summary - the disk brake debate
jim beam
we have:
1. annan's theory which calculates supposed ejection force and tells us
that the sky is about to fall.
2. the cpc, the cycling industry and a total lack of accident incidence
saying it doesn't.
3. a theory explaining the reason for the inconsistency - that of actual
pullout force exceeding ejection force
4. the logical conclusion that annan's theory is therefore incomplete.
5. a core of space cadets that argue, despite point 4 above, that there
is some kind of design flaw - much as a bridge is destined to fail as
soon as it's loaded, apparently.
6. an intriguing group of secondary hangers-on that are arguing the toss
in the face of all logic, reason or math, just for the sheer devilment
of it.
and what is the result?
our lemming-like suicide squad of primary morons apparently determined
to undermine and explode any credibility or influence this group may
have on an activity and sport we all supposedly love. all as our
secondary participants & silent watchers throw stones, stand by, watch,
or effectively condone this behavior!!!
no one has the minerals to grasp reality. no one has the grace to
concede any fault - on either side. the word "consensus" has never even
passed the mind. and AMAZINGLY, we have individuals, allegedly of an
engineering bent, who won't discuss the math!!! i'm calling it for what
it is - fucking asinine. i've never seen such sheer bloody-minded
unreasoning stupidity in my life before. you know who you are. you
call yourselves engineers when you fight shy of fact? you need to learn
the meaning of the word "shame". you're a disgrace to your universities.
dvt
> ok, so that idiocy has been rolling on for nearly 3 weeks now, and still
> we have:
[snip]
Thanks for that enlightening and helpful information!
--
Dave
dvt at psu dot edu
James Annan
> ok, so that idiocy has been rolling on for nearly 3 weeks now, and still
> we have:
>
> 1. annan's theory which calculates supposed ejection force
Are you going to share your own estimate? You'll obviously want to take
account of the 235 foot-pounds of torque that Cannondale measured (with
a medium-sized rider riding round a car park):
http://www.ne.jp/asahi/julesandjames/home/disk_and_quick_release/cannondale.html
I'm really surprised why you seem to keep trying to beat yourself up
over this. You guessed wrong, the world passed you by. Better luck next
time eh?
James
--
James Annan
see web pages for email
http://www.ne.jp/asahi/julesandjames/home/
http://julesandjames.blogspot.com/
motorhommer
James Annan Wrote:
> jim beam wrote:
>
> > ok, so that idiocy has been rolling on for nearly 3 weeks now, and
> still
> > we have:
> >
> > 1. annan's theory which calculates supposed ejection force
>
> Are you going to share your own estimate? You'll obviously want to
> take
> account of the 235 foot-pounds of torque that Cannondale measured
> (with
> a medium-sized rider riding round a car park):
>
>
> I'm really surprised why you seem to keep trying to beat yourself up
> over this. You guessed wrong, the world passed you by. Better luck
> next
> time eh?
>
> James
>
>
>
--
motorhommer
James Annan
>>TROLL
Welcome to usenet. In your second and subsequent posts, I hope you will
learn to separate the quoted text from your own original contribution by
indenting to different levels.
jim beam
> jim beam wrote:
>
>> ok, so that idiocy has been rolling on for nearly 3 weeks now, and
>> still we have:
>>
>> 1. annan's theory which calculates supposed ejection force
>
>
> Are you going to share your own estimate? You'll obviously want to take
> account of the 235 foot-pounds of torque that Cannondale measured (with
> a medium-sized rider riding round a car park):
>
> http://www.ne.jp/asahi/julesandjames/home/disk_and_quick_release/cannondale.html
>
>
> I'm really surprised why you seem to keep trying to beat yourself up
> over this. You guessed wrong, the world passed you by. Better luck next
> time eh?
>
> James
james, i already did the math for you, but somehow, incredibly, you will
still not address it. if you were to, you may suddenly find some
credibility and get some traction with your crusade, whatever the heck
the objective of that may be. an axle will not eject if the pullout
force exceeds ejection force. [ignoring lawyer lips of course.] end of
message from planet earth.
gcmsc...@gmail.com
jim beam wrote:
> ok, so that idiocy has been rolling on for nearly 3 weeks now, and still
> we have:
>
> 1. annan's theory which calculates supposed ejection force and tells us
> that the sky is about to fall.
>
> 2. the cpc, the cycling industry and a total lack of accident incidence
> saying it doesn't.
>
> 3. a theory explaining the reason for the inconsistency - that of actual
> pullout force exceeding ejection force
>
> 4. the logical conclusion that annan's theory is therefore incomplete.
>
> 5. a core of space cadets that argue, despite point 4 above, that there
> is some kind of design flaw - much as a bridge is destined to fail as
> soon as it's loaded, apparently.
>
> 6. an intriguing group of secondary hangers-on that are arguing the toss
> in the face of all logic, reason or math, just for the sheer devilment
> of it.
>
> and what is the result?
>
> our lemming-like suicide squad of primary morons apparently determined
> to undermine and explode any credibility or influence this group may
> have on an activity and sport we all supposedly love. all as our
> secondary participants & silent watchers throw stones, stand by, watch,
> or effectively condone this behavior!!!
Such as you, apparently.
Jim, shut the hell up already. I have nearly all the materials in hand
to measure some pullout forces under various conditions.
Until you're ready to show, both with calculations and diagramatically
what in the fuck you have calculated, and are talking about, you're
just as bad as the David Dammerlls and Frank Krygowskis that stupidly
chime in without any sort of additional info, just to see themselves
type in usenet.
Yeah, I know - google. I've looked for your calcualtions and diagrams
and haven't seen them. Consolidate.
> no one has the minerals to grasp reality. no one has the grace to
> concede any fault - on either side.
And that's where you're completely wrong.
If the data turn my arguments away, I have no problem admitting I'm
wrong. And will say so publically, with an apology. Unlike you, or
really most every other poster to usenet, I actually am an adult who
understands I'm not perfect.
> fucking asinine.
Yes, that's exactly what you're being.
Get out your drawings and your calculator, and stop hinting. Show the
math, do an experiement, or shut the fuck up.
E.P.
jim beam
this is exactly what i'm talking about. you, as possibly the most
coherent contributor to that thread, are so polluted with the poison and
acrimony of it all, you're now assuming /everything/ to be b.s.
http://groups.google.com/group/rec.bicycles.tech/msg/78eb5389d1dfaaf2?hl=en&
even with a shear yield at only 100Nmm^-2 for a really soft magnesium
alloy fork end, shearing through 100mm^2 of enmeshed serrations takes
10,000N, order of magnitude. annan's theory resolves only 1000N, order
of magnitude. be my guest, re-work it. annan won't.
gcmsc...@gmail.com
jim beam wrote:
>
> >
> > Get out your drawings and your calculator, and stop hinting. Show the
> > math, do an experiement, or shut the fuck up.
> >
>
> coherent contributor to that thread, are so polluted with the poison and
> acrimony of it all, you're now assuming /everything/ to be b.s.
Bullshit. I want *numbers*. Not conjecture, not anecdotal,
self-selected stories of dubious value. I see now that you have
provided some numbers, which I appreciate.
> http://groups.google.com/group/rec.bicycles.tech/msg/78eb5389d1dfaaf2?hl=en&
>
> even with a shear yield at only 100Nmm^-2 for a really soft magnesium
> alloy fork end, shearing through 100mm^2 of enmeshed serrations takes
> 10,000N, order of magnitude. annan's theory resolves only 1000N, order
> of magnitude. be my guest, re-work it. annan won't.
OK, that's fine - I see where you get the calculation. But that
doesn't address the whole problem, does it? There's the smooth-faced
QR on smooth drop-out that needs to be calculated. It is this case
where James' hypothesis actually comes close to something important.
No serrations to inhibit unscrewing. No shear of DO material is going
to happen there - it's all about clamping, coefficient of friction, and
the forces of braking. *That's* where hay is to be made. It is *that*
situation that needs experiment or dutiful calculations.
I apologize, Jim - I do not mean to be harsh. I tire of weasels who
figure to use logical fallacies to attempt to confound the issue, all
the while shedding no light on the actual soundness of James'
hypothesis.
My experiment is going to address the worst-case scenario.
E.P.
gcmsc...@gmail.com
gcmsc...@gmail.com wrote:
>
http://groups.google.com/group/rec.bicycles.tech/msg/78eb5389d1dfaaf2?hl=en&
Ooops - subsequent attempts at that .pdf give me a "file not found."
Could you retrieve that .pdf. please?
E.P.
Phil Holman
<gcmsc...@gmail.com> wrote in message
news:1128902424.2...@g47g2000cwa.googlegroups.com...
The most conservative case should be the one under consideration and I
agree, this should be a coefficient of friction and not a shear
consideration. To be really safe, one should not rely on any single
event to prevent catastrophe e.g. forgetting to tighten the QR. We are
talking about positioning the caliper in front of the fork and not
behind it. Is there a big deal with doing this for all new bikes?
Phil H
jobst....@stanfordalumni.org
http://groups.google.com/group/rec.bicycles.tech/msg/78eb5389d1dfaaf2?hl=en&
> Ooops - subsequent attempts at that .pdf give me a "file not found."
> Could you retrieve that .pdf. please?
Not to worry, that URL is nothing but a reference to a posting in
which another URL:
http://www.engr.ukans.edu/%7Ektl/bicycle/QRReport1.pdf
is given. It is this one that implies that it contains the answers
sought, but it links to noting. Must this be so cryptic?
Jobst Brandt
jim beam
> jim beam wrote:
>
>>>Get out your drawings and your calculator, and stop hinting. Show the
>>>math, do an experiement, or shut the fuck up.
>>>
>>
>>this is exactly what i'm talking about. you, as possibly the most
>>coherent contributor to that thread, are so polluted with the poison and
>>acrimony of it all, you're now assuming /everything/ to be b.s.
>
>
> Bullshit. I want *numbers*. Not conjecture, not anecdotal,
> self-selected stories of dubious value. I see now that you have
> provided some numbers, which I appreciate.
>
>
>>http://groups.google.com/group/rec.bicycles.tech/msg/78eb5389d1dfaaf2?hl=en&
>>
>>even with a shear yield at only 100Nmm^-2 for a really soft magnesium
>>alloy fork end, shearing through 100mm^2 of enmeshed serrations takes
>>10,000N, order of magnitude. annan's theory resolves only 1000N, order
>>of magnitude. be my guest, re-work it. annan won't.
>
>
> OK, that's fine - I see where you get the calculation. But that
> doesn't address the whole problem, does it?
agreed. i understand that early chris king disk hubs didn't have
serrated axle faces for example, but the serious player in this arena,
shimano, always has afaik. today, every front disk axle i see is serrated.
> There's the smooth-faced
> QR on smooth drop-out that needs to be calculated.
shouldn't be too hard!
