Missy Giove's QR pops open



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Here's my latest (trade-only) news website article on the subject:

Monday 2nd June 2003

ASTM to test Annan's QR/disc brake wheel pop-out theory

The American Society for Testing and Material is the US equivalent to the International Standards
Organization (ISO). The chair of the bicycle fork subcommittee is aware of Annan's claims and will
be creating lab tests to measure QR retention on disc-brake equipped bikes after high-braking loads.
This was revealed to BikeBiz.co.uk by Matt Wiebe, editor of US trade mag Bicycle Retailer.

Wiebe has been in touch with Scott Boyer, ex of Answer/Manitou, who chairs the ASTM fork
subcommittee. Boyer told Wiebe he's aware of Annan's claims and said the ASTM will be developing a
simulation exercise in due course.

But Wiebe, who has canvassed the US bike trade, can find no evidence there's a pop-out problem
out there.

"No Fork manufacturer - Answer, RockShox, Cannondale, Marzocchi or Fox
- had any customers that experienced what Annan claims. Nevertheless all fork makers were currently
evaluating the issue, as part of their ASTM duties and for their own enlightenment."

But, in the same canvassing, Wiebe found bike builders were familiar with a disc brake related
problem with rear wheels.

"Many framebuilders switched to rear-loading horizontal dropouts so they can load the wheel and
clear pivots. Originally they had problems with sharp rear disc application keeping rear wheels in
frames," Wiebe told BikeBiz.co.uk.

"One product manager said at first they were launching rear wheels out of the frames. So they
switched from QR and to bolt-on axles and little pillow blocks to keep the wheels in the frame."

Bike builders reported no similar problems with forks.

"The current situation does not worry fork and bike builders because they have no field reports on
the issue," said Wiebe.

"What they wonder is as disc brakes trickle down to inexpensive bikes and those users are less bike
savvy will this be a problem?"

A UK supplier of mid to top-end bicycles also told BikeBiz.co.uk he wasn't overly worried by Annan's
theory or the "over-blown" coverage to date on BikeBiz.co.uk:

"I feel it's making a mountain out of a mole hill. In any part of the bike, under extreme
circumstances, a failure could occur. We have not experienced one example of this QR issue on
disc bikes."

But, interestingly, he adds:

"There is an issue with titanium QR's stretching so wheels can become loose. Any person who fails to
realise with the design of front forks these days that their QR has become loose and or the skewer
has moved round from the position it was when tightened isn't paying attention."
 
<[email protected]> wrote in message news:[email protected]...
>
> Well, you don't know how it would ride from that if you haven't tried
> it. I ruined a wheel once while riding to work because I failed to close the QR and after a mile
> of city start-stop riding I jumped a curb where the wheel dropped out and the fork came down
> with a dropout ripping out a spoke when it came down. There was no indication that the wheel
> was not secure on sitting and standing acceleration much less while cruising along.

I was around 50 miles into a 100 mile ride a few years ago when I felt a looseness from the front. I
was climbing a mountain road at approx. 20% grade, nearly doing "wheelies" and noticed a "clunk" as
the wheel unweighted. I stopped and discovered the QR was open. As far as I know, I had gone the
entire distance that way, with lots of out of the saddle climbing and fast (40+ mph) descents. There
was no other indication I had a loose wheel. The dropouts had no retention mechanism.
 
In article <[email protected]>, SuperSlinky <[email protected]> wrote:

> David Damerell said...
>
> > Tim's right on the money. James Annan has a real point; people who froth, like you, don't
> > advance the discussion any. If you don't have any technical points to make, blither away in
> > alt.m-b if you like but stay out of r.b.tech.
>
> On the contrary, I made several on-topic points. Where are yours? All I see is a lame 'me
> too' follow up to Mr. McNamara's churlish post. Yes, I flamed Mr. Annan, but I didn't quite
> froth. Perhaps you confused me with your friend Mr. McNamara whose profanity went far beyond
> anything I said.

