"brittle" vs. non-ductile

[Tim McNamara]

In article <[email protected]>,
"Mike Jacoubowsky" <[email protected]> wrote:

> >> 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).
> >
> > Therein is one of the issues in judging the long term safety and
> > durability of CF frames and forks: they just have not been in
> > service very long. I know people with steel frames and forks that
> > have been in use 35+ years, and I know of people whose daily rider
> > bikes are 50+ years old. These bikes are still safe and sound-
> > will that be the same for CF? We won't know for another 35 years
> > or so. And we may not know even then, as currently the folks who
> > tend to buy CF bikes tend to replace their equipment with newer,
> > more up-to-date stuff every couple of years anyway.
>
> Unless you believe that something happens to the fork, either steel
> or carbon, while it is just sitting there, un-used, a track record of
> 15+ years is more than adequate to judge the service life & safety of
> a carbon fiber fork.

Do we know whether there are any aging-related changes in the composite
materials used in bicycles? Or perhaps more to the point, do we know
there are *no* aging-related changes? I don't know one way or another.
But I do know that bikes get damage even when sitting around- somebody
knocks the shovels and rakes over in the garage and they hit the bike,
someone misjudges parking the car and knocks the bike over, etc. Well,
not my bikes because they hang up in the basement out of harm's way, but
many people's bikes just live out in the garage. CF tends to tolerate
those outrageous slings and arrows less gracefully than metals. Around
here that includes freeze-thaw cycles anywhere from -40F to 110F. Does
ultraviolet light affect the CF or the epoxy material? Are there
chemical reactions with atmospheric gases or perhaps things like
gasoline vapors, paint thinner vapors etc?

> It's actual use (on the road) that matters, and as we have seen steel
> forks fail in the past at anywhere from 30-80k miles (some fail
> sooner, some last longer, but that's approximates the average service
> life we've seen over time), the history of carbon forks, as an
> indicator of overall life & safety, becomes clear after no more than
> 10 years, as that will see a fair amount of product achieve that sort
> of mileage.

I've never seen a steel fork failure in the 35 or so years that I have
been dealing with bikes as an enthusiast, but then I only have a few
years of bike shop experience and you have seen thousands more bikes
than I. The odds of you seeing those things is much greater than mine.

> That someone you know has a bike that's 50 years old in daily service
> is likely a testament more to an extraordinarily overbuilt design,
> rather than the material used. If one were to build a fork of the
> same weight out of carbon fiber, it may very well achieve commendable
> life on the roads surrounding Baghdad! But why? Does it make sense to
> build something that will last from one generation to the next, or
> does it make more sense to optimize for the current user, and his/her
> typical lifespan of use (determined not by failure but more often by
> a desire to upgrade)?

That's a defense for planned obsolescence and underbuilding by design to
gain dubious improvements in performance that sound good in marketing
and make no beneficial difference when the rubber meets the road.

Even Lance Armstrong's "optimized" Trek didn't survive the Bag Handle
Crash, suffering a broken chainstay in the process. He only had to ride
it 10 km further, but what if that fracture had been unnoticed and he
had had to rider that bike down a technical descent with the typical
steep cliffs at the side of the road? A material that can just break in
a crash like that is not a suitable material for a bicycle. IMHO, YMMV,
yadda yadda yaddda but I will never buy one.

> The worst thing about this thread is the inference that other
> materials don't fail in normal use. They have in the past. They do
> today. And they will continue to fail tomorrow.

But differences in the failure process are significant. The reports I
have read indicate that CF fails catastrophically and often without
significant warning. Fractures propagate through steel fairly slowly
giving the rider a chance to observe and prevent catastrophic failure.
The original post that started all this was a CF Scott frame that
essentially shattered in a crash.

> It's generally not the material that causes a failure, it's how it's
> used.

That's just a truism. You could build a bicycle from pasta and it
wouldn't fail so long as you didn't try to ride it.

> I would suggest that the rate of frame failures in aluminum, steel &
> ti frames has probably increased since carbon fiber came on the
> market. Why? Because manufacturers have tried to mimic the weight of
> a carbon fiber frame using materials that really aren't suitable for
> that purpose. Sub 3.5lb steel frames, sub 2.8lb aluminum frames, sub
> 3.1-3.3lb ti frames... they're all in dangerous, bleeding-edge
> territory.

The failure modes are different for those materials than CF. They
aren't brittle, aren't damaged as easily and fractures don't propagate
as rapidly. We do agree that stoopid lite is stoopid lite no matter
what material is used.

> But if you created a well-build carbon fiber frame at any
> of those weights, it could be impossible to kill. But that's not what
> people are looking for with carbon fiber, so it shouldn't be a huge
> surprise that's not what they get.

Until we see it, we'll never know.

 

[[email protected]]

Tim McNamara writes:

>>>> 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).

>>> Therein is one of the issues in judging the long term safety and
>>> durability of CF frames and forks: they just have not been in
>>> service very long. I know people with steel frames and forks that
>>> have been in use 35+ years, and I know of people whose daily rider
>>> bikes are 50+ years old. These bikes are still safe and sound-
>>> will that be the same for CF? We won't know for another 35 years
>>> or so. And we may not know even then, as currently the folks who
>>> tend to buy CF bikes tend to replace their equipment with newer,
>>> more up-to-date stuff every couple of years anyway.