> It is this case
> where James' hypothesis actually comes close to something important.
> No serrations to inhibit unscrewing.
i don't see unscrewing as a primary mechanism. possibly secondary
/after/ the axle is already loose, but not until. even then, i need to
see controls to ensure differentiation between user error [mis placed
open cam cups for example] and actual rotation.
> No shear of DO material is going
> to happen there - it's all about clamping, coefficient of friction, and
> the forces of braking. *That's* where hay is to be made. It is *that*
> situation that needs experiment or dutiful calculations.
back in the day, sure, but as above, i don't think you'll find a single
disk axle that's not got serrated faces today. can't imagine anyone
retrofitting to smooth ones just for the sake of it. and filing off
their lawyer lips.
>
> I apologize, Jim - I do not mean to be harsh. I tire of weasels who
> figure to use logical fallacies to attempt to confound the issue, all
> the while shedding no light on the actual soundness of James'
> hypothesis.
>
> My experiment is going to address the worst-case scenario.
>
> E.P.
>
the first part of annan's hypothesis is a mostly correct calc for the
ejection force, and as such, is relatively sound. the problem then is
that rather than analyze the pullout side of the equation and possibly
reach a conclusion that accords with the reality of billions of rider
hours of experience, he digs out some axle pullout figures that just so
happen to allow a sensational "conclusion".[1] and then, incredibly,
the "engineer" contingent swoop in to capitalize on the drama. it's
like some form of lemmingism mitigates being bad at math. or they
subscribe to this pholosophy:
http://en.wikipedia.org/wiki/Big_Lie
[1] - much like annan's highly publicized and sensational $30k bet on
climatic catastrophe during that was all over slashdot/bbc.co.uk a few
weeks ago - that sort of public posturing has to be a psychoanalysis
thesis in its own right.
jim beam
jim beam
typical trivialization jobst.
iirc, it's a report that researches clamping force, but doesn't extend
to influence of clamping force on pullout force, and of cource, not any
effect of serrations. can't have anything inconvenient to the drama,
can we?
Kinky Cowboy
wrote:
>even with a shear yield at only 100Nmm^-2 for a really soft magnesium
>alloy fork end, shearing through 100mm^2 of enmeshed serrations takes
>10,000N, order of magnitude. annan's theory resolves only 1000N, order
>of magnitude. be my guest, re-work it. annan won't.
If it's so hard to shear through the material, why bother? Climbing
over the slopes of the serrations requires the QR skewer to stretch
only fractions of a millimetre. A full tenth of a millimetre of skewer
stretch only adds about 4kN to the tension, i.e the clamping force is
not quite doubled even riding over a 0.1mm serration engagement depth.
If you disregard indentations into the paint, which is as likely to
lubricate the interface as restrain it, 0.1mm seems like some
seriously deep grooving; my Fox certainly doesn't seem anywhere near
that depth. So, in the best case, serrations might add less than 100%
to the clamping force, and therefore pullout force. For steel
dropouts, expect much less.
Shear yield looks like a red herring, but given their ubiquity
serrations should not be ignored completely as a contributor to the
disparity between Annan's prediction and the low reported in service
failure rate
Kinky Cowboy*
*Batteries not included
May contain traces of nuts
Your milage may vary
Zog The Undeniable
> ok, so that idiocy has been rolling on for nearly 3 weeks now, and still
> we have:
>
> 1. annan's theory which calculates supposed ejection force and tells us
> that the sky is about to fall.
>
> 2. the cpc, the cycling industry and a total lack of accident incidence
> saying it doesn't.
>
> 3. a theory explaining the reason for the inconsistency - that of actual
> pullout force exceeding ejection force
>
> 4. the logical conclusion that annan's theory is therefore incomplete.
>
> 5. a core of space cadets that argue, despite point 4 above, that there
> is some kind of design flaw - much as a bridge is destined to fail as
> soon as it's loaded, apparently.
>
> 6. an intriguing group of secondary hangers-on that are arguing the toss
> in the face of all logic, reason or math, just for the sheer devilment
> of it.
Isn't the point that the designers screwed up by putting the caliper on
the wrong side of the fork, but they got away with it because the QR
(supplemented by lawyer lips in most cases) provides enough clamping
force to counteract the ejection force? It's not elegant but it's OK.
Not that I care; my MTB has V's.
Phil Holman
"Zog The Undeniable" <hroth...@yahoo.com> wrote in message
news:434aaec8.0@entanet...
> jim beam wrote:
>
>> ok, so that idiocy has been rolling on for nearly 3 weeks now, and
>> still we have:
>>
>> 1. annan's theory which calculates supposed ejection force and tells
>> us that the sky is about to fall.
>>
>> 2. the cpc, the cycling industry and a total lack of accident
>> incidence saying it doesn't.
>>
>> 3. a theory explaining the reason for the inconsistency - that of
>> actual pullout force exceeding ejection force
>>
>> 4. the logical conclusion that annan's theory is therefore
>> incomplete.
>>
>> 5. a core of space cadets that argue, despite point 4 above, that
>> there is some kind of design flaw - much as a bridge is destined to
>> fail as soon as it's loaded, apparently.
>>
>> 6. an intriguing group of secondary hangers-on that are arguing the
>> toss in the face of all logic, reason or math, just for the sheer
>> devilment of it.
>
> Isn't the point that the designers screwed up by putting the caliper
> on the wrong side of the fork,
No kidding
>but they got away with it because the QR (supplemented by lawyer lips
>in most cases) provides enough clamping force to counteract the
>ejection force? It's not elegant but it's OK.
>
> Not that I care; my MTB has V's.
It only requires a single failure (forgetting to tighten the QR) and you
will probably pull the wheel out when applying the front brake. With
regular rim brakes, this likely would never happen.
Phil H
Doug Huffman
"Phil Holman" <piholmanz@yourservice> wrote in message
news:ruWdnZeeFvLLb9fe...@comcast.com...
>
>
> It only requires a single failure (forgetting to tighten the QR) and you
> will probably pull the wheel out when applying the front brake. With
> regular rim brakes, this likely would never happen.
>
> Phil H
>
"Probably" and "likely" - statistical physics no less here on RBT!
gcmsc...@gmail.com
Zog The Undeniable wrote:
> jim beam wrote:
>
> > ok, so that idiocy has been rolling on for nearly 3 weeks now, and still
> > we have:
> >
> > 1. annan's theory which calculates supposed ejection force and tells us
> > that the sky is about to fall.
> >
> > 2. the cpc, the cycling industry and a total lack of accident incidence
> > saying it doesn't.
> >
> > 3. a theory explaining the reason for the inconsistency - that of actual
> > pullout force exceeding ejection force
> >
> > 4. the logical conclusion that annan's theory is therefore incomplete.
> >
> > 5. a core of space cadets that argue, despite point 4 above, that there
> > is some kind of design flaw - much as a bridge is destined to fail as
> > soon as it's loaded, apparently.
> >
> > 6. an intriguing group of secondary hangers-on that are arguing the toss
> > in the face of all logic, reason or math, just for the sheer devilment
> > of it.
>
> Isn't the point that the designers screwed up by putting the caliper on
> the wrong side of the fork
"Screwed up" in the hypothetical sense - if there are no ejections
documented, then it's pretty hard to call it a screw-up.
> but they got away with it because the QR
> (supplemented by lawyer lips in most cases) provides enough clamping
> force to counteract the ejection force? It's not elegant but it's OK.
It's in the realm of user-installed carbon-fiber stuff. If the user
goofs in installation, injury could result. Heck, with CF it's worse
than that - if you accidentally whack it, the same end result could
occur. Even a small scratch can cause failure.
Not a word passes on r.b.t. about the hideous danger of CF parts.
:)
E.P.
frkr...@yahoo.com
gcmsc...@gmail.com wrote:
>
>
> Not a word passes on r.b.t. about the hideous danger of CF parts.
>
> :)
>
No, you've posted words similar to the above many times. We've
noticed.
What's going on is this: People tend to be more interested in one
issue than another, and they tend to work on the issues that interest
them. Life is like that.
Which is a gentle way of saying, have at it, whatever your name is! If
you think carbon fiber parts are stupidly dangerous, start a thread, or
start a website, or write to Buycycling magazine, or write to the
manufacturers. Whatever.
But the fact that people aren't interested in your distraction has
little to do with the present discussion.
- Frank Krygowski
jim beam
> On Sun, 09 Oct 2005 14:33:25 -0700, jim beam <nos...@example.net>
> wrote:
>
>
>>even with a shear yield at only 100Nmm^-2 for a really soft magnesium
>>alloy fork end, shearing through 100mm^2 of enmeshed serrations takes
>>10,000N, order of magnitude. annan's theory resolves only 1000N, order
>>of magnitude. be my guest, re-work it. annan won't.
>
>
> If it's so hard to shear through the material, why bother? Climbing
> over the slopes of the serrations requires the QR skewer to stretch
> only fractions of a millimetre. A full tenth of a millimetre of skewer
> stretch only adds about 4kN to the tension, i.e the clamping force is
> not quite doubled even riding over a 0.1mm serration engagement depth.
you talk like 4kN is trivial.
> If you disregard indentations into the paint, which is as likely to
> lubricate the interface as restrain it, 0.1mm seems like some
> seriously deep grooving; my Fox certainly doesn't seem anywhere near
> that depth. So, in the best case, serrations might add less than 100%
> to the clamping force, and therefore pullout force. For steel
> dropouts, expect much less.
how do you go from trivializing the increase in clamping force to
dismissing shear??? all that matters is that a serration engages with
an indentation. when it does, you suddenly have to shear through
significant amounts of material if you want to drag it loose as gross
deformation is the only way. depth of shear isn't relevant, it's area.
>
> Shear yield looks like a red herring, but given their ubiquity
> serrations should not be ignored completely as a contributor to the
> disparity between Annan's prediction and the low reported in service
> failure rate
ya think??? sure, reality's got "herring" written all over it.
jim beam
what, you mean like bridge builders screw up by not putting a safety net
underneath in case of failure? dude, if the pullout exceeds ejection by
an order of magnitude, that should be sufficient safety factor to allow
adoption of a design that doesn't expose the risk of the caliper tabs
fatiguing off and losing the brake. just like any modern road
motorcycle you care to mention. any idea what safety factor there is on
the wings of a plane? clue: it's not an order of magnitude.
Phil Holman
"Doug Huffman" <doug.h...@comcast.net> wrote in message
news:3LKdnc_gPtg...@comcast.com...
In top down failure analysis, highly improbable is 10^-9.
