disk brake debate - summary II
jim beam
lawyer lips] there is no argument against disk brake ejection because
there is no pullout figure that the ejection force can easily be shown
to exceed.
2. according to the naysayers, pullout force is apparently /not/ a
function of qr clamping force in conjunction with mechanical interlock
caused by indentation. because by conveniently not acknowledging the
effect of clamping force and interlock, they have no argument. [see
point 1. above.]
3. if pullout force /were/ to be a function of mechanical interlock, no
one has yet shown any willingness to analyze existing estimates of the
material shear force that breaking that interlock would create.
4. yawn.
gcmsc...@gmail.com
An interesting spin on the available data. Your 20kN force has been
totally blown away. Wouldn't it be best to admit you were mistaken
there? Jobst has a point about fretting over time for indentation
reinforcement.
Nobody has addressed the reaction forces in the plane parallel to the
ground - the ones that tend to twist the fork legs. They obviously
exist, yet are completely ignored by the "engineers" here.
I got involved in this because of the research I was doing before
installing disks on both my mountain bikes. I read everything I could
lay my eyes on, and these threads came up in the course of my searches.
After all the reading I've done, I've decided that James and Jobst are
playing Chicken Little, and that my regular QR fork with new XT QRs
(which come with new XT disk hubs) are perfectly acceptable, and will
not eject my wheels with disk brakes in any sort of situation in which
I MTB, including road slicks on dry pavement during the muddy-trail
season. I suspect both James and Jobst have expert witness money
riding on their comments, which is why neither of them will admit to
any portion of the hypothesis as being questionable, let alone wrong.
I have yet to see James admit that anyone else might even have a point,
let alone a good point. There *must* be money involved - no one is
that arrogant.
> 4. yawn.
Dude, we were at "yawn" 400 posts ago. Nothing new here, move
along...
E.P.
P.S. My suggestion is to link to the summary thread during any further
discussion of this issue. None of the previous ones have gone as far
in knocking down James' hypothesis.
John Forrest Tomlinson
<gcmsc...@gmail.com> wrote:
>
>jim beam wrote:
>> 1. in the absence of an iso pullout figure, [and conveniently ignoring
>> lawyer lips] there is no argument against disk brake ejection because
>> there is no pullout figure that the ejection force can easily be shown
>> to exceed.
>>
>> 2. according to the naysayers, pullout force is apparently /not/ a
>> function of qr clamping force in conjunction with mechanical interlock
>> caused by indentation. because by conveniently not acknowledging the
>> effect of clamping force and interlock, they have no argument. [see
>> point 1. above.]
>>
>> 3. if pullout force /were/ to be a function of mechanical interlock, no
>> one has yet shown any willingness to analyze existing estimates of the
>> material shear force that breaking that interlock would create.
>
>An interesting spin on the available data. Your 20kN force has been
>totally blown away.
But he put "summary" in the subject of this thread, so doesn't that
mean he's pulling together the best available knowledge?
JT
****************************
Remove "remove" to reply
Visit http://www.jt10000.com
****************************
James Annan
jim beam wrote:
yet more self-flagellation. Stop humiliating yourself and move on,
can't you? If you pulled your head out of your arse for once you might
be able to make a useful contribution, or at least an interesting
one...
James
jim beam
> jim beam wrote:
>
>>1. in the absence of an iso pullout figure, [and conveniently ignoring
>>lawyer lips] there is no argument against disk brake ejection because
>>there is no pullout figure that the ejection force can easily be shown
>>to exceed.
>>
>>2. according to the naysayers, pullout force is apparently /not/ a
>>function of qr clamping force in conjunction with mechanical interlock
>>caused by indentation. because by conveniently not acknowledging the
>>effect of clamping force and interlock, they have no argument. [see
>>point 1. above.]
>>
>>3. if pullout force /were/ to be a function of mechanical interlock, no
>>one has yet shown any willingness to analyze existing estimates of the
>>material shear force that breaking that interlock would create.
>
>
> An interesting spin on the available data. Your 20kN force has been
> totally blown away. Wouldn't it be best to admit you were mistaken
> there? Jobst has a point about fretting over time for indentation
> reinforcement.
i'm delighted that number's "blown away"! i said from the beginning
that my figure was a guesstimate. joe riel's number is much more
precisely calculated. the point is that no one was addressing the
degree of clamping force, just waving their hands. now we have a usable
number and are removing the void of uncertainty into which smoke can be
blown.
jim beam
that's another example of the logical disconnect that allows you to
claim that indented fork ends don't affect pullout force. james, your
theory is incomplete. you don't address pullout force; and without
that, your ejection force means nothing. all while we're ignoring the
elephant in the room, the presence of lawyer lips. you need to get with
the math. "move on" indeed.
41
But that would require far more than 20kN, which Mr "Metallurgy School"
Jim Beam admits he cannot generate. You see, you have neglected to
account for the mechanical interlock that has resulted from so much
fretting.
Even if such forces were made available to shear the damn thing out,
your assessment of the results is wildly overoptimistic. L
dvt
> that's another example of the logical disconnect that allows you to
> claim that indented fork ends don't affect pullout force.
The data in another thread shows evidence that indented/embossed fork
ends don't greatly affect pullout force. Here's the message ID for that
data in case you missed it: 87zmp6n...@k-online.com.
--
Dave
dvt at psu dot edu
dvt
> The data in another thread shows evidence that indented/embossed fork
> ends don't greatly affect pullout force. Here's the message ID for that
> data in case you missed it: 87zmp6n...@k-online.com.
I just saw your note in the other thread. Use groups.google.com's
advanced search and plug in the message ID I gave above.
James Annan
> gcmsc...@gmail.com wrote:
>
>> An interesting spin on the available data. Your 20kN force has been
>> totally blown away. Wouldn't it be best to admit you were mistaken
>> there? Jobst has a point about fretting over time for indentation
>> reinforcement.
>
>
> i'm delighted that number's "blown away"! i said from the beginning
> that my figure was a guesstimate.
You said "a rough calc shows the clamping force for a normal skewer is
~>20kN", which has been shown to be out by a factor of about 3 from a
plausible upper limit and more like an order of magnitude according to
actual measurements.
No doubt you'll be "delighted" once you work out that the rest of your
argument is similarly wrong.
James
--
James Annan
see web pages for email
http://www.ne.jp/asahi/julesandjames/home/
http://julesandjames.blogspot.com/
jim beam
Avallone, E.A. and Baumeister III, T. (1987). Marks' standard handbook
for mechanical engineers (9th ed.). New York, NY: McGraw-Hill.
Phil H"
correct?
those figures are for smooth surfaces, not what we have here.
James Annan
chuckle.
Thanks for that, I can't honestly say it made 700 posts worth reading,
but it paid back something anyway!
41
James Annan wrote:
> 41 wrote:
>
> > James Annan wrote:
> >
> >>jim beam wrote:
> >>
> >>yet more self-flagellation. Stop humiliating yourself and move on,
> >>can't you? If you pulled your head out of your arse for once you might
> >>be able to make a useful contribution, or at least an interesting
> >>on e...
> >
> >
> > But that would require far more than 20kN, which Mr "Metallurgy School"
> > Jim Beam admits he cannot generate. You see, you have neglected to
> > account for the mechanical interlock that has resulted from so much
> > fretting.
> >
> > Even if such forces were made available to shear the damn thing out,
> > your assessment of the results is wildly overoptimistic. L
> >
>
> chuckle.
>
> Thanks for that, I can't honestly say it made 700 posts worth reading,
> but it paid back something anyway!
It's my pleasure.
Posters here, please note my reply to Mr "Metallurgy School" Jim Beam
in the other thread, which I reproduce in full here:
=========================================================
41 Oct 19, 11:16 am
Newsgroups: rec.bicycles.tech
From: "41" <KingGeorge...@yahoo.fr> Date: 19 Oct 2005 08:16:37 -0700
Local: Wed, Oct 19 2005 11:16 am
Subject: Re: summary - the disk brake debate
jim beam wrote:
> dvt wrote:
> > jim beam wrote:
> >> well, the analysis process has been started - material shear is the
> >> place to look.
> > I'd say the available test data points to the conclusion that material
> > shear is *not* t he place to look. Read Joe Riel's posts from yesterday
> > to see that analysis. Is there something wrong with that analysis?
> to be honest, i'm out of screen real estate and can't follow the thread
> very well any more. if you'd kindly repost in the summary II thread,
> i'd love to look at it.
This is a tactic we've seen from you before. Out of screen real
estate??? In other words, you realize you have been completely
discredited in this thread, and so would like to start all over again
in a new thread, so everything has to be repeated all over again and
again and again. Nobody should fall for this. Summary II thread should
be reserved for disk-brake content-free, but highly a propos ridicule
of its originator.
========================================================================
Werehatrack
I believe that it may be a summary in the same sense as the various
summaries that are supplied to W on a daily basis. One can probably
construct a number of summaries of the threads with wildly different
conclusions supported.
I, for one, have decided not to worry about the issue.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.
dvt
Nope. You have to plug the message ID specifically into the message ID
box on the advanced search page. Try this:
http://groups.google.com/group/rec.bicycles.tech/msg/d9c5065bbb1680e2?hl=en
Michael Press
dvt <dvt+u...@psu.edu> wrote:
We are better off when you enclose the message ID in angle
brackets. Then the reader of the message can retrieve it
from his ISP's news server by clicking on it.
<87zmp6n...@k-online.com>
I want to avoid the google interface. Usenet is a plain
text medium run off port 119, not a mark up medium run off
port 80. google interferes with the plain text format.
They treat us like they own usenet.
--
Michael Press
Michael Press
dvt <dvt+u...@psu.edu> wrote:
As you see, google has substituted their proprietary
identification with the public identification
<87zmp6n...@k-online.com>.
--
Michael Press
Michael Press
<1129735812....@z14g2000cwz.googlegroups.com>,
"41" <KingGe...@yahoo.fr> wrote:
> James Annan wrote:
> > 41 wrote:
> >
> > > James Annan wrote:
> > >
> > >>jim beam wrote:
> > >>
> > >>yet more self-flagellation. Stop humiliating yourself and move on,
> > >>can't you? If you pulled your head out of your arse for once you might
> > >>be able to make a useful contribution, or at least an interesting
> > >>on e...
> > >
> > >
> > > But that would require far more than 20kN, which Mr "Metallurgy School"
> > > Jim Beam admits he cannot generate. You see, you have neglected to
> > > account for the mechanical interlock that has resulted from so much
> > > fretting.
> > >
> > > Even if such forces were made available to shear the damn thing out,
> > > your assessment of the results is wildly overoptimistic. L
Here is what this newsgroup was meant for.
> > >
> >
> > chuckle.
> >
> > Thanks for that, I can't honestly say it made 700 posts worth reading,
> > but it paid back something anyway!
>
> It's my pleasure.
>
> Posters here, please note my reply to Mr "Metallurgy School" Jim Beam
> in the other thread, which I reproduce in full here:
Except for the message ID
<1129734997.7...@g44g2000cwa.googlegroups.com>
That he cannot keep straight his own work is refutation to
his professions of technical competence, and should
persuade all that his assertions must be discounted. I
predict that he will find another forum to join. Likely
sci.engr.metallurgy.
