Are CF frames really safe?

[retrog...@gmail.com]

With the price of a complete CF bicycle now approaching $1,000, one is tempted to buy one; however, I keep hearing stories about forks collapsing unexpectedly and without apparent reason.

Political commentator and devoted cyclist Victor Davis Hanson had such an accident some time back:

http://victorhanson.com/wordpress/the-unforgiving-moment/

So I was wondering what you guys and gals think about this issue. Thanks for your opinions.

[Emanuel Berg]

> With the price of a complete CF bicycle now
> approaching $1,000, one is tempted to buy
> one; however, I keep hearing stories about
> forks collapsing unexpectedly and without
> apparent reason.

I've also heard these stories. When I was in
the shop the other day there was a discussion
about buying a frame from Asia and putting your
own sticker on it, so you had your own bicycle
brand (sort of). Some guy who did bikes from
the 80s said that's unsafe because they can
disintegrate, I actually think it was the fork
in this story as well. Some other guy said
"aren't the pro frames from Asia as well?" The
80s guy said, "yes, but they are tested in
Europe". No idea what is true in all of this.

--
underground experts united
http://user.it.uu.se/~embe8573

[sms]

On 5/19/2017 12:56 PM, retrog...@gmail.com wrote:
> With the price of a complete CF bicycle now approaching $1,000, one is tempted to buy one; however, I keep hearing stories about forks collapsing unexpectedly and without apparent reason.

As long as you avoid CF seatposts, stems, handlebars, forks, and cranks,
you'll be okay. Forks are especially prone to failure. Read
<http://web.archive.org/web/20100531033826/http://www.rivbike.com/products/show/carbonoms-fork/50-718>.

[cycl...@gmail.com]

I've had three carbon fiber forks break on me. One I don't remember about but apparently my group tell me it was a relatively harmless fall.

The second was a fork from IRS built in Italy. It literally exploded while I was leaning over to fix a clicking speedo pickup - no doubt a sign that it was going. I remember just bending over and then waking up 2 1/2 years later.

This one changed my entire life. I fell face first on the asphalt at about 5 mph and from only 18 to 24 inches up. I was knocked out for over 5 minutes. After they released me from the ER I was having seizures often enough that I had no short term memory. No short term memory = nothing to put into long term. I got into four car wrecks that totaled the vehicles. Between that and my condition being such that any charity could talk me into anything, my bank account went from $88,000 to $10,000.

Finally since none of the local neurologists had the slightest clue what was happening my best friend - a retired NCIS agent - took me over to the Stanford Cancer Center - I had lost 42% of my body weight - probably from forgetting to eat. All the doctors on my side of the bay assumed I had some sort of invisible cancer. I checked out clean and they recommended a Professor of Neurology that agreed to take me on as a patient after he gave some calls to the neurologists I was going to. My friend said he came back from the phone calls shaking his head.

It turns out that I had enough damage that I have several different types of seizures. The most common one's I have leave me with no memory of them occurring. A three months supply of medications cost me $200 and I'm on social security. I suppose I could get them mostly for free since I'm VFW but have never discovered the secret passwords. I'm still having some occasional seizures of an odd type that is somewhat self controllable. It's like having a nightmare with your eyes open and like a nightmare they don't make any sense after they happen.

Then late last year I was descending a fairly steep hill on my Colnago C40 and the fork failed just enough that I couldn't control the bike around a turn and not only traveled into the dirt ditch but the ditch ended in a rock culvert. As luck would have it I have bones almost like iron. I can't swim well because of that. (But you never want me to punch you.) That abrupt slamming into a rock wall at 25 mph would probably kill most people but I only felt like I had been killed. VERY sore muscles and abrasions. Something I would recommend you avoid.

There are CF bikes falling apart all over youTube. And the other day a man sent me a youTube reference after I said that aluminum bikes don't fail. He said that it was an aluminum MTB failing.

Well it wasn't - it was a supermarket steel MTB failing with the entire fork tube separating from the top and down tubes. This could not happen to a high quality steel bike and I've never heard of a high quality aluminum bike failing as we have several people in our group with aluminum bikes over 20 years old without a problem.

My recommendations is a medium high quality aluminum MTB with suspension or a high quality steel road bike. The exact tubing of the steel bikes isn't very important as long as it comes from a competent manufacturer. The Japanese make some very good bikes and their quality is equal to the Italians.

DO NOT believe anything you hear about carbon fiber. It they are "overbuilt" I'm sure they would be OK but the entire reason for CF is light weight and so they are all under-built. Colnago doesn't guarantee their bikes in Europe apparently and only allows a two year warranty for original owners.

Two days after my C40 accident my NCIS partner had the steering tube fall off of his C40 too. His small finger is now frozen half extended. He had a custom steel bike made for himself and his wife. The complete custom steel bike cost him less than half of an over-the-counter top end CF bike.

Around here CF bikes are not selling well anymore.

[retrog...@gmail.com]

I tend to agree with you.

It really makes me wonder how the CF bike manufacturers handle their product liability claims. Do they actually buy insurance, or are they self-insured and simply fold the business if there are too many claims?

Ping Jay Beattie!

[jbeattie]

I haven't defended a carbon fork claim in many years. I've had exactly one case where there was a real screw-up -- a construction error (fork blade wasn't bonded, which is the CF equivalent of tack-brazing and failing to fully braze a steel fork). The problem with hand-made forks is that they're made by hand -- hands sometimes attached to absent minded people.

There are hundreds of thousands of CF forks in the market (maybe millions). There is no epidemic of failure. I've been riding on CF forks since 1990, and unlike TK, I haven't broken any. YMMV. I am not as confident of CF steerers, but so far, my forks with CF steerers have not failed.

Most large manufacturers are insured under policies with self-insured retentions of varying sizes, some large. Really large manufacturers may have "fronting" policies (really a form of self-insurance) or an off-shore insurance program where they are the insurance company. "Really large" means companies like Ford.

If you buy from a bike shop, then the shop's policy will respond as well since the shop is the ultimate seller, unless the state has some peculiar tort system that protects the ultimate seller. That's not the way it is on the West Coast. Shops always get sued, too.

Manufacturers like Trek and Specialized do rigorous QC. If in doubt, buy from a reputable company with a lifetime warranty and a US presence. I would steer clear of Colnago in light of TK's experience. Buy from a shop and not online.

-- Jay Beattie.

[John B.]

On Fri, 19 May 2017 12:56:32 -0700 (PDT), retrog...@gmail.com
wrote:

A coupe of years ago I was talking to a chap I know in Singapore who
specializes in taking your old beat up bike and turning it into what
appears to be a brand new unridden bicycle. In the conversation he
mentioned that he also repairs CF bikes and we got into a conversation
about that. I asked him what make of CF bike commonly broke and he
said, "the cheap Chinese ones". At the time of the conversation he
stated that he averaged about one CF bike repair a week.
The population of Singapore was about 4.5 million at the time.

Having said that I rode a Giant OCR2 with a C.F. fork for two years
with no problems at all.
--
Cheers,

John B.

[Sir Ridesalot]

My understanding of carbon fibre bicycles is that on the better quality ones the cloth is laid out in such a way as to give maxinum strength to the frame. Also, the resin used is confirmed to completely impregnate the carbon fiber cloth. On cheap carbon fiber bicycles the cloth is NOT laid out in the most optinum way to ensure that the frame is as strong as possible. Also, one the cheaper carbon fiber bicycles the cloth and/or the resin used may not be as good nor as carefully mixed and applied as it is on a better quality carbon fiber bicycle.

Cheers

[John B.]

On Fri, 19 May 2017 22:08:17 +0200, Emanuel Berg <moa...@zoho.com>
wrote:

Probably most bike frames come from Asia these days, but likely the
big names do ensure that the bikes are made to a standard. For
example, while I have no idea where Columbus C.F. frames and forks are
actually made, their catalog contains a statement, "All of the
products of Columbus Carbon Lab. are tested to, and exceed, the
requirements of European Standard CEN14781", and I would assume that
all European bike sellers adhere to similar standards.
--
Cheers,

John B.

[John B.]

On Fri, 19 May 2017 19:11:00 -0700 (PDT), Sir Ridesalot
<i_am_cyc...@yahoo.ca> wrote:

>On Friday, May 19, 2017 at 10:05:17 PM UTC-4, John B. wrote:
>> On Fri, 19 May 2017 12:56:32 -0700 (PDT), retrog...@gmail.com
>> wrote:
>>
>> >With the price of a complete CF bicycle now approaching $1,000, one is tempted to buy one; however, I keep hearing stories about forks collapsing unexpectedly and without apparent reason.
>> >
>> >Political commentator and devoted cyclist Victor Davis Hanson had such an accident some time back:
>> >
>> >http://victorhanson.com/wordpress/the-unforgiving-moment/
>> >
>> >So I was wondering what you guys and gals think about this issue. Thanks for your opinions.
>>
>> A coupe of years ago I was talking to a chap I know in Singapore who
>> specializes in taking your old beat up bike and turning it into what
>> appears to be a brand new unridden bicycle. In the conversation he
>> mentioned that he also repairs CF bikes and we got into a conversation
>> about that. I asked him what make of CF bike commonly broke and he
>> said, "the cheap Chinese ones". At the time of the conversation he
>> stated that he averaged about one CF bike repair a week.
>> The population of Singapore was about 4.5 million at the time.
>>
>> Having said that I rode a Giant OCR2 with a C.F. fork for two years
>> with no problems at all.
>> --
>> Cheers,
>>
>> John B.
>

>My understanding of carbon fibre bicycles is that on the better quality ones the cloth is laid out in such a way as to give maximum strength to the frame. Also, the resin used is confirmed to completely impregnate the carbon fiber cloth. On cheap carbon fiber bicycles the cloth is NOT laid out in the most optinum way to ensure that the frame is as strong as possible. Also, one the cheaper carbon fiber bicycles the cloth and/or the resin used may not be as good nor as carefully mixed and applied as it is on a better quality carbon fiber bicycle.
>
>Cheers

I don't know, but I do have a good friend in the
"fiberglass business" who uses C.F. from time to time and I've used it
once or twice.