NEVER use absolutes :-)
Phil H
Kinky Cowboy
wrote:
>Kinky Cowboy wrote:
>> On Sun, 09 Oct 2005 14:33:25 -0700, jim beam <nos...@example.net>
>> wrote:
>>
>>
>>>even with a shear yield at only 100Nmm^-2 for a really soft magnesium
>>>alloy fork end, shearing through 100mm^2 of enmeshed serrations takes
>>>10,000N, order of magnitude. annan's theory resolves only 1000N, order
>>>of magnitude. be my guest, re-work it. annan won't.
>>
>>
>> If it's so hard to shear through the material, why bother? Climbing
>> over the slopes of the serrations requires the QR skewer to stretch
>> only fractions of a millimetre. A full tenth of a millimetre of skewer
>> stretch only adds about 4kN to the tension, i.e the clamping force is
>> not quite doubled even riding over a 0.1mm serration engagement depth.
>
>you talk like 4kN is trivial.
No, it's almost doubling the original clamping force; but only if the
serrations are engaged to a depth of 0.1mm, which doesn't seem at all
likely, even for steel serrations biting into Mg dropouts. If the
skewer only has to stretch <0.01mm to let the serrations ratchet past
one another, which is not altogether unreasonable for a steel dropout
with Al QR nuts and axle (the worst case, admittedly, but we have to
consider it) then we only have <400N of extra clamping load, which
really is trivial.
>> If you disregard indentations into the paint, which is as likely to
>> lubricate the interface as restrain it, 0.1mm seems like some
>> seriously deep grooving; my Fox certainly doesn't seem anywhere near
>> that depth. So, in the best case, serrations might add less than 100%
>> to the clamping force, and therefore pullout force. For steel
>> dropouts, expect much less.
>
>how do you go from trivializing the increase in clamping force to
>dismissing shear??? all that matters is that a serration engages with
>an indentation. when it does, you suddenly have to shear through
>significant amounts of material if you want to drag it loose as gross
>deformation is the only way. depth of shear isn't relevant, it's area.
>
Path of least resistance; if it's easier to go over it than through
it, shear is irrelevant. That makes the depth of engagement (and the
slope angle) very relevant. Remember, all that's stopping the
serration from lifting out of the groove is 100mm of 5mm dia. tie rod
under about 5kN of preload. Just like a chain jumping over sprocket
teeth instead of shearing them off. And just like your jumping chain,
it's probably going to shear off very small areas of the peaks; as it
climbs, the load goes up and the area needing to be sheared off goes
down, and some equilibrium point will be reached where it's easier to
flatten off the top of the hill than to go all the way over it. That
pretty much defines the limit of how significant shear is; it happens
when it's providing less resistance than the friction is. At the other
end of the scale, and at the other end of your bike, there's a set of
indentations where you hope the springy bit will ALWAYS deform enough
to stop the pointy bits from wiping the tops off the serrations; it's
called a freewheel. My final paragraph stands; on the numbers you give
shear is irrelevant because there's an easier path, but indentations
can help to increase clamping load in the event of movement, just like
any other kind of wedge.
Jasper Janssen
>how do you go from trivializing the increase in clamping force to
>dismissing shear??? all that matters is that a serration engages with
>an indentation. when it does, you suddenly have to shear through
>significant amounts of material if you want to drag it loose as gross
>deformation is the only way. depth of shear isn't relevant, it's area.
That's not true, you can also skate right over it if the skewer elongates
enough to do so. Which is what he said. Claiming that the *only* option is
shearing through that material is either blinkered or disingenuous. I'm
also extremely suspicious of your 100 mm^2 figure, incidentally.
Jasper
Jasper Janssen
<gcmsc...@gmail.com> wrote:
>Not a word passes on r.b.t. about the hideous danger of CF parts
Bullshit, actually. The dangers of CF parts have been discussed many times
and at length.
Jasper
Jasper Janssen
>dude, if the pullout exceeds ejection by
>an order of magnitude,
Whoa, whoa whoa.. order of magnitude? Where the hell do you get THAT from?
Only calculations I've seen are a factor of *2*, not an order of
magnitude, and that was in the best case.
As an aside, are many cars still fitted with front-opening 'suicide
doors'? As long as you close them before taking off, don't open them while
riding, and the lock doesn't fail, they're perfectly safe, so why don't
manufacturers make them?
Jasper
gcmsc...@gmail.com
Not while I've been reading. And disk brakes have been discussed
umpteen (scientific term for "assload") numbers of times.
Doing a quick title search on "danger" and "carbon fiber" yields very
few posts.
Hmmm, interesting.
E.P.
frkr...@yahoo.com
Kinky Cowboy wrote:
>
>
> Path of least resistance; if it's easier to go over it than through
> it, shear is irrelevant. That makes the depth of engagement (and the
> slope angle) very relevant. Remember, all that's stopping the
> serration from lifting out of the groove is 100mm of 5mm dia. tie rod
> under about 5kN of preload. Just like a chain jumping over sprocket
> teeth instead of shearing them off. And just like your jumping chain,
> it's probably going to shear off very small areas of the peaks; as it
> climbs, the load goes up and the area needing to be sheared off goes
> down, and some equilibrium point will be reached where it's easier to
> flatten off the top of the hill than to go all the way over it. That
> pretty much defines the limit of how significant shear is; it happens
> when it's providing less resistance than the friction is. At the other
> end of the scale, and at the other end of your bike, there's a set of
> indentations where you hope the springy bit will ALWAYS deform enough
> to stop the pointy bits from wiping the tops off the serrations; it's
> called a freewheel. My final paragraph stands; on the numbers you give
> shear is irrelevant because there's an easier path, but indentations
> can help to increase clamping load in the event of movement, just like
> any other kind of wedge.
It occurs to me, there's another factor we've been leaving out.
Jim Beam is convinced that the serrations on a steel QR nut will bite
into the softer dropout, giving some degree of mechanical interlock.
If that's true just one time, then what we have is a set of concave
indentations in the dropout, matching the convex protrusions in the QR
nut.
IOW, matching pegs and holes.
Matching _that time_, that is. There is NO guarantee that the second
installation of the front wheel will put the pegs into the holes. IOW,
a perfectly competent cyclist could put the axle in exactly the same
location, but have the circumferential position of the "pegs" slightly
different than before. He clamps the quick release exactly correctly -
but the "pegs" can be biting on the side slope of the "holes."
If this happens - and, statistically, it must - then any microscopic
motion at that interface would cause the "pegs" to slide deeper into
the "holes," and cause some wear at that slope while doing so.
The result would be a loss in QR skewer tension, equal to the amount of
force corresponding to the amount the "stretching" is reduced when the
pegs slide into the holes. For a 5mm steel skewer, 0.1 mm settling
into previous indentations would reduce skewer tension by about 4 kN =
900+ pounds.
Again, ISTM that at the same time this is happening, it's probably
making the side slope of those indentations shallower.
Now for a conventional braked wheel with conventional dropouts, this
hardly matters. The metal to metal interface of the dropout above the
axle prevents almost all relative motion, because the force on the axle
pushes the axle against dropout metal. And even if the QR loses
tension, it needs to retain only enough force to prevent gravity from
pulling the wheel down when, say, the rider lifts the front wheel.
Not so with a common disk brake setup. The force diagram clearly shows
that hard braking tries to lever the axle down and out. A loss in
skewer tension from this mechanism I described might be significant.
Furthermore, as with all threaded fasteners, loss in tension makes
further loosening by vibration easier. It lessens the normal force at
all contacting surfaces, thus lessening the friction force, thus
increasing the chance that microscopic motion within the clearance
interface of the male and female threads will lead to the thread's
sliding down their helix angle. A self-perpetuating situation.
Idealistic calculations of dropout clamping force and metal shear
stress thus need to be modified, because a certain percentage of the
time, the serrations will NOT match, and a QR will soon be looser than
the operator - or the calculators - think.
By the way, a question for the "It never happens" crew: Did you never
ride a bike with horizontal rear dropouts? Did you never experience
your chain pulling your wheel sideways, causing the tire to rub on the
left chainstay, even though you thought the axle was properly clamped?
ISTM that one experience with that would tell a person "Hmmm. Axles
_can_ slip. That's why I'll make sure my next bike design has the
front axle slots facing _away_ from the direction of the ejection
force."
Maybe the guys who designe the first bike disk brakes always rode with
vertical rear dropouts, and never learned that simple lesson?
- Frank Krygowski
David Damerell
>Jasper Janssen wrote:
>>Bullshit, actually. The dangers of CF parts have been discussed many times
>>and at length.
>Not while I've been reading. And disk brakes have been discussed
>umpteen (scientific term for "assload") numbers of times.
>Doing a quick title search on "danger" and "carbon fiber" yields very
>few posts.
"disk brakes" + "danger", 15 results.
"disc brakes" + "danger", 14 results.
"disk brakes" + "dangerous", 23 results.
"disc brakes" + "dangerous", 24 results.
"carbon fiber" + "danger", 20 results.
"carbon fibre" + "danger", 3 results.
"carbon fiber" + "dangerous", 43 results.
"carbon fibre" + "dangerous", 11 results.
--
David Damerell <dame...@chiark.greenend.org.uk> flcl?
Today is First Teleute, October.
gcmsc...@gmail.com
David Damerell wrote:
> Quoting gcmsc...@gmail.com <gcmsc...@gmail.com>:
> >Jasper Janssen wrote:
> >>Bullshit, actually. The dangers of CF parts have been discussed many times
> >>and at length.
> >Not while I've been reading. And disk brakes have been discussed
> >umpteen (scientific term for "assload") numbers of times.
> >Doing a quick title search on "danger" and "carbon fiber" yields very
> >few posts.
>
> "disk brakes" + "danger", 15 results.
> "disc brakes" + "danger", 14 results.
> "disk brakes" + "dangerous", 23 results.
> "disc brakes" + "dangerous", 24 results.
>
> "carbon fiber" + "danger", 20 results.
> "carbon fibre" + "danger", 3 results.
> "carbon fiber" + "dangerous", 43 results.
> "carbon fibre" + "dangerous", 11 results.
*Title* search?
John Red-Horse
>
>Maybe the guys who designe the first bike disk brakes always rode with
>vertical rear dropouts, and never learned that simple lesson?
>
Maybe the folks who designed the first bike disk brakes did so with
mountain biking as the only application in mind.
That would make sense, since: (1) All the mtb forks that I have have
dropouts that are in-line with the fork stanchions; they aren't parallel
to the braking force direction, based on my eye-balling the pad locations
on the disk, once installed; (2) All the mtb forks that I've seen have
some sort of lawyer lips-style construction in the dropouts; (3) The
calipers need to be rear mounted to enable protection from damage by the
fork legs; (4) The max braking force that's achieveable is limited by
front wheel frictional forces, or reactions to in-plane (endo) overturning
moment; since the application involves dirt and rocks and such, this is
less force than one would experience on dry roads in roadie applications.
john
Phil, Squid-in-Training
Yes, we talked about it already. Magnesium lower castings might not hold up
to the tension forces incurred by placing the caliper in front of the leg.