--
Michael Press
Michael Press
James Annan <still_th...@hotmail.com> wrote:
> jim beam wrote:
>
> > gcmsc...@gmail.com wrote:
> >
> >> An interesting spin on the available data. Your 20kN force has been
> >> totally blown away. Wouldn't it be best to admit you were mistaken
> >> there? Jobst has a point about fretting over time for indentation
> >> reinforcement.
> >
> >
> > i'm delighted that number's "blown away"! i said from the beginning
> > that my figure was a guesstimate.
>
> You said "a rough calc shows the clamping force for a normal skewer is
> ~>20kN", which has been shown to be out by a factor of about 3 from a
> plausible upper limit and more like an order of magnitude according to
> actual measurements.
>
> No doubt you'll be "delighted" once you work out that the rest of your
> argument is similarly wrong.
That 5 mm skewer will plastically deform at 20 kN tension.
--
Michael Press
41
Michael Press wrote:
> In article
> <1129735812....@z14g2000cwz.googlegroups.com>,
> "41" <KingGe...@yahoo.fr> wrote:
> > Posters here, please note my reply to Mr "Metallurgy School" Jim Beam
> > in the other thread, which I reproduce in full he re:
>
> Except for the message ID
> <1129734997.7...@g44g2000cwa.googlegroups.com>
Thanks for that completion.
>
> > =========================================================
> > 41 Oct 19, 11:16 am
> >
> > Newsgroups: rec.bicycles.tech
> > From: "41" <KingGeorge...@yaho o.fr> Date: 19 Oct 2005 08:16:37 -0700
> > Local: Wed, Oct 19 2005 11:16 am
> > Subject: Re: summary - the disk brake debate
> >
> > jim beam wrote:
> > > dvt wrote:
> > > > jim beam wrote:
> >
> > > >> well, the analysis process has been started - mat erial shear is the
> > > >> place to look.
> >
> > > > I'd say the available test data points to the conclusion that material
> > > > shear is *not* t he place to look. Read Joe Riel's posts from yesterday
> > > > to see that analysis. Is there something wrong with that analysis?
> >
> > > to be honest, i'm out of screen real estate and can't follow the thread
> > > very well any more. if you'd kindly repost in the summary II thread,
> > > i'd love to look at it.
> >
> > This is a tactic we've seen fr om you before. Out of screen real
> > estate??? In other words, you realize you have been completely
> > discredited in this thread, and so would like to start all over again
> > in a new thread, so everything has to be repeated all over again and
> > again and again. Nobody should fall for this. Summary II thread should
> > be reserved for disk-brake content-free, but highly a propos ridicule
> > of its originator.
> > ========================================================================
>
> That he cannot keep straight his own work is refutation to
> his professions of technical competence, and should
> persuade all that his assertions must be discounted. I
> predict that he will find another forum to join. Likely
> sci.engr.metallurgy.
He probably realizes he'll find no takers there. He could try
alt.metallurgyskool.diplomas.by.correspondence.
gcmsc...@gmail.com
James Annan wrote:
> jim beam wrote:
>
> > gcmsc...@gmail.com wrote:
> >
> >> An interesting spin on the available data. Your 20kN force has been
> >> totally blown away. Wouldn't it be best to admit you were mistaken
> >> there? Jobst has a point about fretting over time for indentation
> >> reinforcement.
> >
> >
> > i'm delighted that number's "blown away"! i said from the beginning
> > that my figure was a guesstimate.
>
> You said "a rough calc shows the clamping force for a normal skewer is
> ~>20kN", which has been shown to be out by a factor of about 3 from a
> plausible upper limit and more like an order of magnitude according to
> actual measurements.
>
> No doubt you'll be "delighted" once you work out that the rest of your
> argument is similarly wrong.
Actually, it isn't.
But if it helps you to make a buck or three to think otherwise, great.
E.P.
James Annan
> James Annan wrote:
>
>>41 wrote:
>>
>>
>>>James Annan wrote:
>>>
>>>
>>>>jim beam wrote:
>>>>
>>>>yet more self-flagellation. Stop humiliating yourself and move on,
>>>>can't you? If you pulled your head out of your arse for once you might
>>>>be able to make a useful contribution, or at least an interesting
>>>>on e...
>>>
>>>
>>>But that would require far more than 20kN, which Mr "Metallurgy School"
>>>Jim Beam admits he cannot generate. You see, you have neglected to
>>>account for the mechanical interlock that has resulted from so much
>>>fretting.
>>>
>>>Even if such forces were made available to shear the damn thing out,
>>>your assessment of the results is wildly overoptimistic. L
>>>
>>
>>chuckle.
>>
>>Thanks for that, I can't honestly say it made 700 posts worth reading,
>>but it paid back something anyway!
>
>
> It's my pleasure.
>
A conveniently apropos picture which just popped up in another ng:
http://www.edconrad.com/ebay/SimplyMagic/sunshine.jpg
I daresay you could be right, it looks like a tight interlock. jim might
not hear UNLESS WE SHOUT!
Phil Holman
"dvt" <dvt+u...@psu.edu> wrote in message
news:dj5qps$1gn4$1...@f04n12.cac.psu.edu...
results in u = .25 for steel on steel. That is only 1/3 of the cited
value. As Jim pointed out, u = .74 - .78 is for smooth surfaces. One
would expect this figure to be higher with a serrated QR.
Phil H
41
James Annan wrote:
> 41 wrote:
>
> > James Annan wrote:
> >
> >>41 wrote:
> >>
> >>
> >>>James Annan wrote:
> >>>
> >>>
> >>>>jim beam wrote:
> >>>>
> >>>>yet more self-flagellation. Stop humiliating yourself and move on,
> >>>>can't you? If you pulled your head out of your arse for once you might
> >>>>be able to make a useful contribution, or at least an interesting
> >>>>on e...
> >>>
> >>>
> >>>But that would require far more than 20kN, which Mr "Metallurgy School"
> >>>account for the mechanical interlock that has resulted from so much
> >>>fretting.
> >>>
> >>>Even if such forces were made available to shear the damn thing out,
> >>>
> >>
> >>chuckle.
> >>
> >>Thanks for that, I can't honestly say it made 700 posts worth reading,
> >>but it paid back something anyway!
> >
> >
> > It's my pleasure.
> >
>
> A conveniently apropos picture which just popped up in another ng:
>
> http://www.edconrad.com/ebay/SimplyMagic/sunshine.jpg
>
> I daresay you could be right, it looks like a tight interlock. jim might
> not hear UNLESS WE SHOUT!
HOLY CRAP! So we know where his monitor is, and the mouse too I
suppose, but I'm wondering: where does he keep the keyboard?
But no doubt, like everything else, he somehow faked the picture.e
jim beam
> jim beam wrote:
>
>> gcmsc...@gmail.com wrote:
>>
>>> An interesting spin on the available data. Your 20kN force has been
>>> totally blown away. Wouldn't it be best to admit you were mistaken
>>> there? Jobst has a point about fretting over time for indentation
>>> reinforcement.
>>
>>
>>
>> i'm delighted that number's "blown away"! i said from the beginning
>> that my figure was a guesstimate.
>
>
> You said "a rough calc shows the clamping force for a normal skewer is
> ~>20kN", which has been shown to be out by a factor of about 3 from a
> plausible upper limit and more like an order of magnitude according to
> actual measurements.
>
> No doubt you'll be "delighted" once you work out that the rest of your
> argument is similarly wrong.
>
> James
by what factor is your ejection force exceeded by pullout force? oh,
wait, you've not done any analysis. my bad.
Phil Holman
"41" <KingGe...@yahoo.fr> wrote in message
news:1129772904.4...@g49g2000cwa.googlegroups.com...
a 6061-T6 bearing allowable of around 300 MPa, those indentations would
require a clamp-up force of 4kN for an indentation area of 15mm^2 (22
indentations of 2 x .35). An unremarkable result well within the realm
of possibility.
Phil H
41
Oh, puh-lease, no serious posts in this thread! But if you read the
exchanges on this topic, I think you'll find what's wrong with your
argument, explicitly. But please, post anything serious elsewhere.
Like, why not where the discussion actually occurred, in response to
the actual posts that discussed the matter? At the same time you could
read them, which would save repetition.
And by the way, those dropouts shown were chrome-plated steel, not
aluminum. The aluminum ones he showed before that had no indentations
at all, only a little burnishing.
Phil Holman
41 wrote.....
"Like everything else, he somehow faked the picture"
Sorry, I took "everything else" to mean, well, everything else.
>
> And by the way, those dropouts shown were chrome-plated steel, not
> aluminum. The aluminum ones he showed before that had no indentations
> at all, only a little burnishing.
>
http://home.comcast.net/~carlfogel/download/indented.jpeg
Burnishing, please be serious.
http://home.comcast.net/~carlfogel/download/nishiki_indent.jpeg
What do you think, are the dropouts decorative chrome or hard chrome?
Phil H
41
Phil Holman wrote:
>please be serious.
Not in this thread.
Anyrate, you have a bicycle, you have a quick release, the dropouts
have indentations: why not install the QR with serrations out of phase
with the old ones, and see if you get a new set with one normal
clamping operation, no riding? Good luck!!
dvt
> The article implies pullout force is equal to clamping force which
> results in u = .25 for steel on steel. That is only 1/3 of the cited
> value. As Jim pointed out, u = .74 - .78 is for smooth surfaces. One
> would expect this figure to be higher with a serrated QR.
Precisely the point. If the serrated QR was able to "dig in" the
dropouts, then the measured pullout force would be higher than predicted
by friction. But the measurements show that the pullout force is less
than or equal to that predicted by friction. Therefore if the QR is
digging in, it isn't adding much to the pullout force.
Phil Holman
pullout force, the data isn't consistent. Something isn't right.
Phil H
Phil Holman
My point is to remove the "luck" element.
Phil H
James Annan
>
> My point is to remove the "luck" element.
spoilsport!
jim beam
no kidding. saying indentation doesn't add to pullout force is like
saying splines on the output of a driveshaft don't prevent rotation
relative to its receiver. "something isn't right" indeed.
dvt
> "dvt" wrote...
>>Phil Holman wrote:
>>>The article implies pullout force is equal to clamping force which
>>>results in u = .25 for steel on steel. That is only 1/3 of the cited
>>>value. As Jim pointed out, u = .74 - .78 is for smooth surfaces. One
>>>would expect this figure to be higher with a serrated QR.
>>Precisely the point. If the serrated QR was able to "dig in" the
>>dropouts, then the measured pullout force would be higher than
>>predicted by friction. But the measurements show that the pullout
>>force is less than or equal to that predicted by friction. Therefore
>>if the QR is digging in, it isn't adding much to the pullout force.
> It isn't adding much is an understatement; with a measurement of less
> pullout force, the data isn't consistent. Something isn't right.
The data does not support the claim that indentations improve pullout
force significantly. There is an error associated with every
measurement, but that error would have to be quite large (i.e. a factor
of 4 somewhere) before this claim were supported.