>> Unless you believe that something happens to the fork, either steel
>> or carbon, while it is just sitting there, un-used, a track record of
>> 15+ years is more than adequate to judge the service life & safety of
>> a carbon fiber fork.

> Do we know whether there are any aging-related changes in the
> composite materials used in bicycles? Or perhaps more to the point,
> do we know there are *no* aging-related changes? I don't know one
> way or another. But I do know that bikes get damage even when
> sitting around- somebody knocks the shovels and rakes over in the
> garage and they hit the bike, someone misjudges parking the car and
> knocks the bike over, etc. Well, not my bikes because they hang up
> in the basement out of harm's way, but many people's bikes just live
> out in the garage. CF tends to tolerate those outrageous slings and
> arrows less gracefully than metals. Around here that includes
> freeze-thaw cycles anywhere from -40F to 110F. Does ultraviolet
> light affect the CF or the epoxy material? Are there chemical
> reactions with atmospheric gases or perhaps things like gasoline
> vapors, paint thinner vapors etc?

Recall Spinergy four-blade wheels with carbon fiber "spokes". These
lost all their tension through thermal cycling in the back of the car
and probably age... and then they failed in rattling compression under
lateral collapse. I always glad I wasn't present when failure
occurred as one of these rode by, the four spokes fluttering loosely.
It is tension that gives wheels lateral strength, especially ones with
narrow hub width.

>> It's actual use (on the road) that matters, and as we have seen steel
>> forks fail in the past at anywhere from 30-80k miles (some fail
>> sooner, some last longer, but that's approximates the average service
>> life we've seen over time), the history of carbon forks, as an
>> indicator of overall life & safety, becomes clear after no more than
>> 10 years, as that will see a fair amount of product achieve that sort
>> of mileage.

Jobst Brandt

 

[[email protected]]

Tim McNamara writes:

>>>> 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).

>>> Therein is one of the issues in judging the long term safety and
>>> durability of CF frames and forks: they just have not been in
>>> service very long. I know people with steel frames and forks that
>>> have been in use 35+ years, and I know of people whose daily rider
>>> bikes are 50+ years old. These bikes are still safe and sound-
>>> will that be the same for CF? We won't know for another 35 years
>>> or so. And we may not know even then, as currently the folks who
>>> tend to buy CF bikes tend to replace their equipment with newer,
>>> more up-to-date stuff every couple of years anyway.

>> Unless you believe that something happens to the fork, either steel
>> or carbon, while it is just sitting there, un-used, a track record of
>> 15+ years is more than adequate to judge the service life & safety of
>> a carbon fiber fork.

> Do we know whether there are any aging-related changes in the
> composite materials used in bicycles? Or perhaps more to the point,
> do we know there are *no* aging-related changes? I don't know one
> way or another. But I do know that bikes get damage even when
> sitting around- somebody knocks the shovels and rakes over in the
> garage and they hit the bike, someone misjudges parking the car and
> knocks the bike over, etc. Well, not my bikes because they hang up
> in the basement out of harm's way, but many people's bikes just live
> out in the garage. CF tends to tolerate those outrageous slings and
> arrows less gracefully than metals. Around here that includes
> freeze-thaw cycles anywhere from -40F to 110F. Does ultraviolet
> light affect the CF or the epoxy material? Are there chemical
> reactions with atmospheric gases or perhaps things like gasoline
> vapors, paint thinner vapors etc?

Recall Spinergy four-blade wheels with carbon fiber "spokes". These
lost all their tension through thermal cycling in the back of the car
and probably age... and then they failed in rattling compression under
lateral collapse. I was always glad I wasn't present when failure
occurred as one of these rode by, the four spokes fluttering loosely.
It is tension that gives wheels lateral strength, especially ones with
narrow hub width.

>> It's actual use (on the road) that matters, and as we have seen steel
>> forks fail in the past at anywhere from 30-80k miles (some fail
>> sooner, some last longer, but that's approximates the average service
>> life we've seen over time), the history of carbon forks, as an
>> indicator of overall life & safety, becomes clear after no more than
>> 10 years, as that will see a fair amount of product achieve that sort
>> of mileage.

Jobst Brandt

 

[bfd]