My guess is that it isn't just the way that the cloth is laid that
differs but also the type of cloth used. Any of the fabrics used in
composites comes in a multitude of different weaves and thickness
which vary in cost. One of the smaller distributors lists 16 varieties
of C.F. cloth. But certainly some of the weaves are directional so
both the sequence and possibly the direction of the lay-up is
important.

To built a frame or fork three or four, or maybe more, different
weaves might be used to obtain optimum strength and they would be
required to be laid in a certain sequence. It would probably be much
cheaper to use only a single weave.

As for resin, again I'm not sure but anyone who is in the business
will want a resin that hardens consistently, but even a quick look at
epoxy sales houses revels a multitude of blends. As for the actual
mixing that probably isn't a major problem as mixing does effect the
hardening time and that is what would be of the most interest.
--
Cheers,

John B.

[cycl...@gmail.com]

On Friday, May 19, 2017 at 4:51:44 PM UTC-7, jbeattie wrote:
>
> There are hundreds of thousands of CF forks in the market (maybe millions). There is no epidemic of failure. I've been riding on CF forks since 1990, and unlike TK, I haven't broken any. YMMV. I am not as confident of CF steerers, but so far, my forks with CF steerers have not failed.

Let me get this straight - you think that wearing a helmet could help you in a crash but you don't think that a long history of carbon forks is enough for you to chose another path?

>
> Most large manufacturers are insured under policies with self-insured retentions of varying sizes, some large. Really large manufacturers may have "fronting" policies (really a form of self-insurance) or an off-shore insurance program where they are the insurance company. "Really large" means companies like Ford.

> Manufacturers like Trek and Specialized do rigorous QC. If in doubt, buy from a reputable company with a lifetime warranty and a US presence. I would steer clear of Colnago in light of TK's experience. Buy from a shop and not online.

The results of Trek's quality control is that they have built their frames and forks a great deal stronger. And they continue to break. Shortly after a friend got a new frame and fork from Trek after his Gary Fisher broke, I looked at the joint between the down tube and the seat tube. There was a visible split there. Trek replaced it yet again. Now this particular failure was unlikely to grow dangerous but it WAS a frame failure.

The results of Specialize's QC is that they have bought more and more insurance coverage and made lighter and lighter bikes because that's what the market wants.

https://www.youtube.com/watch?v=nvk63bmVpck

http://www.bustedcarbon.com/

This stuff is all over the web.

[cycl...@gmail.com]

John, I have been impressed with the mechanical design of the Giant CF bikes.

I'm not anti-carbon fiber - just that most of them are built to ultra-light specifications and you simply cannot make a safe bike out of paper thin anything.

[cycl...@gmail.com]

The layouts on ALL carbon fiber bikes is limited by the bi-directional characteristics of woven cloth. That means you cannot lay it out so that it gives maximum strength with minimal material.

[cycl...@gmail.com]

This is a strength standard and not a reliability standard.

[jbeattie]

The number of failures is a tiny fraction of the total production, and there is usually poor documentation of failure mode in most of the doom and gloom reports. I'm not saying that CF never fails or breaks. Everything breaks. I've broken four steel frames and just as many aluminum. CF clearly is less impact resistant than steel, although modern resins are making current production more impact resistant. If you drop wrenches on your bikes, you should buy steel.

Specialized Tarmac and Roubaix in the non-S-Works models are actually a little heavier than industry average at the same price point. Specialized does a lot of QC and product testing, and I don't know what you're talking about with the "more and more insurance" bit. IMO, it's always been a reputable company, like Trek -- although both have been faulted for aggressive protection of IP/Trademark. That's a whole other thing.

I ride with guys who are both high mileage current or former racers and engineers or management for outdoor equipment companies. They all ride CF, and they don't change frames every year. My best riding buddy is on a ten year old Pinarello that he loves. The only person I know who had problems was a friend of my son who rode a (you guessed it) Colnago -- that took him 8 months to get warranty replaced. It failed while still in its two (?) year warranty. Again, not saying they're problem free, but its not like riding a ticking time bomb.

-- Jay Beattie.

[AMuzi]

That's a punk thing:
http://www.bikehugger.com/images/blog/bike_bomb.jpg

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

[Jeff Liebermann]

On Fri, 19 May 2017 12:56:32 -0700 (PDT), retrog...@gmail.com
wrote:

>So I was wondering what you guys and gals think about this issue.

No opinions on CF safety but a few comments that might be of interest.

It is very easy to demonstrate that something is unsafe. All one
needs is an anecdotal failure incident, and it becomes unsafe. The
real question is what failure rate are you willing to tolerate? Along
that line, what lifetime are you expecting and what tolerance to
overload are you anticipating?

In other industries, where a catastrophic failure is unacceptable, the
standard practice is regular inspection and testing. In a past life,
I did some acoustic vibration analysis to predict conveyer belt
bearing failures. Lots of other tests for structural damage, cracks,
stresses, and corrosion, etc. Basically, one looks for something that
doesn't belong or has changed.

I don't see any of that in bicycling. I found a service that offers
bicycle CF "active thermography" inspection service in Germany:
<http://carbon-bike-check.com> (German)
<http://www.infratec-infrared.com/thermography/application-area/active-thermography.html>
Basically, they vibrate the frame with ultrasonic energy. Areas where
there are cracks become warmer, which can then be seen on an IR
camera.
<http://carbon-bike-check.com/Motivation_1.jpg>

This lack of testing really bugs me. Most CF owners do a visual
inspection and look for wrinkles in the paint or cracks. A few might
borrow some industrial inspection equipment:
<http://www.olympus-ims.com>
or shove a borescope/endoscope down the tube looking for potential
problems. I have a few of these:
<http://www.ebay.com/itm/351973054942>
The problem is that they only focus between approximately 2.5cm to
10cm. Good enough for automotive work, but not for pipe inspection.
I'm working on finding one with an adjustable focus and better depth
of field. Anyway, there are plenty of tools and toys to help with
inspection, but nobody that I know actually does it on a regular
schedule.

So, if you're going to buy into the CF club, and operate on the bitter
edge of mechanical failure to save a few grams, perhaps it might be
useful to find some inspection equipment and use it. It's much like
backing up a computah hard disk drive. Nobody expects it to fail, but
when it does, it can be catastrophic, happen without warning, and be
very expensive.

--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[Frank Krygowski]

On 5/21/2017 1:00 PM, Jeff Liebermann wrote:
>
> No opinions on CF safety but a few comments that might be of interest.
>
> It is very easy to demonstrate that something is unsafe. All one
> needs is an anecdotal failure incident, and it becomes unsafe. The
> real question is what failure rate are you willing to tolerate?

True. although in some cases you don't need an actual failure rate. If
you can imagine a failure, that sometimes suffices to label something
unsafe.

I'm on the Board of Commissioners managing a natural area owned by our
village. Some members of village council are worried about liability
from dead trees falling on people, even though the state supreme court
positively said there is no such liability regarding recreational users.

Regarding failure rate: I found a research paper that indicates the
entire U.S. has only about 12 such fatalities per year, not counting
those where a motorist runs into a fallen tree (which is impossible in
our forest). A biology professor attacked the issue from a different
direction and computed that the odds against a trail walker being hit by
a tree is up in the billions. And it goes without saying that there's
never been such an incident in the 80 year history of this forest.

But the councilman who is the big "danger!" guy heard of one incident
elsewhere in which a man sitting at a picnic table was hit by a falling
branch. So he (and the solicitor hired by the village) is commanding
that we survey all dead trees in the forest and classify them by a
"danger" ranking, then begin cutting them.


--
- Frank Krygowski

[Duane]

My club has 359 members this year and 80% have CF frames. I've been in
the club 6 years and membership fluctuates between 325 and 400 with a
fairly constant CF presence. The only CF frame or fork damage, not caused
by a crash that I've seen is one seat post that cracked forcing the rider
to do the last 20k of a century standing up. I've seen a couple frames
cracked but both were hit by cars, one from the rear and one T-Boned.

Why would I buy expensive equipment to test my frame? And I back up my
hard drives weekly.

--
duane

[sms]

On 5/21/2017 12:58 PM, Duane wrote:

> Why would I buy expensive equipment to test my frame? And I back up my
> hard drives weekly.

Good idea.

A month ago my daughter's Thinkpad's drive crashed. Yesterday my son's
Thinkpad's drive crashed. I think I need to start replacing drives every
three years.

[Jeff Liebermann]

On Sun, 21 May 2017 19:58:37 -0000 (UTC), Duane <sp...@flarn.com>
wrote:

>Jeff Liebermann <je...@cruzio.com> wrote:
>> So, if you're going to buy into the CF club, and operate on the bitter
>> edge of mechanical failure to save a few grams, perhaps it might be
>> useful to find some inspection equipment and use it. It's much like
>> backing up a computah hard disk drive. Nobody expects it to fail, but
>> when it does, it can be catastrophic, happen without warning, and be
>> very expensive.