All a matter of perspective, perhaps. You frothed invective and ad hominem all over the place, and
added nothing of substance to the conversation. All you did was misattribute ulterior motives to
those who recognize that current disk brake forks are a bad design.
 
James Annan <[email protected]> wrote:

>Doug Taylor wrote:
> > And not
>> ride downhill terrain at downhill speeds on x-c equipment.
>
>Operator error!
>
>"They abused the equipment by riding down hill, your honour. This 'mountain bike' is designed for
>level ground."

Give me a break. Are you seriously suggesting that a failure resulting from using a machine for a
purpose for which it is NOT intended doesn't shift fault to the operator? And this has more to do
with shocks, frames and other bike parts than your QR theory. You don't break your $4000 24 lb. x-c
dualie with 3 inches of travel doing 5 foot drops then blame the manufacturer. Or maybe you do on
your side of the pond. And I thought it was the Yanks who were the litigious ones.

Also, do you have a clue what "downhill terrain at downhill speeds" means? It means that "normal"
people like you and me not only don't but can't do it on any equipment, let alone the motorcycles
without engines that the pro downhillers ride. Check out a World Cup downhill
- say Mt. Snow - sometime and let me know what you think.

--dt
 
Tim McNamara <[email protected]> wrote:

>> On the contrary, I made several on-topic points. Where are yours? All I see is a lame 'me too'
>> follow up to Mr. McNamara's churlish post. Yes, I flamed Mr. Annan, but I didn't quite froth.
>> Perhaps you confused me with your friend Mr. McNamara whose profanity went far beyond anything
>> I said.
>
>All a matter of perspective, perhaps. You frothed invective and ad hominem all over the place, and
>added nothing of substance to the conversation. All you did was misattribute ulterior motives to
>those who recognize that current disk brake forks are a bad design.

While all you do is uncritically jump on Annan's and Jobst's bandwagon and call anyone who doesn't
immediately and unequivocally agree with

think they call that "hoisted on his own petard."

--dt
 
In article <[email protected]>,
"Chris Snell" <[email protected]> wrote:

> I suddenly understand some of James Annan's frustration. "It's never happened to me, it must never
> happen."

Followed up with "you're just an ivory tower academic who doesn't know what happens in the real
world." :-D
 
In article <[email protected]>,
"Chris Snell" <[email protected]> wrote:

> I'm surprised I'm being branded some kind of radical for suggesting there's an advantage to where
> the caliper wound up on motorcycles and bicycles, after years of evolution. As long as wheel
> ejects are eliminated, why not leave the caliper where it is? All I was suggesting to Jobst is
> that there are probably other solutions, which maybe don't have the disadvantage of putting the
> caliper in harms way.

Well, of course the goal is to eliminate wheel ejection. That's a good point. However, bicycles are
not motorcycles and the solution must be light weight and convenient to use if it is going to sell
and be accepted in the marketplace. Unless of course one merely wants to ride an engineless
motocross bike downhill.

If you look at many motorcycle manufacturer Web sites, you can see that many of them position the
caliper not at 3:00 or 4:00 (where bicycle shock forks put it, which results in the problem
identified by James Annan) but nearly at the fork, as close to the top of the wheel as possible.
Even doing that with bicycle forks would help, and most brake and fork combinations look like this
would be possible.

From the mechanical perspective, putting the caliper in front of the fork leg is the correct
solution. Whether that creates a significant risk to damaging the caliper in a collision, I don't
know. In my years of trail riding mostly not on mountain bikes which I don't care for, I really
haven't hit much stuff- if anything- with the front of the left fork leg.

Since my body sticks out much farther from the centerline of the bike, and since I *try* to keep by
body from slamming into immoveable objects when I ride, the fork is pretty safe. IMHO some basically
competent riding skills will prevent damage to the caliper.
 
