CF Bike Shatters Top Tube and Down Tube after hitting a Road Divot

[Tim McNamara]

In article <[email protected]>,
damyth <[email protected]> wrote:

> Yeah, you're a real Einstein.

And the need to be gratuitously nasty comes from...?

> The point here is not just post any random picture of a mangled
> random frame. Show me a mangled frame with 2 (virtually) perfect
> wheels, drivetrain, forks, & stays, etc., and then we can start the
> discussion of whether it constitutes a case of JRA or not.
>
> In the case of the OP's Scott CF bike, having the down tube break in
> two places at the same time is akin to lightning striking the same
> place twice.

We don't know that this is what happened. You're making an unfounded
assumption. The two breaks in the down tube could have happened
sequentially rather than simultaneously and from two different causes.
For example, the front end snaps off and as the bike falls to the
pavement, the down tube end strikes something and breaks a second time.

The break at the middle of "Scott" looks like the downtube was forced
upwards, peeling off a "flap" of CF like the strings in a stick of
celery. That, to me, suggests that it was the second break in the
downtube.

But it's all pretty baseless speculation, since all we have are three
photos and a vague description of the crash.

> What are the odds of that happening without some sort of
> manufacturing defect? If you stuck a well-constructed CF tube in a
> hydraulic bending mandrel, do you think it's going to section off in
> two virtually perfect pieces like that? If you had paused to think
> about this for more than a millisecond, this question ought to have
> to occurred to you.

That was one question. The other question that ought to have occurred
to you was what might have happened to the bike *before* the accident.
Was the downtube already damaged, perhaps by clamping it into a roof
rack with a down tube grabber?

Could it be a manufacturing defect? Sure. Could be be something else?
Sure. We have almost no data from which to work, however.

 

[futrino]

Tim McNamara wrote:
> In article <[email protected]>,
> Paul Myron Hobson <[email protected]> wrote:
>
>
>>>>>Derk wrote:
>>>>>
>>>>>>Tell that to all the people who ride a bike with a MP3 player or
>>>>>>similar in their ears. My experience is that they hear nothing
>>>>>>else.
>>>>>
>>>>jim beam wrote:
>>>>
>>>>>isn't it illegal?
>>>>
>>Tim McNamara wrote:
>>
>>>A quick Google suggests that most states if not all prohibit the
>>>use of earphones in both ears while driving a motor vehicle or
>>>riding a bike. Which means that I see a *lot* of bicyclists
>>>violating that particular law.
>>
>>While it IS dangerous and not something I advocate, that's a pretty
>>meaningless law, eh? I can't have headphones at any volume, but dude
>>can through a 2 kW amp and some subwoofers in his trunk, play loud
>>enough to rattle his trunk lose and that's kosher?
>
>
> Logical consistency across laws is not necessarily the case. Eventually
> that tends to get corrected but not always. Locally there is a "loud
> car stereo" ordinance but it is, as far as I can tell, never enforced.

I just noticed inmy local paper that it was enforced today, cedar
rapids iowa

the fine was $65 but with court costs it =$135.80

http://www.gazetteonline.com/apps/pbcs.dll/article?AID=/20070816/NEWS/70815069/1006/NEWS

 

[Antti Salonen]

damyth <[email protected]> wrote:


> In the case of the OP's Scott CF bike, having the down tube break in
> two places at the same time is akin to lightning striking the same
> place twice. What are the odds of that happening without some sort of
> manufacturing defect?

I wouldn't put that much emphasis on the downtube breaking in two
places. From the photograph it looks like the downtube separated from
the head tube. Following this the top tube snapped in its weakest point
where the rear brake cable is routed inside the tube. I would guess that
the downtube snapped in the middle (probably where the bottle cage
thread is) only after the rider went down hard and the downtube hit the
ground or curb of whatever.