>My club has 359 members this year and 80% have CF frames. I've been in
>the club 6 years and membership fluctuates between 325 and 400 with a
>fairly constant CF presence. The only CF frame or fork damage, not caused
>by a crash that I've seen is one seat post that cracked forcing the rider
>to do the last 20k of a century standing up.

Any idea how many of your club members either had their CF frames
repaired or purchased a replacement frame after noticing that
something was not quite right or after they were informed that the
frame was about to fail?

Assuming 1 bicycle per club member, and that everyone rides equal
distances per year, you have one chance in 400 of experiencing a CF
failure (not caused by a crash or impact) over a 6 year period. Or,
if you prefer, 1 chance in 2400 (or 0.042%) per year. If you add up
the total mileage for the club per year and divide that by 2400, that
would provide you with the number of miles you need to ride before you
might expect a mechanical failure. I don't have any numbers handy,
but my guess(tm) that's about the same as the odds of having a wheel
fall off.

So, what does this tell me about your club? They probably spend lots
of money on CF bicycles and therefore probably take care of them. They
probably ride as a group and are therefore unlikely to encounter
inclement weather, commuter road hazards, of airborne mountain bikes.
You probably have available to you some expertise from the other
members, and probably from an LBS (local bike shop). In other words,
your members are more likely to buy better quality bicycles and
probably do a better job of maintenance. I would expect a much lower
failure rate than among the GUM (great unwashed masses).

>I've seen a couple frames
>cracked but both were hit by cars, one from the rear and one T-Boned.

Those are obvious failures that justify a replacement frame. But what
about minor impacts that leave no visible damage? I know of one CF
frame that fell off a bicycle carrier on the back of an SUV. That's a
drop of about 2-3 ft. About 6 weeks later, the frame suddenly cracked
where the top tube connects to the head tube. The failure occurred at
a very slow speed, so there were no injuries. It was repaired by the
builder. I don't recall the name.

The lesson here is that it takes time for a crack to propagate. If
you happen to be going fast at the time, or are in an awkward
position, having the frame disassemble itself is going to cause some
injuries. It's perfectly ok to believe in luck. Just, don't rely on
it. Another way to look at this is the odds versus the risks. Even
if the odds are tiny, and the likelihood of injury are very small, a
frame or fork failure is just too dangerous too risk.

>Why would I buy expensive equipment to test my frame?

Probably the same thing that was probably told to PG&E management
before San Bruno blew up in a giant natural gas explosion.
<https://en.wikipedia.org/wiki/San_Bruno_pipeline_explosion>
PG&E had reduced their pipeline inspection frequency to the point of
not doing inspections because their statistics showed that the
likelihood of a major incident was insignificant. So, why bother
inspecting when nothing has happened so far? As a result of the
incident, PG&E paid a huge settlement to the victims families, fired a
few senior executives, retired the president, did their best to do
damage control, and went on a pipeline inspection frenzy that found
numerous problems just waiting to do a repeat performance of San
Bruno. I'm sure PG&E would have preferred to have spent the money on
inspections and thus prevented the explosion, than to deal with the
after effects and repercussions. Incidentally, the main high pressure
gas pipeline for the area is under the roadway in front of my palatial
office.

So, so you want to take your chances that everything is perfect and
that nothing can go wrong, go wrong, go wrong, (...) go wrong? Or
would you think it might be better to avoid a prolonged medical
disaster and properly inspect your frame for potential problems?

>And I back up my hard drives weekly.

I do mine monthly with incremental backups in between. However,
there's a problem. I have NOT automated the process. Therefore, it
is subject to human error, just like CF fabric and resin assembly is
prone to human error.

[cycl...@gmail.com]

There is no reason for people to not buy CF except because they have a higher rate of failure than other materials. I have been riding for 40 years and have never heard of a good steel bike having a catastrophic failure. And I haven't heard of ANY aluminum bikes having catastrophic failures.

After I said that a person sent me a youtube reference of an "aluminum" frame failure. Indeed it was a catastrophic failure but it wasn't an aluminum frame but an Australian department store MTB. The entire headtube tore off the bike at the welds.

The construction appeared, from what I could see by stopping the video, to be pretty substandard. About what you would expect from K-Mart or Target. Sears and such are much better materials and techniques.

But why would there be so many videos around about CF failures and so few about other materials? Do you think that it's a conspiracy?

[Jeff Liebermann]

On Sun, 21 May 2017 13:45:44 -0700, sms <scharf...@geemail.com>
wrote:

The average laptop HD lifetime I'm seeing is about 5 years. However,
I do see some failing much earlier.

Crashed, or did they fail to install a monstrous Windoze update
"rollup"? I'm seeing some of that since Microsloth started pushing
"rollups". It looks like a malware problem, where the machine doesn't
boot, or some service fails (like BITS and crypto), but it is really
the result of a failed update. My guess(tm) is MS doesn't bother
testing anything these days, preferring to use the Windoze 10 method
of having the customers do the testing, and reporting back to the
mothership using "telemetry".

Anyway, I suggest an SSD instead of an HD for Win 7 and up. XP with
SSD seem to be a problem for me. Be prepared to tweak the BIOS and
registry for SSD specific settings. I've been installing Samsung 850
EVO drives. Zero failures and no new errors on about 40 drives for
about a year so far.
<https://www.newegg.com/Product/Product.aspx?Item=N82E16820147372>

For image backups, I use Acronis True Image 2017, Macrium Reflect
Free, and Clonezilla. Incidentally, I just did an image of a Win 8.1
Sony i5 laptop using Acronis. 115GB in 30 mins or about 3.8
GBytes/min backup speed to a Seagate USB 3.0 drive. I've seen up to 8
GB/min but that's on faster hardware.

[Jeff Liebermann]

On Sun, 21 May 2017 14:16:42 -0700 (PDT), cycl...@gmail.com wrote:

>There is no reason for people to not buy CF except because they have a higher rate of failure than other materials. I have been riding for 40 years and have never heard of a good steel bike having a catastrophic failure. And I haven't heard of ANY aluminum bikes having catastrophic failures.
>
>After I said that a person sent me a youtube reference of an "aluminum" frame failure. Indeed it was a catastrophic failure but it wasn't an aluminum frame but an Australian department store MTB. The entire headtube tore off the bike at the welds.
>
>The construction appeared, from what I could see by stopping the video, to be pretty substandard. About what you would expect from K-Mart or Target. Sears and such are much better materials and techniques.

Google images usually finds some good examples:
<https://www.google.com/search?q=aluminum+bicycle+frame+failure&tbm=isch>
<https://www.google.com/search?q=steel+bicycle+frame+failure&tbm=isch>
<https://www.google.com/search?q=carbon+fiber+bicycle+frame+failure&tbm=isch>
I learn quite a bit looking at failure photos.

>But why would there be so many videos around about CF failures and
>so few about other materials? Do you think that it's a conspiracy?

Everything is a conspiracy.

In this case, it might be that CF is considered a high price product
which would not be expected to break. CF is also far more expensive
to fix than steel or aluminum. I might also guess(tm) that
self-disassembly of a CF frame at speed might cause more expensive
injuries. Looking at the photos, the CF frames seem to come apart
breaking two or more tubes in the process, while aluminum and steel
just bend or break in one place.

[cycl...@gmail.com]

Jeff - remember I was speaking of catastrophic failures. And while second grade steel and aluminum bikes indeed fail a catastrophic failure is rare. The one's pictures appear to have been at worst ALMOST catastrophic. There's a difference between "Ohshit put the brakes on" and "Hey Charlie - call an ambulance for Tom.

And as we discussed - steel and aluminum bikes in the highest quality are also those least likely to break. Whereas it is just the opposite with CF.

I'm sure that there are exceptions - I have been very impressed with the top end Giant brand. Their construction technique is superb. If you tap a vibrating fork and hold it to the frame and listen to it though the joints they all appear to be all of one piece. Many other CF bikes sound really odd in these areas. The Giants are really light without appearing to be dangerous since they increase joint strength through oversize tubing rather than adding more material to smaller tubes.

I suppose that you can make CF bikes as safe as any other material. But I don't think you can make them reasonably priced and safe at the same time, yet.

And the ride of steel is fantastic in comparison to other materials.

[sms]

On 5/21/2017 2:25 PM, Jeff Liebermann wrote:
> On Sun, 21 May 2017 13:45:44 -0700, sms <scharf...@geemail.com>
> wrote:
>
>> On 5/21/2017 12:58 PM, Duane wrote:
>>
>>> Why would I buy expensive equipment to test my frame? And I back up my
>>> hard drives weekly.
>>
>> Good idea.
>>
>> A month ago my daughter's Thinkpad's drive crashed. Yesterday my son's
>> Thinkpad's drive crashed. I think I need to start replacing drives every
>> three years.
>
> The average laptop HD lifetime I'm seeing is about 5 years. However,
> I do see some failing much earlier.
>
> Crashed, or did they fail to install a monstrous Windoze update
> "rollup"?

First the system got really slow, and hard disk activity was at 100%.

Then it started giving "There has been a signature failure." messages on
the screen. Then it would do nothing. Running diagnostics, that are
apparently not on the drive, resulted in all the drive tests failing,
except the one where it reads the drive information from the drive
controller.

Fry's has a good deal on a 750GB, 7200RPM, 5 year warranty, retail box,
laptop drive, for $49 with promo code, except they don't actually have
any <http://www.frys.com/product/8295426>. I ordered one on Amazon
<https://www.amazon.com/dp/B00DSUTX3O> for same-day delivery, even
though it was more expensive than Fry's (reminds me of the old joke,
"when we're out of chicken we also charge less").

<snip>

> For image backups, I use Acronis True Image 2017, Macrium Reflect
> Free, and Clonezilla.