Tim McNamara <[email protected]> wrote in news:timmcn-
[email protected]:

> In article <[email protected]>, Mark Hickey <[email protected]> wrote:
>
>> I had a skewer break once, but fortunately just as I finished tightened it.
>
> This is something I've never seen. Where did it break (I'd guess at the start of the threads is
> the most likely location)? Had it been damaged in some way before this happened?

I've had the quick-release lever break on a Rolf Vector wheel before. Fortunatly it was the front
wheel and I could ride (very slowly and carefully) home.

Charlie in Houston
 
James Annan <[email protected]> wrote in message news:<[email protected]>...
> Spider wrote:
>
> > The real objections have never been adequately addressed. It's a circular discussion, because
> > the same evidence is being offered up to explain away the objections - no new info has been
> > forthcoming.
>
> I have seen no 'real objections', merely "I haven't seen it", as you repeat below.

I don't repeat "I haven't seen it." I do not believe that you have to strengthen your argument by
making up quotes.

The real objections are the *lack of controlled data to prove your hypothesis.* If that is not a
real objection, then what is it?

> > The unscrewing mechanism. In other applications of repeated assymetric forces on a screw-type
> > fastener, loosening has been observed. OK, so far. Now, it seems as though the test rig for the
> > experiment to verify your hypothesis should be simple at this point. Not cheap, but simple. If
> > it is indeed as much of a certainty as you seem to think it is, then it should be easily
> > verified.
>
> Indeed, and if you feel you need to see it for yourself, I suggest you go ahead and set up the
> experiment.

Unfortunately, that is the responsibility of the one attempting to prove the hypothesis. I think it
might be time for you to open up one of your basic science books and review the "scientific method."
Testing hypotheses is an integral, necessary part.

> You don't seriously expect the manufacturers to publish an objective unbiased study demonstrating
> the failure of their products?

No. But I never claimed they would. Building strawmen does not make your point clearer.

> What else do you intend to do, just sit on the sidelines and snipe and moan?

Ah, now you view it as a personal attack. Facts are facts, James. You have nothing but anecdotal
evidence and simple physics to support your hypothesis. It's not proven, and has yet to be proven.
And now you attack me for daring to question.

> It's your reponsibility to get this problem fixed, just as much as it is mine.

No, it isn't. If there is a problem (which has some probability, I will admit,) then I will buy
equipment that fixes the problem. But the unscrewing mechanism has yet to be proven experimentally.
So I will only acknowledge the probability, based on your analysis. When it is proven, through
experiment, that it happens to MTBs with disk brakes, then I will take further steps.

> > This set of experiments would remove any question of misapplication (using a cross-country
> > set-up on a fast downhill, for instance)
>
> This is getting laughable. Now it's 'operator error' for riding down a hill!

1.) You misunderstand because you don't understand the difference, or

2.) You misunderstand on purpose in order to be witty.

Downhill MTBing is a completely different beast than just "riding down a hill." There is special
equipment for that - the bikes can weight up to 25kg. Yes, kilograms. They have great, big
double-crown forks, long travel, really fat tires, and are built for the stresses of downhilling.

Cross-country bikes are not built for that purpose - it would be like riding a Lemond through a rock
garden. If you ride an 11kg bike on a downhill course, then that bike will probably break. Just the
same as if you used a road bike to ride off-road.

Sort of like trying to drive a Ka in Land Rover fashion. :)

> > I do not even know if wheel ejection happens more often with rim or disk brakes! (As a
> > percentage of total in use.) What is the frequency, and what is the real risk, here?
>
> It's obvious that the frequency is massively greater with disk brakes.

Data? Where's your statistics? Sample size? Standard error? Please
- you can't just B.S. your way through this.

> Another UK rider reported having their skewer unscrew at the weekend, one went to hospital the
> weekend before. These failures are occurring for experienced cyclists. As for rim brake failures,
> despite the hugely larger number of miles ridden, people have to dredge up chilhodd memories when
> they were playing around, forgot to install the wheel at all and dropped it out as they set off
> riding. As the story spreads slowly, every few days I get more email describing at least skewer
> unscrewing, sometimes a complete wheel ejection. This has all happened in the last few years, disk
> brakes have not been widespread for very long.