41
> "dvt" <dvt+u...@psu.edu> wrote in message
> news:dj7vh5$1fj4$1...@f04n12.cac.psu.edu...
> > Phil Holman wrote:
> >> The article implies pullout force is equal to clamping force which
> >> results in u = .25 for steel on steel. That is only 1/3 of the cited
> >> value. As Jim pointed out, u = .74 - .78 is for smooth surfaces. One
> >> would expect this figure to be higher with a serrated QR.
> >
> > Precisely the point. If the serrated QR was able to "dig in" the
> > predicted by friction. But the measurements show that the pullout
> > force is less than or equal to that predicted by friction. Therefore
> >
> It isn't adding much is an understatement; with a measurement of less
> pullout force, the data isn't consistent. Something isn't right.
What isn't right are so many things:
-the idea that those serrations are causing, from clamping force
alone, indentations sufficient to increase the pullout force. This is
obvious and I don't see why you should find it surprising: you have to
have a while of fretting before those serrations auger in to give any
real mechanical interlock. They don't specify in the article, but from
the description of the materials, these were all new dropouts. Forget
any mechanical interlock, it's friction only.
-the coefficient of friction of chrome on steel is generally reported
to be in the 0.16-0.21 range.
-coef ficients of friction are supposed to be for laboratory-clean
material pairs. That's not what it's like in the field or even in the
course of normal maintenance or even just working with your
well-greased skewer and adjusting it. Forget laboratory values of
metal-metal coefficient of friction in the real world. Lubricated,
which I think describes most people's QRs in the real world, steel on
steel has a coefficient of friction in the 0.05-0.16 range.
-the model friction = coefficient of friction x normal is only an
empirical or at best semi-empirical relationship, approximate at that,
and it breaks down at extremes. You can't just quote one generic value
and use it blindly, because the value depends on the testing setup. In
particular, you are using the w rong type of coefficient of friction:
you want, instead of the generic, something like this
-----------------------------------------------------
Coefficient of friction between surfaces clamped by bolts /screws.
These values allow calculation of the sh ear force necessary to cause
slip between surfaces when clamped by bolts.
Contact Surfaces slip coefficient
Steel On Steel- No treatment: 0.15- 0.25
------------------------------------------------------
see
<http://www.roymech.co.uk/Useful_Tables/Tribo logy/co_of_frict.htm>
(scroll about 1/3 of the way down)
And finally, what's even more wrong- and all these mistakes come from
paying any mind whatsoever to some guy who went to "metallurgy skool",
whose goal is to deliberately mislead, divert, and obfu scate: you are
losing the forest for the trees. Forget the calculations, we have a
clear and respectable laboratory study on QR pullout forces and we find
them all over the map, varying widely with skewer brand and setting
conditions, and not even conside ring the grease and gunk at the
interface in the real world. The values clearly overlap the danger
range. And in the real world, mistakes are made on top of all that.
Responsible, serious, competent engineers do not design in so
unforgiving a fashion.
T here are more than 700 posts on this in just these recent threads
alone. Isn't that more than enough already?
p
41
"Good luck" in the sense of it ain't going to happen, period. There is
no "luck" involved in the procedure described. You set the serrations
out of phase deliberately, and this is entirely obvious and under your
control. You close the skewer with whatever typical force you care to
muster, it doesn't matter. The result of new serrations or not will not
be a random process. It will be entirely deterministic. Just do it and
you will see.
jobst....@stanfordalumni.org
How about a new thread title, like "QR analysis", or "John Howard and
Lawyer lips revisited". This has nothing to do with disc brakes.
Jobst Brandt
gcmsc...@gmail.com
Really? I thought this was the crux of the disk brake discussion.
Where have *you* been all this time?
E.P.
jobst....@stanfordalumni.org
>>> The data does not support the claim that indentations improve
>>> pullout force significantly. There is an error associated with every
>>> measurement, but that error would have to be quite large (i.e. a
>>> factor of 4 somewhere) before this claim were supported.
>> How about a new thread title, like "QR analysis", or "John Howard and
>> Lawyer lips revisited". This has nothing to do with disc brakes.
> Really? I thought this was the crux of the disk brake discussion.
> Where have *you* been all this time?
I think you clipped away too much of the discussion tho know what the
subject is. I take it you have been away since the time when this
drifted off into QR effects and nohing else.
Jobst Brandt
gcmsc...@gmail.com
jobst.bra...@stanfordalumni.org snarkily snipes:
> E. P. writes:
>
> >> How about a new thread title, like "QR analysis", or "John Howard and
> >> Lawyer lips revisited". This has nothing to do with disc brakes.
>
> > Really? I thought this was the crux of the disk brake discussion.
> > Where have *you* been all this time?
>
> I think you clipped away too much of the discussion tho know what the
> subject is.
I clipped out all but what I was responding to. Now, since you
obviously have been asleep for the last two weeks, let me recap:
1.) There is an ejection force in WRT to DISK BRAKE bicycle wheels.
2.) This force on DISK BRAKE bicycle wheels has been calculated in the
neighborhood of 1k N at the drop out.
3.) The ISO standard for clamping force of QRs for a DISK BRAKE
bicycle wheel is in the neighborhood of 2k N.
4.) The actual measured force for QRs which could be used on DISK
BRAKE bicycle wheels is in the neighborhood of 5k - 8k N.
5.) Pullout force for DISK BRAKE bicycle wheels is approximately equal
to the clamping force exerted by the QR.
6.) The difference between ISO standard value and measured value might
explain the lack of reported DISK BRAKE bicycle wheel ejection events.
Another reason might be that lawyer lips prevent a loose axle from
fully ejecting.
7.) Serrations on the axle and QR faces used in DISK BRAKE bicycle
wheels might (or might not) increase that pullout force.
This has been the discussion, more or less. I'm sure if I've missed a
salient point, there will be some form of correction/addendum.
> I take it you have been away since the time when this
> drifted off into QR effects and nohing else.
Jobst - what is that thing that retains DISK BRAKE bicycle wheels in
the fork drop outs, again? I forget what it is - would you be so kind
as to name that part? The assumptions surrounding this part whose name
I cannot quite remember are sort of where James' hypothesis has it's
largest hole...
Or, if you prefer, maybe we could discuss the other forces not
addressed - the reaction forces acting in a plane parallel to the
ground, due to the offset of the DISK BRAKE rotor from the wheel
centerline?
Or, maybe we should discuss why hydraulic hoses/fittings or brake
cable/brake actuation parts should probably not be in a leading
position on a DISK BRAKE mountain bike fork leg?
E.P.
Phil Holman
> material pairs. That's not what it's like in the field or even in the
> course of normal maintenance or even just working with your
> well-greased skewer and adjusting it. Forget laboratory values of
> metal-metal coefficient of friction in the real world. Lubricated,
> which I think describes most people's QRs in the real world, steel on
> steel has a coefficient of friction in the 0.05-0.16 range.
Wouldn't you expect to see more failures in this range? In my estimate
(if u=0.1) , this would result in a pullout force of 800N on the left
dropout. For a 90kg rider plus bike, the ejection force would be a lot
higher than 800N, yet wheel ejection is rare. Possible, but rare.
You are preaching to the quoir. The mistake has been made, how deep is
the doodoo?
>
> T here are more than 700 posts on this in just these recent threads
> alone. Isn't that more than enough already?
No, I started late. I'm just getting warmed up.
Phil H
Phil Holman
> Or, if you prefer, maybe we could discuss the other forces not
> addressed - the reaction forces acting in a plane parallel to the
> ground, due to the offset of the DISK BRAKE rotor from the wheel
> centerline?
Forces in a plane horizontal to the ground due to rotor offset? Please
clarify.
>
> Or, maybe we should discuss why hydraulic hoses/fittings or brake
> cable/brake actuation parts should probably not be in a leading
> position on a DISK BRAKE mountain bike fork leg?
>
Something about swapping a headache for a sore throat.
Phil H
Kinky Cowboy
>1.) There is an ejection force in WRT to DISK BRAKE bicycle wheels.
>
>2.) This force on DISK BRAKE bicycle wheels has been calculated in the
>neighborhood of 1k N at the drop out.
I thought it was a bit higher, maybe 2kN,
>3.) The ISO standard for clamping force of QRs for a DISK BRAKE
>bicycle wheel is in the neighborhood of 2k N.
the ISO standard is for symmetrical pullout force, not clamping force,
although these two numbers often turn out to be much the same
>4.) The actual measured force for QRs which could be used on DISK
>BRAKE bicycle wheels is in the neighborhood of 5k - 8k N.
"when correctly installed to manufacturers specification, something
which is hard to guage and may be impossible for some users with poor
hand strength."
>5.) Pullout force for DISK BRAKE bicycle wheels is approximately equal
>to the clamping force exerted by the QR.
>
>6.) The difference between ISO standard value and measured value might
>explain the lack of reported DISK BRAKE bicycle wheel ejection events.
"compared with the predictions of Annan's theory, which assumes that
the in service pullout force is never greater than the ISO minimum"
>Another reason might be that lawyer lips prevent a loose axle from
>fully ejecting.
>7.) Serrations on the axle and QR faces used in DISK BRAKE bicycle
>wheels might (or might not) increase that pullout force.
8.) If the ejection force momentarily exceeds the holding force, the
transverse motion of the QR thread may cause it to loosen.
9.) The ISO standard for wheel pullout provides little or no safety
margin when disk brakes are used with dropouts angled approximately
orthogonal to a line joining the brake pad centre to the axle
10.) Proposed solutions to provide a greater certainty of wheel
retention under heavy braking are:
to change the dropout angle so that it is not aligned with the
ejection force (already being implemented by Marzocchi and
On-One/Planet-X);
to increase the clamping force of the wheel retention system, such as
by the use of solid axles with track nuts or hollow axles with large
diameter bolts;
to provide a wheel retention system in which the ejection force is not
resisted solely by a friction, such as a through axle system (already
rapidly gaining market share on the basis of its other virtues).
If I were feeling Trollish, I might add (this one goes up to 11!)
11.) Proposed solutions rejected on the grounds of stupidity:
moving the disc brake caliper to a position in front of the fork leg
Kinky Cowboy*
*Batteries not included
May contain traces of nuts
Your milage may vary
gcmsc...@gmail.com
Phil Holman wrote:
> >
> > Or, if you prefer, maybe we could discuss the other forces not
> > addressed - the reaction forces acting in a plane parallel to the
> > ground, due to the offset of the DISK BRAKE rotor from the wheel
> > centerline?
>
> Forces in a plane horizontal to the ground due to rotor offset? Please
> clarify.
I have written the details elsewhere in the past two weeks - you could
search for them, if you were interested.
I'm not of a mind to type it all again - sorry about that.
E.P.
gcmsc...@gmail.com
Kinky Cowboy wrote:
> On 20 Oct 2005 16:00:04 -0700, "gcmsc...@gmail.com"
>
> >1.) There is an ejection force in WRT to DISK BRAKE bicycle wheels.
> >
> >2.) This force on DISK BRAKE bicycle wheels has been calculated in the
> >neighborhood of 1k N at the drop out.
