Cannondale's tests of disks and QRs

supertwinkie said...

Lots of fun watching you dig your own grave, but if you had looked at
James' website, you'd see that he has 3 tandems.

A Cannondale:-

http://www.ne.jp/asahi/julesandjames..._tour/sign.jpg

Handmade in the USA


A Ventana:-

http://www.ne.jp/asahi/julesandjames...e/bamboo_1.jpg

oooo - Handmade in the USA


A Calfee:-

http://www.ne.jp/asahi/julesandjames...kies/garth.jpg

yet again - Handmade in the USA


Seems you lose that one.

twinks

Well, James, you went to a lot of trouble to keep yourself anonymous, or
maybe this really is one of your ass boys. But in reality, it changes
little. So the fork was made by a subcontractor for Calfee. I still
haven't seen anything posted about where or by whom it was made, but it
was most likely another small American custom manufacturer. My incorrect
assumption that it was British made should be understandable considering
the creepy Eurocentric attitude, the fact that most of the discussion
regarding it was on UK based message boards with some custom British
builders as contributors, and the fact that it shares some design
characteristics of British made forks. But wherever it was made, it was
an improvised design based on several faulty assumptions. One of the
major disadvantages of buying a specialty item from a boutique
manufacturer is that you may not get tried and true engineering, even
though the quality of materials and workmanship may in fact be the best
available.

It still doesn't answer the question as to what the British regulators
are doing to appease James, or if they had ever been approached by James
or his followers.

supertwinkie said...

So was it not SuperSlinky (SuperWimpy perhaps?) who ran snivelling to
a lawyer when he got his knee bloodied recently:-

http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&c2coff=1&safe=images&selm=MPG.1bafecd1c1cc136998 9947%40netnews.comcast.net&prev=/groups%3Fq%3Dlawyer%2Bauthor:nospam%2540least.com% 26hl%3Den%26lr%3D%26ie%3DUTF-8%26c2coff%3D1%26safe%3Dimages%26scoring%3Dd%26fil ter%3D0

"I am in contact with lawyers now and have been since the second day
after the accident."


twinks

Cool. It seems I have a fan. But like any lying troll, it is easy to
blast your insults to smithereens. I haven't hired any lawyers, but I
have spoken with a couple of them over the phone for free. In my case
liability and negligence is quite clear, and I told the insurance
company from day one that as long as they are fair, I will be too, and
lawyers need not get involved. I'm on a first name basis with the
adjuster and he knows that I haven't exaggerated anything one bit. BTW,
my medical bills are now over $5000 and will climb to five figures if
the orthopedic surgeon deems surgery necessary. I didn't think that my
injuries were all that serious at first, but a month with no
improvement, an MRI, and a half dozen doctors and physical therapists
proved me wrong. I don't think I was bleeding much at all from the
accident. It was all contusions and internal injuries. If I were to give
you the severe beating that you richly deserve, I could make sure there
wasn't a mark on you, but I'm sure you would know every place where my
foot landed.

Most importantly, I wasn't doing something inherently risky such as
bouncing down the side of a steep hill at suicidal speeds then trying to
blame somebody else when things went awry. Let's not forget that one
need not have any sort of mechanical failure at all to end up quite dead
mountain biking. I very much sympathize with those who have been injured
because I have been lucky myself. But maybe I am still in one piece
because I know when to pass on stunts that may prove disastrous. I know
that MTB equipment comes in various strengths and intended purposes and
that it can be pushed beyond its limits. Missy Giove doing 'goofy
stuff' on a Skareb fork was a sterling example of this, but of all the
dozens of people posting to that thread, I was the only one I know of
who pointed out the obvious misuse of equipment. Even the toughest
equipment has strict limits and the only equipment that can get you to
the bottom of that rocky hill safely is the equipment between your
shoulders.

SuperSlinky wrote:

Missy Giove doing 'goofy
stuff' on a Skareb fork was a sterling example of this, but of all the
dozens of people posting to that thread, I was the only one I know of
who pointed out the obvious misuse of equipment.

Yes, I believe you may have been the only one who dredged that
ridiculous jaw-droppingly weak excuse out of the bottom of your
extremely deep and murky barrel. It certainly gave me a good laugh at
the time.

As Answer put it on their web site
(http://www.answerproducts.com/items....id=1&itemid=13)

"For the first time, you can own a superlight 100mm travel fork with the
stiffness to tackle even your most aggressive XC outings, but if you are
a 130 pound female you'll probably need something beefier."

Oh, they don't say that after all. How strange.

If you are so certain that the problem doesn't exist, why are you so
desperate to find ways of blaming the victim when it does?

James
--
If I have seen further than others, it is
by treading on the toes of giants.
http://www.ne.jp/asahi/julesandjames/home/

James Annan said...

Yes, I believe you may have been the only one who dredged that
ridiculous jaw-droppingly weak excuse out of the bottom of your
extremely deep and murky barrel. It certainly gave me a good laugh at
the time.

As Answer put it on their web site
(http://www.answerproducts.com/items....id=1&itemid=13)

"For the first time, you can own a superlight 100mm travel fork with the
stiffness to tackle even your most aggressive XC outings, but if you are
a 130 pound female you'll probably need something beefier."