<[email protected]> wrote in message
news:[email protected]...
> Tim McNamara writes:
>
>>>>> 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).
>
>>>> Therein is one of the issues in judging the long term safety and
>>>> durability of CF frames and forks: they just have not been in
>>>> service very long. I know people with steel frames and forks that
>>>> have been in use 35+ years, and I know of people whose daily rider
>>>> bikes are 50+ years old. These bikes are still safe and sound-
>>>> will that be the same for CF? We won't know for another 35 years
>>>> or so. And we may not know even then, as currently the folks who
>>>> tend to buy CF bikes tend to replace their equipment with newer,
>>>> more up-to-date stuff every couple of years anyway.
>
>>> Unless you believe that something happens to the fork, either steel
>>> or carbon, while it is just sitting there, un-used, a track record of
>>> 15+ years is more than adequate to judge the service life & safety of
>>> a carbon fiber fork.
>
>> Do we know whether there are any aging-related changes in the
>> composite materials used in bicycles? Or perhaps more to the point,
>> do we know there are *no* aging-related changes? I don't know one
>> way or another. But I do know that bikes get damage even when
>> sitting around- somebody knocks the shovels and rakes over in the
>> garage and they hit the bike, someone misjudges parking the car and
>> knocks the bike over, etc. Well, not my bikes because they hang up
>> in the basement out of harm's way, but many people's bikes just live
>> out in the garage. CF tends to tolerate those outrageous slings and
>> arrows less gracefully than metals. Around here that includes
>> freeze-thaw cycles anywhere from -40F to 110F. Does ultraviolet
>> light affect the CF or the epoxy material? Are there chemical
>> reactions with atmospheric gases or perhaps things like gasoline
>> vapors, paint thinner vapors etc?
>
> Recall Spinergy four-blade wheels with carbon fiber "spokes". These
> lost all their tension through thermal cycling in the back of the car
> and probably age... and then they failed in rattling compression under
> lateral collapse. I was always glad I wasn't present when failure
> occurred as one of these rode by, the four spokes fluttering loosely.
> It is tension that gives wheels lateral strength, especially ones with
> narrow hub width.
>

I agree that Spinergy carbon "spokes" appear to be dangerous. However, a
carbon spoke is alot different than a carbon frame. For example, I bought a
USED Calfee carbon fiber frame with a Kestrel carbon fork in 1997 that was
made in 1994 and had approximately 2500 miles of use by the previous owner.
I have put over 25,000 miles since purchasing as I average about 2500 miles
or so per year (hard to get in more mileage with 2 small children). I have
crashed the bike several times, including personal injury to myself. So far,
I have not experience any problems with the carbon fiber frame or fork. I
do inspect both the frame and fork and have seen any sort of damage that
causes concern. There have been paint chips, but I them up with clear nail
polish.

Similarly, Craig Calfee says there are several high mileage riders riding
his frames since he started making carbon frames in 1987. I believe one has
over 200,000 miles on his frame and several others have over 100,000 miles.
You need to check with Craig to find out exactly how many and who these
individual riders are.

 

[Jambo]

> "jim beam" <[email protected]> wrote in message
> news:[email protected]...
>
>>
>> more than 30 years ago, i went to a materials lecture held by a supplier
>> to sikorski. part of the presentation was on rotor blades. according to
>> our guy, they were "quite happy" with composites in that application. it
>> seems the benefit was not only much extended service life, but also
>> something unanticipated - that of being more likely to survive bullet
>> strike in combat. that's not to say every blade was surviving every
>> strike, but apparently, older style aluminum blades had a dismal survival
>> rate. composite blades otoh, if they didn't fail immediately, were much
>> more likely to get you out of the hot zone, or better yet, get you home.

By the way, this story is total rubbish.

"More than 30 years ago" means 1977 and earlier. The Vietnam War has just
ended then.

There were no Sikorsky composite helicopter rotors in military applications
before and during the Vietnam War.

Composite helicopter rotors did not come into military use until the 1980s.

SO, where did your "bullet strike in combat" happen, dumbass? You need to
stop making up ****, no one's believing it. Maybe it's time to let go of
your nom de plume, even though you've invested years in bulshitting your way
through this ng.

 

[Jambo]

"bfd" <[email protected]> wrote in message
news:[email protected]...
> For example, I bought a USED Calfee carbon fiber frame with a Kestrel
> carbon fork in 1997 that was made in 1994 and had approximately 2500 miles
> of use by the previous owner. I have put over 25,000 miles since
> purchasing as I average about 2500 miles or so per year (hard to get in
> more mileage with 2 small children).

Good for you. No one said CF frames fatigue faster than any other material
frames.

> I have crashed the bike several times, including personal injury to
> myself. So far, I have not experience any problems with the carbon fiber
> frame or fork. I do inspect both the frame and fork and have seen any
> sort of damage that causes concern. There have been paint chips, but I
> them up with clear nail polish.

Great. Again, no one said that every and any crash will result in CF frame
failure. Without knowing the forces involved in your crashes, it's only
deduction that you did not damage it.

> Similarly, Craig Calfee says there are several high mileage riders riding
> his frames since he started making carbon frames in 1987. I believe one
> has over 200,000 miles on his frame and several others have over 100,000
> miles. You need to check with Craig to find out exactly how many and who
> these individual riders are.

Durability of CF under duty load is not in question. Low tolerance for
damage for non-duty loads, in parts of the CF components not meant to take
loads, is the issue.

 

[Mike Jacoubowsky]

>> The worst thing about this thread is the inference that other materials
>> don't fail in normal use.
>
> No, the worst thing is the *mode* of CF failure.
>
> > Sub 3.5lb steel frames, sub 2.8lb aluminum frames, sub
>> 3.1-3.3lb ti frames... they're all in dangerous, bleeding-edge territory.
>> But if you created a well-build carbon fiber frame at any of those
>> weights, it could be impossible to kill. But that's not what people are
>> looking for with carbon fiber, so it shouldn't be a huge surprise that's
>> not what they get.
>
> Sure, they get what, a 2.1lb frame? Why bring this up? Nobody is going to
> make the "no kill" CF frame. Who would want it?