>
> I thought it was a bit higher, maybe 2kN,
It's on James' website - I guess I could trouble myself to look it
up...
And you are right! 1825N.
Thanks for the addenda - I wouldn't want to be accusing of hiding
anything pertinent.
E.P.
Benjamin Lewis
> On 20 Oct 2005 16:00:04 -0700, "gcmsc...@gmail.com"
>
>> 1.) There is an ejection force in WRT to DISK BRAKE bicycle wheels.
>>
>> 2.) This force on DISK BRAKE bicycle wheels has been calculated in the
>> neighborhood of 1k N at the drop out.
>
> I thought it was a bit higher, maybe 2kN,
This also assumes braking such that deceleration is 0.6g; but I don't see
why it couldn't be significantly higher than that in some scenarios, for
short enough time periods that the bike doesn't tip over. I haven't done
any calculations at this point, but what I have in mind is a bike landing
on the front wheel with the brake momentarily locked, perhaps with knobby
treads interlocking in a soft surface. Perhaps nobody rides like this,
though.
--
Benjamin Lewis
Now is the time for all good men to come to.
-- Walt Kelly
Joe Riel
> Wouldn't you expect to see more failures in this range? In my estimate
> (if u=0.1) , this would result in a pullout force of 800N on the left
> dropout. For a 90kg rider plus bike, the ejection force would be a lot
> higher than 800N, yet wheel ejection is rare. Possible, but rare.
Each dropout (left and right) has two sides (inside and outside face)
which must both slip. So the force required at each dropout is 2*u*Fc
where Fc is the clamping force.
Joe
James Annan
As I said some time ago (and have said several times since)
Cannondale's own _measurements_ of braking torque imply a peak ejection
force more than twice the value that arises from a 0.6g steady
deceleration, ie around 3800N. Of course that figure is not necessarily
an upper limit.
(google for cannondale brake test).
James
Phil Holman
"Joe Riel" <jo...@k-online.com> wrote in message
news:873bmvo...@k-online.com...
Yes I got that. I was using 400N a side. I had previously calculated a
clamping force of 4kN with u = 1 so if u = 0.1......well, you get the
picture.
Phil H
jim beam
> On 20 Oct 2005 16:00:04 -0700, "gcmsc...@gmail.com"
>
>
>>1.) There is an ejection force in WRT to DISK BRAKE bicycle wheels.
>>
>>2.) This force on DISK BRAKE bicycle wheels has been calculated in the
>>neighborhood of 1k N at the drop out.
>
>
> I thought it was a bit higher, maybe 2kN,
>
>
>>3.) The ISO standard for clamping force of QRs for a DISK BRAKE
>>bicycle wheel is in the neighborhood of 2k N.
>
>
> the ISO standard is for symmetrical pullout force, not clamping force,
> although these two numbers often turn out to be much the same
who cares /what/ the iso standard is? there's no iso standard for fork
fatigue, hydraulic brake pipe burst pressure or stem clamp friction, and
they're all key to rider survival. what matters is whether it exceeds
pullout force, and with a comfortable safety margin.
>
>
>>4.) The actual measured force for QRs which could be used on DISK
>>BRAKE bicycle wheels is in the neighborhood of 5k - 8k N.
>
>
> "when correctly installed to manufacturers specification, something
> which is hard to guage and may be impossible for some users with poor
> hand strength."
>
>
>>5.) Pullout force for DISK BRAKE bicycle wheels is approximately equal
>>to the clamping force exerted by the QR.
>>
>>6.) The difference between ISO standard value and measured value might
>>explain the lack of reported DISK BRAKE bicycle wheel ejection events.
>
>
> "compared with the predictions of Annan's theory, which assumes that
> the in service pullout force is never greater than the ISO minimum"
>
>
>>Another reason might be that lawyer lips prevent a loose axle from
>>fully ejecting.
>
>
>>7.) Serrations on the axle and QR faces used in DISK BRAKE bicycle
>>wheels might (or might not) increase that pullout force.
>
>
> 8.) If the ejection force momentarily exceeds the holding force, the
> transverse motion of the QR thread may cause it to loosen.
dude...
>
> 9.) The ISO standard for wheel pullout provides little or no safety
> margin when disk brakes are used with dropouts angled approximately
> orthogonal to a line joining the brake pad centre to the axle
why bother? that's like saying you want a saftey factor of 5 - just for
the sake of it - when 3 works fine and has the user hours to back it up.
>
> 10.) Proposed solutions to provide a greater certainty of wheel
> retention under heavy braking are:
> to change the dropout angle so that it is not aligned with the
> ejection force (already being implemented by Marzocchi and
> On-One/Planet-X);
> to increase the clamping force of the wheel retention system, such as
> by the use of solid axles with track nuts or hollow axles with large
> diameter bolts;
> to provide a wheel retention system in which the ejection force is not
> resisted solely by a friction, such as a through axle system (already
> rapidly gaining market share on the basis of its other virtues).
>
> If I were feeling Trollish, I might add (this one goes up to 11!)
>
> 11.) Proposed solutions rejected on the grounds of stupidity:
> moving the disc brake caliper to a position in front of the fork leg
rejection is wise.
jim beam
james.
jim beam
he's quiet because he backed the wrong horse on this one ages ago - he
got suckered by the iso red herring, not actual pullout forces. quite
ironic really.
41
> > Responsible, serious, competent engineers do not design in so
> > unforgiving a fashion.
>
> You are preaching to the quoir. The mistake has been made, how deep is
> the doodoo?
If a tree falls in the forest on a mountain biker, and nobody sues, did
it really happen?
It's virtually impossible to know the incidence rate. For cars, like
with the Pinto, or the Firestone/Bridgestone thing, we have an
extensive and thorough legal/safety system which all the accidents were
reported and collated. Even so, it took some while before the patterns
could be identified. It was not easy. For bicycles, we have nothing.
After a crash, the police and the medical professionals just want to
know: "was he wearing a helmet?" The fork manufacturers are telling
people to reset the QRs for every ride. Many MTB people typically drive
to the scene with their bikes on a rack or in the back, front wheel
removed, so they are resetting after every ride anyway. If there is any
serious accident, it gets blamed on operator error anyway, no accident
professional is going through the evidence to reconstruct what
happened. It's all one giant black hole. All we know is that multiple
people have reported problems, we have at least two serious accidents
and probably more, one of these resulting in paralysis. What counts
then is that it simply is not a forgiving design, and should be changed
in some way, at least by turning the dropouts around.
Recently I came across a dude on a hefty MTB with disk brakes... and a
boutique open cam skewer. I chatted with him a bit about the system. He
knew nothing. But, from what I could gather, he was regularly resetting
the QR, either from basic removing and replacing the wheel, or else
just checking that it was tight. From the looks of it he just used it
to ride around in the city anyway. Lucky guy, so far.
gcmsc...@gmail.com
41 wrote:
> Phil Holman wrote:
> > "41" <KingGe...@yahoo.fr> wrote in message
>
> > > Responsible, serious, competent engineers do not design in so
> > > unforgiving a fashion.
> >
> > You are preaching to the quoir. The mistake has been made, how deep is
> > the doodoo?
>
> If a tree falls in the forest on a mountain biker, and nobody sues, did
> it really happen?
>
> It's virtually impossible to know the incidence rate.
That's correct - we have no data whatsoever on how many or few
incidents there have been.
> For bicycles, we have nothing.
A miracle - a concession of lack of knowledge!
> The fork manufacturers are telling
> people to reset the QRs for every ride.
I know for a fact that this doesn't happen for a large contingent of
MTB/disk brake riders.
> If there is any
> serious accident, it gets blamed on operator error anyway, no accident
> professional is going through the evidence to reconstruct what
> happened.
Is it possible that user error is responsible for any potential
incidents?
> All we know is that multiple
> people have reported problems
Err, we have some reports that just so happen to correspond with James'
hypothesis...
> we have at least two serious accidents
> and probably more, one of these resulting in paralysis.
With exactly what *proof* it was caused by disk brakes issues - any of
the issues we're discussing?
None? That's right. The logical fallacy of argument from ignorance.
Nobody has any clue as to how the end result came to be, let alone fix
the blame on bad fork/brake design.
> What counts
> then is that it simply is not a forgiving design, and should be changed
> in some way, at least by turning the dropouts around.
Actually, we have no idea how forgiving the design is. The higher the
peak hypothetical ejection forces, the less bad the design looks. In
fact, it may well be, anecdotal evidence aside, that *no* ejections
have actually occured.
BTW, that completely sets aside jim beam's commentary. I'm arguing
from available data supplied by the side you are arguing from.
E.P.
41
gcmsc...@gmail.com wrote:
> 41 wrote:
> > Phil Holman wrote:
> > > "41" <KingGe...@yahoo.fr> wrote in message
> > What counts
> > then is that it simply is not a forgiving design, and should be changed
> > in some way, at least by turning the dropouts around.
>
> Actually, we have no idea how forgiving the design is. The higher the
> peak hypothetical ejection forces, the less bad the design looks.
You don't understand the concept of a forgiving design. It has nothing
to do with best case scenarios, but rather with middling and worst. w
James Annan
gcmsc...@gmail.com wrote:
> 41 wrote:
> > Phil Holman wrote:
> > > "41" <KingGe...@yahoo.fr> wrote in message
> >
> > > > Responsible, serious, competent engineers do not design in so
> > > > unforgiving a fashion.
> > >
> > > You are preaching to the quoir. The mistake has been made, how deep is
> > > the doodoo?
> >
> > If a tree falls in the forest on a mountain biker, and nobody sues, did
> > it really happen?
> >
> > It's virtually impossible to know the incidence rate.
>
> That's correct - we have no data whatsoever on how many or few
> incidents there have been.
Unless you take even the most cursory glance at a web forum for MTBers,
when you are likely to find...oh look, right at the top of the list of
most recently posted topics:
http://singletrackworld.com/forum/read.php?f=2&i=1996377&t=1996377
Sure, there are people there saying it can't happen. There are also
about half-a-dozen saying they have experienced it directly themselves,
including one describing how the problem appeared immmediately on
upgrading from Vs to disks.
>
> Is it possible that user error is responsible for any potential
> incidents?
It is possible, but is it likely for an individual event on the balance
of probability? If so, you'vev got some explaining to do. Why are there
not similar lists of failures involving v-brakes? What error do you
think the rider I mention above might have made?
>
> > All we know is that multiple
> > people have reported problems
>
> Err, we have some reports that just so happen to correspond with James'
> hypothesis...
Yes, and since the vast majority of them came after I fully described
the problem, the fact that the observed details (unscrewing lever, and
slipping on the LHS) often clearly confirm it is substantial
corroboration. How could I have predicted these things in such detail
if the whole theory was pure speculation? Why can no-one, including
yourself, come up with anything even close to a description as to what
else might possibly be going on here? It's akin to an apple being
dropped, and you saying "well no-one has *proved* it fell due to
gravity". Perhaps you have a theory of Intelligent Falling, or in the
case of QRs, Intelligent Loosening? Please share.
