Re: x-post: Bike Biz: Wheel ejection theory goes legal



Patrick Lamb wrote on 09/02/2007 03:58 +0100:
>
> I was going to note that an appeal to expert judges might be
> considered preferable, until I remembered the political hacks that
> inhabit our (US) Supreme Court.
>


I remember struggling for how to politely answer a question from a US
judge on "how many milligrams thick" something was.

--
Tony

"...has many omissions and contains much that is apocryphal, or at least
wildly inaccurate..."
Douglas Adams; The Hitchhiker's Guide to the Galaxy
 
On Thu, 08 Feb 2007 21:58:45 -0600, Patrick Lamb <[email protected]>
wrote:

>On Thu, 08 Feb 2007 07:57:55 +0000, Tony Raven <[email protected]>
>wrote:
>>Werehatrack wrote on 08/02/2007 04:22 +0100:
>>> Your courts are at variance from those in the US in many instances, I
>>> believe. Here, it is not uncommon for the result of a civil suit to
>>> be dramatically at variance with the law and/or the facts, due
>>> entirely to the effects of the "who has the better lawyer" rule.
>>>

>>
>>That's because we use an expert judge and you use a lay jury to hear the
>>case. We reserve the lay jury for the appeal to the House of Lords ;-)

>
>I was going to note that an appeal to expert judges might be
>considered preferable, until I remembered the political hacks that
>inhabit our (US) Supreme Court.


We routinely deplore the ethics of our lawyers and the conduct of our
politicians, yet are surprised at the behavior of judges, the one creature that
most completely combines the two.

Ron
 
In news:[email protected],
A Muzi <[email protected]> tweaked the Babbage-Engine to tell us:

> If it's any consolation, large numbers of Americans of all political
> stripes think the Supremes are biased against their interests
> -including many of the presidents who appointed the waffling creeps.


Must...resist...Temptation...to..insert...Motown...joke...


--
Dave Larrington
<http://www.legslarry.beerdrinkers.co.uk>
Wood is an excellent material for making trees, but is otherwise
not to be trusted.
 
In article <[email protected]>,
Patrick Lamb <[email protected]> wrote:

> On Thu, 08 Feb 2007 07:57:55 +0000, Tony Raven
> <[email protected]> wrote:
> >Werehatrack wrote on 08/02/2007 04:22 +0100:
> >> Your courts are at variance from those in the US in many
> >> instances, I believe. Here, it is not uncommon for the result of
> >> a civil suit to be dramatically at variance with the law and/or
> >> the facts, due entirely to the effects of the "who has the better
> >> lawyer" rule.
> >>

> >
> >That's because we use an expert judge and you use a lay jury to hear
> >the case. We reserve the lay jury for the appeal to the House of
> >Lords ;-)

>
> I was going to note that an appeal to expert judges might be
> considered preferable, until I remembered the political hacks that
> inhabit our (US) Supreme Court


Who are disliked by both the liberals and the conservatives. Hmmm.
Maybe the Supreme Court is actually doing its job.
 
In article <[email protected]>,
RonSonic <[email protected]> wrote:

> On Thu, 08 Feb 2007 21:58:45 -0600, Patrick Lamb
> <[email protected]> wrote:
>
> >On Thu, 08 Feb 2007 07:57:55 +0000, Tony Raven
> ><[email protected]> wrote:
> >>Werehatrack wrote on 08/02/2007 04:22 +0100:
> >>> Your courts are at variance from those in the US in many
> >>> instances, I believe. Here, it is not uncommon for the result of
> >>> a civil suit to be dramatically at variance with the law and/or
> >>> the facts, due entirely to the effects of the "who has the better
> >>> lawyer" rule.
> >>>
> >>
> >>That's because we use an expert judge and you use a lay jury to
> >>hear the case. We reserve the lay jury for the appeal to the House
> >>of Lords ;-)

> >
> >I was going to note that an appeal to expert judges might be
> >considered preferable, until I remembered the political hacks that
> >inhabit our (US) Supreme Court.

