Carlton Reid on QR safety

"Jay Beattie" writes:

"Tim McNamara" wrote...
"Marvin" writes:

But you haven't actually *given* a magnitude for this force. All
you've done is show a relationship to another force (which you
can't measure either). If you can put a number to any of these
forces, that would indeed be a step forward.

Those numbers have already been given, they are available on James
Annan's Web page. Numbers from Cannondale have also been given:

http://www.ne.jp/asahi/julesandjames...quick_release/

Generally the forces have been given in Newtons, however, which is
confusing to the non-engineers and non-physicists. It's an
appropriate unit to use, though, since this problem is largely
about Newton's law (for every action...). ;-) Let me try using
more common units of measurement. I am sure that my math and my
assumptions will be adequately scrutinized by both sides of the
discussion.

big snip

I hope that helps make the picture clearer, Marvin. If you use
disk brakes, use a good skewer such as a Shimano MTB as jim beam
has pointed out in the past. Also as jim pointed out, use hubs
with serrated locknuts to "bite" into the inner faces of the
dropouts. And clamp those babies down tight. I'd carry a second
skewer, BTW, because we've had reports of skewers breaking. Use
your rear brake a lot since it doesn't have this problem- it pushes
the axle into the dropout instead of trying to push it out, because
the rear caliper is mounted in front of the axle. Stop every so
often to check on the tightness of the skewer. And when the
problem is fixed by eliminating the ejection force or eliminating
the open dropout, upgrade!

Other confounding factors include the design of the drop out and
the location of the disc caliper. I have an Avid mechanical disc
which has a caliper mounted at a fairly high angle in
relationship to the drop out. The drop out also has downward
facing, "U" shaped opening rather than the usual swept-back
opening on a traditional road dropout.

Yes, one undeclared assumption- for the sake of simplicity- was that
the direction of the ejection force was parallel to the exit of the
dropout. In the real world, there are variations in the location of
the caliper and the exit direction of the dropout.

Boyle M. Owl wrote:
...
Following your [Jobst Brandt's] example.

I would not even pretend to be an expert in physics, but I would not
expect a physicist who has not been in my field to claim to be an expert
in machining or toolmaking, either.

When did Jobst Brandt metamorphose from a mechanical engineer to a
physicist?

--
Tom Sherman

Tim McNamara wrote:

"Ed Pirrero" writes:
Logical fallacy - calling for the proof of a negative.

Good, at least you have some basic grasp of logic. I was starting to
wonder.

Not really. "Proof of a negative" is quite possible. Or perhaps our sock
puppet has proof that you can't prove a negative?

--
Benjamin Lewis

Now is the time for all good men to come to.
-- Walt Kelly

Tim McNamara wrote:

jim beam writes:
1. ejection incidence is effectively zero and cannot be distinguished
from operator error.

That does not mean that there are no incidents. Since we all have
been brought up on the notion that all wheel ejections are the fault
of operator error, it is likely that riders will attribute any wheel
ejections to operator error.

Yes, and also end-overs caused when the axle slips but the wheel is
retained by lawyer lips. Of course, because I can't *prove* that this has
ever occurred in practice, it must not have.

--
Benjamin Lewis

Now is the time for all good men to come to.
-- Walt Kelly

Boyle M. Owl wrote:

I, myself, don't see the big deal about QR issue. If you're experiencing
pullout, replace the hollow axels with solid ones and nuts. Problem
solved. However, I can sit here, close my eyes, and be confounded at how
wheel pullout can happen if the skewers are properly tightened in the
first place. The braking force has to overcome the clamping force of the
properly tightened skewer _and_ make the skewer jump over the lawyer
lips. For that to happen, you have to make the skewer _stretch_ by making
it exceed its yeild point.

As Jobst pointed out earlier, axle slipping can cause end-over even if the
wheel is retained by lawyer lips, due to the sudden non-linearity in
braking response when the disk cants sideways in the caliper.

--
Benjamin Lewis

Now is the time for all good men to come to.
-- Walt Kelly

James Annan wrote:

I'm just asking you to clarify what you mean by a "third party", and
what you might consider "verification".

What difference does my opinion in this matter make? You don't have
anything besides your *conjecture* on the subject.

You made claims - claims you can't back up with anything except *your
own personal conjecture*.

That's as far away from confirmation as exists. You do not have ANY
independent confirmation at all.

An intellectually honest person would at leat mitigate their claims
with some sort of disclaimer.

It would be easier to accept your analysis if you had intellectual
honesty.