> > we have at least two serious accidents
> > and probably more, one of these resulting in paralysis.
>
> With exactly what *proof* it was caused by disk brakes issues - any of
> the issues we're discussing?
*proof* doesn't work in the real world. "balance of probabilities" and
"beyond reasonable doubt" are two more reasonble tests, the first of
which is obviously passed for many of the accidents (or else there
would be many more involving v brakes) and the second of which is
obviously passed for many of the descriptions of partial failure such
as repeated skewer slipping and unscrewing, although harder to prove
after the fact for an individual crash.
Attempting to cast spurious doubt where there is esentially none is of
course a standard denialist tactic in many spheres of life.
James
gcmsc...@gmail.com
41 wrote:
> gcmsc...@gmail.com wrote:
> > 41 wrote:
> > > Phil Holman wrote:
> > > > "41" <KingGe...@yahoo.fr> wrote in message
>
> > > What counts
> > > then is that it simply is not a forgiving design, and should be changed
> > > in some way, at least by turning the dropouts around.
> >
> > Actually, we have no idea how forgiving the design is. The higher the
> > peak hypothetical ejection forces, the less bad the design looks.
>
> You don't understand the concept of a forgiving design.
Of course I do. Where one draws the line is up for discussion.
> It has nothing
> to do with best case scenarios, but rather with middling and worst.
And the higher the peak forces, the more this design seems able to
handle it. The shear dearth of reported, much less verified, problems
is testimony to that.
E.P.
gcmsc...@gmail.com
James Annan wrote:
> gcmsc...@gmail.com wrote:
> > 41 wrote:
> > > Phil Holman wrote:
> > > > "41" <KingGe...@yahoo.fr> wrote in message
> > >
> > > > > Responsible, serious, competent engineers do not design in so
> > > > > unforgiving a fashion.
> > > >
> > > > You are preaching to the quoir. The mistake has been made, how deep is
> > > > the doodoo?
> > >
> > > If a tree falls in the forest on a mountain biker, and nobody sues, did
> > > it really happen?
> > >
> > > It's virtually impossible to know the incidence rate.
> >
> > That's correct - we have no data whatsoever on how many or few
> > incidents there have been.
>
> Unless you take even the most cursory glance at a web forum for MTBers,
> when you are likely to find...oh look, right at the top of the list of
> most recently posted topics:
>
> http://singletrackworld.com/forum/read.php?f=2&i=1996377&t=1996377
Which, again, says how many or how few incidents have happened? Notice
that *this* thread supports my "proper equipment, used properly" angle.
> > Is it possible that user error is responsible for any potential
> > incidents?
>
> It is possible, but is it likely for an individual event on the balance
> of probability? If so, you'vev got some explaining to do. Why are there
> not similar lists of failures involving v-brakes? What error do you
> think the rider I mention above might have made?
Before you brought it up, I don't think anyone ever thought about it at
all. "Hey, my QR is loose - better fix that up." Never, before the
advent of disk brakes, was there ever a QR loose for some unknown
reason?
This is why your anecdotes don't do much to support you - there's not a
statistic to be found, there's no control group, and every reporter is
self-selected. The ones you present are doubly self-selected.
"On balance of probabilities", my impression, from reading all of this
(not just the parts that suit my biases), is that the system works
fairly well.
In fact, tomorrow I'm going to convert two V-brake bikes to Avid
mechanical disk brakes. And since I actually ride real trails out here
in the western U.S., these bikes probably will see the range of
decelerations indicated in your hypothesis.
> > > All we know is that multiple
> > > people have reported problems
> >
> > Err, we have some reports that just so happen to correspond with James'
> > hypothesis...
>
> Yes, and since the vast majority of them came after I fully described
> the problem, the fact that the observed details (unscrewing lever, and
> slipping on the LHS) often clearly confirm it is substantial
> corroboration.
You're seeing what you want to see. We have no idea what value these
stories have as real data.
You consistently pick the data that supports your view, and dismiss the
data that doesn't. That's got a name over here - "junk science".
> How could I have predicted these things in such detail
> if the whole theory was pure speculation?
Easy - you took available data, and came up with a hypothesis. Then you
present every piece of data that supports your hypothesis while
rejecting any that don't. Viola!
> Why can no-one, including
> yourself, come up with anything even close to a description as to what
> else might possibly be going on here?
We have, James - the fact that you ignore or dismiss alternate ideas
doesn't make them vanish.
> > > we have at least two serious accidents
> > > and probably more, one of these resulting in paralysis.
> >
> > With exactly what *proof* it was caused by disk brakes issues - any of
> > the issues we're discussing?
>
> *proof* doesn't work in the real world.
Of course it does. That's what science is, James. You test your
hypothesis in a controlled manner, and see if experimental result
matches hypothesis. I remember learning this thing called "the
scientific method" in my very first high school chemistry class. I'm
surprised you've never heard of it.
> "balance of probabilities" and
> "beyond reasonable doubt" are two more reasonble tests
If you're a lawyer, yes, that's true. And especially if the issue
cannot be proven in a scientific manner.
But this isn't one of those issues. This one can be proven in a
scinetific manner.
> the first of
> which is obviously passed for many of the accidents (or else there
> would be many more involving v brakes)
*What* accidents? I have heard of *two*, you and Russ Pinder. We have
no idea if his accident was caused in the manner that you describe.
> and the second of which is
> obviously passed for many of the descriptions of partial failure such
> as repeated skewer slipping and unscrewing, although harder to prove
> after the fact for an individual crash.
You're off your rocker. Beyond a reasonable doubt? You already admit
that user error is possible, so there's your doubt right there.
> Attempting to cast spurious doubt where there is esentially none is of
> course a standard denialist tactic in many spheres of life.
While that's really nice of you to say, there are only a very few folk
who have "no doubt". Heck, you don't even know what the clamping
forces of the QR are! I'm not convinced at all that every reaction
force has been addressed, and I am wondering how all those reported "QR
slipping" folks suddenly fixed everything up with a new Shimano QR.
That is one strange piece of data. Totally ignored by you, as well.
I suppose we may see igloos in Hades before the 7700N clamping/pullout
figure makes it onto your webpage, or any of the "I slipped, but then I
found Shimano fixed me right up" stories, hmm?
Remember, only take the data that supports, and ignore the data that
doesn't, and your case is made and accepted. Right?
E.P.
James Annan
>
>
>>>Is it possible that user error is responsible for any potential
>>>incidents?
>>
>>It is possible, but is it likely for an individual event on the balance
>>of probability? If so, you'vev got some explaining to do. Why are there
>>not similar lists of failures involving v-brakes? What error do you
>>think the rider I mention above might have made?
>
>
> Before you brought it up, I don't think anyone ever thought about it at
> all. "Hey, my QR is loose - better fix that up." Never, before the
> advent of disk brakes, was there ever a QR loose for some unknown
> reason?
They all assumed it was user error, because there was no known
alternative. Now they are seeing that a huge preponderance of these
supposed "user error" events happen with disk brakes. How do you explain
that? If you seriously wish to dispute this plain fact, you can start by
finding say 5 cases of rim brake users who found their QR loose
recently, and one person who says it happens reliably.
>
>>>>All we know is that multiple
>>>>people have reported problems
>>>
>>>Err, we have some reports that just so happen to correspond with James'
>>>hypothesis...
>>
>>Yes, and since the vast majority of them came after I fully described
>>the problem, the fact that the observed details (unscrewing lever, and
>>slipping on the LHS) often clearly confirm it is substantial
>>corroboration.
>
>
> You're seeing what you want to see. We have no idea what value these
> stories have as real data.
>
> You consistently pick the data that supports your view, and dismiss the
> data that doesn't. That's got a name over here - "junk science".
So find any data that suggests it happens with rim brakes, to within an
order of magnitude of frequency. Like I said, 5 recent cases including
at least one with repeated problems would be a start.
>
>>Why can no-one, including
>>yourself, come up with anything even close to a description as to what
>>else might possibly be going on here?
>
>
> We have, James - the fact that you ignore or dismiss alternate ideas
> doesn't make them vanish.
>
You don't _have_ any alternative ideas. Just "I don't think it's
proven", while carefully looking the other way when more evidence is put
under your nose.
>
>>the first of
>>which is obviously passed for many of the accidents (or else there
>>would be many more involving v brakes)
>
>
> *What* accidents? I have heard of *two*, you and Russ Pinder. We have
> no idea if his accident was caused in the manner that you describe.
>
If you've bothered to read anything, you will know that there have been
several accidents similar to his, linked from my web pages. If you
haven't even found out that much, just WTF do you think you have to
contribute to this thread?
James
--
James Annan
see web pages for email
http://www.ne.jp/asahi/julesandjames/home/
http://julesandjames.blogspot.com/
jim beam
here-say & conjecture? this is not like you james. oh, wait, maybe it
is. being as you've got nothing to back up your incomplete hypothesis.
tell me, you wouldn't have a bet on this theory of yours would you?
41
gcmsc...@gmail.com wrote:
> 41 wrote:
> > It has nothing
> > to do with best case scenarios, but rather with middling and worst.
>
> And the higher the peak forces, the more this design seems able to
> handle it.
That reply makes no sense whatsoever.
Good luck with your new disk brakes. 6" rotors? Open cam skewer?
Lawyer's lips? Please don't cheat by constantly resetting the QR. Set
it once and forget it, as it was designed to be operated.
gcmsc...@gmail.com
41 wrote:
> gcmsc...@gmail.com wrote:
> > 41 wrote:
>
> > > It has nothing
> > > to do with best case scenarios, but rather with middling and worst.
> >
> > And the higher the peak forces, the more this design seems able to
> > handle it.
>
> That reply makes no sense whatsoever.
To you, I suppose that's true.
> Good luck with your new disk brakes. 6" rotors?
Yes.
> Open cam skewer?
No. New XT.
> Lawyer's lips?
Yes, on both forks.
> Please don't cheat by constantly resetting the QR.
No problem - I plan on setting it and leaving it until I need to change
a tube. My bike racks don't require wheel removal.
> Set
> it once and forget it, as it was designed to be operated.
And I will report if and when I have movement or find my QR loose.
Unlike you folks whose egos are completely wrapped up in being right, I
only care about data.
Oh, BTW - one of the bikes will be used with slick tires on asphalt for
commuting. Since I only use the front brake when I'm commuting, 0.6g
deceleration figures should be easy to accomplish - every day, several
times. In fact, while I'm bedding in the pads, I'll be doing quite a
number of these sorts of stops.
E.P.
gcmsc...@gmail.com
James Annan wrote:
> gcmsc...@gmail.com wrote:
> > James Annan wrote:
> >
> >>gcmsc...@gmail.com wrote:
> >>
>
> >
> >
> >>>Is it possible that user error is responsible for any potential
> >>>incidents?
> >>
> >>It is possible, but is it likely for an individual event on the balance
> >>of probability? If so, you'vev got some explaining to do. Why are there
> >>not similar lists of failures involving v-brakes? What error do you
> >>think the rider I mention above might have made?