Antti

 

[Artoi]

In article <[email protected]>,
A Muzi <[email protected]> wrote:

> Steel bike: this downtube actually _isn't_ cracked in 2 places:
> http://www.yellowjersey.org/BIACTA.JPG

Ummm... We can weld it right back. Good as new!
--

 

[Paul Myron Hobson]

still me wrote:
> On Thu, 16 Aug 2007 07:21:57 -0400, John Forrest Tomlinson
> <[email protected]> wrote:
>
>>> Tim McNamara wrote:
>>>> A quick Google suggests that most states if not all prohibit the use of
>>>> earphones in both ears while driving a motor vehicle or riding a bike.
>>>> Which means that I see a *lot* of bicyclists violating that particular
>>>> law.
>>> While it IS dangerous and not something I advocate, that's a pretty
>>> meaningless law, eh? I can't have headphones at any volume, but dude
>>> can through a 2 kW amp and some subwoofers in his trunk, play loud
>>> enough to rattle his trunk lose and that's kosher?
>> Good point.
>
>
> Despite my personal objection to those idiots with music playing way
> too loud in their cars, you have to realize that can't legislate
> everything. Even a factory car radio at somewhat reasonable volume can
> mask many road sounds (horns, sirens, etc) unless they are very close.
>
> We don't need the gov't telling us what volume settings are
> permissible in our cars.

Agreed 100% My only point was that just because something is illegal
doesn't mean it's wrong and vise versa. But that's just life, eh?

\\paul

 

[!Jones]

On Wed, 15 Aug 2007 17:01:52 -0500, in rec.bicycles.tech Tim McNamara
<[email protected]> wrote:

>A quick Google suggests that most states if not all prohibit the use of
>earphones in both ears while driving a motor vehicle or riding a bike.
>Which means that I see a *lot* of bicyclists violating that particular
>law.

I have seen it proposed; however, to the best of my knowledge (which
is less than exhaustive), it has not beed codified very many places.

My favorite idiotic law was the time Austin, TX required helmets. A
week or so after passage, TX repealed the helmet law for motorcycles.
Thus, helmets were required for bicycles, but not motorcycles... it
didn't last long.

Samey-same driving while dialing. I see it proposed all of the time
to prohibit it, but it doesn't happen.

Not that a law against plugging both ears is "idiotic"; it'll never be
enforced, so why bother?

Jones

 

[Pikachu]

In article <[email protected]>,
Paul Myron Hobson <[email protected]> wrote:

> >>> Derk wrote:
> >>>> Tell that to all the people who ride a bike with a MP3 player or
> >>>> similar in their ears. My experience is that they hear nothing
> >>>> else.
>
> >> jim beam wrote:
> >>> isn't it illegal?
>
> Tim McNamara wrote:
> > A quick Google suggests that most states if not all prohibit the use of
> > earphones in both ears while driving a motor vehicle or riding a bike.
> > Which means that I see a *lot* of bicyclists violating that particular
> > law.
>
> While it IS dangerous and not something I advocate, that's a pretty
> meaningless law, eh? I can't have headphones at any volume, but dude
> can through a 2 kW amp and some subwoofers in his trunk, play loud
> enough to rattle his trunk lose and that's kosher?

In addition to really loud music, how about the sound insulation of new
luxury cars? Inside any of the modern luxury cars such as a Lexus
LS460, it is actually insulated enough to be able to hold a quiet
conversation at highway speeds. Wouldn't that be akin to playing loud
music, since the net effect is the same in that you can't hear any
external (read: warning) sounds?

Pikachu

 

[Tom \Johnny Sunset\ Sherman]

"still me" wrote:
>
> We don't need the gov't telling us what volume settings are
> permissible in our cars.

Yes, volume level INSIDE your car should not be regulated by the
government. We do need the government to regulate the volume level
OUTSIDE the car, however (or to legalize the use of RPG's on "boom cars").