I may try Clonezilla on the drive since often Linux can read a failing
drive when Windows can't), or I will reinstall Windows 10 from scratch.
On my daughter's machine, the hard drive was unreadable with the "click
of death."

Before it completely failed I tried to do a System Restore but there
were no restore points.

[AMuzi]

Jay Beattie said it correctly- everything breaks.

Please review Frame and Fork sections here:
http://pardo.net/bike/pic/fail-001/000.html

extra credit:
http://www.yellowjersey.org/paint.html

[AMuzi]

http://www.bustedcarbon.com/2009/12/giant-tcr.html
http://pardo.net/bike/pic/fail-001/FAIL-088.html
http://www.bustedcarbon.com/2009/07/broken-fork-on-giant-ocr-alliance-comp.html
http://roues-aerolithe.over-blog.com/article-reparation-cadre-casse-tube-superieur-118777093.html

I have nothing against Giant and I have no idea whether
their failure rate is above or below the industry overall.

[Duane]

Well your probably right about the type of riding, the quality or the bikes
and subsequently the care taken with them.

As for the crashes, I had a couple of pretty hard crashes with my last
bike. After both I brought it to the shop to be checked out. They didn't
use any specific equipment, mostly just a thorough inspection. I had
about 30,000 km on it when I traded it in for my current bike. Nothing
fell apart.

I don't doubt what you say about the bike falling off the rack and cracking
later. I just don't think it's a common thing. As Jay reports, bikes
break. I've broken an aluminum fork myself. No reason that CF bikes
wouldn't break.

Automating backups is the best way to deal with data protection.

--
duane

[John B.]

On Sun, 21 May 2017 10:00:49 -0700, Jeff Liebermann <je...@cruzio.com>
wrote:

I've always wondered whether a simple "dye check" could not be used.
That is three "rattle cans" and a rag. It wouldn't check for internal
cracks of course, but then I believe that C.F. front forks are solid
so it ought to work for them and it certainly would have caught the
recently posted "funny scratch on the crank" problem.
--
Cheers,

John B.

[John B.]

Couldn't you have either the State, or maybe Federal, Forest Service
do a survey? I vaguely remember, when I was a kid, an argument about
the value of an elm tree that the town wanted to cut and I think that
they called in some sort of "forest" guy who did some sort of study
about age, number of board feet in tree, current price of elm lumber,
etc.

But more germane, doesn't "Act of God" enter into the equation? You
elect to walk in the forest, a forest has trees, trees have limbs,
etc.?
--
Cheers,

John B.

[John B.]

On Sun, 21 May 2017 13:45:44 -0700, sms <scharf...@geemail.com>
wrote:

I just read a Seagate announcement that they do not rate their hard
disks in MTBF as they say that doesn't present a true picture. Now
they use Annualized Failure Rate (AFR) which hey say presents a more
accurate assessment of potential drive life.

Example: The Barracuda ES.2 Near-Line Serial ATA drive:
"The product shall achieve an Annualized Failure Rate - AFR - of 0.73%
(Mean Time Between Failures - MTBF - of 1.2 Million hrs) when operated
in an environment that ensures the HDA case temperatures do not exceed
40°C"
--
Cheers,

John B.

[Frank Krygowski]

I've consulted with two attorneys I know well. One provided me with a
state supreme court brief that in his and my view give the village
absolute protection from liability. It doesn't matter. The solicitor
gave a vague hand-waving explanation, "Yes, I've seen that brief, but I
think there may be another avenue that an injured person might be able
to use to sue the village. But I don't want to say what it is and give
them hints." And the village councilman shouted "THIS IS NOT
NEGOTIABLE! THIS IS A LIABILITY ISSUE!"

Our tax dollars at work, I guess. :-/

--
- Frank Krygowski

[Frank Krygowski]

About failures like those shown in the links: It occurs to me that with
failed metal parts, one can often examine the fracture and get clues as
to whether the failure was sudden overload vs. long term fatigue, about
the direction of loads, etc. But AFAIK those techniques can't be used
on composite parts. Can anyone confirm that?


--
- Frank Krygowski

[Frank Krygowski]

On 5/21/2017 5:16 PM, cycl...@gmail.com wrote:
> There is no reason for people to not buy CF except because they have a higher rate of failure than other materials. I have been riding for 40 years and have never heard of a good steel bike having a catastrophic failure. And I haven't heard of ANY aluminum bikes having catastrophic failures.

Well, our good steel fork on our custom Reynolds 531 tandem failed
catastrophically. Fortunately, we were going very slow (less than 10
mph) so our bodies didn't suffer catastrophic failure. We just got
banged up a bit.

It turned out to be a case of very badly chosen fork blades, by a
builder in a hurry. I think he just used what he had on hand, rather
than proper tandem fork blades.

--
- Frank Krygowski

[John B.]

I can't quantify this but I believe that the inspection of composite
structures is basically an inspection of, essentially, fiber
condition, condition of the resin-fiber bonds and condition of the
resin bond - water content, etc.

I would believe that direction and severity of stress can be
determined and/or calculated but as a break in a composite is largely
a failure of the fibers I wonder whether long term fatigue figures
could be determined.

For example, a golf club shaft would be tested by flexing the shaft a
large number of times but I don't believe that there would be a change
in the material itself although it is likely that C.F. fiber might be
progressive rather then catatonic.

Common inspection methods include Ultrasonic (several different
methods), X-ray, Moisture detection, Thermography and Neutron
Radiography, all of which seem to measure density rather than
strength.

I haven't studied laminates strengths in depth but what I have read
talks about essentially fiber strengths. there are calculations that
show that once a sufficient amount of fiber breakage that breakage
then accelerates but I've seen nothing about determining degree of
broken fiber within a structure.

I have no idea whether, other then fiber breakage, repeated stress is
damaging to a composite structure. Whether "work hardening", per se,
is a property of composites.
--
Cheers,

John B.

[James]

Actually wood has better impact resistance than steel. Renovo made a
video showing this.

>
> Specialized Tarmac and Roubaix in the non-S-Works models are actually
> a little heavier than industry average at the same price point.
> Specialized does a lot of QC and product testing, and I don't know
> what you're talking about with the "more and more insurance" bit.
> IMO, it's always been a reputable company, like Trek -- although both
> have been faulted for aggressive protection of IP/Trademark. That's a
> whole other thing.
>
> I ride with guys who are both high mileage current or former racers
> and engineers or management for outdoor equipment companies. They
> all ride CF, and they don't change frames every year. My best riding
> buddy is on a ten year old Pinarello that he loves. The only person I
> know who had problems was a friend of my son who rode a (you guessed
> it) Colnago -- that took him 8 months to get warranty replaced. It
> failed while still in its two (?) year warranty. Again, not saying
> they're problem free, but its not like riding a ticking time bomb.
>

I've had a couple of CFRP forks with Al steerer on steel frame bikes.
They work fine. Current is an Easton EC70 I think. While I don't stop
on the front wheel often, I have had the back wheel floating above the
road a few times under heavy braking. The forks have not broken yet,
after many tens of thousands of kilometers.

--
JS

[Jeff Liebermann]

On Mon, 22 May 2017 07:26:23 +0700, John B. <sloc...@gmail.com>
wrote:

>I've always wondered whether a simple "dye check" could not be used.

It can, if the paint doesn't get in the way. I've seen tubing filled
with oil or water with a phosphorescent dye added. Apply pressure and
the fluid will try to squeeze through any holes in the tubing. A UV
light might show the leak (if the paint doesn't get in the way). Don't
suggest transparent coatings instead of paint. Most clear coats block
UV but not all of them. This formulation is clear, but apparently
passes UV:
<http://www.frozencpu.com/products/3854/uvp-01/Clearneon_UV_Reactive_Clear_Coat_Paint_-_Blue.html>
<https://www.clearneon.com>

For really small leaks and really large bank accounts, helium gas and
a Fluorinert bubble tank as used in the semiconductor industry for
detecting leaks.

>That is three "rattle cans" and a rag. It wouldn't check for internal
>cracks of course, but then I believe that C.F. front forks are solid
>so it ought to work for them and it certainly would have caught the
>recently posted "funny scratch on the crank" problem.

Yep. I suppose that there will be some resistance to adding fill and
drain pressure holes or fittings to the frame, seat stays, chain
stays, and forks. If the entire frame could be pressurized, a leak
detector might work. However, if the forks are solid, there's no
cavity to pressurize and a leak detector won't work.

Actually, if the frame could be pressurized, some vacuum head is going
to suggest pumping the air out of the internal cavity to lighten the
weight of the frame by a few milligrams.

[Jeff Liebermann]

On Sun, 21 May 2017 15:02:35 -0700 (PDT), cycl...@gmail.com wrote:

>I have been very impressed with the top end Giant brand.

They also honor their warranty:
"I Broke My Bike! Giant Trance Advanced Chainstay Fail"
<https://www.youtube.com/watch?v=Whai0dkf5QA>

[sms]

I went to a concert tonight and one duo was playing carbon fiber cellos.

They sounded wonderful, even better than ebony cellos. They are very
expensive, and I wonder about the longevity.

<https://luisandclark.com/product/cello/>

[John B.]

On Sun, 21 May 2017 21:41:17 -0400, Frank Krygowski

The U.S. never fails to amaze me. If the town puts up a sign "WARNING!
Sidewalk under repairs" and strings up a rope to keep people out, and
some one ducks under the rope and then stumbles it seems to (somehow)
be the fault of the town. Over here if the same thing happened the
stumbler" would be considered a clumsy oaf.
--
Cheers,

John B.