>
> We routinely deplore the ethics of our lawyers and the conduct of our
> politicians, yet are surprised at the behavior of judges, the one
> creature that most completely combines the two.


A judge is wise and just when he agrees with you, and an activist when
he doesn't. I think that the prejudices and behavior of the public are
as much a part of the picture as those of politicians and judges.
 
On Feb 8, 4:55 pm, Gary Young <[email protected]> wrote:
>
> You only have to look at the rbt threads on this subject to see the filter
> in use -- just look at how many people dismiss the reports as being the
> product of misuse of skewers without knowing anything about the facts of
> individual cases.
>


The same could be said for the other side of the argument as well.

The two are are on equal footing from a data/proof standpoint.

E.P.
 
Ed Pirrero wrote:
> On Feb 8, 4:55 pm, Gary Young <[email protected]> wrote:
>> You only have to look at the rbt threads on this subject to see the filter
>> in use -- just look at how many people dismiss the reports as being the
>> product of misuse of skewers without knowing anything about the facts of
>> individual cases.
>>

>
> The same could be said for the other side of the argument as well.
>
> The two are are on equal footing from a data/proof standpoint.
>
> E.P.
>

except that single digit data supporting the catastrophe hypothesis as
opposed to millions of units in service over many years without problem
is about as conclusive as you could ever get.
 
On Feb 8, 7:34 pm, jim beam <[email protected]> wrote:
>
>
> it really is most unlikely that the thumbscrew is unthreading from the
> skewer - not on any modern skewer. they all have nylock inserts and the
> thumb screw faces are serrated.


The nylon inserts are negligible. They are not nearly the same as
commercial "nylock" inserts in real locknuts.

The latter have a full-circle ring of nylon that undergoes severe
compression and thus exerts a large frictional resistance torque.
Quick release nuts have a nylon insert that's sliced and cantilevered
so it exerts very little resistance torque. It can easily be twisted
with two fingers. QR nuts' nylon is intended only to retain
adjustment when the QR is completely loose, no more.

In a previous discussion on this, I gave torque readings for a real
nylok nut and a QR nut. Again, the QR nut's resistance was negligible
by comparison. I'm sure Carl can look up that post.

- Frank Krygowski
 
[email protected] wrote:
> On Feb 8, 7:34 pm, jim beam <[email protected]> wrote:
>>
>> it really is most unlikely that the thumbscrew is unthreading from the
>> skewer - not on any modern skewer. they all have nylock inserts and the
>> thumb screw faces are serrated.

>
> The nylon inserts are negligible. They are not nearly the same as
> commercial "nylock" inserts in real locknuts.
>
> The latter have a full-circle ring of nylon that undergoes severe
> compression and thus exerts a large frictional resistance torque.
> Quick release nuts have a nylon insert that's sliced and cantilevered
> so it exerts very little resistance torque. It can easily be twisted
> with two fingers. QR nuts' nylon is intended only to retain
> adjustment when the QR is completely loose, no more.
>
> In a previous discussion on this, I gave torque readings for a real
> nylok nut and a QR nut. Again, the QR nut's resistance was negligible
> by comparison. I'm sure Carl can look up that post.
>
> - Frank Krygowski
>
>

are you saying that the nylon retainer has no effect? and what about
serrations? and much more important, "negligible" as defined by whom?
and why hasn't /my/ hill-hammered, disk braked, vertical dropout q.r.
ever loosened? you want me to believe that /two/ retaining mechanisms
can be ignored don't you?

how you can clutch at straws like this when simple user error has not
been eliminated is quite amazing.
 
> Dear Tim,
>
> Calculation arguments aside, do you know if anyone has ever reproduced
> the claimed phenomenon?
>
> That is, are there any experiments that confirm or refute claims that
> a bicycle wheel with a reasonably tightened quick-release can be
> ejected by disk-brake brake forces before the tire skids?
>
> Cheers,
>
> Carl Fogel- Hide quoted text -
>
> - Show quoted text -


Well, the wheel didn't come completely out, but it did move...