E-mail testimonials are not data - the sample is not statistically valid and we both know it. Please
do not pretend otherwise.

> > You will note that I do not dismiss, nor do I minimize any part of your idea. I am calling for
> > MORE DATA. Data with controls. Data compiled by those who have the understanding of the
> > significance of the experiments, and can control them down to the smallest, least significant
> > detail. Operating temperature? Etc. etc.
>
> Go and get it then. Good luck. As you say, it should be easy enough, it will just cost money to
> pick up a range of equipment to test.

Again, we both know it is the responsibility of the person positing the hypothesis to prove that
hypothesis. Since it is logically impossible to prove a negative, I will say that your attempt to
shift the burden of proof to me is laughable.

All I'm asking for is for the step between "it can happen" and "it does happen."

"It can happen" has been shown. "It does happen" has not.

Spider
 
Tim McNamara writes:

>> I suddenly understand some of James Annan's frustration. "It's never happened to me, it must
>> never happen."

> Followed up with "you're just an ivory tower academic who doesn't know what happens in the real
> world." :-D

That's an old saw that we've seen here often. Throwing rocks at presumed ivory towers is an old
favorite among the unwashed.

Jobst Brandt [email protected] Palo Alto CA
 
In news:[email protected], [email protected]
<[email protected]> typed:
>
> That's an old saw that we've seen here often. Throwing rocks at presumed ivory towers is an old
> favorite among the unwashed.
>

As is pouring cold water on the unwashed by the ivory towerers ;-)

Tony

--
http://www.raven-family.com

"All truth goes through three steps: First, it is ridiculed. Second, it is violently opposed.
Finally, it is accepted as self-evident." Arthur Schopenhauer
 
[email protected] wrote:

>Mark Hickey writes:
>
>> My whole point is that no matter which of the three scenarios applies, a significant amount of
>> time that the wheel will be loose enough to cause lots o' brake rub, but too snug to exit the
>> bike. I'll agree with the hierarchy of the above three scenarios (in order of "noticeability"). I
>> know I notice brake rub (though I don't run discs on my personal bikes) immediately - I can
>> imagine that it would be possible to miss the noise on a very bumpy, or gravel covered descent.
>> That's not to say there wouldn't be VERY apparent issues with the way the bike is responding -
>> but I CAN visualize someone not noticing.
>
>I don't think you've tried this. Just loosen your QR and ride slowly (on a lawn if you like)
>pedaling both while sitting and standing, and notice that you must do some odd gyrations for the
>wheel to rub on the brakes. During normal use, the wheel does not tilt out of the dropouts. You
>have to lunge and lift on the bars while sprinting for that to occur.

That sounds exactly like every MTB ride I do here in Arizona. Contrary to the experience of those
who have ridden miles on an open QR, an even slightly loose wheel will be rubbing the brake pads
aggressively many, many times - and a QR-less wheel would fall out before I got 100 meters into my
favorite ride. And no, I hope NOT to prove that.

>> I had a skewer break once, but fortunately just as I finished tightened it.
>
>Well, you don't know how it would ride from that if you haven't tried
>it. I ruined a wheel once while riding to work because I failed to close the QR and after a mile
> of city start-stop riding I jumped a curb where the wheel dropped out and the fork came down
> with a dropout ripping out a spoke when it came down. There was no indication that the wheel
> was not secure on sitting and standing acceleration much less while cruising along.

I once helped call an ambulance for a rider who lost a front wheel going down the approach road to
the trails on South Mountain. It's far from a "tough trail", but certainly produces enough fork
compression to shed a loose front wheel. But I agree that it's probably quite possible to ride many
miles on the road without a QR (again, I don't plan to test this premise).