That's actually not true. We're beginning to see lesser-performance, heavier
carbon fiber frames used in less-expensive bikes. They don't ride as
smoothly, they're not as light, and generally just don't feel as lively as
the leading-edge products, but frankly, some of the stuff we're now seeing
is probably going to be one heck of a dent into a car before having a
problem itself. These frames will run close to 3 pounds, so on the one hand,
they lose the appeal of ultra-lightweight that people come to expect from
carbon fiber. But on the other hand, they're probably going to outlast many
cycling careers.

But the question is, will people buy a carbon frame that weighs more, and
costs more, than a similarly-equipped bike with an aluminum frame?
Unfortunately, nobody in the bike biz is going to promote such bikes as
being ultra-durable, because the inference will be that other bikes aren't
(and, obviously, not just inference but fact). More likely the only reason
such bikes will sell is because people will want to buy in on the coolness
of carbon fiber, and the added strength will be an incidental benefit that
they'll know nothing of.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com

 

[Aeek]

On Sat, 8 Sep 2007 21:17:14 -0700, "Mike Jacoubowsky"
<[email protected]> wrote:

>I agree. Materials that fail in common use should be banned from bikes.
>
>Oh, darn. All those failing aluminum stems... ****. That's quite a few
>thousand dollars of inventory I'm going to have to dump. And the failed
>Belleri handlebars. ****. That's going to be many thousands of dollars more
>of inventory I can't trust.
>
>Oh, darn. All those steel frames that buckled under impact, causing the
>front wheel to make contact with the downtube and throwing the rider
>violently. ****. We can't use steel for frames anymore.
>
>Oh, darn. All those titanium frames that had sheared downtubes, due to
>cracks beginning at the downtube cable guides. ****.
>
>Oh, wait, nevermind. It wasn't the material that was the issue, it was how
>it was used. Incredibly dangerous failure modes, yet nobody was calling for
>manufacturers to stop using aluminum, steel or titanium for bike parts.

The common factor isn't the materials, its the rider. Clearly we
shouldn't use anything where there is a human involved. Oh, hang on.

 

[Michael Press]

In article <[email protected]>,
"Mike Jacoubowsky" <[email protected]> wrote:

> >> 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).
> >
> > Therein is one of the issues in judging the long term safety and
> > durability of CF frames and forks: they just have not been in service
> > very long. I know people with steel frames and forks that have been in
> > use 35+ years, and I know of people whose daily rider bikes are 50+
> > years old. These bikes are still safe and sound- will that be the same
> > for CF? We won't know for another 35 years or so. And we may not know
> > even then, as currently the folks who tend to buy CF bikes tend to
> > replace their equipment with newer, more up-to-date stuff every couple
> > of years anyway.
>
> Unless you believe that something happens to the fork, either steel or
> carbon, while it is just sitting there, un-used, a track record of 15+ years
> is more than adequate to judge the service life & safety of a carbon fiber
> fork. It's actual use (on the road) that matters, and as we have seen steel
> forks fail in the past at anywhere from 30-80k miles (some fail sooner, some
> last longer, but that's approximates the average service life we've seen
> over time), the history of carbon forks, as an indicator of overall life &
> safety, becomes clear after no more than 10 years, as that will see a fair
> amount of product achieve that sort of mileage.
>
> That someone you know has a bike that's 50 years old in daily service is
> likely a testament more to an extraordinarily overbuilt design, rather than
> the material used. If one were to build a fork of the same weight out of
> carbon fiber, it may very well achieve commendable life on the roads
> surrounding Baghdad! But why? Does it make sense to build something that
> will last from one generation to the next, or does it make more sense to
> optimize for the current user, and his/her typical lifespan of use
> (determined not by failure but more often by a desire to upgrade)?
>
> The worst thing about this thread is the inference that other materials
> don't fail in normal use. They have in the past. They do today. And they
> will continue to fail tomorrow. It's generally not the material that causes
> a failure, it's how it's used. I would suggest that the rate of frame
> failures in aluminum, steel & ti frames has probably increased since carbon
> fiber came on the market. Why? Because manufacturers have tried to mimic the
> weight of a carbon fiber frame using materials that really aren't suitable
> for that purpose. Sub 3.5lb steel frames, sub 2.8lb aluminum frames, sub
> 3.1-3.3lb ti frames... they're all in dangerous, bleeding-edge territory.
> But if you created a well-build carbon fiber frame at any of those weights,
> it could be impossible to kill. But that's not what people are looking for
> with carbon fiber, so it shouldn't be a huge surprise that's not what they

You are glossing over the reports here describing the
fragility of carbon fiber resin composites. There _is_
a material difference between carbon fiber resin and
other bicycle frame materials. Difference in impact
resistance, difference in failure mode, and difference
in ease of damage assessment.

As a retailer with a reputation to maintain you should
bring technological arguments to bear or gracefully
hold your peace. Saying that it makes no difference in
practice may not be the best course.

--
Michael Press

 

[Michael Press]

In article
<[email protected]>,
"Mike Jacoubowsky" <[email protected]> wrote:

> But you suspect there's more to it than that, and there is. People don't buy
> much of anything expecting it to last forever, and it's normal for people to
> expect that many expensive items (TVs, for example) aren't to be repaired
> but simply tossed out and replaced if something goes wrong. That sort of
> thinking determines what's made available to people. And as long as people
> are willing to accept it, the product engineers are going to work within
> those parameters when they design something. If they have the choice of
> designing something that will weigh 1/2 pound more but be repairable, vs
> lighter and disposable if it breaks, they're going to go for lighter.