[John B.]

On Sun, 21 May 2017 21:54:47 -0700, Jeff Liebermann <je...@cruzio.com>
wrote:

>On Mon, 22 May 2017 07:26:23 +0700, John B. <sloc...@gmail.com>
>wrote:
>
>>I've always wondered whether a simple "dye check" could not be used.
>
>It can, if the paint doesn't get in the way. I've seen tubing filled
>with oil or water with a phosphorescent dye added. Apply pressure and
>the fluid will try to squeeze through any holes in the tubing. A UV
>light might show the leak (if the paint doesn't get in the way). Don't
>suggest transparent coatings instead of paint. Most clear coats block
>UV but not all of them. This formulation is clear, but apparently
>passes UV:
><http://www.frozencpu.com/products/3854/uvp-01/Clearneon_UV_Reactive_Clear_Coat_Paint_-_Blue.html>
><https://www.clearneon.com>
>

Are C.F. frames painted? Do the frames crack without disturbing the
coating, whatever it may be? Why all the folderol with phosphorescent
stuff when the conventional "dye Check" kit will show cracks and you
can pay a couple of dollars more and get the set that shows up under
ultraviolet light.

After all, it is used to inspect vehicles that thunder along 5 miles
up in the air while a bicycle runs along on the surface :-)

--
Cheers,

John B.

[Frank Krygowski]

On 5/21/2017 11:54 PM, John B. wrote:

With long term fatigue failures of metal, one can often see "beach
marks" which are sort of ripples in the fractured surface. They
generally show the direction of the fracture's gradual progression.
Sudden impact failures have a different appearance of the fracture
surface. But I'm not aware of any similar features of a CF break.


--
- Frank Krygowski

[AMuzi]

They are generally painted or at least coated in UV block
clear just like aircraft components.

[cycl...@gmail.com]

Going down through the listings of failures almost none of those were catastrophic failures and the one's that were usually had damn good reasons for failure - Fox suspension forks DO NOT have both drop-outs break off. So you know that it had to be on a hard downhill and the victim getting a flat, veering off-course and hitting something damned hard.

Almost all of the steel frame failures were relatively minor plus they were on less than stellar brands. I don't consider GT (especially the older models) to be top line bikes. I don't consider bearing failures or a top end Shimano bottom bracket that had the one in a million failure by breaking off on the drive side to be anything other than a freak accident.

My brother contacted me last night since his son-in-law knows one of the local sales distributors for a major brand. The guy is trying to unload the very highest level for dealer prices or even distributor prices. Why? Not because they have a bad reputation or because they've had any failures that I know of - but because people have lost their confidence in carbon fiber. And that isn't from me talking to you people. I don't badmouth CF anywhere but here. After all, I'm trying to sell a lot of CF stuff that is really good.

[cycl...@gmail.com]

"This is what carbon looks like after hitting the side of a car"
"the failure is the result of an accident"

The third is absolutely inexplicable and is obviously a CF failure of the sort that is turning people off of CF. But that is a 2008 Giant. If you look at the previous photo of the Giant that was in the accident you can see the inflatable bladder that they NOW use in order to compress the inside of the frame so that these frames can be essentially in a mold inside and out.

But it does give me additional ammunition to think that NO CF frames will be safe under any conditions.

I am able to forgive any material for failing in a heavy enough accident. But my last fork failure was not from hitting a pothole but from hitting a sharp bump. And my fork failed almost immediately - not by falling apart but by cracking up the outside of the left leg so that the bike wouldn't steer quite right. In a left hand turn the bike drifted to the right and into the dirt and eventually into that stone culvert.

My friend was in front of my on his totally babied C40 and hit the bump first. We were travelling so fast I didn't have time to prepare for it.

Two days later he was riding with another friend up to the Golden Gate Bridge and as he got on the bridge path the entire front end fell off. Luckily it happened there and at 5 mph or so since at the other side of the bridge he would have been descending into Sausalito at 40 mph. The mind boggles.

[cycl...@gmail.com]

Then this would hardly qualify as a "good" steel bike. Tandems in particular absolutely must have proper construction as you discovered. A fork designed (especially with Reynolds tubing) for a single would hardly be appropriate for a tandem.

But of course viewing something from a historic perspective is easy.

[cycl...@gmail.com]

Andrew gave those examples of the Giant's failing. If you look at the pictures carefully you can see that the layup was faultless and that the failures were due to simply mechanical failure from building them too light.

The Giant TCR-0 of my brother's weighs 16 lbs with total DuraAce components. That's so damn light I can't even imagine riding it. And the latest one's are said to weigh 14 lbs. Other carbon fiber bikes on the market are 12 lbs.

My brother had been using a carbon fiber saddle but just like clockwork once a year they would break.

[cycl...@gmail.com]

One of the cheapest and best sounding Trumpets on the market is a plastic one.

[jbeattie]

You're friend was on a C40? That bike was first produced in 1993-94, and its a Colnago. I'm amazed it lasted that long. With your history with Colnagos, I'm amazed you let your friend ride it at all. Those things are death traps.

I was riding my post-crash SuperSix yesterday, and it didn't break again. I do need to check the left chain stay because it got rubbed by the wheel a few years ago when the drop-out got loose (long story, a screw on the drop-out/derailleur hanger fell out), but the shop people say its fine. My worst CF problem was my shoes. Hot foot. I need some different insoles or something.

-- Jay Beattie.

[Jeff Liebermann]

On Mon, 22 May 2017 14:39:19 +0700, John B. <sloc...@gmail.com>
wrote:

>Are C.F. frames painted?

Yes, unless you like the basket weave look.

>Do the frames crack without disturbing the
>coating, whatever it may be?

Good point. I don't know. I'm assuming that the bicycle paint is
like automotive paint, which flexes a little to prevent the thermal
expansion and contraction of the underlying car body from cracking the
paint. My guess(tm) is that if the underlying carbon fiber tube moves
a little, the paint will stretch to fit, rather than crack.

>Why all the folderol with phosphorescent
>stuff when the conventional "dye Check" kit will show cracks and you
>can pay a couple of dollars more and get the set that shows up under
>ultraviolet light.

Because a dye leakage test will show cracks in the paint, not cracks
in the underlying CF tubing. At best, it's a good way to test the
quality of the paint job. I don't think anyone has crashed riding a
bicycle with cracks in their paint job.

>After all, it is used to inspect vehicles that thunder along 5 miles
>up in the air while a bicycle runs along on the surface :-)

I'm not sure, but methinks some other method is used on painted
surfaces and that dyes are only used on parts with exposed surfaces.

[sms]

An inexperienced builder choosing the wrong type of fork for a tandem,
and then having it fail, doesn't mean much. On a tandem you want a
stronger fork and stronger wheels.

My Trek tandem has never had a fork failure, and it's got a CroMo fork.
Using Frank's statistical logic, my example of one proves that steel is
the best.

[cycl...@gmail.com]

I didn't notice Frank saying that the builder was inexperienced.

[Frank Krygowski]

I agree, that fork disqualified it as a "good" steel bike. Or more specifically,
it disqualified the fork.

It does make me wonder, if you're buying a custom frame, how do you know what
you're getting? The builder of this frame, a guy named Jim Bradford, had a
good reputation. I never thought to ask him "Did you perhaps use fork blades
intended for racing single bikes on velodromes?" And once they were in, the
only way to tell that the wall thickness was 1/3 of what it should have been
would be to weigh the fork and look up other fork weights for comparison. I
certainly never thought to do that.

- Frank Krygowski

[Frank Krygowski]

He was not. He was locally well known, and recommended by a couple different
sources. He'd built lots of bikes, including at least one other tandem, the
one he and his fiance rode.

I suspect the problem was he was way behind schedule and was cutting corners.
When I picked up the bike, it was painted the wrong color, and various other
details were not as ordered. He said "Look, I'm going to Europe for my
honeymoon in a couple weeks. Do you want the bike or not?"

- Frank Krygowski

[jbeattie]

I've mentioned this before, but I had a friend who lost a fork blade on a Rodriguez tandem -- another well-respected tandem builder. I think it was incompletely brazed. He suffered serious injuries, as did his girlfriend/stoker. I recall more than one story of a tack brazed fork that mistakenly went into the paint queue during the Italiano bike craze in the late '70s. Apparently someone didn't finish it up when it came around on the carousel.

-- Jay Beattie.

[AMuzi]

Nothing's changed regarding humans or Murphy's Law:

http://www.yellowjersey.org/photosfromthepast/mt17f.jpg

I pulled those darned-near-brazed ends out of a fork last
Monday morning. They were 'brazed' in April, crooked, but
the joints cracked when it came here for alignment.

[Doug Landau]

On Sunday, May 21, 2017 at 5:57:07 PM UTC-7, John B. wrote:
> On Sun, 21 May 2017 13:45:44 -0700, sms <scharf...@geemail.com>
> wrote:
>
> >On 5/21/2017 12:58 PM, Duane wrote:
> >
> >> Why would I buy expensive equipment to test my frame? And I back up my
> >> hard drives weekly.
> >
> >Good idea.
> >
> >A month ago my daughter's Thinkpad's drive crashed. Yesterday my son's
> >Thinkpad's drive crashed. I think I need to start replacing drives every
> >three years.
>
> I just read a Seagate announcement that they do not rate their hard
> disks in MTBF as they say that doesn't present a true picture. Now
> they use Annualized Failure Rate (AFR) which hey say presents a more
> accurate assessment of potential drive life.
>
> Example: The Barracuda ES.2 Near-Line Serial ATA drive:
> "The product shall achieve an Annualized Failure Rate - AFR - of 0.73%
> (Mean Time Between Failures - MTBF - of 1.2 Million hrs) when operated
> in an environment that ensures the HDA case temperatures do not exceed
> 40°C"

LOL Well they had to say -something- !! They are still smarting from the 3TB 43% failure debacle 2 yrs ago.

https://www.eteknix.com/3tb-seagate-hard-drives-43-failure-rate-constant-use/
http://www.pcworld.com/article/3028981/storage/seagate-slapped-with-a-class-action-lawsuit-over-hard-drive-failure-rates.html

[John B.]