>From http://groups.google.com/group/rec.bicycles.tech/msg/

b8c838ebb057a500?hl=en&

******* Quote:
>From reading previous threads, I'd think about the ejection factor.


>Seems tb almost-universally regarded as moot on a single given lawyer lips, but
>I'd want to look into the implications for a tandem given the extra braking
>effort...


Yes, thanks for mentioning that. I'm actually worried a bit about the
disc force tending to eject the wheel.

A friend had movement in his disc-braked front wheel. He has a hybrid
bike with rigid fork and Avid mechanical discs, not unlike this one:
http://www.giantbicycles.com/us/030.000.000/030.000.000.asp?model=10807


He had just installed mudguards and couldn't figure why the front one
rubbed the tyre. After he installed the mudguards (mudguard and tyre
centred) he gave it a test ride. After he came to a stop the disc
side
of the front axle had moved from the top of the slot to the lawyer
tabs, causing the tyre to rub the mudguard. We re-centred the wheel
and repeated the effect a few times. It was easily repeatable, and
easily observable.


His solution was to reverse the front skewer so the nut (with its
serrated steel ring) was on the disc side.


Even though he's fixed the problem (for now), I know what *might*
happen someday...

******* End quote.*******
 
On 9 Feb 2007 12:46:37 -0800, [email protected] wrote:

>On Feb 8, 7:34 pm, jim beam <[email protected]> wrote:
>>
>>
>> it really is most unlikely that the thumbscrew is unthreading from the
>> skewer - not on any modern skewer. they all have nylock inserts and the
>> thumb screw faces are serrated.

>
>The nylon inserts are negligible. They are not nearly the same as
>commercial "nylock" inserts in real locknuts.
>
>The latter have a full-circle ring of nylon that undergoes severe
>compression and thus exerts a large frictional resistance torque.
>Quick release nuts have a nylon insert that's sliced and cantilevered
>so it exerts very little resistance torque. It can easily be twisted
>with two fingers. QR nuts' nylon is intended only to retain
>adjustment when the QR is completely loose, no more.
>
>In a previous discussion on this, I gave torque readings for a real
>nylok nut and a QR nut. Again, the QR nut's resistance was negligible
>by comparison. I'm sure Carl can look up that post.
>
>- Frank Krygowski


Dear Frank,

Carl is sure that he can look it up, too, but Carl also wonders why
anyone would be too lazy to google the archives for his own posts.

But Carl is probably just grouchier than usual because of his
infirmities, his feeble character, and the unusually cold winter.

So Carl will go through the far-from-tricky steps involved in finding
buried treasure in hopes that if people are taught how to fish for
themselves, they will send Carl lobsters.

First, go to RBT on Google Groups:

http://groups.google.com/group/rec.bicycles.tech/topics?hl=en

Next, search for "frank" and "nylock":

http://groups.google.com/group/rec.bicycles.tech/search?hl=en&group=rec.bicycles.tech&q=frank+nylock

The first of the four hits is obviously what we want, so . . .

http://groups.google.com/group/uk.r...&q=frank+nylock&rnum=1&hl=en#cf3182de0e6449f9

Google just takes you to the 10-post section that includes your
target, so page down to post 138, click on "more options", click on
"individual message", and cut and paste the address:

http://groups.google.com/group/uk.rec.cycling/msg/cf3182de0e6449f9?hl=en&

Carl mistakenly thinks that everyone knows how to do this, so
sometimes it helps to go through the steps and addresses. The sun has
come out, the temperature has dropped to 26F, the drugs are taking
hold, and Carl is going to go fox-hunting on foot with his camera and
faithful hound.

Cheers,

Carl Fogel
 
On Feb 9, 4:05 pm, jim beam <[email protected]> wrote:
> [email protected] wrote:
> >

>
> > In a previous discussion on this, I gave torque readings for a real
> > nylok nut and a QR nut. Again, the QR nut's resistance was negligible
> > by comparison. I'm sure Carl can look up that post.

>
> are you saying that the nylon retainer has no effect?


Certainly, no practical effect. They are not intended nor designed
for that purpose.

> and what about serrations?