> >
> >
> > Before you brought it up, I don't think anyone ever thought about it at
> > all. "Hey, my QR is loose - better fix that up." Never, before the
> > advent of disk brakes, was there ever a QR loose for some unknown
> > reason?
>
> They all assumed it was user error, because there was no known
> alternative.
Exactly - and the same sorts of errors still exist. Disk brakes did
not all of a sudden make these errors disappear.
> Now they are seeing that a huge preponderance of these
> supposed "user error" events happen with disk brakes.
Huge preponderance? LOL. Quantify in numbers, with some statistical
analysis.
> How do you explain
> that?
Explain what? These sorts of errors happened before disk brakes, and
are continuing to happen. Thus far, you have presented NOTHING in the
way of separating them. We have absolutely no idea what the actual
real-world effect happens to be. THis is probably my biggest problem
with your position - you take these stories as evidence, when you have
no idea what the signal:noise is.
> If you seriously wish to dispute this plain fact, you can start by
> finding say 5 cases of rim brake users who found their QR loose
> recently, and one person who says it happens reliably.
Because, repeating your erroneous sampling method thus makes it data?
LOL.
You're not talking to some rube with no clue as to proper data
collection methods. You'll not convince me that any of the anecdotes
you present is anything like data, until your sampling method and
statistical analysis methods are presented.
> >>>>All we know is that multiple
> >>>>people have reported problems
> >>>
> >>>Err, we have some reports that just so happen to correspond with James'
> >>>hypothesis...
> >>
> >>Yes, and since the vast majority of them came after I fully described
> >>the problem, the fact that the observed details (unscrewing lever, and
> >>slipping on the LHS) often clearly confirm it is substantial
> >>corroboration.
> >
> >
> > You're seeing what you want to see. We have no idea what value these
> > stories have as real data.
> >
> > You consistently pick the data that supports your view, and dismiss the
> > data that doesn't. That's got a name over here - "junk science".
>
> So find any data that suggests it happens with rim brakes, to within an
> order of magnitude of frequency. Like I said, 5 recent cases including
> at least one with repeated problems would be a start.
So, if I engage in junk science, that validates your junk science?
Holy crap.
> >>Why can no-one, including
> >>yourself, come up with anything even close to a description as to what
> >>else might possibly be going on here?
> >
> > We have, James - the fact that you ignore or dismiss alternate ideas
> > doesn't make them vanish.
> >
>
> You don't _have_ any alternative ideas.
You trimmed at least one from my last post. The other is that the QR
grips somewhat better than you seem to believe.
Chopped liver?
> Just "I don't think it's
> proven", while carefully looking the other way when more evidence is put
> under your nose.
So far, the only "evidence" you have is a FBD. The rest of your
"evidence", I don't accept as data, but I do concede that it is
interesting.
> >>the first of
> >>which is obviously passed for many of the accidents (or else there
> >>would be many more involving v brakes)
> >
> > *What* accidents? I have heard of *two*, you and Russ Pinder. We have
> > no idea if his accident was caused in the manner that you describe.
>
> If you've bothered to read anything, you will know that there have been
> several accidents similar to his, linked from my web pages.
Yes, and they are even less valuable than Russ' incident, as far as
"evidence" goes. I had an accident, there's an ejection force, BINGO!
Argument from ignorance.
I am allowing both Russ' and your accidents as potential ejection
events. The others, not so much. Show me your sampling and analysis
methods, and we'll have something more to discuss about the stories
you've collected, which, oh by the way, happen to support your
contentions.
E.P.
Jasper Janssen
>James Annan wrote:
>> As I said some time ago (and have said several times since)
>> Cannondale's own _measurements_ of braking torque imply a peak ejection
>> force more than twice the value that arises from a 0.6g steady
>> deceleration, ie around 3800N. Of course that figure is not necessarily
>> an upper limit.
>>
>> (google for cannondale brake test).
>and still it's not high enough to cause ejection! clutch those straws
4 grand compared to 7 grand-when-done-up-perfectly-with-good-skewers isn't
very comforting as a safety margin though. You keep saying that it doesn't
matter that sometimes users do something wrong, because then it's their
own damn fault if they wipe out on the track. That's really my primary
reason for thinking you're an arrogant son-of-a-bitch with no real
conception of a) the real world and b) the legal world.
Jasper
Jasper Janssen
<gcmsc...@gmail.com> wrote:
>Which, again, says how many or how few incidents have happened? Notice
>that *this* thread supports my "proper equipment, used properly" angle.
[...]
>While that's really nice of you to say, there are only a very few folk
>who have "no doubt". Heck, you don't even know what the clamping
>forces of the QR are! I'm not convinced at all that every reaction
>force has been addressed, and I am wondering how all those reported "QR
>slipping" folks suddenly fixed everything up with a new Shimano QR.
>That is one strange piece of data. Totally ignored by you, as well.
>
>I suppose we may see igloos in Hades before the 7700N clamping/pullout
>figure makes it onto your webpage, or any of the "I slipped, but then I
>found Shimano fixed me right up" stories, hmm?
So, what you're saying is that riding with Shimpy skewers is just fine and
dandy, but anyone who uses a different skewer and finds problems it's his
own damn fault? Even if it were true that Shimano skewers never failed,
that rather indicates that the margin of error is fairly narrow, if merely
switching to lesser skewers causes serious, lethal problems.
Jasper
Jasper Janssen
>In article <dj5i21$1gjs$1...@f04n12.cac.psu.edu>,
> dvt <dvt+u...@psu.edu> wrote:
>
>> jim beam wrote:
>> > that's another example of the logical disconnect that allows you to
>> > claim that indented fork ends don't affect pullout force.
>>
>> The data in another thread shows evidence that indented/embossed fork
>> ends don't greatly affect pullout force. Here's the message ID for that
>> data in case you missed it: 87zmp6n...@k-online.com.
>
>We are better off when you enclose the message ID in angle
>brackets. Then the reader of the message can retrieve it
>from his ISP's news server by clicking on it.
><87zmp6n...@k-online.com>
If you had an even halfway decent reader, it'd deal with bracketless
msgIDs just fine.
>I want to avoid the google interface. Usenet is a plain
>text medium run off port 119, not a mark up medium run off
>port 80. google interferes with the plain text format.
>They treat us like they own usenet.
Bull and shit. What they in *fact* own is Google Groups, which is *an*
interface to usenet. They don't attempt in any way to push standards onto
greater usenet. In fact, what they do is treat Google Groups like they own
it.
Which they do.
Jasper
James Annan
>
> here-say & conjecture? this is not like you james. oh, wait, maybe it
> is. being as you've got nothing to back up your incomplete hypothesis.
> tell me, you wouldn't have a bet on this theory of yours would you?
>
I will bet $10,000 that I could set up a straightforward test in which a
correctly operated skewer slips under normal riding conditions.
For a $20,000 bet I would fly to the states (or wherever your rock
happens to be) and do it in front of your face.
Time to wriggle and squirm a bit more jim....
James Annan
> James Annan wrote:
>
>>If you seriously wish to dispute this plain fact, you can start by
>>finding say 5 cases of rim brake users who found their QR loose
>>recently, and one person who says it happens reliably.
>
>
> Because, repeating your erroneous sampling method thus makes it data?
> LOL.
>
> You're not talking to some rube with no clue as to proper data
> collection methods.
I'm talking to some clueless anonymous troll who is relying on
invincible ignorance as a justification for "I don't believe it".
>>You don't _have_ any alternative ideas.
>
>
> You trimmed at least one from my last post. The other is that the QR
> grips somewhat better than you seem to believe.
How does that explain the list of stories?
Oh look, here is another one, from just last week:
Can you say anything more interesting than "lalalalala I'm not listening"?
gcmsc...@gmail.com
James Annan wrote:
> gcmsc...@gmail.com wrote:
>
> > James Annan wrote:
> >
> >>If you seriously wish to dispute this plain fact, you can start by
> >>finding say 5 cases of rim brake users who found their QR loose
> >>recently, and one person who says it happens reliably.
> >
> >
> > Because, repeating your erroneous sampling method thus makes it data?
> > LOL.
> >
> > You're not talking to some rube with no clue as to proper data
> > collection methods.
>
> I'm talking to some clueless anonymous troll who is relying on
> invincible ignorance as a justification for "I don't believe it".
LOL. A sure indication that you have lost traction in an argument is
to call names.
It's obvious that you know I'm *exactly right*. Your *data* wouldn't
stand any scrutiny from the scientific community, and only a bit from
the ambulance-chasers.
> >>You don't _have_ any alternative ideas.
> >
> >
> > You trimmed at least one from my last post. The other is that the QR
> > grips somewhat better than you seem to believe.
>
>
> How does that explain the list of stories?
It doesn't. Or, I should say more exactly, it explains them just as
well as you have done. They are just stories, with so many unknown
variables as to be worthless as data.
> Oh look, here is another one, from just last week:
>
> <http://www.bikemagic.com/forum/forummessages/mps/UTN/69377/URN/3/dt/1/srchdte/0/cp/1/v/6/sp/622851226925494229658>
>
> Can you say anything more interesting than "lalalalala I'm not listening"?
Yeah - what kind of brakes was this poor fellow using? His post
doesn't make it clear. Surely you didn't just ASSume he was using disk
brakes, right? Another example of you using a story with important
unknown variables. The use of inductive reasoning is termed "junk
science", James.
The rest of the posts make clear that Hope QRs aren't the best for MTB
applications, but it seems that the name Shimano comes up again as the
cure - what an odd result. But surely not ALL those poor folks in that
thread that decried Hope QRs are using disk brakes, right?
Better whip out your calculator again, James. Seems something's amiss
with your hypothesis.
E.P.
gcmsc...@gmail.com
Jasper Janssen wrote:
> On Thu, 20 Oct 2005 19:25:12 -0700, jim beam <nos...@example.net> wrote:
> >James Annan wrote:
>
> >> As I said some time ago (and have said several times since)
> >> Cannondale's own _measurements_ of braking torque imply a peak ejection
> >> force more than twice the value that arises from a 0.6g steady
> >> deceleration, ie around 3800N. Of course that figure is not necessarily
> >> an upper limit.
> >>
> >> (google for cannondale brake test).
>
> >and still it's not high enough to cause ejection! clutch those straws
>
> 4 grand compared to 7 grand-when-done-up-perfectly-with-good-skewers isn't
> very comforting as a safety margin though.
This ASSumes that the calculated ejection force is actually correct.
Or that the retention forces from the experiments are not artificially
low for some reason.
If folks are getting 3800N spikes, and still retaining their wheels
(allowing that to be qualified with "in very large part"), then James'
calculation must be missing *something* *somewhere*. 3800N exceeds the
minimum standard by over 50%.
E.P.
James Annan
> James Annan wrote:
>
>>gcmsc...@gmail.com wrote:
>>
>>
>>>James Annan wrote:
>>>
>>>
>>>>If you seriously wish to dispute this plain fact, you can start by
>>>>finding say 5 cases of rim brake users who found their QR loose
>>>>recently, and one person who says it happens reliably.
>>>
>>>
>>>Because, repeating your erroneous sampling method thus makes it data?
>>>LOL.