--
Phil, Squid-in-Training
Phil, Squid-in-Training
Yes. I skidded across the road bleeding profusely. My QR was not
sufficiently tightened. I loosened up the cones in the hub, then I properly
tightened my steel QR onto my steel frame and steel locknuts, and have had
no problems since.
--
Phil, Squid-in-Training
Jasper Janssen
<phil_leeIHEA...@hotmail.com> wrote:
>Yes, we talked about it already. Magnesium lower castings might not hold up
>to the tension forces incurred by placing the caliper in front of the leg.
Which of course is bullshit. Fatigue is something you can design for and
eliminate. User error *must* be designed for because it cannot be
eliminated.
Jasper
Jasper Janssen
<phil_leeIHEA...@hotmail.com> wrote:
>> By the way, a question for the "It never happens" crew: Did you never
>> ride a bike with horizontal rear dropouts? Did you never experience
>> your chain pulling your wheel sideways, causing the tire to rub on the
>> left chainstay, even though you thought the axle was properly clamped?
>
>Yes. I skidded across the road bleeding profusely. My QR was not
>sufficiently tightened. I loosened up the cones in the hub, then I properly
>tightened my steel QR onto my steel frame and steel locknuts, and have had
>no problems since.
So would you have preferred a front wheel ejection for exactly the same
mistake?
Jasper
Phil, Squid-in-Training
My dropouts don't have lawyer lips.
--
Phil, Squid-in-Training
jim beam
> On Mon, 10 Oct 2005 20:15:46 -0700, jim beam <nos...@example.net> wrote:
>
>
>>dude, if the pullout exceeds ejection by
>>an order of magnitude,
>
>
> Whoa, whoa whoa.. order of magnitude? Where the hell do you get THAT from?
> Only calculations I've seen are a factor of *2*, not an order of
> magnitude, and that was in the best case.
i'm sorry, did i write my previous posts in invisible ink? here, let me
spell it all out one more time:
you /do/ know the purpose of doing math in orders of magnitude, right?
>
> As an aside, are many cars still fitted with front-opening 'suicide
> doors'? As long as you close them before taking off, don't open them while
> riding, and the lock doesn't fail, they're perfectly safe, so why don't
> manufacturers make them?
that herring is so vermillion, it's just insulting.
>
> Jasper
jim beam
> On Mon, 10 Oct 2005 20:15:20 -0700, jim beam <nos...@example.net> wrote:
>
>
>>how do you go from trivializing the increase in clamping force to
>>dismissing shear??? all that matters is that a serration engages with
>>an indentation. when it does, you suddenly have to shear through
>>significant amounts of material if you want to drag it loose as gross
>>deformation is the only way. depth of shear isn't relevant, it's area.
>
>
> That's not true, you can also skate right over it if the skewer elongates
> enough to do so.
"if" it elongates enough??? a rough calc shows the clamping force for a
normal skewer is ~>20kN. you're going to "skate" over a set of
indentions being held together like that???
> Which is what he said. Claiming that the *only* option is
> shearing through that material is either blinkered or disingenuous.
like being "supicious" about an area calc you can easily check ourself?
> I'm
> also extremely suspicious of your 100 mm^2 figure, incidentally.
get your calipers out and measure it. area = pi.r^2
>
> Jasper
jim beam
what, like this you mean?
http://home.comcast.net/~carlfogel/download/Img_3199.jpg
that wheel had been inserted & reinserted approximately 100 times. the
indentaion pattern looks remarkably persistent to me. but maybe that's
why shimano makes the serrations with sloping faces to ensure they
always mesh. just like a dog clutch in a gear box.
>
> If this happens - and, statistically, it must
"must" it? it's not evidenced above.
> - then any microscopic
> motion at that interface would cause the "pegs" to slide deeper into
> the "holes," and cause some wear at that slope while doing so.
>
> The result would be a loss in QR skewer tension, equal to the amount of
> force corresponding to the amount the "stretching" is reduced when the
> pegs slide into the holes. For a 5mm steel skewer, 0.1 mm settling
> into previous indentations would reduce skewer tension by about 4 kN =
> 900+ pounds.
that's a real sqirm. any regular user of qr skewers can feel when it's
tightening solidly or not. pictorial evidence shows no attrition that
would be caused by the description you're desperately trying to
artificially manufacture.
>
> Again, ISTM that at the same time this is happening, it's probably
> making the side slope of those indentations shallower.
>
> Now for a conventional braked wheel with conventional dropouts, this
> hardly matters. The metal to metal interface of the dropout above the
> axle prevents almost all relative motion, because the force on the axle
> pushes the axle against dropout metal. And even if the QR loses
> tension, it needs to retain only enough force to prevent gravity from
> pulling the wheel down when, say, the rider lifts the front wheel.
>
> Not so with a common disk brake setup. The force diagram clearly shows
> that hard braking tries to lever the axle down and out. A loss in
> skewer tension from this mechanism I described might be significant.
>
> Furthermore, as with all threaded fasteners, loss in tension makes
> further loosening by vibration easier. It lessens the normal force at
> all contacting surfaces, thus lessening the friction force, thus
> increasing the chance that microscopic motion within the clearance
> interface of the male and female threads will lead to the thread's
> sliding down their helix angle. A self-perpetuating situation.
>
> Idealistic calculations of dropout clamping force and metal shear
> stress thus need to be modified, because a certain percentage of the
> time, the serrations will NOT match, and a QR will soon be looser than
> the operator - or the calculators - think.
go ahead and modify them frank - you're supposed to be the engineering
professor. get with the math.
jim beam
> On Tue, 11 Oct 2005 18:12:14 -0400, "Phil, Squid-in-Training"
> <phil_leeIHEA...@hotmail.com> wrote:
>
>
>>Yes, we talked about it already. Magnesium lower castings might not hold up
>>to the tension forces incurred by placing the caliper in front of the leg.
>
>
> Which of course is bullshit. Fatigue is something you can design for and
> eliminate.
damned right - you put the caliper behind the fork!!!
> User error *must* be designed for because it cannot be
> eliminated.
true. just like steering over-ride mechanism that stops me crashing
into trees? or maybe you mean the ankle chain that stops me leaving my
sofa because the minute i jump on my bike, i'm exposed to all kinds of
danger my sofa does just not offer? i mean, that's /real/ risk elimination.
>
> Jasper
James Annan
jim beam wrote:
> "if" it elongates enough??? a rough calc shows the clamping force for a
> normal skewer is ~>20kN.
I think you should check your working on that "rough calc".
Or do you imagine that just tossing out random (and wildly inaccurate)
numbers will lend some spurious air of authority to your guesses?
James
jim beam
intellect...
frkr...@yahoo.com
jim beam wrote:
> frkr...@yahoo.com wrote:
> >
> >
> > It occurs to me, there's another factor we've been leaving out.
> >
> > Jim Beam is convinced that the serrations on a steel QR nut will bite
> > into the softer dropout, giving some degree of mechanical interlock.
> >
> > If that's true just one time, then what we have is a set of concave
> > indentations in the dropout, matching the convex protrusions in the QR
> > nut.
> > IOW, matching pegs and holes.
> >
> > Matching _that time_, that is. There is NO guarantee that the second
> > installation of the front wheel will put the pegs into the holes. IOW,
> > a perfectly competent cyclist could put the axle in exactly the same
> > location, but have the circumferential position of the "pegs" slightly
> > different than before. He clamps the quick release exactly correctly -
> > but the "pegs" can be biting on the side slope of the "holes."
>
> what, like this you mean?
>
> http://home.comcast.net/~carlfogel/download/Img_3199.jpg
>
> that wheel had been inserted & reinserted approximately 100 times. the
> indentaion pattern looks remarkably persistent to me. but maybe that's
> why shimano makes the serrations with sloping faces to ensure they
> always mesh. just like a dog clutch in a gear box.
I see no particular way sloping faces on the QR serrations are going to
guarantee locking into those same serrations. In fact, it looks like
the flat spot between serrations is roughly twice as wide as the
serration grooves themselves. That means on a random insertion,
there's only a one-out-of-three chance of mesh.
I admit, I'm surprised at the apparent consistency of the serrations.
I just checked my Cannondale rear dropouts and I saw no such grooves.
:-) Of course, if I were "gmschemist" or whatever his name is, I'd
simply say "We don't _know_ what you say is true" and avoid the issue.
But instead I'll just ask, do you do something special to locate the
same circumferential position each time? Again, odds are two to one
that it wouldn't happen by random chance for a given instance.
>
> >
> > If this happens - and, statistically, it must - then any microscopic
> > motion at that interface would cause the "pegs" to slide deeper into
> > the "holes," and cause some wear at that slope while doing so.
> >
> > The result would be a loss in QR skewer tension, equal to the amount of
> > force corresponding to the amount the "stretching" is reduced when the
> > pegs slide into the holes. For a 5mm steel skewer, 0.1 mm settling
> > into previous indentations would reduce skewer tension by about 4 kN =
> > 900+ pounds.
>
> that's a real sqirm. any regular user of qr skewers can feel when it's
> tightening solidly or not.
Pay attention, please. If the serrations were right on the edge of
meshing, but not quite meshing, they _would_ clamp tightly. The
operator could feel it.
But if there were some slight movement, the nearly-meshed serrations
could come into mesh, with the "pegs" settling into the "holes." That
would cause a loss of tension.
> pictorial evidence shows no attrition that
> would be caused by the description you're desperately trying to
> artificially manufacture.
One picture shows something different, and we don't know what makes it
different. My dropouts don't show any serrations at all. (Sorry, no
digital camera lives here.) By my count, you're one-for-two.
Now I'd like an explanation of how your QR beats the obvious two-to-one
odds against landing precisely in the same grooves. Seems to me the
chance of that happening every time by random chance over 100
installations is (1/3)^100 or about 2E-48.
- Frank Krygowski
frkr...@yahoo.com
Phil, Squid-in-Training wrote:
> Jasper Janssen wrote:
> >
> >
> > So would you have preferred a front wheel ejection for exactly the
> > same mistake?
>
> My dropouts don't have lawyer lips.
>
Phil, that did not answer the question.
Let me ask another. What would _you_ think about riding a
conventional-brake road bike whose front fork dropout slots faced
upward? Would you call that a good design?
None of your teammates seem willing to answer.
- Frank Krygowski
frkr...@yahoo.com
jim beam wrote:
> Jasper Janssen wrote:
> > On Tue, 11 Oct 2005 18:12:14 -0400, "Phil, Squid-in-Training"
> > <phil_leeIHEA...@hotmail.com> wrote:
> >
> >
> >>Yes, we talked about it already. Magnesium lower castings might not hold up
> >>to the tension forces incurred by placing the caliper in front of the leg.