But, like I said in my first post in this topic, this is all about
feeding your ego, which is exactly why you can't fathom actually doing
real tests to measure the actual forces. Your ego wouldn't stand the
crushing blow if it turned out that your hypothesis was somehow
inaccurate in any respect.

You have very nicely dodged the question, though. And now you'll snip
and start yet another red herring attempt.

E.P.

Tim McNamara wrote:
jim beam writes:

Tim McNamara wrote:
jim beam writes:

James Annan wrote:

Ed Pirrero wrote:


James Annan wrote:

How would you know what a "real scientist" would think? Have you
ever met one? James

he is one annan. he's all over the web if you know who you're
looking for.

He's all over Usenet, anyway, but that's only proof of an Internet
connection. I find nothing by him that is scientific or scholarly,
certainly not in this newsgroup. Is he just another sock puppet of
yours, perhaps?

the chickens taking up too much of the intellectual resources tim?
"ed" is not his real name. there, that was hard to figure out,
wasn't it.

Then we only have your word and his, and neither of you is credible.

You making a judgement on scientific credibility is laughable. Here's
a clue - the social "sciences" really aren't much about science. But
hey, if it makes *you* feel more important, that's fine by me.

Hell, I think they even call economics "science" nowadays. ROTFL.

E.P.

Ed Pirrero wrote:
James Annan wrote:

I'm just asking you to clarify what you mean by a "third party", and
what you might consider "verification".

What difference does my opinion in this matter make?

Since you are the one asking for "verification" by a "third party" it
seems worthwhile for me to check what you mean, so you don't invent
spurious grounds for rejection.

If you can't specify what you mean by either of these terms, it seems
like a pretty meaningless request. If you won't specify what you mean,
it seems like an obviously dishonest one.

James

wrote:
Ed Pirrero wrote:


There is a force. Whether the force is sufficient to cause anything
but consternation in engineering purists *has not yet been proven*.

Rather, "has not been proven" to _your_ satisfaction (or jim beam's).

When there are actual experiments (as opposed to drawings and
calculations) I will consider those numbers to be the final word.

There will always
be people so welded to their own view that no amount of evidence and
logic will suffice.

A lovely strawman. Knock it down!


There is a known mechanism for loosening
threaded fasteners, and there is no reason to presume that that
mechanism cannot apply to bicycles.

Another presumption. It *might*. But *does it*? We don't know,
because nobody has actually done any controlled testing.

Our of curiosity, Ed, why do you think that well known mechanism for
loosening of industrial threaded fasteners would _not_ apply to
fasteners with far less locking power and far greater transverse loads?

Who says they don't?

Oh, that's right, another strawman.

But hey, *maybe*, since all the other fasteners on a bike seem to hold
without the two anti-loosening strategies used commonly in QRs, it
seems incredibly odd that MTBs don't routinely fall to pieces.

Or maybe, just maybe, not everything is known about the system. It
could be that James is 100% correct. I don't discount that possiblity,
because I understand how hypotheses work. But it sure would be nice to
see SOMETHING other than supposition and conjecture.

Can you identify any specific mechanical reason, or is it just another
"you can't prove it" thing?

The onus is not on me to disprove James' hypothesis. You know that
just as well as I. Your query is yet another rhetorical device in a
long line of folks too frightened to gather any sort of data
whatsoever.

Where's the testing? So far, only Cannondale has bothered. And their
test seems to not support James' hypothesis. "It's not a fair test!"
James moans. OK, that's fine - but in the absence of your own data
collection, that's all there is. And I consider data over hypothesis
every day.

E.P.

James Annan wrote:
Ed Pirrero wrote:
James Annan wrote:

I'm just asking you to clarify what you mean by a "third party", and
what you might consider "verification".

What difference does my opinion in this matter make?

Since you are the one asking for "verification" by a "third party" it
seems worthwhile for me to check what you mean, so you don't invent
spurious grounds for rejection.

Nonsense. If you had any sort of confirmation, you'd have presented it
ages ago. Even the most questionable of third parties get quoted by
you immediately when they say anything that resembles support of your
hypothesis.

Does anyone other than yourself, besides some lawyer, claim on the
record that the accidents *you claim* were caused by disk brakes were
actually caused that way?

No? Then all your fishing for rhetorical advantage comes to nothing.
It's easy to reject third-party confirmation when none actually exists.

You got something, or not? If not, then knock it off. If so, let's
see it. Your weaselling is tiresome.

E.P.