>> It would sure be nice to be able to test various levels of QR tightness without risking dental
>> work! ;-) Barring that, I suspect that a random inspection of lots of bikes at a race (or popular
>> weekend riding spot) would garner a lot of useful (though anecdotal) information. For example,
>> checking for:
>
>> 1) Loose or improperly closed QR skewers
>> 2) Visual clues that the QR has moved in the fork dropout at some point in time
>> 3) Damage to lawyer lips (including intentional removal)
>
>> ... would net some interesting data.
>
>Well? Go collect some instead of hypothesizing with nothing but a vivid imagination to build your
>scenarios.

Actually, I'm not hypothesizing, but extrapolating - based on years of riding off-road. I know that
even with a properly adjusted QR, the minimal clearance on my front V-brake allows brake rub under
some of the steeper out-of-the-saddle efforts, and this is clearly audible. It would also be clear
if the brake rub got worse, or happened at other "less stressful" times.

One thing that did surprise me was the number of QR skewers clearly positioned improperly in the
photos from the Big Bear cross country race. I suspect it would only be worse in the "weekend
warrior" crowd. Still, I wonder how most of these riders would react to a request to check their QR
and dropouts...

Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $695 ti frame
 
Tim McNamara <[email protected]> wrote:

>In article <[email protected]>, Mark Hickey <[email protected]> wrote:
>
>> I had a skewer break once, but fortunately just as I finished tightened it.
>
>This is something I've never seen. Where did it break (I'd guess at the start of the threads is the
>most likely location)? Had it been damaged in some way before this happened?

As far as I know, there was no damage to the skewer before it broke. And this wasn't some chi chi
titanium skewer either - it was a newish Campy steel skewer (no older than '95).

I had just changed a flat, and was remounting the front wheel. I snugged it down nice and tight.
Then for no apparent reason, I gave the skewer one more little bump with my palm. POW!

The skewer's rod broke at the base of the threads, ejecting the fixed nut from the wheel.

I can only hope that if HAD broken later in that ride that it a) would have made enough noise to get
my attention and b) NOT been on the descent 3 miles down the road that I often exceed 40mph on.

Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $695 ti frame
 
On Tue, 3 Jun 2003 09:39:36 +0100, "Tony Raven" <[email protected]> wrote:
>In news:[email protected], Tim McNamara <[email protected]> typed:
>>
>> Given that two major manufacturers- including one of the world's leading bike companies- have
>> acknowledged that they are looking into this issue explicitly as a result of Annan's work
>> suggests that there is a significant issue which he has revealed.

>Nothing of the sort - they are just reacting as any company has to react to cover themselves
>legally should there turn out to be any substance. Remember how much McDonald's got fined for not
>telling people that hot coffee was hot?

Please use a different example when you want to talk about these things. The McDonalds case was a
completely legitimate one.

Look it up, there's plenty of material out there that is *not* written by tendentious journalists
with an axe to grind. I will not be commenting any further upon this here.

Jasper
 
On 3 Jun 2003 03:24:44 -0700, [email protected] (Carlton Reid, BikeBiz.co.uk) wrote:

>The American Society for Testing and Material is the US equivalent to the International Standards
>Organization (ISO).

Not unless the ASTM is incredibly badly named. ISO does not test anything or have anything to do
with Materials, it only sets voluntary standards.

Jasper
 
Tony Raven wrote:

> Why is that the correct solution? Why not have a forward facing dropout with the caliper at the
> back of the leg?

Because that still leaves the loosening aspect of the problem much the same as before. The axle
doesn't need a long slot to slide up and down in order to loosen, there is enough slack across the
dropout slot (as shown by the numerous reports of rear wheel loosening). Of course changing the slot
angle will reduce the likelihood of the wheel being forcibly ejected, but it will still require
unreasonable skewer tension to hold in place.