They may help for a time. But the limitations of similar features on
industrial nuts and bolts are fairly well known. I don't believe the
serrations on some QR nuts are curative enough to make up for the
defective design.

> and why hasn't /my/ hill-hammered, disk braked, vertical dropout q.r.
> ever loosened?


:) Let me guess: Because every component on your bike is forged and
fitted with fatigue-proof rolled threads?

Seriously, I can't guess. But so far, nobody seems to be saying every
bike ridden by every rider exhibits evidence of the problem. It seems
to happen only under certain circumstances. Perhaps your "hill
hammering" is below some required minimum. Perhaps your QR has
amazingly high strength, is stripped and maintained daily, and is
fastened ultra-diligently with your vise-like grip. Perhaps there are
other explanations.

> you want me to believe that /two/ retaining mechanisms
> can be ignored don't you?


And you want me to believe that many reports of QRs loosening, axles
shifting, and even wheel ejections, _despite_ operators checking
against their possible errors, can be ignored, don't you?

> how you can clutch at straws like this when simple user error has not
> been eliminated is quite amazing.


Knowing you, I'm sure that user error will never be eliminated to
_your_ satisfaction. That is, even if someone reports carefully
tightening the QR at hilltop, and marking the position of the nut, and
checking at hill bottom and seeing a position change, and doing more
than once.

Come to think of it, that's already happened, hasn't it?

- Frank Krygowski
 
[email protected] wrote:
> On Feb 9, 4:05 pm, jim beam <[email protected]> wrote:
>> [email protected] wrote:
>>> In a previous discussion on this, I gave torque readings for a real
>>> nylok nut and a QR nut. Again, the QR nut's resistance was negligible
>>> by comparison. I'm sure Carl can look up that post.

>> are you saying that the nylon retainer has no effect?

>
> Certainly, no practical effect. They are not intended nor designed
> for that purpose.


no practical effect quantified how? and if it's not there for a
purpose, what's it there for? across all brands and models.

>
>> and what about serrations?

>
> They may help for a time.


so that's "negligible"???

> But the limitations of similar features on
> industrial nuts and bolts are fairly well known.


yeah, they're not locking wire, but what are we trying to achieve here?
if they're sufficient for the job, and statistics indicate they are,
what else do we urgently need to achieve?

> I don't believe the
> serrations on some QR nuts are curative enough to make up for the
> defective design.


what's defective design? serrations or alleged wheel ejection?

>
>> and why hasn't /my/ hill-hammered, disk braked, vertical dropout q.r.
>> ever loosened?

>
> :) Let me guess: Because every component on your bike is forged and
> fitted with fatigue-proof rolled threads?


idiot.

>
> Seriously, I can't guess.


no kidding.

> But so far, nobody seems to be saying every
> bike ridden by every rider exhibits evidence of the problem. It seems
> to happen only under certain circumstances.


sure - not tightening the skewer properly.

> Perhaps your "hill
> hammering" is below some required minimum. Perhaps your QR has
> amazingly high strength, is stripped and maintained daily, and is
> fastened ultra-diligently with your vise-like grip. Perhaps there are
> other explanations.


don't want to do more unfounded guess work then professor?

>
>> you want me to believe that /two/ retaining mechanisms
>> can be ignored don't you?

>
> And you want me to believe that many reports of QRs loosening, axles
> shifting, and even wheel ejections, _despite_ operators checking
> against their possible errors, can be ignored, don't you?


statistically, what significance do single digit ejections have against
many million rider-hours of operation without problem? crank arms break
more frequently than wheels eject, but i hear no bleating from professor
krygowski about redesign.

>
>> how you can clutch at straws like this when simple user error has not
>> been eliminated is quite amazing.

>
> Knowing you, I'm sure that user error will never be eliminated to
> _your_ satisfaction.


screw /my/ satisfaction, what about the stats?

> That is, even if someone reports carefully
> tightening the QR at hilltop, and marking the position of the nut, and
> checking at hill bottom and seeing a position change, and doing more
> than once.
>
> Come to think of it, that's already happened, hasn't it?
>

so why doesn't it happen to my bike? it's a study in prolonged neglect.
i even have the q.r. on the disk side, supposedly the wrong way
around, and still no effect. you don't even ride disk.

but all this is ridiculous nonsense until operator error can be
eliminated from the stats.
 