> >
> >
> > Which of course is bullshit. Fatigue is something you can design for and
> > eliminate.
>
> damned right - you put the caliper behind the fork!!!
:-) Right! That's EXACTLY why all front cantilever studs face
backward! Right, Jim?
After all, we _know_ nobody can safely design members in tension! ;-)
- Frank Krygowski
James Annan
"A man convinced against his will,
Is of the same opinon still".
I'll let you go through your own working, maybe do a little googling,
and perhaps even read that document you cited a few days ago...
One thing that has been interesting to me over the last couple of years
is to see how people have adopted this idea, pretty much at their own
speed, as an inreasing proportion have come to see how it fits with
their (and their friends') experiences. Whenever someone posts (on a
web forum or here) about their difficulty with a slipping or loosening
QR, someone quickly pops up with the answer and a link to my pages.
I don't really see that there is much point in _my_ trying to argue the
case in any detail, especially with anonymous usenet trolls such as
yourself. But you can hardly have avoided noticing how your supposed
"summary" brought out criticism from even the likes of "gcmschemist"
(hardly my strongest supporter!) who seems to recognise your
smokescreen and bluster for what it is.
James
jim beam
wow - you're just obsessed with this aren't you. no one answers because
it's so dumb. but since being dumb seems to be the order of the day for
this debate - the answer, professor, is that the g's of an impact can
easily exceed anything seen in in any other mode of service. how about
you do a little math and demonstrate the problem since you seem so
damned fixed on posing such a defeatingly stupid question?
jim beam
typical. you can't get with the analysis now. you couldn't get with
the analysis then, judging by your complete lack of response to
photographic evidence:
much safer to play to the peanut gallery isn't it james. you know, no
one to point out the problems, no one that can see through the smoke.
that's the arena in which you can hope to get away with it - just like
your ridiculous sensationalistinc posturing in the media about climatic
disaster. give us a break.
jim beam
"not quite meshing"??? so how come i can so unerringly and completely
manage to get such consistently comlete repetition over 100
insertions??? am i secretly using some precision alignment device that
micro-rotates my axle to an exactly pre-determined position as i throw
it in from the trunk of my car?
> The
> operator could feel it.
>
> But if there were some slight movement, the nearly-meshed serrations
> could come into mesh, with the "pegs" settling into the "holes." That
> would cause a loss of tension.
absolutely there's movement. that's how it shows up in the same indent
pattern every time!!! but there's no logical connection with your
assumption that the operator can't feel whether it's clamping tight from
the lever resistance. and that's why you re-tighten if you can feel
it's not clamping tight enough.
>
>
>>pictorial evidence shows no attrition that
>>would be caused by the description you're desperately trying to
>>artificially manufacture.
>
>
> One picture shows something different, and we don't know what makes it
> different. My dropouts don't show any serrations at all. (Sorry, no
> digital camera lives here.) By my count, you're one-for-two.
how damned convenient. and you /dare/ you trot out a smooth faced
non-disk axle in this debate? you got chutzpah frank.
>
> Now I'd like an explanation of how your QR beats the obvious two-to-one
> odds against landing precisely in the same grooves.
"obvious" assumptions trying to stack the odds against the photographic
evidence you can't/[won't] try to refute with your own? yeah, right.
> Seems to me the
> chance of that happening every time by random chance over 100
> installations is (1/3)^100 or about 2E-48.
>
> - Frank Krygowski
>
you're really grasping for those straws there frank - keep it up! if
one set of facts don't fit, why, just make some others up! or maybe i'm
just very very good at photoshop. why don't you try that red herring
for a lark and make that accusation? i'm sure you'll get someone to
corroborate that fabrication of that photo is technically feasible.
jim beam
that someone that dare to teach this otherwise exacting discipline has
the balls to deliberately ignore application data that is so public and
so commonly used in critical systems design. are you for real?
Phil, Squid-in-Training
> Phil, Squid-in-Training wrote:
>> Jasper Janssen wrote:
>>>
>>>
>>> So would you have preferred a front wheel ejection for exactly the
>>> same mistake?
>>
>> My dropouts don't have lawyer lips.
>>
>
> Phil, that did not answer the question.
He didn't ask a relevant question.
> Let me ask another. What would _you_ think about riding a
> conventional-brake road bike whose front fork dropout slots faced
> upward? Would you call that a good design?
Sure, if I knew it was time-tested, worked well in my experience, and didn't
have glaringly obvious problems that affected the vast majority of riders.
Sounds like QR disc brakes are a good design. A running design mod is okay
by me, too.
If it were up to me, I would redesign the quick-release to make it
idiot-proof, not the disc brake. But it looks like we'll have to settle for
forward-facing dropouts.
--
Phil, Squid-in-Training
James Annan
Actually, I can, but you were the one who plucked the 20kN figure out
of thin air, and it would surely be much more straightforward for you
to explain where it came from than for anyone else to try to
second-guess what set of implausible assumptions it is based on.
But I can understand your reluctance to show your working. After all,
you already cited a document that flatly contradicts you (although if
you'd bothered trying to read it, you might have found out that the url
you provided was broken).
James
jim beam
and pullout force has already been discussed at length. not that i'm
surprised of course - avoidance is to be expected since if you were
/really/ interested in solving a problem rather than creating one and
enjoying your 15 minutes of infamy, you'd have bothered to analyze both
sides of this equation rather than just one.
and you've repeatedly avoided the math every single time i've challenged
you on this subject james. why is that? [rhetorical] for myself, i
absolutely refuse to do your homework for you. as the initiator of this
ridiculous charade, /you/ are the guy that has to do the donkey work.
for clamping force, you simply derive it as a function of cam
displacement. you reckon you're an expert in this stuff. you go ahead
& figure it out.
James Annan
I don't believe I'm at all confused on the matter, and it is clear from
the quotes above that it was you who produced the claim that "clamping
force for a normal skewer is ~>20kN". I'm merely asking you where you
got that figure from, as it is wildly out of line with all the other
estimates and measurements I have seen (including the measurements you
referenced yourself recently).
> and pullout force has already been discussed at length.
It's also been measured at length, and observations of slippage of
correctly used equipent has also been presented at length.
> for myself, i
> absolutely refuse to do your homework for you.
Don't do it for me, do it for yourself.
James
--
James Annan
see web pages for email
http://www.ne.jp/asahi/julesandjames/home/
http://julesandjames.blogspot.com/
jim beam
you are unreal. i've quoted ~>20kN clamping force [that's just the
closing force of the skewer] as a response to the claim that serrations
can easily "climb" out of indentation pits and 10kN order of magnitude
pullout force as a function of dropout shear for those indentation pits.
to confuse the two requires either psychiatric assessment or a degree
of retardation that would require life support. stop squirming annan.
analyze the pullout force. in public. you started this shit. now you
finish it.
David Damerell
>David Damerell wrote:
>>Quoting gcmsc...@gmail.com <gcmsc...@gmail.com>:
>>>Doing a quick title search on "danger" and "carbon fiber" yields very
>>>few posts.
[numbers of hits in article bodies are very similar for CF and disc brakes]
>*Title* search?
Oh, in the Subject: line? Call it by its name, please.
Then I get no hits at all for dis(c|k) brakes and either "danger" or
"dangerous". This equally does not demonstrate that people are more
concerned about disc brakes than CF components.
--
David Damerell <dame...@chiark.greenend.org.uk> Distortion Field!
Today is First Oneiros, October.
Jasper Janssen
<phil_leeIHEA...@hotmail.com> wrote:
>If it were up to me, I would redesign the quick-release to make it
>idiot-proof, not the disc brake. But it looks like we'll have to settle for
>forward-facing dropouts.
Feel free to elaborate on *how* to idiotproof QRs.
Jasper
Jasper Janssen
>that's a real sqirm. any regular user of qr skewers can feel when it's
>tightening solidly or not. pictorial evidence shows no attrition that
>would be caused by the description you're desperately trying to
>artificially manufacture.
So now you have to be a 'regular user' aka an expert to safely operate
QRs? Keep diggin', man.
Jasper
Jasper Janssen
>Jasper Janssen wrote:
>> On Mon, 10 Oct 2005 20:15:46 -0700, jim beam <nos...@example.net> wrote:
>>
>>>dude, if the pullout exceeds ejection by
>>>an order of magnitude,
>>
>> Whoa, whoa whoa.. order of magnitude? Where the hell do you get THAT from?
>> Only calculations I've seen are a factor of *2*, not an order of
>> magnitude, and that was in the best case.
>
>i'm sorry, did i write my previous posts in invisible ink? here, let me
>spell it all out one more time:
>you /do/ know the purpose of doing math in orders of magnitude, right?
Yeah, and you're totally abusing the privilege.
>> As an aside, are many cars still fitted with front-opening 'suicide
>> doors'? As long as you close them before taking off, don't open them while
>> riding, and the lock doesn't fail, they're perfectly safe, so why don't
>> manufacturers make them?
>
>that herring is so vermillion, it's just insulting.
Really? Fancy that. Well, whatever floats your boat.
Jasper
gcmsc...@gmail.com
David Damerell wrote:
> Quoting gcmsc...@gmail.com <gcmsc...@gmail.com>:
> >David Damerell wrote:
> >>Quoting gcmsc...@gmail.com <gcmsc...@gmail.com>:
> >>>Doing a quick title search on "danger" and "carbon fiber" yields very
> >>>few posts.
> [numbers of hits in article bodies are very similar for CF and disc brakes]
> >*Title* search?
>
> Oh, in the Subject: line? Call it by its name, please.
That *is* its name, you pedantic shithead.
> Then I get no hits at all for dis(c|k) brakes and either "danger" or
> "dangerous".
Then you're an idiot.
E.P.
gcmsc...@gmail.com
James Annan wrote:
>
> I don't really see that there is much point in _my_ trying to argue the
> case in any detail, especially with anonymous usenet trolls such as
> yourself.
As opposed to named usenet trolls? Is there *really* a difference?
> But you can hardly have avoided noticing how your supposed
> "summary" brought out criticism from even the likes of "gcmschemist"
> (hardly my strongest supporter!) who seems to recognise your
> smokescreen and bluster for what it is.
You're a liar. A damned ballsy liar as well.
I criticize because I want to see the numbers, the calculation and all
of the middle work.
That does NOT imply that I believe it to be smokescreen and bluster, it
is explicit that I want to see the data and the calculation!
James, you've had your shot at it. Now, I'd like to see Jim Beam
produce the calculations from which he derives 20kN. I can't get that
number, so I'm obviously missing SOMETHING. I realize that if Jim were
to produce a detailed calculation, you wouldn't have the balls to say
he was right - you are a very small person after all.