--
Tom Sherman - Holstein-Friesland Bovinia

--
Posted via a free Usenet account from http://www.teranews.com

 

[Tom \Johnny Sunset\ Sherman]

Tim McNamara wrote:
> In article <[email protected]>,
> Paul Myron Hobson <[email protected]> wrote:
>
>>>>> Derk wrote:
>>>>>> Tell that to all the people who ride a bike with a MP3 player or
>>>>>> similar in their ears. My experience is that they hear nothing
>>>>>> else.
>>>> jim beam wrote:
>>>>> isn't it illegal?
>> Tim McNamara wrote:
>>> A quick Google suggests that most states if not all prohibit the
>>> use of earphones in both ears while driving a motor vehicle or
>>> riding a bike. Which means that I see a *lot* of bicyclists
>>> violating that particular law.
>> While it IS dangerous and not something I advocate, that's a pretty
>> meaningless law, eh? I can't have headphones at any volume, but dude
>> can through a 2 kW amp and some subwoofers in his trunk, play loud
>> enough to rattle his trunk lose and that's kosher?
>
> Logical consistency across laws is not necessarily the case. Eventually
> that tends to get corrected but not always. Locally there is a "loud
> car stereo" ordinance but it is, as far as I can tell, never enforced.

In Aurora Illinois, the police impound cars with excessively loud
stereo's, leaving the occupants to find alternate transportation home
from the police station.

--
Tom Sherman - Holstein-Friesland Bovinia

--
Posted via a free Usenet account from http://www.teranews.com

 

[Tom \Johnny Sunset\ Sherman]

Andrew Muzi wrote:
> -snip-
>>>> This is the ultimate CF "nightmare scenario." You
>>>> don't see this kind of **** happening on metal frames. Certainly no
>>>> metal down tube would have broken in two places at the same time.
>
>> A Muzi wrote:
>>> Steel bike: this downtube actually _isn't_ cracked in 2 places:
>>> http://www.yellowjersey.org/BIACTA.JPG
>>> I happen to prefer steel bikes but does that prove something?
>>> Crash reconstruction isn't a trivial thing.
>
> jim beam wrote:
>> nice one! "jra"?
>
> Middle of Lake Shore Drive, Chicago. Fell from a bus rack into traffic
> in a center lane....

See - LSD and cycling do not mix.

--
Tom Sherman - Holstein-Friesland Bovinia

--
Posted via a free Usenet account from http://www.teranews.com

 

[Tom \Johnny Sunset\ Sherman]

John Forrest Tomlinson wrote:
> On Thu, 16 Aug 2007 11:58:35 -0500, A Muzi <[email protected]>
> wrote:
>> http://www.yellowjersey.org/BIACTA.JPG
>
> A lot of those scratches will buff right out.

Good opportunity for a repaint in a better color than "Waste Water
Treatment Plant Green".

--
Tom Sherman - Holstein-Friesland Bovinia

--
Posted via a free Usenet account from http://www.teranews.com

 

[datakoll]

a small stone? how small?

reading occasional testimonials to carbon tubing, occasional carbon
craving, and very occasional bike waving roadside carbon riders, ya
gotta wonder what a survey would reveal on "if I buy it will I crash."
I haven't gone to the New River fest yet but always stop to chat with
the occasional 2 stroke hangglider-parafoil set, always carrying a
stick just in case.
I guess the incidence for sudden carbon tube failure is fairly low.
any guesses on what it is?

 

[Tom \Johnny Sunset\ Sherman]

datakoll aka gene daniels wrote:
> ...
> reading occasional testimonials to carbon tubing, occasional carbon
> craving...

I only eat carbon based food.

--
Tom Sherman - Holstein-Friesland Bovinia

--
Posted via a free Usenet account from http://www.teranews.com

 

[still me]

On Thu, 16 Aug 2007 21:42:05 -0500, "Tom \"Johnny Sunset\" Sherman"
<[email protected]> wrote:

>> We don't need the gov't telling us what volume settings are
>> permissible in our cars.
>
>Yes, volume level INSIDE your car should not be regulated by the
>government. We do need the government to regulate the volume level
>OUTSIDE the car, however (or to legalize the use of RPG's on "boom cars").

I agree that it's annoying - but so is a jack hammer, or the loud
party next door, etc. Until it reaches "disturbing the peace" I don't
think it's a legislative issue (yes, I know some of them do).