On Fri, 09 Feb 2007 16:06:02 -0700, [email protected] wrote:

>On 9 Feb 2007 12:46:37 -0800, [email protected] wrote:
>
>>On Feb 8, 7:34 pm, jim beam <[email protected]> wrote:
>>>
>>>
>>> it really is most unlikely that the thumbscrew is unthreading from the
>>> skewer - not on any modern skewer. they all have nylock inserts and the
>>> thumb screw faces are serrated.

>>
>>The nylon inserts are negligible. They are not nearly the same as
>>commercial "nylock" inserts in real locknuts.
>>
>>The latter have a full-circle ring of nylon that undergoes severe
>>compression and thus exerts a large frictional resistance torque.
>>Quick release nuts have a nylon insert that's sliced and cantilevered
>>so it exerts very little resistance torque. It can easily be twisted
>>with two fingers. QR nuts' nylon is intended only to retain
>>adjustment when the QR is completely loose, no more.
>>
>>In a previous discussion on this, I gave torque readings for a real
>>nylok nut and a QR nut. Again, the QR nut's resistance was negligible
>>by comparison. I'm sure Carl can look up that post.
>>
>>- Frank Krygowski

>
>Dear Frank,
>
>Carl is sure that he can look it up, too, but Carl also wonders why
>anyone would be too lazy to google the archives for his own posts.
>
>But Carl is probably just grouchier than usual because of his
>infirmities, his feeble character, and the unusually cold winter.
>
>So Carl will go through the far-from-tricky steps involved in finding
>buried treasure in hopes that if people are taught how to fish for
>themselves, they will send Carl lobsters.
>
>First, go to RBT on Google Groups:
>
>http://groups.google.com/group/rec.bicycles.tech/topics?hl=en
>
>Next, search for "frank" and "nylock":
>
>http://groups.google.com/group/rec.bicycles.tech/search?hl=en&group=rec.bicycles.tech&q=frank+nylock
>
>The first of the four hits is obviously what we want, so . . .
>
>http://groups.google.com/group/uk.r...&q=frank+nylock&rnum=1&hl=en#cf3182de0e6449f9
>
>Google just takes you to the 10-post section that includes your
>target, so page down to post 138, click on "more options", click on
>"individual message", and cut and paste the address:
>
>http://groups.google.com/group/uk.rec.cycling/msg/cf3182de0e6449f9?hl=en&
>
>Carl mistakenly thinks that everyone knows how to do this, so
>sometimes it helps to go through the steps and addresses. The sun has
>come out, the temperature has dropped to 26F, the drugs are taking
>hold, and Carl is going to go fox-hunting on foot with his camera and
>faithful hound.
>
>Cheers,
>
>Carl Fogel


Foxes are easier to find than ejected wheels, harder than posts about
nylock nuts:

http://i5.tinypic.com/34fbak3.jpg

CF
 
On Feb 9, 6:25 pm, jim beam <[email protected]> wrote:
> [email protected] wrote:
> > On Feb 9, 4:05 pm, jim beam <[email protected]> wrote:
> >> [email protected] wrote:
> >>> In a previous discussion on this, I gave torque readings for a real
> >>> nylok nut and a QR nut. Again, the QR nut's resistance was negligible
> >>> by comparison. I'm sure Carl can look up that post.
> >> are you saying that the nylon retainer has no effect?

>
> > Certainly, no practical effect. They are not intended nor designed
> > for that purpose.

>
> no practical effect quantified how? and if it's not there for a
> purpose, what's it there for? across all brands and models.


The weak nylon teeth in a QR's nut are there so when you spin the nut
by hand, it maintains adjustment until the QR is properly clamped.
That's all.

Any frictional anti-rotation device that can be twisted by two fingers
is NOT going to prevent loosening under heavy vibration. (Good grief,
have you _never_ used a real Nylok nut? Have you _never_ worked on
machines bigger than bicycles?)