James
 
"Tim McNamara" <[email protected]> wrote in message
news:[email protected]...
> In article <[email protected]>,
> "Chris Snell" <[email protected]> wrote:
>
> > I'm surprised I'm being branded some kind of radical for
suggesting
> > there's an advantage to where the caliper wound up on motorcycles and bicycles, after years of
> > evolution. As long as wheel ejects
are
> > eliminated, why not leave the caliper where it is? All I was suggesting to Jobst is that there
> > are probably other solutions, which maybe don't have the disadvantage of putting the caliper in
> > harms way.
>
> Well, of course the goal is to eliminate wheel ejection. That's a good point. However,
> bicycles are not motorcycles and the solution must be light weight and convenient to use if it
> is going to sell
and
> be accepted in the marketplace. Unless of course one merely wants
to
> ride an engineless motocross bike downhill.
>
> If you look at many motorcycle manufacturer Web sites, you can see that many of them position the
> caliper not at 3:00 or 4:00 (where bicycle shock forks put it, which results in the problem
> identified
by
> James Annan) but nearly at the fork, as close to the top of the
wheel
> as possible. Even doing that with bicycle forks would help, and
most
> brake and fork combinations look like this would be possible.
>
> From the mechanical perspective, putting the caliper in front of the fork leg is the correct
> solution. Whether that creates a
significant
> risk to damaging the caliper in a collision, I don't know. In my years of trail riding mostly not
> on mountain bikes which I don't
care
> for, I really haven't hit much stuff- if anything- with the front of the left fork leg.
>
> Since my body sticks out much farther from the centerline of the
bike,
> and since I *try* to keep by body from slamming into immoveable objects when I ride, the fork is
> pretty safe. IMHO some basically competent riding skills will prevent damage to the caliper.

I was thinking along the lines of a locating pin on the lever side of the QR, cast into the face
that contacts the dropout, 180 degrees from the lever when it is in the closed position. This pin
would sit in the dropout gap, and prevent more than a few degrees of rotation, even if the QR is
sliding. Regular lawyers lips would prevent eject, this pin is just to stop the QR from spinning
loose. I think the knurling on the nut side is sufficient to prevent the nut from loosening. You
would set the lever side in the correct position to engage the pin, screw down the nut side to set
tension, then close the lever, very much like a current quick release, except there's no guesswork
about where to point the lever.

With this system it would also be harder for new users to point the lever in the wrong direction,
such as forward or down. Rear view: _
| |
| | <- QR lever shown in closed position
| |
| |
| |
| | <Left cap Right nut
| |======================O=== <- QR skewer
| |) <- tab/pin/post
---

Or possibly shape the QR lever such that it hooks behind the fork leg, again just to prevent it from
spinning loose. When released this would give a nice crank shape to the lever for quickly
unscrewing. L nut R nut
||O==========O=
||
=== <---- this is the new bit added to the lever.
looking down at the QR, QR shown in closed position.

Sorry the ascii drawings look such ****.

Such QR's should work with existing equipment. No need to replace fork or brake.

I agree, calipers should be as tight to the fork as possible.

I use armor on my lower appendages: shins, knees when I'm really serious, and 3/4-cut skate shoes. I
suspect my bike wishes I didn't.

- Chris.
 
"Chris Snell" <[email protected]> wrote in message
news:[email protected]...
>blah blah blah

But having said all that, if the current QR system were completely redesigned, I'd have no trouble
with that. All this fiddle fiddle too tight fiddle loose fiddle finally right stuff is a pain. The
advent of lawyers lips really worsened QR convenience. I'm sure better minds than mine will come up
with elegant solutions.

- Chris.
 
In article <[email protected]>, Chris Snell
<[email protected]> wrote:
>"Chris Snell" <[email protected]> wrote in message
>news:[email protected]...
>>blah blah blah
>
>But having said all that, if the current QR system were completely redesigned, I'd have no trouble
>with that. All this fiddle fiddle too tight fiddle loose fiddle finally right stuff is a pain. The
>advent of lawyers lips really worsened QR convenience. I'm sure better minds than mine will come up
>with elegant solutions.

They already have-- QRs with more throw. I got a set of inexpensive TI skewers from Performance and
was delighted to find that they go over the lawyer lips on a Ouzo Pro without fiddling with the nut.