More annoying to me are loud motorcycles. They're outrageous now, and
I don't see the Fed's regulating it out of the factory or the states
doing anything at their level. It's out of control.

 

[Tom \Johnny Sunset\ Sherman]

"still me" wrote:
> On Thu, 16 Aug 2007 21:42:05 -0500, "Tom \"Johnny Sunset\" Sherman"
> <[email protected]> wrote:
>
>>> We don't need the gov't telling us what volume settings are
>>> permissible in our cars.
>> Yes, volume level INSIDE your car should not be regulated by the
>> government. We do need the government to regulate the volume level
>> OUTSIDE the car, however (or to legalize the use of RPG's on "boom cars").
>
> I agree that it's annoying - but so is a jack hammer, or the loud
> party next door, etc. Until it reaches "disturbing the peace" I don't
> think it's a legislative issue (yes, I know some of them do).

The jackhammer user is (almost always) performing a work task. Boom cars
and loud parties are in the same category.

> More annoying to me are loud motorcycles. They're outrageous now, and
> I don't see the Fed's regulating it out of the factory or the states
> doing anything at their level. It's out of control.

Quite a few cops ride loud motorcycles while off-duty, or wish that
their wife would allow them to ride a loud motorcycle while off-duty.

--
Tom Sherman - Holstein-Friesland Bovinia
BEER IS FOOD

--
Posted via a free Usenet account from http://www.teranews.com

 

[damyth]

On Aug 16, 3:14 pm, Tim McNamara <[email protected]> wrote:
> In article <[email protected]>,
>
> damyth <[email protected]> wrote:
> > Yeah, you're a real Einstein.
>
> And the need to be gratuitously nasty comes from...?
>
> > The point here is not just post any random picture of a mangled
> > random frame. Show me a mangled frame with 2 (virtually) perfect
> > wheels, drivetrain, forks, & stays, etc., and then we can start the
> > discussion of whether it constitutes a case of JRA or not.
>
> > In the case of the OP's Scott CF bike, having the down tube break in
> > two places at the same time is akin to lightning striking the same
> > place twice.
>
> We don't know that this is what happened. You're making an unfounded
> assumption. The two breaks in the down tube could have happened
> sequentially rather than simultaneously and from two different causes.
> For example, the front end snaps off and as the bike falls to the
> pavement, the down tube end strikes something and breaks a second time.
>
> The break at the middle of "Scott" looks like the downtube was forced
> upwards, peeling off a "flap" of CF like the strings in a stick of
> celery. That, to me, suggests that it was the second break in the
> downtube.
>
> But it's all pretty baseless speculation, since all we have are three
> photos and a vague description of the crash.
>
> > What are the odds of that happening without some sort of
> > manufacturing defect? If you stuck a well-constructed CF tube in a
> > hydraulic bending mandrel, do you think it's going to section off in
> > two virtually perfect pieces like that? If you had paused to think
> > about this for more than a millisecond, this question ought to have
> > to occurred to you.
>
> That was one question. The other question that ought to have occurred
> to you was what might have happened to the bike *before* the accident.
> Was the downtube already damaged, perhaps by clamping it into a roof
> rack with a down tube grabber?
>
> Could it be a manufacturing defect? Sure. Could be be something else?
> Sure. We have almost no data from which to work, however.

It's obvious from your post that you've never handled carbon fiber
tubing, certainly not enough to be familiar with their properties.
Why don't you compare the typical breaking strength of carbon fiber
tubing with the yield strength of metal tubing used on bikes, and get
back to me whether you still think your theory of the second break of
the down tube by a "grounding crash" holds water. Quite frankly, your
theory is laughable to anyone with even the most rudimentary
understanding of the properties of (well-constructed) CF tubing.

When I said "at the same time," I didn't actually mean the same
instantaneous moment in time, more like "on the same ride." I could
have been clearing in my original post but all you ditto-heads who
clung to the obvious "more than JRA" theory (despite lack of evidence
for or against it) was just getting plain annoying, especially if
you've never batted around a CF tube to understand how unlikely it is
to break transversely as in the OP's pictures.