> >> and what about serrations?

>
> > They may help for a time.

>
> so that's "negligible"???


Depends on the amount of time, and the consequences of them not
working. How would you feel about a parachute harness that held you,
oh, till you were about halfway to the ground?

> > But the limitations of similar features on
> > industrial nuts and bolts are fairly well known.

>
> yeah, they're not locking wire, but what are we trying to achieve here?


We're trying to achieve a front end design that will never eject the
front wheel when a user has properly installed equipment sold as
adequate for its intended use, and used it in the intended manner.
Seems reasonable to me.

> if they're sufficient for the job, and statistics indicate they are,
> what else do we urgently need to achieve?


I think you're defiining "the job" rather loosely. I don't doubt that
standard QR hardware plus lawyer lips are adequate for disk brakes in
normal road riding or light off-road. And of course, we know that
sort of riding predominates the "statistics."

But the hardware in question is advertised as suitable for really
rough, aggressive riding. I believe that, if we could examine
statistics for those bikes used on long, rough, hard-braking
downhills, the statistics would be damning. You'll note that's the
type of ride that generates almost all the complaints.


> > But so far, nobody seems to be saying every
> > bike ridden by every rider exhibits evidence of the problem. It seems
> > to happen only under certain circumstances.

>
> sure - not tightening the skewer properly....
>
> but all this is ridiculous nonsense until operator error can be
> eliminated from the stats.


Why not read the accounts here http://www.ne.jp/asahi/julesandjames/
home/disk_and_quick_release/#support
and tell us what the operator error was in each of those instances?

Or (for just one other example) this one I've quoted:

"Author: SteveM
Date: 30/03/03 19:59

"I had a scary experience of this sort yesterday and this explanation
works for me, I got to the bottom of the very twisty/bermy decsent at
Glentress, the one just before Delerverance, I thought that I had been
dropping like a muppet, even worse than normal, and had just put it
down to the fact that Lucy was buzzing my back tyre and that had put
me off, as we all set off again I realised the front was all floppy
and glanced down to see my Hope Steel QR had completley opened up, I
know for a fact it had been tight at the start of the ride because I
had heard the rumours about Russ's accident and have been a little
paranoid ever since so had checked it in the carpark ?, this QR is one
of the older designs BTW."


If someone is actually afraid of this happening, therefore double
checks, yet still experiences the problem, it must require an uncommon
degree of user skill to prevent your hypothetical user error!

IOW, it sounds like you're claiming the designer's defense is: "All he
did was follow the instructions. He should have done much more."

I don't think that defense works in product liability cases!

- Frank Krygowski
 
On 9 Feb 2007 17:03:57 -0800, [email protected] wrote:

[snip]

>Or (for just one other example) this one I've quoted:
>
>"Author: SteveM
>Date: 30/03/03 19:59
>
>"I had a scary experience of this sort yesterday and this explanation
>works for me, I got to the bottom of the very twisty/bermy decsent at
>Glentress, the one just before Delerverance, I thought that I had been
>dropping like a muppet, even worse than normal, and had just put it
>down to the fact that Lucy was buzzing my back tyre and that had put
>me off, as we all set off again I realised the front was all floppy
>and glanced down to see my Hope Steel QR had completley opened up, I
>know for a fact it had been tight at the start of the ride because I
>had heard the rumours about Russ's accident and have been a little
>paranoid ever since so had checked it in the carpark ?, this QR is one
>of the older designs BTW."
>
>
>If someone is actually afraid of this happening, therefore double
>checks, yet still experiences the problem, it must require an uncommon
>degree of user skill to prevent your hypothetical user error!
>
>IOW, it sounds like you're claiming the designer's defense is: "All he
>did was follow the instructions. He should have done much more."
>
>I don't think that defense works in product liability cases!
>
>- Frank Krygowski


Dear Frank,

It's an interesting anecdote, but . . .

The poster has a bicycle old enough to use a QR with the "older
designs", yet he apparently never suffered a noticeable problem in any
previous rides.

The problem only appeared after the poster became "a little paranoid"
and says that he carefully checked his bike before a ride.