Oh, they don't say that after all. How strange.

If you are so certain that the problem doesn't exist, why are you so
desperate to find ways of blaming the victim when it does?

James

You don't believe that a professional downhiller doing 'goofy stuff' on
one of the flexiest XC racing forks on the market is misuse of
equipment? I just find that amazing. Well, maybe it isn't so amazing
considering you have the attitude of a trial lawyer who tries to twist
everything in the universe to his own advantage. And since you, and
quite a few others, won't be objective about the issue, I think it is
important that some of the rest of us tell the other side of the story.
If you were more objective, then I would have more time on my hands to
discuss the issue in a less adversarial sort of way.

In fact, I have admitted from day one that you discovered something that
the rest of us knew nothing about. But it appears by all of the
evidence, and much of the evidence has been argued ad nauseam, that
extreme and unusual circumstances are required for a catastrophic
failure to occur. No, the current disc brake and dropout system is not
ideal and could use some refinement. I believe that every fork
manufacturer should use a little trigonometry the next time they
redesign the tooling for their forks to minimize or eliminate any forces
that work to push the axle out of the dropout. But there just isn't any
evidence that the system, when used properly, is any more dangerous than
any other part of the bike, taking into consideration that it is an
inherently dangerous sport that continuously pushes equipment to its
limits. I can break a frame, pedal, crank arm, rim, bars, stem, seatpost
or whatever at any time. From all I have seen, wheel loss of any sort is
rare compared to any of the other failures I just listed. I guess some
of us want to cultivate the bike culture instead of destroy it.

On Sun, 26 Sep 2004 21:25:58 GMT, SuperSlinky wrote
in message :

the current disc brake and dropout system is not
ideal and could use some refinement. I believe that every fork
manufacturer should use a little trigonometry the next time they
redesign the tooling for their forks to minimize or eliminate any forces
that work to push the axle out of the dropout. But there just isn't any
evidence that the system, when used properly, is any more dangerous than
any other part of the bike, taking into consideration that it is an
inherently dangerous sport that continuously pushes equipment to its
limits.

So you don't think a change form a system where there was no force
tending to eject the wheel, to one where there is such a force, and
which has apparently resulted in at least two serious crashes we know
of, leaving at least one man paraplegic, is "any more dangerous than
any other part of the bike?"

I'm not sure I buy that at all.

Especially when the remedy appears to be mechanically trivial, and the
principal reason for not applying that remedy would seem to be fear
that it will be taken as tacit admission of fault, allowing the
lawyers a field day.

Cannondale's test looks a lot like "go away and prove that this is not
a problem" rather than "go away and find out what has to be done to
make this problem happen". As an engineer by training, knowing that
the problem almost certainly has happened at least twice, I would be
inclined to take the later approach. As a corporation with potential
lawsuits to consider, I'd maybe take the first option. No I wouldn't,
but I can see why someone else might.

So, the issue still has not been adequately investigated. And none of
us have the cash to do so. Back to square one.

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington University

SuperSlinky wrote:

You don't believe that a professional downhiller doing 'goofy stuff' on
one of the flexiest XC racing forks on the market is misuse of
equipment?

The fork is recommended for riders of up to 250 pounds. No, I don't
think it is reasonable to claim that a sub-130 pound rider is committing
"obvious abuse" just by riding such equipment, however skilled they are.
I guess it might be theoretically possible that she was abusing the
equipment, but her riding partner at the time said:

"The goofing around wasn't in the Wade Simmons league either. Just hard
riding."

Can you suggest something abusive that she might have been doing to
cause a QR failure of any sort?

In fact, I have admitted from day one that you discovered something

Very gracious of you to say so. All I wanted from the start was an
honest and open treatment of this problem, which may be quite rare but
has undoubtely cause several horriffic crashes which some victims have
been very lucky to survive. I posted one of these links before to a
story about a rider who spent two weeks in a coma, if there hadn't been
an MRT team already called out in the area it might have taken several
hours to get him to hospital and onto a ventilator rather than the
amazing 51 minutes quoted in the second link:

http://www.singletrackworld.com/article.php?sid=1309
http://www.mountainrescue.org.uk/news.html

However, rather than deal with the problem, it seems like the
manufacturers have done everything in their powers to brush it under the
carpet and wish it away. As a result of which, more riders have been
seriously injured, like the one whose email I posted a few days ago.
What would you do in these circumstances? Shrug your shoulders and say
it's not your problem?

James
--
If I have seen further than others, it is
by treading on the toes of giants.
http://www.ne.jp/asahi/julesandjames/home/

Just zis Guy, you know? wrote:
On 25 Sep 2004 04:51:17 -0700, (Pieter) wrote in
message :


I have tried to understand James' description and think it is flawed.
His diagram shows forces D and B but he doesn't show the reaction
forces -D and -B which are transmitted through the structure of the
disc, hub, spokes, rim and tyres to the front axle.


It is not necessary to show how braking force is transmitted through
the structure of the wheel in order to understand how the resultantof
forces at the dropout could cause the wheel to be ejected.