I works both ways. It is easier and cheaper to built a
monolithic unrepairable TV with a built in failure rate
than to build a TV that is good, and good twenty years
later. I have one of the last good Sony televisions.
Had a problem and found a guy to repair it. Two
components on a solder board. He said Sony televisions
today have bad color, bad picture, and will not stay in
adjustment. My tv has a magnificent picture that has
not drifted in over a decade.

If the manufacturers only build monolithic TV's people
will only buy monolithic TV's.

--
Michael Press

 

[Ben C]

On 2007-09-09, Michael Press <[email protected]> wrote:
> In article
><[email protected]>,
> "Mike Jacoubowsky" <[email protected]> wrote:
>
>> But you suspect there's more to it than that, and there is. People don't buy
>> much of anything expecting it to last forever, and it's normal for people to
>> expect that many expensive items (TVs, for example) aren't to be repaired
>> but simply tossed out and replaced if something goes wrong. That sort of
>> thinking determines what's made available to people. And as long as people
>> are willing to accept it, the product engineers are going to work within
>> those parameters when they design something. If they have the choice of
>> designing something that will weigh 1/2 pound more but be repairable, vs
>> lighter and disposable if it breaks, they're going to go for lighter.
>
> I works both ways. It is easier and cheaper to built a
> monolithic unrepairable TV with a built in failure rate
> than to build a TV that is good, and good twenty years
> later. I have one of the last good Sony televisions.
> Had a problem and found a guy to repair it. Two
> components on a solder board. He said Sony televisions
> today have bad color, bad picture, and will not stay in
> adjustment.

Just get an LCD TV (made by Sony if you like).

You will wonder why you spent so many years staring down a glass tube
at an electron gun.

> My tv has a magnificent picture that has
> not drifted in over a decade.
>
> If the manufacturers only build monolithic TV's people
> will only buy monolithic TV's.

The important variable for many consumers including myself is ultimate
reliability. I would trade repairability for that any day, which is why
I don't sympathize with people who whine about wanting their SU carbs
back.

TVs are getting less reliable these days because they run so much
software, which is of course full of bugs.

Bikes are different because I don't know if frames are any more reliable
now than they ever were for being less repairable. But similar
economics: a new cheap aluminium frame probably costs less than paying
someone to braze your PX-10 back together. Unless you live near Yellow
Jersey Cycles.

 

[Tim McNamara]

In article <[email protected]>,
"Mike Jacoubowsky" <[email protected]> wrote:

> I agree. Materials that fail in common use should be banned from
> bikes.
>
> Oh, darn. All those failing aluminum stems... ****. That's quite a
> few thousand dollars of inventory I'm going to have to dump. And the
> failed Belleri handlebars. ****. That's going to be many thousands of
> dollars more of inventory I can't trust.

Like this tem owned by a friend, who discovered this condition the day
after a 104 mile ride we undertook on hilly road including gravel and
rough pavement?

http://www2.bitstream.net/~timmcn/stemphotos/stem_right.png

How would a CF stem have fared with cracking like this?

> Oh, darn. All those steel frames that buckled under impact, causing
> the front wheel to make contact with the downtube and throwing the
> rider violently. ****. We can't use steel for frames anymore.
>
> Oh, darn. All those titanium frames that had sheared downtubes, due
> to cracks beginning at the downtube cable guides. ****.
>
> Oh, wait, nevermind. It wasn't the material that was the issue, it
> was how it was used. Incredibly dangerous failure modes, yet nobody
> was calling for manufacturers to stop using aluminum, steel or
> titanium for bike parts.

As hyperbole goes, this doesn't work very well. The failure mode for
these materials is rarely catastrophic unlike CF and is thus not
"incredibly" dangerous. The problem with steel frame in your example
was the impact- a CF frame would have shattered rather than bending.
The problem with the titanium frames didn't result in the downtube just
snapping.

 

[jim beam]

[email protected] wrote:
> Tim McNamara writes:
>
>>>>> 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).
>
>>>> Therein is one of the issues in judging the long term safety and
>>>> durability of CF frames and forks: they just have not been in
>>>> service very long. I know people with steel frames and forks that
>>>> have been in use 35+ years, and I know of people whose daily rider
>>>> bikes are 50+ years old. These bikes are still safe and sound-
>>>> will that be the same for CF? We won't know for another 35 years
>>>> or so. And we may not know even then, as currently the folks who
>>>> tend to buy CF bikes tend to replace their equipment with newer,
>>>> more up-to-date stuff every couple of years anyway.
>
>>> Unless you believe that something happens to the fork, either steel
>>> or carbon, while it is just sitting there, un-used, a track record of
>>> 15+ years is more than adequate to judge the service life & safety of
>>> a carbon fiber fork.
>
>> Do we know whether there are any aging-related changes in the
>> composite materials used in bicycles? Or perhaps more to the point,
>> do we know there are *no* aging-related changes? I don't know one
>> way or another. But I do know that bikes get damage even when
>> sitting around- somebody knocks the shovels and rakes over in the
>> garage and they hit the bike, someone misjudges parking the car and
>> knocks the bike over, etc. Well, not my bikes because they hang up
>> in the basement out of harm's way, but many people's bikes just live
>> out in the garage. CF tends to tolerate those outrageous slings and
>> arrows less gracefully than metals. Around here that includes
>> freeze-thaw cycles anywhere from -40F to 110F. Does ultraviolet
>> light affect the CF or the epoxy material? Are there chemical
>> reactions with atmospheric gases or perhaps things like gasoline
>> vapors, paint thinner vapors etc?
>
> Recall Spinergy four-blade wheels with carbon fiber "spokes". These
> lost all their tension through thermal cycling in the back of the car
> and probably age... and then they failed in rattling compression under
> lateral collapse. I was always glad I wasn't present when failure
> occurred as one of these rode by, the four spokes fluttering loosely.
> It is tension that gives wheels lateral strength,