So, Mr. Beam - *I* want to see the numbers. I never got any .pdf in my
inbox, so I can't actually see the calculations, data and assumptions
you are basing your conclusions upon. So, I am *asking*, in a pleasant
fashion I hope, if you will please show all data, calculations,
assumptions and if standard values are used, from what source they were
obtained.
If people such as Frank accept James' hypothesis based solely on a FBD,
then surely through proper calculations you can fully rebutt his
conclusions.
Thank you,
E.P.
frkr...@yahoo.com
Phil, Squid-in-Training wrote:
> frkr...@yahoo.com wrote:
> > Phil, Squid-in-Training wrote:
> >> Jasper Janssen wrote:
> >>>
> >>>
> >>> So would you have preferred a front wheel ejection for exactly the
> >>> same mistake?
> >>
> >> My dropouts don't have lawyer lips.
> >>
> >
> > Phil, that did not answer the question.
>
> He didn't ask a relevant question.
:-) Oh? When we're dealing with a design that has generated many
accounts of front axles slipping loose, and at least one of a wheel
ejection and consequent paralysis, then wheel ejection isn't relevant?
Sorry, Phil. That's an extremely weak excuse. The danger of this
design is the heart of the matter.
>
> > Let me ask another. What would _you_ think about riding a
> > conventional-brake road bike whose front fork dropout slots faced
> > upward? Would you call that a good design?
>
> Sure, if I knew it was time-tested,
Clearly, it's not. Front fork dropouts do not normally open in the
direction of ejection force.
> worked well in my experience,
Obviously, if we gave you a conventional bike with upward facing
dropout slots, you would have no experience with it. Sounds to me like
that gives you a way of saying "No."
> and didn't
> have glaringly obvious problems that affected the vast majority of riders.
Hey, I'm talking about giving you the prototype to ride. There would
be no vast majority of riders. You'd be the test pilot - assuming you
approved the design.
And in real life, as opposed to stubborn Usenet debate, you'd never
ride such a prototype on a regular basis. At least, nobody with normal
intelligence and normal motives of self-preservation would do so.
> Sounds like QR disc brakes are a good design. A running design mod is okay
> by me, too.
I don't think anyone is trying to condemn all QR / disk brake
combinations. We're just trying to reject a system that is too prone
to unnecessary failure. The fix is trivial - so there's no reason not
to fix it.
> If it were up to me, I would redesign the quick-release to make it
> idiot-proof, not the disc brake. But it looks like we'll have to settle for
> forward-facing dropouts.
Fine. Again, there's no reason NOT to do something like that. There
is simply no practical downside.
- Frank Krygowski
frkr...@yahoo.com
> > conventional-brake road bike whose front fork dropout slots faced
> > upward? Would you call that a good design?
> >
> > None of your teammates seem willing to answer.
> >
>
> it's so dumb.
I'll agree with this: Having a dropout opening in the direction of
ejection force _is_ dumb, unless there's a VERY good reason for doing
it, AND the consequences are minor.
Neither is true in the case of the current designs of QR disk brake
front forks.
> but since being dumb seems to be the order of the day for
> this debate
:-) Half of it, anyway! ;-)
> - the answer, professor, is that the g's of an impact can
> easily exceed anything seen in in any other mode of service.
Oh, no, wait, James! When designing a conventional fork with upward
facing dropouts, wouldn't the designer just calculate the clamping
force from a quick release? Wouldn't he then use Brinell data (or
similar data) to calculate the depth of indentation from the serrations
on a QR nut? Wouldn't he then figure a theoretical pullout force? And
wouldn't he then say "The theoetical pullout force should handle the
'g's of an impact' so my upward facing dropouts are perfectly fine,
provided the installation meets my ideal case"?
After all, your entire argument has been that we need no metal in the
way of the ejecting force. Friction, perhaps with a little help from
indentations, ought to do it.
Isn't it odd that in 150 years of bicycle design, nobody's used your
logic to design and defend upward facing front dropouts?
- Frank Krygowski
frkr...@yahoo.com
jim beam wrote:
> frkr...@yahoo.com wrote:
> >
> > Pay attention, please. If the serrations were right on the edge of
> > meshing, but not quite meshing, they _would_ clamp tightly.
>
> "not quite meshing"??? so how come i can so unerringly and completely
> manage to get such consistently comlete repetition over 100
> insertions??? am i secretly using some precision alignment device that
> micro-rotates my axle to an exactly pre-determined position as i throw
> it in from the trunk of my car?
I don't know what you're doing. I don't know the history of the bike
in the photograph.
What's your theory for the precise duplication of the circumferential
position of the indentations? Do you disagree that random positioning
would mean they usually _wouldn't_ match from one insertion to the
next? Is there not twice as much space between dents as the width of
the dents themselves?
What's your explanation?
> >>pictorial evidence shows no attrition that
> >>would be caused by the description you're desperately trying to
> >>artificially manufacture.
> >
> >
> > One picture shows something different, and we don't know what makes it
> > different. My dropouts don't show any serrations at all. (Sorry, no
> > digital camera lives here.) By my count, you're one-for-two.
>
> how damned convenient. and you /dare/ you trot out a smooth faced
> non-disk axle in this debate? you got chutzpah frank.
?? I'm looking at a quick release, not an axle. The face of the quick
release nut is not smooth, it's serrated. And it's steel, chrome
plated. The dropout it's clamping into is aluminum.
The bike is old, and that axle has been clamped many, many times. But
I saw nothing that looked like your indentations. Harder aluminum
alloy? Weaker quick release? Completely random serration positioning
causing no easily visible dents? I can't say.
All I can say is your picture looked completely different from my
dropout - and simple probability says your serrations would not grip in
exactly the same circumferential position each time by random chance.
Possibilities that occur to me are these: Perhaps you're in the habit
of feeling for those dents, rotating the nut and lever so they mesh.
That would be extraordinary. I know of nobody else that does that.
Perhaps you're hiding something from us. That is, perhaps those dents
are the result of ONE very large clamping force. That sounds harsh,
but no more than your (and "gmschemist's") claim that all the reporters
of problems are lying incompetents.
Or perhaps you really did position that QR mechanism completely
randomly, and a one-out-of-three chance came true over 100 times in a
row. That's not impossible. There's a one in 2E-48 chance it can
happen.
At this point, you really need to give us the details. Is one of my
guesses correct? If not, what _is_ the explanation for the
improbability? IOW, what exactly happens when the teeth on your QR
land between those grooves as you're clamping?
No that this is the most important point in this debate, of course.
- Frank Krygowski
gcmsc...@gmail.com
frkr...@yahoo.com wrote:
> That sounds harsh,
> but no more than your (and "gmschemist's") claim that all the reporters
> of problems are lying incompetents.
You're a liar. I never claimed that at all.
E.P.
John Red-Horse
>
>:-) Oh? When we're dealing with a design that has generated many
>accounts of front axles slipping loose, and at least one of a wheel
>ejection and consequent paralysis, then wheel ejection isn't relevant?
>
Why do you think lawyer lips were dreamt up in the first place? Hint: it
was prior to the introduction of bike disk brakes. How is that relevant?
Wheel ejection was a problem *before* the whole disk brake topic ever
arose.
I've both heard of and personally observed far more cases where user-error
resulted in loose QR's, which later resulted in crashes or near-crashes,
on bikes without disks than with---the latter of which, I've known of zero
save for these arguments on Usenet.
I agree with Phil, it'd be great if someone could invent a better axle
attachment system; I just don't see how it'll be possible.
john
Kinky Cowboy
Red-Horse) wrote:
>
>I agree with Phil, it'd be great if someone could invent a better axle
>attachment system; I just don't see how it'll be possible.
>
It exists, is widely available and carries the following premiums;
about $20 more expensive, about 100g heavier and wheel replacement
takes about 2 minutes longer. It's a 20mm through axle.
The only people who need a NEW design are XC racers with disc brakes,
for whom the slow wheel change is a problem. If everybody else
switched to 20mm through axles, the weight and price premiums would
all but disappear.
Kinky Cowboy*
*Batteries not included
May contain traces of nuts
Your milage may vary
Phil, Squid-in-Training
We can take some hints from the Buell Lightning:
http://www.bikez.com/bike/20739/index2.jpg
Too bad our wheels aren't cast, and they go out of true.
--
Phil, Squid-in-Training
Phil, Squid-in-Training
We could use some sort of locking device that wouldn't engage until past a
certain point.
A high-pitch helical gear with detents or an internal shelf that would
"click" into place once the required tension is acquired. If it doesn't
click into place, it immediately becomes totally loose again, making it
obvious that the QR is in the open position.
That would be more idiot-proof than the current one.
--
Phil, Squid-in-Training
Phil, Squid-in-Training
> Phil, Squid-in-Training wrote:
>> frkr...@yahoo.com wrote:
>>> Phil, Squid-in-Training wrote:
>>>> Jasper Janssen wrote:
>>>>>
>>>>>
>>>>> So would you have preferred a front wheel ejection for exactly the
>>>>> same mistake?
>>>>
>>>> My dropouts don't have lawyer lips.
>>>>
>>>
>>> Phil, that did not answer the question.
>>
>> He didn't ask a relevant question.
>
> :-) Oh? When we're dealing with a design that has generated many
> accounts of front axles slipping loose, and at least one of a wheel
> ejection and consequent paralysis, then wheel ejection isn't relevant?
>
>
> Sorry, Phil. That's an extremely weak excuse. The danger of this
> design is the heart of the matter.
The rear dropouts didn't have lawyer lips while disc forks, for the most
part, do. This makes the comparison not quite equivalent. I understood
Jasper's point, however. I was just being a little evasive.
>>
>>> Let me ask another. What would _you_ think about riding a
>>> conventional-brake road bike whose front fork dropout slots faced
>>> upward? Would you call that a good design?
>>
>> Sure, if I knew it was time-tested,
>
> Clearly, it's not. Front fork dropouts do not normally open in the
> direction of ejection force.
>
>> worked well in my experience,
>
> Obviously, if we gave you a conventional bike with upward facing
> dropout slots, you would have no experience with it. Sounds to me
> like that gives you a way of saying "No."
>
>> and didn't
>> have glaringly obvious problems that affected the vast majority of
>> riders.
>
> Hey, I'm talking about giving you the prototype to ride. There would
> be no vast majority of riders. You'd be the test pilot - assuming you
> approved the design.
I'm a really bad person to ask that, because I build things like 8-spoke
rear wheels, and I weld beercan aluminum frames that are cracked at the
chainstay, proceed to not heat-treat it, and then race it.
> And in real life, as opposed to stubborn Usenet debate, you'd never
> ride such a prototype on a regular basis. At least, nobody with
> normal intelligence and normal motives of self-preservation would do
> so.
Excellent point. We knew the answer at the beginning.