During the downhill braking, the poster states that his QR "had
completely opened up" during a single descent after being carefully
checked at the start.

Either this complete-opening-up is exaggerated, or else we have
impressive evidence that a front wheel with a completely open QR will
not be ejected during fierce downhill disk braking.

Do you think that a carefully checked front QR in reasonable condition
completely opened up during a single descent? If so, why aren't
thousands of riders routinely losing front wheels every week?

Do you think that the poster could carefully check his QR again and
reproduce the problem on the same descent? If so, why didn't it appear
on any previous rides?

It seems to be a trail that the poster rides often--he mentions that
things were "even worse than normal".

This is why I'm wary of anecdotes and would like to see a test showing
an actual wheel ejection caused by repeated plausible braking forces
loosening a reasonably tightened QR.

I'm willing to be convinced that the problem is real, but anecdotes
(presumably sincere) are subject to considerable question.

After all, there's lots of sincere anecdotal evidence that parked
Audis accelerate through brick walls, no matter how hard the drivers
push on what they sincerely think is the brake pedal.

Cheers,

Carl Fogel
 
Frank Krygowski writes:

>>> In a previous discussion on this, I gave torque readings for a
>>> real nylok nut and a QR nut. Again, the QR nut's resistance was
>>> negligible by comparison. I'm sure Carl can look up that post.


>> are you saying that the nylon retainer has no effect?


> Certainly, no practical effect. They are not intended nor designed
> for that purpose.


>> and what about serrations?


> They may help for a time. But the limitations of similar features
> on industrial nuts and bolts are fairly well known. I don't believe
> the serrations on some QR nuts are curative enough to make up for
> the defective design.


>> and why hasn't /my/ hill-hammered, disk braked, vertical dropout
>> q.r. ever loosened?


> :) Let me guess: Because every component on your bike is forged and
> fitted with fatigue-proof rolled threads?


> Seriously, I can't guess. But so far, nobody seems to be saying
> every bike ridden by every rider exhibits evidence of the problem.
> It seems to happen only under certain circumstances. Perhaps your
> "hill hammering" is below some required minimum. Perhaps your QR
> has amazingly high strength, is stripped and maintained daily, and
> is fastened ultra-diligently with your vise-like grip. Perhaps
> there are other explanations.


>> you want me to believe that /two/ retaining mechanisms can be
>> ignored don't you?


> And you want me to believe that many reports of QRs loosening, axles
> shifting, and even wheel ejections, _despite_ operators checking
> against their possible errors, can be ignored, don't you?


>> how you can clutch at straws like this when simple user error has
>> not been eliminated is quite amazing.


> Knowing you, I'm sure that user error will never be eliminated to
> _your_ satisfaction. That is, even if someone reports carefully
> tightening the QR at hilltop, and marking the position of the nut,
> and checking at hill bottom and seeing a position change, and doing
> more than once.


> Come to think of it, that's already happened, hasn't it?


This reminds me of a road overpass and on-ramp that had dozens of
serious crashed including death. When the road was reviewed, the
highway department showed "conclusively" that all these cars were
traveling too fast where these two highways me because there was a
speed limit sign before the overpass.

The point was completely overlooked that the definition of a dangerous
road is one that has many crashes. It took about five years of
repeated citizens meetings with government to get that bridge rebuilt,
after which there were no more crashes. SFO had a similar bridge from
which cars went over a retaining wall that was solid black with tire
marks, to land on US101 below.

We have a similar curve locally that even has a wide crash-apron on
the outside. One day the highway department increased the
superelevation of the road without any change in alignment. It was
not that the curve could be taken faster, but that it was visible and
drivers recognize it now.

A repeated movement of a QR wheel in the dropouts is what got rid of
horizontal rear dropouts after the advent of the derailleur. I hope
it will not take as long on disk brakes. Repeating "the user is
wrong" will not improve the situation. That's just a bunch of self
righteousness or liturgical turgidity.