I probably should have specified "paint" a bit more diligently as I
think that the outer layer may be some sort of UV proof resin rather
then a "paint". At least that is how a boat is built. The mold is
first sprayed with a "Gel Coat" which is a colored resin coating that
provides the smooth, slick, colored (usually white in a boat), U.V.
proof, visible surface of the structure.

Given that modern C.F. bike frames are built in a mold it would seem
likely that somewhat the same technique would be used. The outer,
visible, layer of C.F. cloth on most fanes, for example, is normally
cosmetic not structural.

--
Cheers,

John B.

[John B.]

I don't believe that composites work that way as the metal structure
basically changes its nature with stress while a composite structure
looses strength as individual fibers inside the cured resin are
broken. Ultimately, of course, the composite structure fails but from
what I read there isn't any visual change on the surface.
--
Cheers,

John B.

[AMuzi]

That's right. People expect a woven clothlike look or as a
Famous Designer used to call the stuff, "carbon wallpaper".

Structural carbon is usually fine-fiber sheet in a single
layer much like tubular tire sidewalls. Layers are aligned
in various directions and planes with a 2-part carrier then
pressure molded to remove most or at least some of the air
pockets and excess adhesive.

[John B.]

On Mon, 22 May 2017 08:38:18 -0700, Jeff Liebermann <je...@cruzio.com>
wrote:

>On Mon, 22 May 2017 14:39:19 +0700, John B. <sloc...@gmail.com>
>wrote:
>
>>Are C.F. frames painted?
>
>Yes, unless you like the basket weave look.
>
>>Do the frames crack without disturbing the
>>coating, whatever it may be?
>
>Good point. I don't know. I'm assuming that the bicycle paint is
>like automotive paint, which flexes a little to prevent the thermal
>expansion and contraction of the underlying car body from cracking the
>paint. My guess(tm) is that if the underlying carbon fiber tube moves
>a little, the paint will stretch to fit, rather than crack.
>

This is what I mentioned in another post. My experience with
composites is that when built in a mold, as is a bicycle fame, the
first move is to spray the mold with a "gel coat" which provides the
visible outer surface of the structure. As this is "the easy way" to
produce a slick, shiny, outer surface I had assumed that bicycle
frames were likely the same.

The common visible "fabric" C.F. outer layer is usually simply a
cosmetic feature and provides very little to the strength of the
structure.

>>Why all the folderol with phosphorescent
>>stuff when the conventional "dye Check" kit will show cracks and you
>>can pay a couple of dollars more and get the set that shows up under
>>ultraviolet light.
>
>Because a dye leakage test will show cracks in the paint, not cracks
>in the underlying CF tubing. At best, it's a good way to test the
>quality of the paint job. I don't think anyone has crashed riding a
>bicycle with cracks in their paint job.

But if the frame is built as a boat hull is, using a "gel coat", there
is no cracking of the outer surface with normal temperature induced
expansion and contraction. Again, from what I read a gel coat is
commonly used in bike frame manufacturer.

I also came across the following which does seem to agree with
articles I have read regarding strength of composite structures, that
fibers fail individually until the strength reaches a certain point
when the whole structure fails catastrophically.

http://www.gone.training/?p=111
"Additionally Carbon Fiber is highly susceptible to a phenomena called
Barely Visible Impact Damage (BVID). The Carbon Fiber looks fine on
the surface, however the structural integrity of the fibers below the
surface is less than satisfactory. The amount of damage below the
surface varies depending on the type and amount of force of the
impact. NDT is able to detect this damage using ultrasonic's, if they
have a suitable standard to compare the frame against. If not detected
or repaired this can lead to catastrophic failure. Could get really
ugly on a downhill run."

>
>>After all, it is used to inspect vehicles that thunder along 5 miles
>>up in the air while a bicycle runs along on the surface :-)
>
>I'm not sure, but methinks some other method is used on painted
>surfaces and that dyes are only used on parts with exposed surfaces.

Dyes would only work on cracks.
--
Cheers,

John B.

[John B.]

On Mon, 22 May 2017 12:10:40 -0700, sms <scharf...@geemail.com>
wrote:

But what is "CroMo"? One assumes you mean "Chrome Millennium Steel:
commonly called "chrome-moly" which simply identifies the basic
alloying elements. But SAE lists some 12 different chrome-moly steels
ranging from SAE 4118 with a yield strength of ~53,000 psi to SAE 4164
with a yield strength of ~80,000 psi.

--
Cheers,

John B.

[John B.]

Weighing might not have told you anything either as the fork crown is
usually the heaviest part of a fork and weights vary from about 300
Gr. down to arond 100 Gr. Steerer tubes also vary in weight for the
same diameter.
--
Cheers,

John B.

[sms]

On 5/22/2017 8:38 AM, Jeff Liebermann wrote:
> On Mon, 22 May 2017 14:39:19 +0700, John B. <sloc...@gmail.com>
> wrote:
>
>> Are C.F. frames painted?
>
> Yes, unless you like the basket weave look.
>
>> Do the frames crack without disturbing the
>> coating, whatever it may be?
>
> Good point. I don't know. I'm assuming that the bicycle paint is
> like automotive paint, which flexes a little to prevent the thermal
> expansion and contraction of the underlying car body from cracking the
> paint. My guess(tm) is that if the underlying carbon fiber tube moves
> a little, the paint will stretch to fit, rather than crack.
>
>> Why all the folderol with phosphorescent
>> stuff when the conventional "dye Check" kit will show cracks and you
>> can pay a couple of dollars more and get the set that shows up under
>> ultraviolet light.
>
> Because a dye leakage test will show cracks in the paint, not cracks
> in the underlying CF tubing. At best, it's a good way to test the
> quality of the paint job. I don't think anyone has crashed riding a
> bicycle with cracks in their paint job.
>
>> After all, it is used to inspect vehicles that thunder along 5 miles
>> up in the air while a bicycle runs along on the surface :-)
>
> I'm not sure, but methinks some other method is used on painted
> surfaces and that dyes are only used on parts with exposed surfaces.

The experts agree that the key thing is to have your CF frame inspected
periodically for damage. It's strong, but fragile. The wrong car
carrier, bumping it against a hard object, etc., can create flaws that
are not easy to see.

It's a good idea to strip all the components off once a year and have an
ultrasound done. See
<http://carbonfibrerepair.com/ultrasound-inspection/>. Probably
someplace similar in the U.S..

[sms]

On 5/22/2017 5:58 PM, John B. wrote:

<snip>

> But what is "CroMo"? One assumes you mean "Chrome Millennium Steel:
> commonly called "chrome-moly" which simply identifies the basic
> alloying elements. But SAE lists some 12 different chrome-moly steels
> ranging from SAE 4118 with a yield strength of ~53,000 psi to SAE 4164
> with a yield strength of ~80,000 psi.

Trek's catalog for that year says "Trek designed Tru-Temper tandem
Cro-Moly" for the frame tubes and "Tange Durango double-butted Cro-Moly
w/cast fork ends" for the fork. I don't know any more details.

[cycl...@gmail.com]

Well, the only point I was trying to make was that the builder may have had time constraints and assumed that a good single fork would be a descent tandem fork. We know what assumptions lead to.

[cycl...@gmail.com]

My suspicion from looking at them is that there is an interior "balloon" mode and then after the entire outer surface is laid they put it in an exterior mold that squeezes it. The two halves of the outer mold squeeze a little of the resin between their halves which are then ground off. But it makes it look like there is a seam there when there isn't.

The frame is then painted.

[cycl...@gmail.com]

Crappy spelling checker - Chrome Molybdenum Steel. These steels can have higher strengths with heat treating. But this is negated by welding so Columbus EL tubing used via Fillet Brazing is neither heat treated or butted if memory serves. This makes a very light frame but I don't know about their strength other than via hearsay.

[cycl...@gmail.com]

Double butting in forks sounds suspicious. Because fork legs can be used for very small or very large forks the butting would have to be pretty short.

[John B.]

I even found some in a shop. It isn't really carbon fiber but it looks
like it is and it has a sticky back so you can cut out pieces and
stick them on the bike. For a while I had one C.F. chain stay and half
the handlebars were C.F. :-}

>Structural carbon is usually fine-fiber sheet in a single
>layer much like tubular tire sidewalls. Layers are aligned
>in various directions and planes with a 2-part carrier then
>pressure molded to remove most or at least some of the air
>pockets and excess adhesive.

They also have pre-preg C.F. although I'm not sure whether it is used
in bicycle frames. You lay it up, apply pressure and stick it in an
autoclave and Presto, a carbon fiber thingamajig.
--
Cheers,

John B.

[John B.]

On Mon, 22 May 2017 20:07:05 -0700, sms <scharf...@geemail.com>
wrote:

Like many things concerning bicycles descriptions seem much like
advertisements. Henry James seems to be the largest supplier (or maybe
the most vocal) of True-Temper tubes and like most tube makers,
Tru-Temper sells a wide range of tubes. A quick look shows HOXPLAT01,
the material is stated to be Proprietary RC 40, the next page lists
RC2ST, Material 4130 AO, Hardness RB 90 - 105.