>> Sounds like QR disc brakes are a good design. A running design mod
>> is okay by me, too.
>
> I don't think anyone is trying to condemn all QR / disk brake
> combinations. We're just trying to reject a system that is too prone
> to unnecessary failure. The fix is trivial - so there's no reason not
> to fix it.
Yup - we're on the same page.
>> If it were up to me, I would redesign the quick-release to make it
>> idiot-proof, not the disc brake. But it looks like we'll have to
>> settle for forward-facing dropouts.
>
> Fine. Again, there's no reason NOT to do something like that. There
> is simply no practical downside.
And it's good to see products in the market doing just that.
--
Phil, Squid-in-Training
James Annan
> you are unreal. i've quoted ~>20kN clamping force
You made it up, you mean. I'm simply asking you where you plucked this
number from. It is contradicted by all measurements and credible
estimates I have seen, including the measurements you yourself referred
to recently (have you actually read that QR report yet?).
Jasper Janssen
Red-Horse) wrote:
>Why do you think lawyer lips were dreamt up in the first place? Hint: it
>was prior to the introduction of bike disk brakes. How is that relevant?
>Wheel ejection was a problem *before* the whole disk brake topic ever
>arose.
Indeed. Which means that it's even more of a problem when there is an
actual force that presses the wheel out of the dropouts, rather than it
simply falling out.
>I've both heard of and personally observed far more cases where user-error
>resulted in loose QR's, which later resulted in crashes or near-crashes,
>on bikes without disks than with---the latter of which, I've known of zero
>save for these arguments on Usenet.
Is it possible you have more experience with non-disc bikes than with
disked bikes? If you have a loose QR through user error on a disk-braked
bike, you should have a crash at the very first use of saif brake.
>I agree with Phil, it'd be great if someone could invent a better axle
>attachment system; I just don't see how it'll be possible.
There is one: through-axles. You give up QR (or you'd need to do up QRs on
both sides of the fork separately), and there is presumably some weight
penalty, but it is an inherently much stronger and safer system (if only
because loosening of one side of the axle keeps the other side firmly in
place -- redundancy).
That said, given that QRs do get loose, evne if it's usually through user
error, it's not a good idea to design something that worsens the
consequences of that fact if there aren't good, solid reasons for doing
so. So far, the only real reason given (discounting the ludicrous "yeah,
but you can't braze/weld on things to be loaded in tension) is that the
calipers get less dirty behind the fork legs. The reasons for having pure
downward opening dropouts rather than 45-90 degrees angled forward are
completely ludicrous. The only counterargument I've seen the other side
offer is "yeah, but it costs money to retool!".. and of course, fork
makers use the same jigs and tools in perpetuity. Just like Sturmey
Archer.
Jasper
Jasper Janssen
>On Wed, 12 Oct 2005 19:46:27 +0000 (UTC), jrr...@swcp.com (John
>Red-Horse) wrote:
>It exists, is widely available and carries the following premiums;
>about $20 more expensive, about 100g heavier and wheel replacement
>takes about 2 minutes longer. It's a 20mm through axle.
Only 2 minutes? Is that for QR-equipped through axle fastenings or the
allen screw ones? 'Cause the latter take hours longer if you don't have an
appropriate allen key with you..
>The only people who need a NEW design are XC racers with disc brakes,
>for whom the slow wheel change is a problem. If everybody else
*Any* racers with disc brakes, really -- why not MTBers?
>switched to 20mm through axles, the weight and price premiums would
>all but disappear.
I'm surprised it only costs you 100 grams and $20. It looks a lot more
expensive than that (in both senses).
Jasper
James Annan
> James Annan wrote:
>
>>I don't really see that there is much point in _my_ trying to argue the
>>case in any detail, especially with anonymous usenet trolls such as
>>yourself.
>
>
> As opposed to named usenet trolls? Is there *really* a difference?
>
>
>>But you can hardly have avoided noticing how your supposed
>>"summary" brought out criticism from even the likes of "gcmschemist"
>>(hardly my strongest supporter!) who seems to recognise your
>>smokescreen and bluster for what it is.
>
>
> You're a liar. A damned ballsy liar as well.
I obviously misunderstood what you mean with your comments such as
"Get out your drawings and your calculator, and stop hinting. Show the
math, do an experiement, or shut the fuck up."
> James, you've had your shot at it. Now, I'd like to see Jim Beam
> produce the calculations from which he derives 20kN.
Wouldn't we all. You may have noticed that I have already asked several
times.
> I can't get that
> number, so I'm obviously missing SOMETHING. I realize that if Jim were
> to produce a detailed calculation, you wouldn't have the balls to say
> he was right - you are a very small person after all.
If Jim continues to refuse to justify his figure, will you perhaps deign
to consider the possibility that he is just making stuff up in the hope
of confusing as many people as possible? I realise it will be difficult
for you to admit that I could be right about anything.
Jasper Janssen
<gcmsc...@gmail.com> wrote:
>David Damerell wrote:
>> Quoting gcmsc...@gmail.com <gcmsc...@gmail.com>:
>> >David Damerell wrote:
>> >>Quoting gcmsc...@gmail.com <gcmsc...@gmail.com>:
>> >>>Doing a quick title search on "danger" and "carbon fiber" yields very
>> >>>few posts.
>> [numbers of hits in article bodies are very similar for CF and disc brakes]
>> >*Title* search?
>>
>> Oh, in the Subject: line? Call it by its name, please.
>
>That *is* its name, you pedantic shithead.
The Subject: line's name is "Title"? Can you give me a good reason why?
Both the actual header and google call it a Subject.
Jasper
Phil, Squid-in-Training
It is. There are typically no race-weight 20mm thru-axle forks/wheels,
barring the Maverick designs. And the Maverick forks are a pretty penny.
What problems would be encountered with a standard 10mm thru-axle? A new
10mm smooth axle, not based on the current threaded one.
--
Phil, Squid-in-Training
Phil, Squid-in-Training
How about drilling holes longitudinally through the ends of the dropouts of
regular QR disc brake forks, and then tapping one side, and screwing in a
small screw on the other side? Sort of a mini-retro that would prevent a
wheel from ever fully ejecting. The profile of the dropout wouldn't allow
much "clamping" onto the axle so to speak, but it would be a block to
prevent the wheel from leaving the fork completely.
--
Phil, Squid-in-Training
gcmsc...@gmail.com
James Annan wrote:
> gcmsc...@gmail.com wrote:
>
> > James Annan wrote:
> >
> >>I don't really see that there is much point in _my_ trying to argue the
> >>case in any detail, especially with anonymous usenet trolls such as
> >>yourself.
> >
> >
> > As opposed to named usenet trolls? Is there *really* a difference?
> >
> >
> >>But you can hardly have avoided noticing how your supposed
> >>"summary" brought out criticism from even the likes of "gcmschemist"
> >>(hardly my strongest supporter!) who seems to recognise your
> >>smokescreen and bluster for what it is.
> >
> >
> > You're a liar. A damned ballsy liar as well.
>
> I obviously misunderstood what you mean with your comments such as
You obviously did. I do not think it "smokescreen or bluster."
I think that it needs to be shown to we folks who have not seen all the
relevant information.
James - stop inferring things and just quote relevant comments.
> > James, you've had your shot at it. Now, I'd like to see Jim Beam
> > produce the calculations from which he derives 20kN.
>
> Wouldn't we all. You may have noticed that I have already asked several
> times.
As have I. But sniping and bullshitting from the periphery doesn't
answer the question.
> > I can't get that
> > number, so I'm obviously missing SOMETHING. I realize that if Jim were
> > to produce a detailed calculation, you wouldn't have the balls to say
> > he was right - you are a very small person after all.
>
> If Jim continues to refuse to justify his figure, will you perhaps deign
> to consider the possibility that he is just making stuff up in the hope
> of confusing as many people as possible?
I will entertain the notion that he is in error. You are implying,
again without proof, motives which aren't evident from the writings.
But I am less likely to accept Jim's word for it without *something*
tangible to back it up.
> I realise it will be difficult
> for you to admit that I could be right about anything.
Oh, quit pouting!
I have accepted *some* of your hypothesis. So, again, I blow up your
carefully-crafted strawman. One of my biggest problems with your
hypothesis is they way you defend it - not with data, but with
unnececcarily sarcastic and just plain shitty commentary. Put down
that big bong of ego you're smoking and join in a discussion in which
you surely do not have all the answers.
And stop lying. I have said that if it turns out that my experiments
confirm your hypothesis...
Heck, just go and read the last thread where I said exactly what I
would do in that case.
You could be gracious and offer an apology, but I doubt that will be
forthcoming.
E.P.
James Annan
> James Annan wrote:
>
>>gcmsc...@gmail.com wrote:
>>
>>
>>>James Annan wrote:
>>>
>>>
>>>>I don't really see that there is much point in _my_ trying to argue the
>>>>case in any detail, especially with anonymous usenet trolls such as
>>>>yourself.
>>>
>>>
>>>As opposed to named usenet trolls? Is there *really* a difference?
>>>
>>>
>>>
>>>>But you can hardly have avoided noticing how your supposed
>>>>"summary" brought out criticism from even the likes of "gcmschemist"
>>>>(hardly my strongest supporter!) who seems to recognise your
>>>>smokescreen and bluster for what it is.
>>>
>>>
>>>You're a liar. A damned ballsy liar as well.
>>
>>I obviously misunderstood what you mean with your comments such as
>
>
> You obviously did. I do not think it "smokescreen or bluster."
Ok, I misunderstood how much progress you had made, but I hope (and in
fact believe) that you at least entertain the possibility that jim
beam's claim of a "~>20kN" clamping force is just smokescreen and
bluster. After all, he's been give ample opportunity to justify it, and
ducked and weaved in the style we all know and love.
Be sure to let us know if and when the penny finally drops :-)
> I have accepted *some* of your hypothesis. So, again, I blow up your
> carefully-crafted strawman. One of my biggest problems with your
> hypothesis is they way you defend it - not with data, but with
> unnececcarily sarcastic and just plain shitty commentary.
I have stated the facts as clearly as I can on my website and previously
many times here. I agree that explaining things to (some) people doesn't
work well in practice, which is why I encourage them to work out some of
the answers to their own satisfaction. Don't forget that from my point
of view, I've had a continuous stream of cluless nerds, many of whom
don't even understand the basic force diagrams, try to "teach me
physics" (for well over 2 years now). Tolerance of fools never was a
particular strength of mine. So forget _me_, and think about the _issues_.
Kinky Cowboy
wrote:
>On Wed, 12 Oct 2005 21:39:14 +0100, Kinky Cowboy <us...@domain.com> wrote:
>>On Wed, 12 Oct 2005 19:46:27 +0000 (UTC), jrr...@swcp.com (John
>>Red-Horse) wrote:
>
>>It exists, is widely available and carries the following premiums;
>>about $20 more expensive, about 100g heavier and wheel replacement
>>takes about 2 minutes longer. It's a 20mm through axle.