>>>
>>>You're not talking to some rube with no clue as to proper data
>>>collection methods.
>>
>>I'm talking to some clueless anonymous troll who is relying on
>>invincible ignorance as a justification for "I don't believe it".
>
>
> LOL. A sure indication that you have lost traction in an argument is
> to call names.
>
> It's obvious that you know I'm *exactly right*. Your *data* wouldn't
> stand any scrutiny from the scientific community, and only a bit from
> the ambulance-chasers.
>
I'll repeat the offer I made to jim beam. $10,000 says I can demonstrate
this failure under normal operating conditions. Put up, or shut up...or
squirm pathetically about how you don't really believe it but but but...
Your call.
gcmsc...@gmail.com
James Annan wrote:
> gcmsc...@gmail.com wrote:
>
> I'll repeat the offer I made to jim beam. $10,000 says I can demonstrate
> this failure under normal operating conditions.
Using the equipment of my choice, set up by me, of course.
E.P.
gcmsc...@gmail.com
Jasper Janssen wrote:
> On 21 Oct 2005 06:03:12 -0700, "gcmsc...@gmail.com"
> <gcmsc...@gmail.com> wrote:
>
> >Which, again, says how many or how few incidents have happened? Notice
> >that *this* thread supports my "proper equipment, used properly" angle.
> [...]
> >While that's really nice of you to say, there are only a very few folk
> >who have "no doubt". Heck, you don't even know what the clamping
> >forces of the QR are! I'm not convinced at all that every reaction
> >force has been addressed, and I am wondering how all those reported "QR
> >slipping" folks suddenly fixed everything up with a new Shimano QR.
> >That is one strange piece of data. Totally ignored by you, as well.
> >
> >I suppose we may see igloos in Hades before the 7700N clamping/pullout
> >figure makes it onto your webpage, or any of the "I slipped, but then I
> >found Shimano fixed me right up" stories, hmm?
>
What I am saying is written above.
> ...if merely
> switching to lesser skewers causes serious, lethal problems.
My, oh, my! Lethal, huh?
OK.
E.P.
Phil Holman
<gcmsc...@gmail.com> wrote in message
news:1129937779.0...@o13g2000cwo.googlegroups.com...
I'll go one better. Under normal operating conditions, I'll bet I can
set up the bike for failure or not. There, what does that prove?
Phil H
James Annan
Using equipment widely available in the marketplace, set up using
standard advice from manufacturers and (eg) the Barnett manual.
Based on your comment above, it seems that you don't believe that my
conditions will ensure safety - which is precisely my point.
James Annan
It proves that the system is not designed correctly, as it should be
guaranteed safe under correct usage (and some would argue it should have
a significant margin of safety even for slightly incorrect use - I don't
need to go that far to make my point though).
James Annan
> Jasper Janssen wrote:
>
>
>>...if merely
>>switching to lesser skewers causes serious, lethal problems.
>
>
> My, oh, my! Lethal, huh?
>
It seems likely that this guy would have died had there not been a
rescue helicopter on a training exercise in the area (IIRC he got to
hospital within an hour of his crash in open countryside!). As it was,
he spent 2 weeks in a coma:
http://www.singletrackworld.com/article.php?sid=1309
Surprise, the article doesn't mention his disk brakes. It's odd that a
trade-supported MTB publication didn't want to mention that fact, no?
Of course, since you already read my web pages, you already know about
this story.
frkr...@yahoo.com
gcmsc...@gmail.com wrote:
> >
> LOL. A sure indication that you have lost traction in an argument is
> to call names.
If so, that's an indication that your lost traction in your argument
long ago!
Quoting "gmschemist" from September 21: "You're obviously a
blithering idiot..."
Quoting "gmschemist" from October 12: "... you pedantic shithead."
At least, try for internal consistency. It won't make you look
intelligent, but it will make you look a _little_ less biased.
- Frank Krygowski
jim beam
> jim beam wrote:
>
>>
>> here-say & conjecture? this is not like you james. oh, wait, maybe
>> it is. being as you've got nothing to back up your incomplete
>> hypothesis. tell me, you wouldn't have a bet on this theory of yours
>> would you?
>>
>
> I will bet $10,000 that I could set up a straightforward test in which a
> correctly operated skewer slips under normal riding conditions.
>
> For a $20,000 bet I would fly to the states (or wherever your rock
> happens to be) and do it in front of your face.
>
> Time to wriggle and squirm a bit more jim....
>
> James
you want to fly here to pay me $20k? you're insane.
jim beam
> gcmsc...@gmail.com wrote:
>
>> James Annan wrote:
>>
>>> gcmsc...@gmail.com wrote:
>>>
>>> I'll repeat the offer I made to jim beam. $10,000 says I can demonstrate
>>> this failure under normal operating conditions.
>>
>>
>>
>> Using the equipment of my choice, set up by me, of course.
>
>
> Using equipment widely available in the marketplace, set up using
> standard advice from manufacturers and (eg) the Barnett manual.
>
> Based on your comment above, it seems that you don't believe that my
> conditions will ensure safety - which is precisely my point.
>
> James
set out your stall - show us the math. show us that ejection exceeds
pullout.
jim beam
> gcmsc...@gmail.com wrote:
>
>> Jasper Janssen wrote:
>>
>>
>>> ...if merely
>>> switching to lesser skewers causes serious, lethal problems.
>>
>>
>>
>> My, oh, my! Lethal, huh?
>>
>
> It seems likely that this guy would have died had there not been a
> rescue helicopter on a training exercise in the area (IIRC he got to
> hospital within an hour of his crash in open countryside!). As it was,
> he spent 2 weeks in a coma:
>
> http://www.singletrackworld.com/article.php?sid=1309
>
> Surprise, the article doesn't mention his disk brakes. It's odd that a
> trade-supported MTB publication didn't want to mention that fact, no?
>
> Of course, since you already read my web pages, you already know about
> this story.
>
> James
eh? you have some serious victim persecution complex there james.
perhaps that's why you fled to an alien land where the natives don't
understand you but forgive you on the basis of cultural idiosyncrasy?
gcmsc...@gmail.com
James Annan wrote:
> gcmsc...@gmail.com wrote:
>
> > James Annan wrote:
> >
> >>gcmsc...@gmail.com wrote:
> >>
> >>I'll repeat the offer I made to jim beam. $10,000 says I can demonstrate
> >>this failure under normal operating conditions.
> >
> >
> > Using the equipment of my choice, set up by me, of course.
>
> Using equipment widely available in the marketplace, set up using
> standard advice from manufacturers and (eg) the Barnett manual.
>
> Based on your comment above, it seems that you don't believe that my
> conditions will ensure safety - which is precisely my point.
No, I believe it entirely possible to pick some absolute worst
combination that might fail under some circumstance.
Which, if you haven't been paying attention, I have acknowledged was
possible from the beginning.
But, when I think on it a bit, I'm already making a wager. On one
side, there's my health, and if the hyperbole is to be believed, my
very life. If I win, I get the pleasure of a braking system that works
more reliably in conditions under which my current system is marginal.
Which, BTW, can be quite dangerous.
On the other side, if my set-up fails, you have the pleasure of being
able to gloat and say "I told you so" when I need an expert witness for
the surely successful lawsuit against several manufacturers. You will
have the honor of being handsomely rewarded, in addition to the main
benefit of gloating rights. Of course, it'll be a slam dunk, because
nobody in their right mind will be able to assail my committment to
avoiding user error.
Now, that's a wager you should be completely able to accept. No risk
for you, and chance of substantial ego and monetary rewards. All the
risk for me, and no reward other than the pleasure of riding bike.
Now, in order to make the forensic portion complete, remember that
there will be TWO bikes, equally set up. One will have slicks, and be
a commuter. the other will be a regular mountain bike, ridden for that
purpose. Anyone will be able to examine the other bike for whether or
not I properly operated the proper equipment.
Science, James. Nothing more, nothing less.
Are we on?
E.P.
jim beam
you're wasting your time. annan's not interested in the science or he'd
have done the pullout math at any time in the last 2 years. all he
wants is attention & sensation. which i guess he's already getting.
gcmsc...@gmail.com
James Annan wrote:
> gcmsc...@gmail.com wrote:
>
> > Jasper Janssen wrote:
> >
> >
> >>...if merely
> >>switching to lesser skewers causes serious, lethal problems.
> >
> >
> > My, oh, my! Lethal, huh?
> >
>
> It seems likely that this guy would have died had there not been a
> rescue helicopter on a training exercise in the area (IIRC he got to
> hospital within an hour of his crash in open countryside!). As it was,
> he spent 2 weeks in a coma:
>
> http://www.singletrackworld.com/article.php?sid=1309
>
> Surprise, the article doesn't mention his disk brakes. It's odd that a
> trade-supported MTB publication didn't want to mention that fact, no?
>
> Of course, since you already read my web pages, you already know about
> this story.
LOL. Conspiracy against James Annan.
Right.
E.P.
gcmsc...@gmail.com
frkr...@yahoo.com wrote:
> gcmsc...@gmail.com wrote:
> > >
> > LOL. A sure indication that you have lost traction in an argument is
> > to call names.
>
> If so, that's an indication that your lost traction in your argument
> long ago!
>
> Quoting "gmschemist" from September 21: "You're obviously a
> blithering idiot..."
Said to you, who have nothing of substance to offer, and in fact claim
that things that are obviously in existence can't possibly be.
> Quoting "gmschemist" from October 12: "... you pedantic shithead."
Said to David Damerell, about something other than disk brakes.
> At least, try for internal consistency. It won't make you look
> intelligent, but it will make you look a _little_ less biased.
Please shut up. Your cherrypicked quotes do nothing to support your
point, and nothing to minimize mine.
E.P.
gcmsc...@gmail.com
James Annan wrote:
> Phil Holman wrote:
>
> > <gcmsc...@gmail.com> wrote in message
> > news:1129937779.0...@o13g2000cwo.googlegroups.com...
> >
> >>James Annan wrote:
> >>
> >>>gcmsc...@gmail.com wrote:
> >>>
> >>>I'll repeat the offer I made to jim beam. $10,000 says I can
> >>>demonstrate
> >>>this failure under normal operating conditions.
> >>
> >>Using the equipment of my choice, set up by me, of course.
> >
> >
> > I'll go one better. Under normal operating conditions, I'll bet I can
> > set up the bike for failure or not. There, what does that prove?
>
> It proves that the system is not designed correctly, as it should be
> guaranteed safe under correct usage
Define "correct useage". But before you do, make sure everyone agrees
on what that entails. Your personal definition isn't binding on
everyone.
E.P.
Andrew Lee
You are so dense. Why do you think he would be doing the paying? What he
wants to show you has already been observed and mentioned in numerous cases.
For example this link was posted here last week:
http://www.velonews.com/tech/report/articles/5432.0.html
Quoting Zinn:
"Clearly, if you have a dropout that opens straight down, as most forks
have, you had better have that hub clamped tightly in the dropout or it will
come straight down out of the dropout slot! Now, not all QR skewers are
created equal. I have noticed on my own mountain bikes, all of which have
disc brakes, that if I use a skewer where the lever is aluminum with an
off-center hole at its rounded end to create the cam, I get downward
movement of the axle in the dropout. After riding, I notice this by flipping
the front skewer open when the bike is standing on its wheels. If the fork
drops down a bit to clunk back down onto the axle, I know that that hub
moved down in the dropout while riding."
