damage to carbon components cannot be seen; but many types
> of damage are not visible. Delamination is almost always not visible, and
> any deformations where fibers have broken but the plastic matrix hasn't
> plastically deformed (such as bumps). All damage aren't caused by crashes
> where things become visible externally: I can overtorque a clamp on a carbon
> handlebar, or overload my seatpost and not notice anything until it fails.
>
>> so it's not the case that a damaged carbon tube allways instantaneously
>> and catastrophically fails.

>
> Sure, it depends on where the damage is, as I've also indicated before.
> However, you've only mentioned frames - a cracked BB weld may take a while
> to grow to noticeable size, but I've seen many CF handlebars and seatposts
> fail catastrophically with almost no warning.


how convenient. and you must have abused a lot of personal equipment if
you have direct personal experience of this stuff failing with "no warning".

/or/, you're saying that you've seen other failures, and are /presuming/
there is no warning - something that those of us that have some
familiarity with this material don't believe, and which you'll have a
hard time convincing anybody of if it wasn't your own equipment.


>
>> 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.

>
> Your method may work for some damage, but not for all. I wouldn't ride a
> crashed bike that has only been checked by your coin tap and squeeze tube
> technique, and I wouldn't recommend anyone do so either: there are many
> types of serious CF damage that are undetectable by these techniques.
> Google the topic of NDI and carbon composites.


here we go again - name a /single/ application outside aerospace where
that kind of testing is mandated. for any material. to claim it's
necessary fro cfrp bikes, but not for metals is a crock.


>
>>> 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.

>
> Of course, no one said that the other side is consequently true: that Al
> alloys do not fail catastrophically. The fact is that CF will fail much
> more readily after plastic deformation than Al, by a magnitude percent.


eh? cfrp doesn't plastically deform so don't confuse the two
deformation systems!!! and cfrp fails at a much higher limit than the
the al which is bent hopelessly long before the carbon.


>
>>> 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.

>
> Except that "common sense" isn't really all that common. Some may argue
> that if it doesn't look damaged, doesn't feel damaged, then it must be ok -
> common sense to the uninitiated.


straw clutching.


>
>> 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.

>
> That may be a factor, but the main danger is the failures experienced by
> those who use CF in high-injury likelihood components such as stems,
> handlebars, seatposts - as I've indicated before, check out the pictures and
> stories at mtbr.com for examples.


why not check r.b.t for examples? there's been over a decade of users,
and many many ned lud's bleating their fear of the unknown. and yet,
despite the many people just itching to criticize and millions of rider
miles on this "desperately dangerous" material, we have failures we can
count on the fingers of one hand. and all of them were preventable if
the rider had simply observed warning signs.

oh well, never let reality get in the way of a good fight - simply
******** your way along if people insist on pointing out the truth.
 
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> jim beam wrote:
>>>> Mike Jacoubowsky wrote:
>>>>> Someone wrote:
>>>>>> Every time we've seen a CFRP bike part that has been hit or loaded
>>>>>> hard enough to break it, it has been broken completely through. That
>>>>>> seems to indicate the the energy to complete a fracture isn't
>>>>>> much, at
>>>>>> least for carbon-epoxy such as we see in bikes.
>>>>>
>>>>> This is both true and incredibly misleading. There are a lot of
>>>>> people out there riding on damaged (broken) carbon frames & forks
>>>>> that aren't aware of it. Few know what to look for, and even fewer
>>>>> *want* to look for the damage, preferring instead to think "phew,
>>>>> looks like it came out OK, I don't have to shell out a ton of money!"
>>>>
>>>> indeed.
>>>
>>> This is probably the best demonstration of why CF is bad for "prime
>>> time".

>>
>> er, you ought to let boeing into your secret then...

>
> The aircraft industry works to higher standards than joe (jim) consumer.
> That's the point.


i /hate/ to point this out, but the people that /started/ using cfrp in
bikes used experience /from/ the aerospace industry. damn.


>
>
>>
>>
>>>
>>>
>>>>> So yes, it's true that few have "seen" a carbon fiber product
>>>>> that's broken and not yet completely failed, but that doesn't mean
>>>>> they're not out there.
>>>
>>> First you say that there are lots of people riding damaged CF without
>>> knowing, then few have seen these (unless you're splitting "damaged"
>>> and "broken" and "failed"). Seems contradictory, unless you mean
>>> there are lots of damaged frames and forks that don't have symptoms?
>>> (something I have no trouble believing).

>>
>> misconstruction.
>>
>>>
>>>
>>>> absolutely - the warning signs are there but are frequently ignored.
>>>
>>> He seems to say there aren't any.

>>
>> putting words into peoples mouths...

>
> 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.

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

2. ask advice on this forum from people that are familiar with the
material and its failures. or even, if sufficiently desperate,

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

as a guy that doesn't understand the difference between elasticity and
plasticity, you're not exactly well positioned to try spreading fud. at
least, not to people that aren't gullible fools.
 
jim beam 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.
>
> 1. the bike comes with an owners manual outlining inspection and
> warnings. or


I have. They (Trek) essentially say "if you suspect damage, bring it
in". What if you don't suspect damage? The material I've found asserts
that "tap, squeeze and peek" often won't find existing damage.