no it's not - it's bracing angle that gives lateral strength! reduce
the angle to zero and see how much lateral strength you have!!!

superimposed tension is a zero-sum game. imparting "compressive
strength" on a skinny spoke wire comes at the expense of "borrowing"
compressive strength [and thus load capacity] from the rim.

> especially ones with
> narrow hub width.

yeah, bracing angle, not tension.

>
>>> It's actual use (on the road) that matters, and as we have seen steel
>>> forks fail in the past at anywhere from 30-80k miles (some fail
>>> sooner, some last longer, but that's approximates the average service
>>> life we've seen over time), the history of carbon forks, as an
>>> indicator of overall life & safety, becomes clear after no more than
>>> 10 years, as that will see a fair amount of product achieve that sort
>>> of mileage.
>

 

[jim beam]

Jambo wrote:
> "bfd" <[email protected]> wrote in message
> news:[email protected]...
>> For example, I bought a USED Calfee carbon fiber frame with a Kestrel
>> carbon fork in 1997 that was made in 1994 and had approximately 2500 miles
>> of use by the previous owner. I have put over 25,000 miles since
>> purchasing as I average about 2500 miles or so per year (hard to get in
>> more mileage with 2 small children).
>
> Good for you. No one said CF frames fatigue faster than any other material
> frames.
>
>> I have crashed the bike several times, including personal injury to
>> myself. So far, I have not experience any problems with the carbon fiber
>> frame or fork. I do inspect both the frame and fork and have seen any
>> sort of damage that causes concern. There have been paint chips, but I
>> them up with clear nail polish.
>
> Great. Again, no one said that every and any crash will result in CF frame
> failure. Without knowing the forces involved in your crashes, it's only
> deduction that you did not damage it.

and it's only presumption that you did!


>
>> Similarly, Craig Calfee says there are several high mileage riders riding
>> his frames since he started making carbon frames in 1987. I believe one
>> has over 200,000 miles on his frame and several others have over 100,000
>> miles. You need to check with Craig to find out exactly how many and who
>> these individual riders are.
>
> Durability of CF under duty load is not in question. Low tolerance for
> damage for non-duty loads, in parts of the CF components not meant to take
> loads, is the issue.
>
>


so, to recap, carbon is good, except for when it's not. brilliant.

 

[jim beam]

Michael Press wrote:
> In article <[email protected]>,
> "Mike Jacoubowsky" <[email protected]> wrote:
>
>>>> 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).
>>> Therein is one of the issues in judging the long term safety and
>>> durability of CF frames and forks: they just have not been in service
>>> very long. I know people with steel frames and forks that have been in
>>> use 35+ years, and I know of people whose daily rider bikes are 50+
>>> years old. These bikes are still safe and sound- will that be the same
>>> for CF? We won't know for another 35 years or so. And we may not know
>>> even then, as currently the folks who tend to buy CF bikes tend to
>>> replace their equipment with newer, more up-to-date stuff every couple
>>> of years anyway.
>> Unless you believe that something happens to the fork, either steel or
>> carbon, while it is just sitting there, un-used, a track record of 15+ years
>> is more than adequate to judge the service life & safety of a carbon fiber
>> fork. It's actual use (on the road) that matters, and as we have seen steel
>> forks fail in the past at anywhere from 30-80k miles (some fail sooner, some
>> last longer, but that's approximates the average service life we've seen
>> over time), the history of carbon forks, as an indicator of overall life &
>> safety, becomes clear after no more than 10 years, as that will see a fair
>> amount of product achieve that sort of mileage.
>>
>> That someone you know has a bike that's 50 years old in daily service is
>> likely a testament more to an extraordinarily overbuilt design, rather than
>> the material used. If one were to build a fork of the same weight out of
>> carbon fiber, it may very well achieve commendable life on the roads
>> surrounding Baghdad! But why? Does it make sense to build something that
>> will last from one generation to the next, or does it make more sense to
>> optimize for the current user, and his/her typical lifespan of use
>> (determined not by failure but more often by a desire to upgrade)?
>>
>> The worst thing about this thread is the inference that other materials
>> don't fail in normal use. They have in the past. They do today. And they
>> will continue to fail tomorrow. It's generally not the material that causes
>> a failure, it's how it's used. I would suggest that the rate of frame
>> failures in aluminum, steel & ti frames has probably increased since carbon
>> fiber came on the market. Why? Because manufacturers have tried to mimic the
>> weight of a carbon fiber frame using materials that really aren't suitable
>> for that purpose. Sub 3.5lb steel frames, sub 2.8lb aluminum frames, sub
>> 3.1-3.3lb ti frames... they're all in dangerous, bleeding-edge territory.
>> But if you created a well-build carbon fiber frame at any of those weights,
>> it could be impossible to kill. But that's not what people are looking for
>> with carbon fiber, so it shouldn't be a huge surprise that's not what they
>
> You are glossing over the reports here describing the
> fragility of carbon fiber resin composites. There _is_
> a material difference between carbon fiber resin and
> other bicycle frame materials. Difference in impact
> resistance, difference in failure mode, and difference
> in ease of damage assessment.