I don't know if they're built this way on purpose or it is a happy accident. I expect it's
on purpose.

All it takes is a different cam shape. If its done right it won't be any harder to tighten
appropriately.

Eric
 
In article <[email protected]>, Doug Taylor
<[email protected]> wrote:

> Tim McNamara <[email protected]> wrote:
>
> >> On the contrary, I made several on-topic points. Where are yours? All I see is a lame 'me too'
> >> follow up to Mr. McNamara's churlish post. Yes, I flamed Mr. Annan, but I didn't quite froth.
> >> Perhaps you confused me with your friend Mr. McNamara whose profanity went far beyond anything
> >> I said.
> >
> >All a matter of perspective, perhaps. You frothed invective and ad hominem all over the place,
> >and added nothing of substance to the conversation. All you did was misattribute ulterior motives
> >to those who recognize that current disk brake forks are a bad design.
>
> While all you do is uncritically jump on Annan's and Jobst's bandwagon and call anyone who doesn't
> immediately and unequivocally

> idiot." I think they call that "hoisted on his own petard."

long diatribe full of invective and ad hominem which added nothing to the discussion. I don't
know what that guy's beef with Ralph Nader is, but he obviously thinks the comparison is
insulting and painful.

You seem to have missed out on a few things in the history of this discussion, however. For one
thing, I was the first person to challenge Annan's first post announcing his Web site by dismissing
it as "operator error." The reason for that is that "everyone knows" that QRs don't come loose. I'm
even quoted- by name- on Annan's Web site as an example of the typical knee-jerk reaction to his
model. This was several months ago.

After a lot of discussion, further explanation, some home experiments with brakes, etc., it finally
dawned on me that Annan's main point- that current fork design places the disk brake caliper in a
location that results in a strong force pushing the axle out of the dropout- was correct. In fact,
it's self-evident and incontrovertible to anyone with even a high school grasp of physics or a
modicum of common sense. The design has to produce such forces unless Newton's laws can be repealed.
And the application of such forces to the front wheel of a bicycle is a Bad Thing, thanks to the
consequences of losing the front wheel while riding. This in fact *is* the key issue- the rest of
the protracted argument about skewers and lawyer lips is mostly red herring.

So, then, the next issue is whether the force is enough to shove the axle out of the dropout despite
the clamping force of the QR. Annan was able to show that the ejection force exceeds the clamping
force with simple enough calculations that even an algebraic illiterate like myself could understand
it. Annan was also able to show a simple linkage between the forces caused by the disk brake, which
are asymmetric with regard to the left and right dropouts, and well-known issues with nuts and bolts
unscrewing from vibration and cyclic loading. This reduces the tension in the skewer and thus the
clamping force, allowing the brake to have an easier time of shoving the axle out of the dropout.

Now, no-one fussed very much about this model until it was cross-posted to a.m-b which introduced it
to a whole new audience- an audience with its own lore, its own knee-jerk reactions, etc. The
r.b.t crowd raised technical objections whereas this round of threads has instead veered to personal
attacks on Annan, Brandt and myself. Somehow Annan has managed to challenge the manhood of an
entire newsgroup by simply pointing out that fork and brake manufacturers overlooked a rather
important piece of their homework. I suppose it's the idea that you can lose the front wheel off
your bike- mostly likely at an inconvenient moment such as maximal braking on a steep descent-
through no fault of your own, which of course in turn means that there may be nothing you can do
to prevent it, that raises such dudgeon. Perhaps people feel like they are being told they were
stupid for falling for the disk brake hype, which in fact is not at all the point. The point is
that there is a significant flaw in the design which seems to have resulted in serious risks of
personal injury.

Fortunately cooler heads are prevailing, with Trek and Orbit among others looking into this. These
entities, however, are between a rock and a hard place. If they admit the problem, that paves the
way for litigation. If they deny the problem, that paves the way for different litigation. Hopefully
they will be ethical and courageous enough to do good investigation and to honestly report the
findings, whatever they may be.
 
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