Jobst Brandt
 
[email protected] wrote:

>Do you think that a carefully checked front QR in reasonable condition
>completely opened up during a single descent? If so, why aren't
>thousands of riders routinely losing front wheels every week?
>
>Do you think that the poster could carefully check his QR again and
>reproduce the problem on the same descent? If so, why didn't it appear
>on any previous rides?
>
>It seems to be a trail that the poster rides often--he mentions that
>things were "even worse than normal".
>
>This is why I'm wary of anecdotes and would like to see a test showing
>an actual wheel ejection caused by repeated plausible braking forces
>loosening a reasonably tightened QR.
>
>I'm willing to be convinced that the problem is real, but anecdotes
>(presumably sincere) are subject to considerable question.


I'm a "skewer skeptic" (sic) based on the following assumptions...

1) A number of people will fail to properly tighten their skewer
before a given ride. This might be from inattention, or could be
because the skewer caught the edge of the lawyer lip or other debris
(preventing it from fully closing).

2) The number of wheel ejections we've heard about (directly and
indirectly) are quite small.

3) I think it's very reasonable to assume that the number of case
number 1 scenarios could eaily exceed the number of case number 2
scenarios. Ipso facto, it's not at all unreasonable to assume that
I've got very little to worry about when I'm riding my MTB.

>After all, there's lots of sincere anecdotal evidence that parked
>Audis accelerate through brick walls, no matter how hard the drivers
>push on what they sincerely think is the brake pedal.


Well, you have to remember that 20/20 did an "expose'" on the evil
Audis, though it turns out that they KNEW the facts that absolutely
proved it couldn't happen (including confession from the mother who
ran over her son that she told several witnesses that "her foot
slipped off the brake onto the gas"). I would have LOVED to see 20/20
sued into the ground by Audi (who suffered huge market losses as a
direct result) and by the owners of all Audis (who lost a LOT of
resale value overnight).

I guess it only goes to prove that you can get almost anyone to
believe almost anything if it's flashed at them at 30 frames per
second on a large Cathode Ray Tube. Sigh...

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame
 
Mark Hickey writes:

>> After all, there's lots of sincere anecdotal evidence that parked
>> Audis accelerate through brick walls, no matter how hard the
>> drivers push on what they sincerely think is the brake pedal.


> Well, you have to remember that 20/20 did an "expose'" on the evil
> Audis, though it turns out that they KNEW the facts that absolutely
> proved it couldn't happen (including confession from the mother who
> ran over her son that she told several witnesses that "her foot
> slipped off the brake onto the gas"). I would have LOVED to see
> 20/20 sued into the ground by Audi (who suffered huge market losses
> as a direct result) and by the owners of all Audis (who lost a LOT
> of resale value overnight).


> I guess it only goes to prove that you can get almost anyone to
> believe almost anything if it's flashed at them at 30 frames per
> second on a large Cathode Ray Tube. Sigh...


That may be true, but the auto industry as a whole ignored the age old
problem with automatic transmissions of being able to drop it in gear
while the engine is running fast and to change from park to some other
position, possibly on a steep slope, without realizing the danger.

As you see, today we have the interlock that the foot must be on the
brake to drop out of park and into a gear. That is the effect the
industry failed to address. Audi got stuck with it. That was too bad.
As it turned out, Cadillac had many such incidents over the past but
some sort of nationalism or other quirk brought 20/20 out of a deep
sleep on this.

This disk brake force reaction should be seen in a similar manner. It
needs a design change of which the best is still the motorcycle axle
solution with a QR clamp on the axle bore in the fork.

Jobst Brandt
 
jim beam wrote:
>
> in news at 10, chains experience tensile stress, and pedal spindles are
> subject to fatigue loading!


I've broken pedals off before just by pushing them. You?

Problems like disk front wheel ejection are not routine; if they were,
they'd have been corrected during product development. This is
clearly a "corners of the envelope" issue, but that's precisely what
makes it a concern. We've identified the mechanism of failure, and
we've identified examples of failures in the field. The corrective
measures are simple and straightforward. Why not fix the problem?

Most Ford Pintos didn't burn to the ground in rear end collisions,
either. But there was an issue there, and it was addressed.

Chalo
 

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