> 2. ask advice on this forum from people that are familiar with the
> material and its failures. or even, if sufficiently desperate,


The few on this forum that seem to have some level of expertise of CF
agree with what I've dug up (and cited).


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


I wouldn't for 2 reasons: they're not (in most cases) technically
qualified and they have a conflict of interest.


> as a guy that doesn't understand the difference between elasticity and
> plasticity, you're not exactly well positioned to try spreading fud. at
> least, not to people that aren't gullible fools.


You can repeat that claim ad nauseam, it doesn't make it true.
 
jim beam wrote:
> Peter Cole wrote:
>> Luke wrote:
>>> In article <[email protected]>, jim beam

>>
>>>> bottom line, i smell "agenda" in this question, and it has nothing
>>>> to do with curiosity about materials.
>>>
>>> Lotta aromas circulating...I detect overtones of bull feces in your
>>> evasiveness.

>>
>> You're learning why arguing with this guy is pointless.

>
> but you don't argue. you merely make up some gainsay position, try to
> justify it with ********, then continue to repeat yourself in the hope
> that repetition will obliterate the real facts. "cfrp is brittle -
> except for when it's not". what a crock.


It's not "a crock". Easy example: uniaxial, brittle on axis, non-brittle
off. Too hard?
 
Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> Luke wrote:
>>>> In article <[email protected]>, jim beam
>>>
>>>>> bottom line, i smell "agenda" in this question, and it has nothing
>>>>> to do with curiosity about materials.
>>>>
>>>> Lotta aromas circulating...I detect overtones of bull feces in your
>>>> evasiveness.
>>>
>>> You're learning why arguing with this guy is pointless.

>>
>> but you don't argue. you merely make up some gainsay position, try to
>> justify it with ********, then continue to repeat yourself in the hope
>> that repetition will obliterate the real facts. "cfrp is brittle -
>> except for when it's not". what a crock.

>
> It's not "a crock". Easy example: uniaxial, brittle on axis, non-brittle
> off. Too hard?


a configuration not used in bike componentry - too obvious?
 
Peter Cole wrote:
> jim beam 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.
>>
>> 1. the bike comes with an owners manual outlining inspection and
>> warnings. or

>
> I have. They (Trek) essentially say "if you suspect damage, bring it
> in". What if you don't suspect damage? The material I've found asserts
> that "tap, squeeze and peek" often won't find existing damage.


now that is presumptive ********!!!! but it sure is great to fabricate
something to be frightened of!!!


>
>
>> 2. ask advice on this forum from people that are familiar with the
>> material and its failures. or even, if sufficiently desperate,

>
> The few on this forum that seem to have some level of expertise of CF
> agree with what I've dug up (and cited).


no they don't. you've got the usual retards competing for the stupidity
prize, and one other joker that dismisses the very aerospace standards
he tried to espouse.


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

>
> I wouldn't for 2 reasons: they're not (in most cases) technically
> qualified and they have a conflict of interest.


ah, the jobstian dodge - insult, question competence and make false
accusation. nice.


>
>
>> as a guy that doesn't understand the difference between elasticity and
>> plasticity, you're not exactly well positioned to try spreading fud.
>> at least, not to people that aren't gullible fools.

>
> You can repeat that claim ad nauseam, it doesn't make it true.


but we have your own words and they're on archive!!! "plasticity",
"elasticity", "ductility", "fracture energy absorption" are all terms
with which you're on record as being hopelessly "confused".
 
On Sep 6, 11:57 pm, jim beam <[email protected]> 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.

- Frank Krygowski
 
"jim beam" <[email protected]> wrote in message
news:[email protected]...
> Peter Cole wrote:
>> The aircraft industry works to higher standards than joe (jim) consumer.
>> That's the point.

>
> i /hate/ to point this out, but the people that /started/ using cfrp in
> bikes used experience /from/ the aerospace industry. damn.


This is your say so, not fact. Geez, you're incredibly gullible.
 
On 2007-09-07, [email protected] <[email protected]> wrote:
> On Sep 6, 11:57 pm, jim beam <[email protected]> wrote:

[...]
>> 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"!


When he has ever given bad advice?

[...]
> 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.


Now I'm confused. I was pleased to learn a few days ago that cycling is
basically safer than sitting on a sofa watching TV. But not if I use a
CF frame?
 
"jim beam" <[email protected]> wrote in message
news:p[email protected]...
> Jambo wrote:
>> Sure, it depends on where the damage is, as I've also indicated before.
>> However, you've only mentioned frames - a cracked BB weld may take a
>> while to grow to noticeable size, but I've seen many CF handlebars and
>> seatposts fail catastrophically with almost no warning.

>
> how convenient. and you must have abused a lot of personal equipment if
> you have direct personal experience of this stuff failing with "no
> warning".


Yes, I have, as opposed to your speculations. And they're not personal
equipment, but other people's.