 

[Pikachu]

In article <[email protected]>,
Michael Press <[email protected]> wrote:

> In article
> <[email protected]>,
> Peter Cole <[email protected]> wrote:
>
> > Jay Beattie wrote:
> >
> > > The important point for raam is that my "no case" quip was a joke. I
> > > am a defense guy -- I am pathologically predisposed to saying there is
> > > no case. But like you say, it all depends on the failure. In the true
> > > JRA failure, the manufacturer settles -- 'cause bikes are not supposed
> > > to fall apart. I have defended those kinds of cases, although they
> > > are rare, and like I say, they usually result from someone in
> > > production getting sleepy after lunch . . . or they involve a Chinese
> > > OEM dabbling in cutting edge componentry (hey, topical and
> > > inflammatory -- but true, sorry). Most of my other failure cases (and
> > > I have done a lot of them) involve: (1) people beating the sh** out of
> > > their bikes, or (2) new designs that fail to account for some weird
> > > stress -- like when shock forks were first introduced and they were
> > > ripping the front-ends off Al frames (thus, gussets). Notwithstanding
> > > all the complaining in this group about the lack of engineering in the
> > > bike field, I have worked with in-house engineers at some big
> > > manufacuters who were well credentialed, one of whom was in the nuke-
> > > bomb industry before moving to the bike business. -- Jay Beattie.
> >
> > The thing that concerns me about CF is that it's an inherently
> > labor-intensive process. That, combined with the fact that the only real
> > reason to use it is to shave weight means that parts won't be
> > over-designed and manufacturers will constantly try to squeeze costs.
> > Cheap CF seems like a recipe for disaster. I think it's much easier for
> > a piece of sloppy work to slip through CF production than the
> > highly-automated metal frame production.
>
> How is carbon fiber frame building more labor critical
> than steel frame building? Overheating that steel head
> tube joint is a serious risk.

How about aluminium, which probably is the most popular material for
low-mid range bicycles nowadays? At a Taipei bike show many years ago,
they exhibited a machine that accepted raw aluminium tubing and produced
completed frames (sans paint). I am assuming that the welding performed
by this type of machine is of consistent, acceptable quality, as there
does not seem to be any reports of frames with defective welds.

Pikachu

 

[Peter Cole]

Michael Press wrote:
> In article
> <[email protected]>,
> Peter Cole <[email protected]> wrote:
>
>> The thing that concerns me about CF is that it's an inherently
>> labor-intensive process. That, combined with the fact that the only real
>> reason to use it is to shave weight means that parts won't be
>> over-designed and manufacturers will constantly try to squeeze costs.
>> Cheap CF seems like a recipe for disaster. I think it's much easier for
>> a piece of sloppy work to slip through CF production than the
>> highly-automated metal frame production.
>
> How is carbon fiber frame building more labor critical
> than steel frame building? Overheating that steel head
> tube joint is a serious risk.
>

I said labor-intensive, not labor critical. It's labor-intensive simply
because more manual operations are involved, more man-hours in the
process. Other than small operations, most metal frames these days are
fabricated by machine in highly automated processes. Tube cutting,
shaping, welding and painting are often done with robots.

Hand-made metal frames can suffer the same imperfections if
manufacturers push the cost cutting too far, by rushing the work or
using inadequately skilled workers. Since automated processes are so
repeatable, quality is more uniform.

Cheap CF is still constrained by the first law of bicycle design:
"cheap, light, reliable -- pick any two". Unreliable CF is a bit scarier
than unreliable metal due to the "sudden catastrophic failure" phenomenon.