but there are latent issues with metallic systems!!! example: aluminum
was the "fatigue prone" whipping boy until carbon somehow attracted the
attention of the professional bleaters instead.


>
> As a retailer with a reputation to maintain you should
> bring technological arguments to bear or gracefully
> hold your peace. Saying that it makes no difference in
> practice may not be the best course.

ridiculous - if anyone is qualified to relate their experience of how
this stuff holds up in real world usage, the guy that sells it and that
handles any failures or warranty claims is /just/ the guy to relate
their experience. professional bleaters with no personal experience are
precisely /not/ the people qualified to speak.

 

[jim beam]

Tim McNamara wrote:
> In article <[email protected]>,
> "Mike Jacoubowsky" <[email protected]> wrote:
>
>> I agree. Materials that fail in common use should be banned from
>> bikes.
>>
>> Oh, darn. All those failing aluminum stems... ****. That's quite a
>> few thousand dollars of inventory I'm going to have to dump. And the
>> failed Belleri handlebars. ****. That's going to be many thousands of
>> dollars more of inventory I can't trust.
>
> Like this tem owned by a friend, who discovered this condition the day
> after a 104 mile ride we undertook on hilly road including gravel and
> rough pavement?
>
> http://www2.bitstream.net/~timmcn/stemphotos/stem_right.png
>
> How would a CF stem have fared with cracking like this?

a quality carbon stem wouldn't have cracked! but nor would quality
aluminum within its service life.


>
>> Oh, darn. All those steel frames that buckled under impact, causing
>> the front wheel to make contact with the downtube and throwing the
>> rider violently. ****. We can't use steel for frames anymore.
>>
>> Oh, darn. All those titanium frames that had sheared downtubes, due
>> to cracks beginning at the downtube cable guides. ****.
>>
>> Oh, wait, nevermind. It wasn't the material that was the issue, it
>> was how it was used. Incredibly dangerous failure modes, yet nobody
>> was calling for manufacturers to stop using aluminum, steel or
>> titanium for bike parts.
>
> As hyperbole goes, this doesn't work very well. The failure mode for
> these materials is rarely catastrophic unlike CF

eh? that aluminum stem failure is catastrophic. and carbon rarely
fails without warning.


> and is thus not
> "incredibly" dangerous. The problem with steel frame in your example
> was the impact- a CF frame would have shattered rather than bending.

so you say, but at a stress level many times /after/ that at which the
steel would have crumpled.


> The problem with the titanium frames didn't result in the downtube just
> snapping.

no, it buckles. at stress levels well below that of carbon.

 

[jim beam]

Jambo wrote:
>> "jim beam" <[email protected]> wrote in message
>> news:[email protected]...
>>
>>> more than 30 years ago, i went to a materials lecture held by a supplier
>>> to sikorski. part of the presentation was on rotor blades. according to
>>> our guy, they were "quite happy" with composites in that application. it
>>> seems the benefit was not only much extended service life, but also
>>> something unanticipated - that of being more likely to survive bullet
>>> strike in combat. that's not to say every blade was surviving every
>>> strike, but apparently, older style aluminum blades had a dismal survival
>>> rate. composite blades otoh, if they didn't fail immediately, were much
>>> more likely to get you out of the hot zone, or better yet, get you home.
>
> By the way, this story is total rubbish.
>
> "More than 30 years ago" means 1977 and earlier. The Vietnam War has just
> ended then.
>
> There were no Sikorsky composite helicopter rotors in military applications
> before and during the Vietnam War.
>
> Composite helicopter rotors did not come into military use until the 1980s.

********!!! here's the very first chopper i look for, and guess what -
glass fiber blades, 1962.

http://www.chinook-helicopter.com/standards/areas/blade.html

chinook was a vietnam workhorse.

huey's also had composite blades. and sikorski sea kings.

>
> SO, where did your "bullet strike in combat" happen, dumbass? You need to
> stop making up ****, no one's believing it. Maybe it's time to let go of
> your nom de plume, even though you've invested years in bulshitting your way
> through this ng.

have you figured out what modulus is yet?

 

[Mike Jacoubowsky]

>> bikes.
>>
>> Oh, darn. All those failing aluminum stems... ****. That's quite a
>> few thousand dollars of inventory I'm going to have to dump. And the
>> failed Belleri handlebars. ****. That's going to be many thousands of
>> dollars more of inventory I can't trust.
>
> Like this tem owned by a friend, who discovered this condition the day
> after a 104 mile ride we undertook on hilly road including gravel and
> rough pavement?
>
> http://www2.bitstream.net/~timmcn/stemphotos/stem_right.png
>
> How would a CF stem have fared with cracking like this?