If we assume that they are both made of SAE 4130 steel then the first
tube mentioned would have a tensile strength in the neighborhood of
180,000 psi and the second would be in the range of 90,000 psi.

Thus the simple description of "chrome-moly" can be a bit misleading
:-)
--
Cheers,

John B.

[Duane]

Chromium and Molybdenum. I assume millennium was a typo.
https://en.m.wikipedia.org/wiki/41xx_steel



--
duane

[AMuzi]

It's a misnomer. Fork blades are not double butted.

Plain gauge forks end up thin at the crown (where you want
strength) and thick at the bottom (where you'd prefer
resilience).

Taper gauge blades end up constant-wall:
http://www.yellowjersey.org/photosfromthepast/FORKSEC.JPG

[cycl...@gmail.com]

That's a lot more as I would expect. The way that steel can be worked is amazing.

[Jeff Liebermann]

On Tue, 23 May 2017 15:07:26 +0700, John B. <sloc...@gmail.com>
wrote:

>>That's right. People expect a woven clothlike look or as a
>>Famous Designer used to call the stuff, "carbon wallpaper".
>
>I even found some in a shop. It isn't really carbon fiber but it looks
>like it is and it has a sticky back so you can cut out pieces and
>stick them on the bike. For a while I had one C.F. chain stay and half
>the handlebars were C.F. :-}

The CF pattern is quite popular as a laptop cover.
<https://www.google.com/search?q=carbon+fiber+laptop+cover&tbm=isch>
It's not real CF, but is made to look like it. Oddly, while bicycle
CF is covered with a clear coat and made to look smooth, the laptop CF
covers have a textured finish (which is perfect for collecting dirt)
and made to feel rough.

I just took inventory and realized that I don't have anything made
from CF or made to look like it.

[AMuzi]

On 5/23/2017 11:49 AM, Jeff Liebermann wrote:
> On Tue, 23 May 2017 15:07:26 +0700, John B. <sloc...@gmail.com>
> wrote:
>
>>> That's right. People expect a woven clothlike look or as a
>>> Famous Designer used to call the stuff, "carbon wallpaper".
>>
>> I even found some in a shop. It isn't really carbon fiber but it looks
>> like it is and it has a sticky back so you can cut out pieces and
>> stick them on the bike. For a while I had one C.F. chain stay and half
>> the handlebars were C.F. :-}
>
> The CF pattern is quite popular as a laptop cover.
> <https://www.google.com/search?q=carbon+fiber+laptop+cover&tbm=isch>
> It's not real CF, but is made to look like it. Oddly, while bicycle
> CF is covered with a clear coat and made to look smooth, the laptop CF
> covers have a textured finish (which is perfect for collecting dirt)
> and made to feel rough.
>
> I just took inventory and realized that I don't have anything made
> from CF or made to look like it.
>
>

If not now, when? If not you, who?
Be the first kid on your block with an F-35!

[Jeff Liebermann]

On Tue, 23 May 2017 07:33:22 +0700, John B. <sloc...@gmail.com>
wrote:

>I also came across the following which does seem to agree with
>articles I have read regarding strength of composite structures, that
>fibers fail individually until the strength reaches a certain point
>when the whole structure fails catastrophically.
>
>http://www.gone.training/?p=111
>"Additionally Carbon Fiber is highly susceptible to a phenomena called
>Barely Visible Impact Damage (BVID). The Carbon Fiber looks fine on
>the surface, however the structural integrity of the fibers below the
>surface is less than satisfactory. The amount of damage below the
>surface varies depending on the type and amount of force of the
>impact. NDT is able to detect this damage using ultrasonic's, if they
>have a suitable standard to compare the frame against. If not detected
>or repaired this can lead to catastrophic failure. Could get really
>ugly on a downhill run."

I wonder if using clear resin for making CF parts would make visual
inspection easier?

Also, carbon fiber are conductive? If so, it should be possible to
measure the DC resistance between the ends of a tube. If any strands
break, there would be a corresponding increase in DC resistance.
<https://www.quora.com/Does-carbon-fibre-conduct-electricity-Why-or-why-not>
Getting a reliable electrical connection on the ends would be tricky,
but not impossible.

I've suggested in the (distant) past that riding CF is much like
riding a bicycle made from glass. Glass is strong, hard, and stiff.
If it were not for the weight, glass would probably make a usable
bicycle frame. Just one problem. It's not very tough. Bend it a
little too much and it will break. Create a stress riser by
scratching the surface, and it will crack starting at the surface.
Temper the outside, and it will shatter into a zillion pieces when hit
with metal or concrete. To ride a glass bicycle, all one needs to do
is avoid bending, scratching the surface, impact damage, and hitting
it with metal.

CF is much the same, except that it weighs less and can tolerate more
abuse before falling apart. If you ride a CF bicycle as if it were
made from glass, you should not have any safety or reliability
problems.

[cycl...@gmail.com]

That sounds good but my guess is that you couldn't measure a significant change in resistance until it was already to fail.

[Jeff Liebermann]

On Tue, 23 May 2017 11:03:20 -0700 (PDT), cycl...@gmail.com wrote:

>> Also, carbon fiber are conductive? If so, it should be possible to
>> measure the DC resistance between the ends of a tube. If any strands
>> break, there would be a corresponding increase in DC resistance.
>> <https://www.quora.com/Does-carbon-fibre-conduct-electricity-Why-or-why-not>
>> Getting a reliable electrical connection on the ends would be tricky,
>> but not impossible.

>That sounds good but my guess is that you couldn't measure a
>significant change in resistance until it was already to fail.

I was also thinking of treating it like a transmission line and
running a TDR (time domain reflectometer) pulse down the tubing to see
if it shows any discontinuities. I really don't know what I'll see
(if anything) until after I try it. Incidentally, an electrical
connection might not be necessary if I can induce some current though
the CF bundle using an induction coil (at low power so it doesn't
vaporize the CF tubing).

I'm late for a free lunch. More later...

[Jeff Liebermann]

On Tue, 23 May 2017 11:59:35 -0500, AMuzi <a...@yellowjersey.org> wrote:

>Be the first kid on your block with an F-35!

This F-35?
<http://www.bikesportmichigan.com/reviews/felt35.shtml>
Aluminum frame, CF forks and handlebars. Close enough.

[John B.]

Columbus makes a single butted round fork blade with Top Dia. of
28.6mm, bottom is 21.2. Top thickness is 1.23 and bottom is 0.9,
lengths from 460 - 540mm. Butted end ranges from 135 to 90mm in
length.
--
Cheers,

John B.

[John B.]

On Tue, 23 May 2017 11:59:35 -0500, AMuzi <a...@yellowjersey.org> wrote:

Andrew, you must be doing well. The F-35A's cost per flying hour in
2012 dollars is $32,500 :-)
--
Cheers,

John B.

[John B.]

On Tue, 23 May 2017 10:05:37 -0700, Jeff Liebermann <je...@cruzio.com>
wrote:

>On Tue, 23 May 2017 07:33:22 +0700, John B. <sloc...@gmail.com>
>wrote:
>
>>I also came across the following which does seem to agree with
>>articles I have read regarding strength of composite structures, that
>>fibers fail individually until the strength reaches a certain point
>>when the whole structure fails catastrophically.
>>
>>http://www.gone.training/?p=111
>>"Additionally Carbon Fiber is highly susceptible to a phenomena called
>>Barely Visible Impact Damage (BVID). The Carbon Fiber looks fine on
>>the surface, however the structural integrity of the fibers below the
>>surface is less than satisfactory. The amount of damage below the
>>surface varies depending on the type and amount of force of the
>>impact. NDT is able to detect this damage using ultrasonic's, if they
>>have a suitable standard to compare the frame against. If not detected
>>or repaired this can lead to catastrophic failure. Could get really
>>ugly on a downhill run."
>
>I wonder if using clear resin for making CF parts would make visual
>inspection easier?
>

I would guess no. Even using glass you can only see the top most layer
of cloth.

>Also, carbon fiber are conductive? If so, it should be possible to
>measure the DC resistance between the ends of a tube. If any strands
>break, there would be a corresponding increase in DC resistance.
><https://www.quora.com/Does-carbon-fibre-conduct-electricity-Why-or-why-not>
>Getting a reliable electrical connection on the ends would be tricky,
>but not impossible.
>

I think it would be rather unwieldy as I would guess that there are a
number of shorter lengths of cloth used to build a bicycle fame that
may not be connected, electrically to the ends of the tube.

>I've suggested in the (distant) past that riding CF is much like
>riding a bicycle made from glass. Glass is strong, hard, and stiff.
>If it were not for the weight, glass would probably make a usable
>bicycle frame. Just one problem. It's not very tough. Bend it a
>little too much and it will break. Create a stress riser by
>scratching the surface, and it will crack starting at the surface.
>Temper the outside, and it will shatter into a zillion pieces when hit
>with metal or concrete. To ride a glass bicycle, all one needs to do
>is avoid bending, scratching the surface, impact damage, and hitting
>it with metal.

Just weave the glass into a cloth, soak with epoxy and lay it into a
mold :-)

>
>CF is much the same, except that it weighs less and can tolerate more
>abuse before falling apart. If you ride a CF bicycle as if it were
>made from glass, you should not have any safety or reliability
>problems.

:-) You appear to be comparing carbon fibers to a solid glass
structure. Which is not apples and apples.
--
Cheers,

John B.