 

[Tim McNamara]

In article <[email protected]>,
damyth <[email protected]> wrote:

> On Aug 16, 3:14 pm, Tim McNamara <[email protected]> wrote:
> > In article <[email protected]>,
> >
> > damyth <[email protected]> wrote:
> > > Yeah, you're a real Einstein.
> >
> > And the need to be gratuitously nasty comes from...?
> >
> > > The point here is not just post any random picture of a mangled
> > > random frame. Show me a mangled frame with 2 (virtually) perfect
> > > wheels, drivetrain, forks, & stays, etc., and then we can start
> > > the discussion of whether it constitutes a case of JRA or not.
> >
> > > In the case of the OP's Scott CF bike, having the down tube break
> > > in two places at the same time is akin to lightning striking the
> > > same place twice.
> >
> > We don't know that this is what happened. You're making an
> > unfounded assumption. The two breaks in the down tube could have
> > happened sequentially rather than simultaneously and from two
> > different causes. For example, the front end snaps off and as the
> > bike falls to the pavement, the down tube end strikes something and
> > breaks a second time.
> >
> > The break at the middle of "Scott" looks like the downtube was
> > forced upwards, peeling off a "flap" of CF like the strings in a
> > stick of celery. That, to me, suggests that it was the second
> > break in the downtube.
> >
> > But it's all pretty baseless speculation, since all we have are
> > three photos and a vague description of the crash.
> >
> > > What are the odds of that happening without some sort of
> > > manufacturing defect? If you stuck a well-constructed CF tube in
> > > a hydraulic bending mandrel, do you think it's going to section
> > > off in two virtually perfect pieces like that? If you had paused
> > > to think about this for more than a millisecond, this question
> > > ought to have to occurred to you.
> >
> > That was one question. The other question that ought to have
> > occurred to you was what might have happened to the bike *before*
> > the accident. Was the downtube already damaged, perhaps by clamping
> > it into a roof rack with a down tube grabber?
> >
> > Could it be a manufacturing defect? Sure. Could be be something
> > else? Sure. We have almost no data from which to work, however.
>
> It's obvious from your post that you've never handled carbon fiber
> tubing, certainly not enough to be familiar with their properties.
> Why don't you compare the typical breaking strength of carbon fiber
> tubing with the yield strength of metal tubing used on bikes, and get
> back to me whether you still think your theory of the second break of
> the down tube by a "grounding crash" holds water. Quite frankly,
> your theory is laughable to anyone with even the most rudimentary
> understanding of the properties of (well-constructed) CF tubing.
>
> When I said "at the same time," I didn't actually mean the same
> instantaneous moment in time, more like "on the same ride." I could
> have been clearing in my original post but all you ditto-heads who
> clung to the obvious "more than JRA" theory (despite lack of evidence
> for or against it) was just getting plain annoying, especially if
> you've never batted around a CF tube to understand how unlikely it is
> to break transversely as in the OP's pictures.

And yet you're illogical enough to claim that (1) a CF tube is so strong
that it's almost impossible to break and (2) it can spontaneously blow
apart when hitting a pothole. You must be partaking of the jim beam.
You're also missing my point and that of the others- we don't have
enough information to form an opinion as to what happened. Period. And
yet for some reason you continue to waste time trying to convince us
that there's a manufacturing defect. Unless you're clairvoyant or you
were there when the crash happened, you don't have enough information
either.

 

[Tom Nakashima]

"Tim McNamara" <[email protected]> wrote in message
news:[email protected]...
>
> And yet you're illogical enough to claim that (1) a CF tube is so strong
> that it's almost impossible to break and (2) it can spontaneously blow
> apart when hitting a pothole. You must be partaking of the jim beam.
> You're also missing my point and that of the others- we don't have
> enough information to form an opinion as to what happened. Period. And
> yet for some reason you continue to waste time trying to convince us
> that there's a manufacturing defect. Unless you're clairvoyant or you
> were there when the crash happened, you don't have enough information
> either.

We have worked and experimented with prepreg carbon-fiber sheets here at the
Stanford Linear Accelerator Center. While working with the material, we
noticed there are such things as "voids" in the epoxy as well as voids in
the layers. We also noticed how important temperature and time is when
layering the sheets together. So I can believe there could be manufacturing
defects that could get by the quality control department.

In a conversation with John Slawta of Landshark Bicycles, he told me about a
few NEW carbon-fiber forks he has broken by gently squeezing the ends before
he paints them. He would not mention the brand.
-tom