It doesn't matter whether a carbon fiber stem would have survived with a
crack like that; the relevant question is whether it would have developed
that crack.

>> Oh, darn. All those steel frames that buckled under impact, causing
>> the front wheel to make contact with the downtube and throwing the
>> rider violently. ****. We can't use steel for frames anymore.
>>
>> Oh, darn. All those titanium frames that had sheared downtubes, due
>> to cracks beginning at the downtube cable guides. ****.
>>
>> Oh, wait, nevermind. It wasn't the material that was the issue, it
>> was how it was used. Incredibly dangerous failure modes, yet nobody
>> was calling for manufacturers to stop using aluminum, steel or
>> titanium for bike parts.
>
> As hyperbole goes, this doesn't work very well. The failure mode for
> these materials is rarely catastrophic unlike CF and is thus not
> "incredibly" dangerous.

That's the part of this discussion I find so incredible. Catastrophic
failure modes have been around for as long as manufacturing. Carbon fiber
didn't invent them. Carbon fiber didn't cause them. Flawed designs &
manufacturing did. Back in the day, we saw a lot of "catastrophic" failures.
People have either forgotten about that, or else, because those failures
were on "tried & true" technology, materials that had been around for some
time, they were, for some reason, tolerated. Why?

There is obviously something appealing about taking on the latest technology
and putting it down. It becomes a fun game, apparently, to see someone post
a picture of a failed frame on the Internet and, without ANY corroboration
of the JRA (Just Riding Along) story, extrapolate wildly from it.

The smartest person I know in the "warranty" department (which I put in
quotes because most of what he deals with isn't actually a "warranty"), when
presented a failure that might be questionable, always ask one simple
question. "What do you think *really* happened?" It gets you to thinking a
bit outside the oral or written history actually presented. And sometimes
you get a customer with a "JRA" and you ask him (almost always a "him" by
the way) "What do you think really happened" and, hold down the fort, they
will actually tell you. Bizarre yet true. They come in claiming it's a JRA,
but you ask for details and yikes, it's something entirely different.

> The problem with steel frame in your example
> was the impact- a CF frame would have shattered rather than bending.
> The problem with the titanium frames didn't result in the downtube just
> snapping.

You're making an assumption that is rarely correct. Modern carbon frames &
forks will, I will claim, generally "survive" a head-on impact more readily
than the steel frames of yesteryear. They will not survive as readily an
impact from the side. These claims come from observations over many years,
many product lines, many customers, many impacts.

And the titanium frame that you didn't think resulted in a downtube
snapping? Think again. I was there. Time between first hearing something and
failure was about 3 miles. We obviously aborted the ride after hearing a
strange noise and running it down (a very small tear on the downtube), and
decided to ride back to where he'd parked his car, 6 relatively-flat miles
away. After three miles the tube had torn through and I had to go get my
car. The failure was definitely catastrophic, although since we were keeping
an eye on it there was no injury, no crash. If we hadn't figured out what
the noise was coming from, it could have been otherwise.

If we want to get personal, I did the carbon bike into car gig myself. 16mph
into the side of a Mustang some kid backed out of his driveway onto the
road. My teeth fared much worse than my bike.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com

 

[Jambo]

"jim beam" <[email protected]> wrote in message
news:[email protected]...
>
> bravo! well said.

Eh, moron, he just confirmed that your bleatings are idiotic!

 

[Jambo]

"Mike Jacoubowsky" <[email protected]> wrote in message
news:[email protected]...

>> Breaking frames may not be as dramatic nor as likely to result in severe
>> injury (although I can be enlightened from that notion). But breaking
>> handlebars, stems and seatposts is definitely likely to be - and that
>> goes for Al alloys too, for sure. However, given CF's characteristic for
>> lower damage tolerance (than metals) in directions different to fiber
>> orientation, why increase the risk?
>
> I agree. Materials that fail in common use should be banned from bikes.
>
> Oh, darn. All those failing aluminum stems... ****. That's quite a few
> thousand dollars of inventory I'm going to have to dump. And the failed
> Belleri handlebars. ****. That's going to be many thousands of dollars
> more of inventory I can't trust.

You fail to see the point. CF has lower damage tolerance than Al.

> Oh, darn. All those steel frames that buckled under impact, causing the
> front wheel to make contact with the downtube and throwing the rider
> violently. ****. We can't use steel for frames anymore.

You fail to see the point. CF has lower damage tolerance than steel.

> Oh, darn. All those titanium frames that had sheared downtubes, due to
> cracks beginning at the downtube cable guides. ****.

You fail to see the point. CF has lower damage tolerance than Ti.

> Oh, wait, nevermind. It wasn't the material that was the issue, it was how
> it was used. Incredibly dangerous failure modes, yet nobody was calling
> for manufacturers to stop using aluminum, steel or titanium for bike
> parts.

You fail to see the point. CF has lower damage tolerance than Al, steel,
and Ti.

Mike, ad absurdum arguments rarely, if ever, advances knowledge. Take a
deep breath and re-read what you've been posted. Since you've already
admitted that inspection techniques for bike CF frames are inadequate, the
question you can answer is, tell us what the difference is between
manufacturers recommendations on how to inspect/deal with damage to CF and
Al, Ti, and steel.