[Doug Landau]

> >Also, carbon fiber are conductive? If so, it should be possible to
> >measure the DC resistance between the ends of a tube. If any strands
> >break, there would be a corresponding increase in DC resistance.
> ><https://www.quora.com/Does-carbon-fibre-conduct-electricity-Why-or-why-not>
> >Getting a reliable electrical connection on the ends would be tricky,
> >but not impossible.
> >
> I think it would be rather unwieldy as I would guess that there are a

> number of shorter lengths of cloth ...

Interesting... I was thinking it's a crack in the resin, not discontinuities in the carbon, that one is worried about, but either way, this raises a good point: that conductors could be built into the tubes specifically for this purpose. With exposed test points at appropriate places, or carrying shifter signals, a strand of metal flakes running the length of the tube might be easy to test and might be made to be effective at revealing radial cracks.

Frames will one day come with stickers that say "Electronically Tested" like condoms.

http://www.conductivecomposites.com/pdf/Nanostrand%20Applications%20SAMPE%20Journal%20May%202011%20final.pdf

[AMuzi]

Right but if I can coax Lieberman into one I'll ask to
borrow it!

[John B.]

Well then, is Lieberman doing that well :-?
--
Cheers,

John B.

[avag...@gmail.com]

Are older CF frames degrading, wearing out ?

[cycl...@gmail.com]

On Wednesday, May 24, 2017 at 8:14:35 PM UTC-7, avag...@gmail.com wrote:
> Are older CF frames degrading, wearing out ?

As a sample of one manufacturer - Colnago - they do not offer any warranties on their frames in Europe. In the US they will only give you a two year warranty and you must be the original purchaser. The letter returned to me gave me the impression that they are quite worried about American's sue crazy legal system. All I was doing was informing them of the failure and requesting information on where to obtain a replacement fork.

After the information that John supplied I can see why. The loss of strength in resins holding the frames and forks together is substantial and as a guess would be greatly accelerated with reduced thickness of the resin layers and the manner of conditions a sport bicycle is used in. The condition of California roads and probably most of the roads in this country since California's weather conditions are very mild in comparison subjects CF bikes to the bending that deteriorates the resins rather rapidly.

[avag...@gmail.com]

itsnot road conditions ....who rides into potholes ?

prob is factory quality control

JB is prob keeping a close magnifier on his CF

we due for a JB CF Report any day now...

prob crack above The Hub

[jbeattie]

The Hub? http://hopworksbeer.com/ I'm waiting for Tom to post a link supporting his claim that CFRP "deteriorates rapidly" riding on rough California roads. I think the CF big-hit bike guys would be surprised to hear this. I can see UV and a harsh environment attacking the polymer (assuming no decent paint job and a bike chained-up outside), but fatigue cycles alone don't cause "rapid" deterioration. The deterioration is less rapid than with aluminum or steel in terms of the number of cycles to failure.

I've broken most bicycle-related things -- frames, cranks, pedals, seat posts, handlebars, hubs. I haven't broken a CF anything yet, but I would expect to break a CF frame one day, and I do keep an eye on the fork and steerer. I'm not sure about the strength of CF steerers, although they seem to be working out fine. I sure wouldn't buy a Colnago. All my CF bikes (a SuperSix and a Roubaix) have lifetime warranties.

-- Jay Beattie.

[cycl...@gmail.com]

On Thursday, May 25, 2017 at 8:53:36 AM UTC-7, avag...@gmail.com wrote:

What are you talking about? We aren't talking about pot holes, but just increasingly rough pavement that causes the frame and fork to flex. This required a lot of motion in the large fiberglass frames with very heavy construction but not very large for very thin and light cross sections of CF.

[cycl...@gmail.com]

Jay, did you read the reference John had? At the end of that paper they showed a graph of the reduction in the strength of the various resins via flexing.

The flexing of those thick sections vs the thing sections in a bicycle would show that simple road imperfections would vibrate or "flex" the tubing causing the drop in resin strength.

The Trek my friend had also had a lifetime warranty and it broke within a week of delivery. They replaced the frame (the problem was a rather harmless crack but a break none-the-less) but he had to pay for the disassembly of the old frame and the assembly of the new.

The pictures of the broken CF frames are of course all of the worst possible occurrences. And many of them are from collisions with a car which should not be in the same classification. But lifetime warranties are not the same thing same thing as a guarantee.

[avag...@gmail.com]

well, I lived 10 years in the deep freeze near Canada where frost goes 5' down

6 year in Lower Pa with antique road surface with frost maybe 2.5'

6 crossing California on too and back from the San Juans to Yuma/San Diego.

Cals roads are fairly good. Up in the Mtns on very secondary roads there may be some roughness bot on the whole...no the roads are OK

Down at the Beach many roads crack along the N-S road line from subsidence. Avoid.

If there's no frost n no building with triax, roads are ok

'asphalt' is flexible. Todays ripples from yesterdays weather may settle out tomorrow

[jbeattie]

Yes, CFRP has a fatigue life. For a bike frame, its longer than steel -- at least for the frames that were tested and reported on Sheldon's site.

The more interesting question is why CFRP forks or frames fail in use, and whether the failure rate is higher than with other frame or fork materials.

The fact is that the vast majority of light-weight road bikes (CF, steel and aluminum) are shipped with CFRP forks. Cannondale started shipping the 2.8 with Kinesis CF forks in about '95 (after three years of the dreadful sub-one aluminum forks). Trek 5500 with CF forks was 1992 -- so 22-25 years of mass-produced bikes with CF forks.

I bought a pair of Kestrel after-market forks in '92 to replace the aluminum forks on my 2.8, so contrary to my 30 year statement previously, I've been riding CFRP forks since '92 -- a scant 25 years. I even had some cheap-o Nashbar CF forks that I bought for my old SP steel racing bike and my Cannondale T1000. They all had aluminum steerers and were not bleeding edge technology. Anyway, none of them broke, but I would be interested in some real investigation of the frequency and causes of CF fork failures. The failures I've seen involved objects stuck in spokes with the sole exception of one pair where the blade was not bonded to the crown.

-- Jay Beattie.

[cycl...@gmail.com]

On Thursday, May 25, 2017 at 11:42:39 AM UTC-7, avag...@gmail.com wrote:
>
> Cals roads are fairly good. Up in the Mtns on very secondary roads there may be some roughness bot on the whole...no the roads are OK
>
> Down at the Beach many roads crack along the N-S road line from subsidence. Avoid.
>
> If there's no frost n no building with triax, roads are ok
>
> 'asphalt' is flexible. Todays ripples from yesterdays weather may settle out tomorrow

Not around and in the cities. Even out in farm country the roads have been torn up from trucks and lack of repair.

[James]

On 26/05/17 08:19, jbeattie wrote:

>
> Yes, CFRP has a fatigue life. For a bike frame, its longer than
> steel -- at least for the frames that were tested and reported on
> Sheldon's site.
>

What that test demonstrates is that the steel frames are not designed
well enough to cope with the applied cyclic stress input. You can see
from the graph here <https://en.wikipedia.org/wiki/Fatigue_limit> that
if the applied cyclic stress is below a certain magnitude, the cyclic
fatigue life of steel is near infinite.

I wonder how many more years of service I'll get from my steel frame,
aluminium steerer and CFRP forks? According to Strava, I'll have ridden
over 75,000km on it in a few more months. Currently 72,302.5 km. Mind
you, I don't weigh anything like 120kg (75kg more like), so it would be
difficult for me to ever press on the pedals with 1200N as per the test.

--
JS

[John B.]

On Fri, 26 May 2017 14:22:48 +1000, James <james.e...@gmail.com>
wrote:

Regarding testing it might be remembered that all tests are designed
to be severe enough to fail the item being tested. If the item never
fails the test has proven nothing.

Had the test been carried out with 75 kg. or 62% of the load actually
used the test might well be still going on and your bike might,, as a
Chinese bike shop assured me when discussing a Flying Pidgin, "be a
bike that you can pass on to your descendents" :-)
--
Cheers,

John B.

[cycl...@gmail.com]

That curve shows that steel at 75% of it's max loading lasts forever. The chart that John gave us showed that carbon forks should probably be replaced every couple of years. The aluminum steerer on your chart suggests that the fork should be replaced reasonably often as well.

You will probably ignore this warning and you probably won't have any problems. But if my theory about the vibrations being the sort of loads that can wear CF components you do so at your own risk.

[Frank Krygowski]

On 5/26/2017 12:22 AM, James wrote:
> On 26/05/17 08:19, jbeattie wrote:
>
>>
>> Yes, CFRP has a fatigue life. For a bike frame, its longer than
>> steel -- at least for the frames that were tested and reported on
>> Sheldon's site.
>>
>
> What that test demonstrates is that the steel frames are not designed
> well enough to cope with the applied cyclic stress input. You can see
> from the graph here <https://en.wikipedia.org/wiki/Fatigue_limit> that
> if the applied cyclic stress is below a certain magnitude, the cyclic
> fatigue life of steel is near infinite.

I'm not sure "not designed well enough" is accurate. I think in various
competitive situations, engineers design things knowing they won't last
forever. I think it was John who referenced Colin Chapman's words on
race cars falling apart as they cross the finish line. A less
theoretical example might be "top fuel dragsters," where engines are
torn down and parts replaced after each 1/4 mile run.

Of course, you wouldn't want that situation for the car you drive on a
vacation journey or a trip to the store. But at least some supposedly
normal bicycles are designed with light weight a bigger priority than
long service life.

I think the reason it pays off for the manufacturers is that at least in
the U.S., most bikes spend almost their entire life hanging in garages.
Very few ever accumulate even 10,000 miles.


--
- Frank Krygowski