> /or/, you're saying that you've seen other failures, and are /presuming/
> there is no warning - something that those of us that have some
> familiarity with this material don't believe, and which you'll have a hard
> time convincing anybody of if it wasn't your own equipment.


Well, people have related to me personally that there were no warnings, and
I've seen failures as they happened, with no warnings. So no, there are no
presumptions involved. And since it's obvious that you have no familiarity
whatsoever with CF components, your speculations are quite useless.

>> Your method may work for some damage, but not for all. I wouldn't ride a
>> crashed bike that has only been checked by your coin tap and squeeze tube
>> technique, and I wouldn't recommend anyone do so either: there are many
>> types of serious CF damage that are undetectable by these techniques.
>> Google the topic of NDI and carbon composites.

>
> here we go again - name a /single/ application outside aerospace where
> that kind of testing is mandated. for any material. to claim it's
> necessary fro cfrp bikes, but not for metals is a crock.


Eh, dood, you said the folks who use CF components on bikes used "aerospace
experience" - so to claim that NDI is necessary for aerospace but not for
bikes is stoopid. Contradict yourself much?

I suggest you learn more about CF and composites in general before you try
to engage in any kind of argument over it. Google is your friend.

>> Of course, no one said that the other side is consequently true: that Al
>> alloys do not fail catastrophically. The fact is that CF will fail much
>> more readily after plastic deformation than Al, by a magnitude percent.

>
> eh? cfrp doesn't plastically deform so don't confuse the two deformation
> systems!!! and cfrp fails at a much higher limit than the the al which is
> bent hopelessly long before the carbon.


How can you claim to be a "former metallurgist" when you're so clueless
about materials? CFRP does plastically deform - and elongation to failure
is 1.4%. Don't get confused now.

>> Except that "common sense" isn't really all that common. Some may argue
>> that if it doesn't look damaged, doesn't feel damaged, then it must be
>> ok - common sense to the uninitiated.

>
> straw clutching.


Another devastating retort from a "former metallurgist". How does that
work, by the way? You're either a metallurgist or you're not.

>> That may be a factor, but the main danger is the failures experienced by
>> those who use CF in high-injury likelihood components such as stems,
>> handlebars, seatposts - as I've indicated before, check out the pictures
>> and stories at mtbr.com for examples.

>
> why not check r.b.t for examples? there's been over a decade of users,
> and many many ned lud's bleating their fear of the unknown.


Why ignore mtbr.com, and any other fora where failures are reported?
Because it doesn't fit into your fantasy world, that's why!

> and yet, despite the many people just itching to criticize and millions of
> rider miles on this "desperately dangerous" material, we have failures we
> can count on the fingers of one hand.


That's with your discounting the other fora with reports of failures.

"La-la-la, if I close my eyes and hum loudly, all of these nasties will
disappear!"

> and all of them were preventable if the rider had simply observed warning
> signs.


Now we're back to user fault!

What a fool. You just keep breaking your lowest point every time you post.

> oh well, never let reality get in the way of a good fight - simply
> ******** your way along if people insist on pointing out the truth.


You're very entertaining, at least you have that going for you!
 
"jim beam" <[email protected]> wrote in message
news:[email protected]...
> which is exactly where you were intending to go from the start, hence my
> original comment. present your own work - i'm not going to do your
> arguing for you.


Translation - "I can't remember the ******** I spewed before, and I've
spewed so much, why don't you remind me which one you're talking about, lest
I conradict myself yet again".
 
Ben C? writes:


>>> 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"!


> When he has ever given bad advice?


>> 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.


> Now I'm confused. I was pleased to learn a few days ago that cycling
> is basically safer than sitting on a sofa watching TV. But not if I
> use a CF frame?


I think he got it. I think he's got it! ('enry 'iggins).

Jobst Brandt
 
On Sep 7, 8:24 am, "Jambo" <[email protected]> wrote:
> "jim beam" <[email protected]> wrote in message
>
> news:[email protected]...
>
> > Peter Cole wrote:
> >> The aircraft industry works to higher standards than joe (jim) consumer.
> >> That's the point.

>
> > i /hate/ to point this out, but the people that /started/ using cfrp in
> > bikes used experience /from/ the aerospace industry. damn.

>
> This is your say so, not fact. Geez, you're incredibly gullible.


Another point of clarification: are CF bicycle frames over built,
vis., stronger than necessary to take in to consideration the
limitations of the material? I ask this because I have not see an
epidemic of broken CF frames or forks, and I have been riding CF forks
for over 15 years (different ones). I have seen broken CF forks, but
only at the crown glue joint or at the crown steerer (aluminum steerer
and crown). I remember the early problems with the BB insert in the
Trek CF frames, but that was a different type of bonding problem and
not delamination like we are discussing here. I don't seem to
remember any more broken CF frames than, let's say, Al (e.g.
Cannondale was having a hard time there for a few years with the 2.8
design). I ride a Cannondale, so I am not trying to justify a CF
purchase. I am just trying to get a handle on the real risk to the
average rider of a decent CF frame.-- Jay Beattie.
 

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