I would laugh if you can say that Zinn doesn't know how to operate a quick
release. Annan would just have to repeat the same thing that Zinn has
experienced and you would be the one paying up. Remember the conditions:
correctly operated skewer slips under normal riding conditions. Quoting
Zinn's solution:
"The solution I have adopted for my own bikes is to only use front skewers
that have a high clamping force. An example would be Shimano and Campagnolo
skewers where the end of the lever is formed into a cam bent at 90 degrees
from the lever arm and inserted into a round hole in the end of the skewer
rod. These and the type of skewers on Mavic Ksyrium or CrossMax wheels seem
to create a higher clamping force for the same amount of force used pushing
the lever over when installing the wheel. After riding with skewers like
these, if I flip my front lever open, the bike does not clunk down onto the
axle; it is still fully seated into the dropout. No matter what, you need to
tighten your front skewer about as hard as you can with a front disc brake."
So, Zinn recommends Shimano or Campagnolo skewers tightened "about as hard
as you can". Didn't someone in this thread point out that new Campagnolo
skewers and axle nuts have flat faces? And tightened "about as hard as you
can" is doing much more than just "correctly operating" a skewer. Unless
fork manufacturers are listing acceptable skewers, there is no reason to say
that using skewers other than Shimano or Campagnolo is not following correct
procedures. That would be following your recommendation, not the fork
manufacturer's. How many people do you think read what you write on
rec.bicycles.tech? I would bet that 95+% of cyclists using disc brakes have
not heard of the ejection possibility in the first place. For this large
group, using ANY widely availabe skewer with MODERATE tightness would be
using "correct procedures". The ones with technical background like Zinn
realize what is going on when they find their axles dropping back down onto
the axle. Others that have the same issue don't notice or and don't give a
second thought to the physical evidence in front of them until something
really goes wrong... after all, no one told them of the possibility.
gcmsc...@gmail.com
He'll get it if my front wheel separates and I crash. After a year of
research on disk brakes, and holding off for several months while I
read every thread in these interminable r.b.t ego-fests, I decided,
that on balance of probabilities, my disk brake/QR set-up will not give
me a moment of trouble.
James' jihad, along with his sycophantic hangers-on, will fade into
obscurity. The design will be modified slightly on further QR
disk-brake forks, but I doubt we'll ever see 100% through-axle or any
front-caliper/QR forks.
How may brake pad sets should I wear out before I can call my
experiment success?
E.P.
Andrew Lee
Why do you need to do the math? It has been demonstrated. If your math
doesn't show that it's possible, then you picked the wrong assumptions or
did the math wrong. Refer to my other post above regarding Zinn's
observations.
gcmsc...@gmail.com
James Annan wrote:
> gcmsc...@gmail.com wrote:
>
> > James Annan wrote:
> >
> >>gcmsc...@gmail.com wrote:
> >>
> >>
> >>>James Annan wrote:
> >>>
> >>>
> >>>>If you seriously wish to dispute this plain fact, you can start by
> >>>>finding say 5 cases of rim brake users who found their QR loose
> >>>>recently, and one person who says it happens reliably.
> >>>
> >>>
> >>>Because, repeating your erroneous sampling method thus makes it data?
> >>>LOL.
> >>>
> >>>You're not talking to some rube with no clue as to proper data
> >>>collection methods.
> >>
> >>I'm talking to some clueless anonymous troll who is relying on
> >>invincible ignorance as a justification for "I don't believe it".
> >
> >
> > LOL. A sure indication that you have lost traction in an argument is
> > to call names.
> >
> > It's obvious that you know I'm *exactly right*. Your *data* wouldn't
> > stand any scrutiny from the scientific community, and only a bit from
> > the ambulance-chasers.
> >
>
> I'll repeat the offer I made to jim beam. $10,000 says I can demonstrate
> this failure under normal operating conditions.
I see you trimmed yet another inconvenient question about your "data".
Whenever it comes to answering the hard questions, it's red herring
time at the Annan Place...
E.P.
gcmsc...@gmail.com
Andrew Lee wrote:
> "jim beam" <nos...@example.net> wrote:
>
> > you're wasting your time. annan's not interested in the science or he'd
> > have done the pullout math at any time in the last 2 years. all he wants
> > is attention & sensation. which i guess he's already getting.
>
> Why do you need to do the math? It has been demonstrated.
It has? *Some* math has been demonstrated.
And some has been left out. And some not considered at all.
No, if all the math required had already been done, there'd be carnage.
But there isn't. So, more math is required. Probably in conjunction
with controlled experiments.
E.P.
James Annan
Of course. It seems clear that the main point of possible disagreement
would be in skewer tension. I already pointed to manufacturers'
instructions and Barnett as possible definitions of "correct". Since I
have a quote to hand, DeLong (Cycling Science 1991) recommends a
_maximum_ closing force of 45 pounds applied at 55mm from the pivot
(about 20 foot-pounds of torque). If you object to that, please suggest
an alternative (and your rationale). Do you think there are any other
important details to nail down?
James Annan
> James Annan wrote:
>
>>gcmsc...@gmail.com wrote:
>>
>>
>>>James Annan wrote:
>>>
>>>
>>>>gcmsc...@gmail.com wrote:
>>>>
>>>>I'll repeat the offer I made to jim beam. $10,000 says I can demonstrate
>>>>this failure under normal operating conditions.
>>>
>>>
>>>Using the equipment of my choice, set up by me, of course.
>>
>>Using equipment widely available in the marketplace, set up using
>>standard advice from manufacturers and (eg) the Barnett manual.
>>
>>Based on your comment above, it seems that you don't believe that my
>>conditions will ensure safety - which is precisely my point.
>
>
> No, I believe it entirely possible to pick some absolute worst
> combination that might fail under some circumstance.
Even under correct operation? With equipment that is commonly available
and widely used?
In that case, I don't think we have any further disagreement about the
engineering aspects.
The moral, legal and economic implications of the engineering are a
different matter, but not particularly relevant to r.b.tech.
James Annan
> gcmsc...@gmail.com wrote:
>
>> Define "correct useage". But before you do, make sure everyone agrees
>> on what that entails. Your personal definition isn't binding on
>> everyone.
>
>
> Of course. It seems clear that the main point of possible disagreement
> would be in skewer tension. I already pointed to manufacturers'
> instructions and Barnett as possible definitions of "correct". Since I
> have a quote to hand, DeLong (Cycling Science 1991) recommends a
> _maximum_ closing force of 45 pounds applied at 55mm from the pivot
> (about 20 foot-pounds of torque). If you object to that, please suggest
> an alternative (and your rationale). Do you think there are any other
> important details to nail down?
Salsa recommend a closing force of 24-30 pounds - they do not actually
give a torque, but the standard 55mm distance from the pivot implies a
value of around 15 foot-pounds of torque should be ample.
James Annan
> James Annan wrote:
>
>> gcmsc...@gmail.com wrote:
>>
>
>>> Define "correct useage". But before you do, make sure everyone agrees
>>> on what that entails. Your personal definition isn't binding on
>>> everyone.
>>
>>
>>
>> Of course. It seems clear that the main point of possible disagreement
>> would be in skewer tension. I already pointed to manufacturers'
>> instructions and Barnett as possible definitions of "correct". Since I
>> have a quote to hand, DeLong (Cycling Science 1991) recommends a
>> _maximum_ closing force of 45 pounds applied at 55mm from the pivot
>> (about 20 foot-pounds of torque). If you object to that, please
>> suggest an alternative (and your rationale). Do you think there are
>> any other important details to nail down?
>
>
> Salsa recommend a closing force of 24-30 pounds - they do not actually
> give a torque, but the standard 55mm distance from the pivot implies a
> value of around 15 foot-pounds of torque should be ample.
Sorry, those torque values are nonsense. The quoted numbers are correct
though - which means a torque of about 50-60 pound-inches must be
considered ample. Nashbar also quotes 43-65 inch-pounds for their
skewers (which may mean their own brand, or general advice for all the
varieties they sell, I don't know).
jim beam
does it happen that zinn does what i do? yes. does he do it /because/
i do it or have written about it? i have no idea - and doubt it. do
r.b.t lurkers outnumber contributors and talk to their friends who talk
to lawyers, engineers, people in the industry? who knows! and i really
don't care. if i did, i'd write books, tirelessly promote them, publish
web pages and control content so that no one else had any input, all in
an attempt to bend the world to suit me.
bottom line, this is an open forum. you can say whatever you want, and
disagree as much as you want, rhyme, reason or none. is good skewer
practice essential? yes, of course. and so is good handlebar
attachment practice, good brake maintenance practice, good frame crack
inspection practice, etc. perhaps you want to broaden this discussion
by debating front positioning of road bike brake calipers instead of
rear where it would be safer. how about brake caliper cable clamp designs?
you see where i'm going? what matters is whether the freds are injuring
themselves. and with disk brakes, they're not. just like with the
other potentially fatal "design flaws" i've cited above. why the
disparity between disk brake ejection theory and practice? there /has/
to be a reason! all /you/ need to do, as someone that's shown at least
a little technical interest in the past, is consider the facts as they
have been discussed. if you disagree with any summaries of the debate
so far, go ahead and write your own and post accordingly. if i disagree
with you, you'll hear about it. but rehashing of old material, bringing
nothing new to the table, achieves what? instead, maybe you could take
a stab at the pullout force calc? no one else around here seems to be
interested. or capable.
frkr...@yahoo.com
gcmsc...@gmail.com wrote:
> frkr...@yahoo.com wrote:
> > gcmsc...@gmail.com wrote:
> > > >
> > > LOL. A sure indication that you have lost traction in an argument is
> > > to call names.
> >
> > If so, that's an indication that your lost traction in your argument
> > long ago!
> >
> > Quoting "gmschemist" from September 21: "You're obviously a
> > blithering idiot..."
>
True, and nicely confessed.
> > Quoting "gmschemist" from October 12: "... you pedantic shithead."
>
> Said to David Damerell...
True again. Oh, and other examples are possible, of course. But
further confessions are redundant.
>
> > At least, try for internal consistency. It won't make you look
> > intelligent, but it will make you look a _little_ less biased.
>
> Please shut up. Your cherrypicked quotes...
They are, indeed, quotes. i.e. the guy who claimed namecalling
indicates weak argument is, indeed, indulging in namecalling. And, I
might add, lacks courage to give his real name.
To me, it looks like bias combined with cowardice and (by his own
standards) weak argument.
- Frank Krygowski
jim beam
technical side of this debate frank - pissing match being the only thing
to which you've devoted any time. what kind of example do you think
that sets your students? do your departmental peers enjoy similarly
enlightening contributions from you - or is this just a behavior you
reserve for a forum in which there's no risk of personal confrontation?
41
Frank, if you looked over the list of students you've flunked out over
the years, probably this dude is on it..