Whatever your view on the argument, there is no possible doubt that in
the case of disc brakes there is a significant resultant component of
force tending to eject the wheel, which component is essentially
absent from rim-braked wheels. It is also clear that the geometry of
dropouts is founded on rim brakes not discs, and somewhere along the
line "they" simply forgot to think about it.


I therefore contend that under normal braking conditions
(no slipping) the axle (QR) is pushed upwards and forwards.


This is a very curious statement. Are you saying that if the QR
doesn't slip it doesn't slip? Or that if you lock the brakes it
doesn't slip?

I have bikes with and without discs. It was a simple matter to loosen
the QR on both types, hit the brake with the bike moving along
(pushing, I'm not stupid enough to try it while riding), and observe
the result.

It was an unnecessary experiment, as elementary static mechanics has
already provided the answer, but I have a literal mind so I tried it
anyway.

The disc-braked wheel moved down in the dropouts, the rim-braked wheel
did not.

There are two questions remaining: first, does this force ever
overcome the retaiing force exerted by the QR skewer; second, does
the repeated application of these large off-centre forces cause a QR
to loosen. Cannondales tests do not answer either of these questions
because the braking force was inadequate, the vibration was inadequate
and the downforce on the handlebars was excessive in comparison. So
the questions remain unanswered.

I think James' arguments are plausible. The fact that Cannondale's
tests were so obviously hopeless does little to reassure me.


The proposition that the QR can be ejected as a result of braking in
my view is hogwash.


You might want to run that by Russ Pinder.


That view is supported by practical experience in
that when one uses the front brake on a bike then the front gets
compresssed not extended as the ejection theory would have it.


The explanation of why there is a resultant force tending to eject the
wheel is very clear, and mechanically unassailable. Whether that
force, or its repeated application, can result in the QR loosening or
slipping, is unproven. I think James' argument is plausible, but I
don't think he has the resources necessary to run the necessary
experiments. Cannondale - who do have the resources - seem to have
worked surprisingly hard to ensure that they never got close to
real-world forces, which some may see as telling and others may count
as merely incompetent.

Guy

well, let's put this into perspective.

http://groups.google.com/groups?selm...&output=gplain

bleating about risk of ejection is like bleating about brake cable being
at risk of pull-through at the clamping point - exactly the same
principle applies. if the force generate by braking is 1/3 that of the
force necessary to cause slippage [ignoring of course lawyer lips], then
i can't see what the fuss is about. 1/3 of yield is a well accepted margin.

personally, i'd be more worried about hydraulic hose failure or brake
levers fatiguing than axle slippage.

On 26/9/04 11:53 pm, in article , "jim
beam" wrote:

personally, i'd be more worried about hydraulic hose failure or brake
levers fatiguing than axle slippage.

In terms of frequency or severity?

The immediate consequences of brake failure are that you stay upright and
have at least a chance to remedy the situation.

With a wheel disappearing you have no options left open.

...d

Just zis Guy, you know? wrote:

So you don't think a change form a system where there was no force
tending to eject the wheel, to one where there is such a force, and
which has apparently resulted in at least two serious crashes we know
of, leaving at least one man paraplegic, is "any more dangerous than
any other part of the bike?"


I think the important word is "apparently" as there has yet been no
direct evidence to show that those crashes were caused by disc brake
mediated wheel ejection other than they crashed and the wheel was out
after the event. I have followed a friend who crashed on a road bike
with rim brakes under far less severe circumstances and afterwards the
wheel was lying at the side of the road so the wheel being out is not a
defintive indicator.

It would be better if the ejection force were not along the drop out
exit but my concern is that there has been AFAIK, no proper analysis of
the above accidents. History is full of examples of fixing the wrong
problem through jumping to conclusions rather than undertaking a
critical examination of the evidence. A proper analysis of the forks and
wheels would tell you whether the wheel had left the forks in the manner
proposed or in another way but so far no-one seems to have done those
simple investigations. I may be wrong and perhaps the mystery Mr Ex
Disc User has already done that

Tony

Tony Raven wrote:

So you don't think a change form a system where there was no force
tending to eject the wheel, to one where there is such a force, and
which has apparently resulted in at least two serious crashes we know
of, leaving at least one man paraplegic, is "any more dangerous than
any other part of the bike?"

I think the important word is "apparently" as there has yet been no
direct evidence to show that those crashes were caused by disc brake
mediated wheel ejection other than they crashed and the wheel was out
after the event.

I quite agree. But the mechanics are such that at the very least it merits
an experiment to find out just how much force would be required to cause the
problem, rather than one which looks designed to prove that some arbitrary
(probably unrepresentatively small) force is not sufficient.

It would be better if the ejection force were not along the drop out
exit but my concern is that there has been AFAIK, no proper analysis
of the above accidents.

Mine too. And Cannondale have not helmed to bridge the gap. Probably
because of the liability issue. I wonder if anyone is going to do a proper
job?

I'm not on anyone's side here. These threads seem to be shedding more heat
than light on the issue. The only thing of which I am reasonably sure is
that we don't know enough - and actually that is enough for me to be
reasonably confident that proper investigation is merited :-)

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington
University