>
>Only 2 minutes? Is that for QR-equipped through axle fastenings or the
>allen screw ones? 'Cause the latter take hours longer if you don't have an
>appropriate allen key with you..
Yeah, going out without tools can slow you down a bit :-)
Even if it's 10 minutes, getting a 10 minute break when you puncture
is better than the endo/face plant scenario which a QR might expose
you to
>>The only people who need a NEW design are XC racers with disc brakes,
>>for whom the slow wheel change is a problem. If everybody else
>
>*Any* racers with disc brakes, really -- why not MTBers?
I figured XC racing was the only kind where disc brakes are common AND
riders can win or lose based on a quick puncture repair. Other MTB
classes (DH, 4X) already switched to 20mm and don't need to fix
punctures mid-race anyway, Cyclo-X has some disc braked riders but
they're likely to be on tubulars and can ride to the end of the lap
and swap bikes.
>>switched to 20mm through axles, the weight and price premiums would
>>all but disappear.
>
>I'm surprised it only costs you 100 grams and $20. It looks a lot more
>expensive than that (in both senses).
>
Like-for-like; there's only a couple of forks available in both
styles, for example Chain Reaction currently have 2005 Marzocchi DJ2
in both styles at the same price, although the Junior T carries a
substantial premium. For 2006, Marzocchi are offering the DJ3 in both
styles at exactly the same listed weight, probably excludes the axle.
Hubs sometimes cost a little more for the same for similar quality,
e.g. Atomlab GI GBP40 for the 20mm and GBP30 for the QR, DMR Revolver
37.50/32.50, DT Swiss 440 no difference. The 440 20mm hub is actually
listed by DT as 3g lighter than the QR, again excluding the axle but
the QR version excludes the skewer too. So today you can already
choose some 20mm front end combos with absolutely no price premium
over their QR equivalent, and with a weight penalty of whatever a
Marzocchi 20mm axle weighs over a QR skewer, i.e. not very much. I'm
not pulling mine out to weigh it now, but I've measured it in situ and
180mm of Aluminium tube 20mm OD, 14mm ID amounts to about 75g and an
XTR front skewer weighs 57g according to weightweenies.starbike.com,
so my 100g looks like a 400% over estimate!
Right at the bottom end of the market, it might never be possible to
make a 20mm hub as cheap as a 9mm QR style, but I'd expect the premium
to come down to ~$5 at the "supermarket bike" level; that's much less
than the premium people are already paying for useless suspension and
shitty cable-actuated discs on such bikes.
gcmsc...@gmail.com
James Annan wrote:
> gcmsc...@gmail.com wrote:
>
> >
> > You obviously did. I do not think it "smokescreen or bluster."
>
> Ok, I misunderstood how much progress you had made, but I hope (and in
> fact believe) that you at least entertain the possibility that jim
> beam's claim of a "~>20kN" clamping force is just smokescreen and
> bluster.
Again, you are making a backhanded accusation of fraud where there is
no real evidence to support your accusation. If the data, calcualtions
and assumptions are not forthcoming, then the credence I lend to his
postings on the matter goes down significantly.
That does not imply that your hypothesis is 100% correct, however. Nor
does it imply that your conclusions are appropriate.
Stick to FACTS, James, and leave the dark, shadowy, *non-provable*
motives out of it.
> After all, he's been give ample opportunity to justify it, and
> ducked and weaved in the style we all know and love.
He *did* provide a URL, which turned out to be dead. That's pretty
long way to go to merely bluster. He offered to send me the data via
e-mail, if he had it on his hard drive. I will allow the benefit of
the doubt - after all, he implies that the calculations are
straightforward. I await them, as do you.
> > I have accepted *some* of your hypothesis. So, again, I blow up your
> > carefully-crafted strawman. One of my biggest problems with your
> > hypothesis is they way you defend it - not with data, but with
> > unnececcarily sarcastic and just plain shitty commentary.
>
> I have stated the facts as clearly as I can on my website and previously
> many times here.
And if you stopped right there, I'd have more respect for you and your
conclusions. But because of snide and snotty comments, I assume that
there's some kind of smokescreen being generated.
> I agree that explaining things to (some) people doesn't
> work well in practice, which is why I encourage them to work out some of
> the answers to their own satisfaction.
Why does saying just like that pain you so?
> Don't forget that from my point
> of view, I've had a continuous stream of cluless nerds, many of whom
> don't even understand the basic force diagrams, try to "teach me
> physics" (for well over 2 years now).
You're trying to convince. Having manners helps. It's just that
simple.
> Tolerance of fools never was a
> particular strength of mine. So forget _me_, and think about the _issues_.
To me, part of the issue is your lack of acceptance of the doubt
raised, and the vehemence with which you try to dismiss that doubt.
There is a disconnect between your hypothesis and the verifiable
instances of wheel ejection. The prediction from the ISO value makes
the set-up dicey at best, yet it seems to work reliably for a vast
majority of users. The instance of reported, *purported* QR unscrewing
or actual ejection is very low, and those have to be taken with a large
grain of salt due to lack of full information regarding initial
conditions. As a scientist, I crave repeatable data, and none of the
supporting anecdotes provided satisfy in the least. The only hard bit
of evidence we have is your calculation of the force at the dropout.
Even *that* should be experimentally verified, but I take it as given
for now.
As soon as I assemble my rig, and get all the necessary bits, I am
going to perform experiments. They will be written in such a way that
anyone could repeat them if they desired. Such is the way of science -
hypothesis, testing, lather, rinse, repeat. After all is said and
done, Conclusion, with experimental and theoretical support. And a
nice paper in some obscure journal. :)
E.P.
Michael Press
Kinky Cowboy <us...@domain.com> wrote:
> On Wed, 12 Oct 2005 19:46:27 +0000 (UTC), jrr...@swcp.com (John
> Red-Horse) wrote:
>
>
> >
> >I agree with Phil, it'd be great if someone could invent a better axle
> >attachment system; I just don't see how it'll be possible.
> >
>
> It exists, is widely available and carries the following premiums;
> about $20 more expensive, about 100g heavier and wheel replacement
> takes about 2 minutes longer. It's a 20mm through axle.
I do not want a through axle that only exists because of a
faulty disc brake configuration. I want a disck brake that
engages the disc in front of the fork.
--
Michael Press
jobst....@stanfordalumni.org
attacking logical presentation with which they disagree, is striking.
Beyond that they give no explanation other than calling the author
with whom they disagree insulting names and citing articles that no
one can find.
This immediately reduces these respondents credibility to near zero
for such a public debate.
Jobst Brandt
gcmsc...@gmail.com
jobst....@stanfordalumni.org wrote:
> As I peruse these postings, the rudeness of anonymous writers while
> attacking logical presentation with which they disagree, is striking.
Equally as striking is the rudeness of supposedly non-anonymous
posters, who do *exactly the same thing*.
Keep riding that nym high-horse, Jobst - it's really taking you
places...
E.P.
jim beam
> James Annan wrote:
>
>>I don't really see that there is much point in _my_ trying to argue the
>>case in any detail, especially with anonymous usenet trolls such as
>>yourself.
>
>
> As opposed to named usenet trolls? Is there *really* a difference?
>
>
>>But you can hardly have avoided noticing how your supposed
>>"summary" brought out criticism from even the likes of "gcmschemist"
>>(hardly my strongest supporter!) who seems to recognise your
>>smokescreen and bluster for what it is.
>
>
> You're a liar. A damned ballsy liar as well.
hey, if you're going to lie, go big. audacity makes it more believable.
>
> I criticize because I want to see the numbers, the calculation and all
> of the middle work.
>
> That does NOT imply that I believe it to be smokescreen and bluster, it
> is explicit that I want to see the data and the calculation!
>
> James, you've had your shot at it. Now, I'd like to see Jim Beam
> produce the calculations from which he derives 20kN. I can't get that
> number, so I'm obviously missing SOMETHING. I realize that if Jim were
> to produce a detailed calculation, you wouldn't have the balls to say
> he was right - you are a very small person after all.
>
> So, Mr. Beam - *I* want to see the numbers. I never got any .pdf in my
> inbox, so I can't actually see the calculations, data and assumptions
> you are basing your conclusions upon. So, I am *asking*, in a pleasant
> fashion I hope, if you will please show all data, calculations,
> assumptions and if standard values are used, from what source they were
> obtained.
elongation = force x length / modulus x area.
rearrange that for force, then use the following assumptions:
skewer diameter ~= 5mm
elongation ~= 2/3mm, based on cam displacement.
length of the skewer ~= 110mm
modulus = 200GPa
that gives you the clamping force. clamping force does not directly
resist pullout - it simply ensures serrations stay seated in
indentations. it's the indentation/serration interlock that provides
pullout resistance, and that we discussed before.
jim beam
wow, what a great attempt at the persecutor/victim switcheroo. even
jobst would be proud of that one. one minute you're all about
accusation & hostility, the next, you're whining like an injured infant
making out like the bully beat you.
fact james: many people have told you many times just exactly where
your theory is incomplete and yet you've done nothing to address it.
and here you still are, five days into yet another thread on the same
subject /still/ refusing to be drawn. it's quite incredible.
jim beam
> jim beam wrote:
>
>> you are unreal. i've quoted ~>20kN clamping force
>
>
> You made it up, you mean. I'm simply asking you where you plucked this
> number from. It is contradicted by all measurements and credible
> estimates I have seen, including the measurements you yourself referred
> to recently (have you actually read that QR report yet?).
>
> James
another evasion. address pullout force james. be a man.
jim beam
hey pot, let me introduce you to kettle; kettle, here's pot.
jim beam
>>>conventional-brake road bike whose front fork dropout slots faced
>>>upward? Would you call that a good design?
>>>
>>>
>>
>>wow - you're just obsessed with this aren't you. no one answers because
>>it's so dumb.
>
>
> I'll agree with this: Having a dropout opening in the direction of
> ejection force _is_ dumb, unless there's a VERY good reason for doing
> it, AND the consequences are minor.
>
> Neither is true in the case of the current designs of QR disk brake
> front forks.
>
>
>
>> but since being dumb seems to be the order of the day for
>>this debate
>
>
> :-) Half of it, anyway! ;-)
>
>
>
>>- the answer, professor, is that the g's of an impact can
>>easily exceed anything seen in in any other mode of service.
>
>
> Oh, no, wait, James! When designing a conventional fork with upward
> facing dropouts, wouldn't the designer just calculate the clamping
> force from a quick release? Wouldn't he then use Brinell data (or
> similar data) to calculate the depth of indentation from the serrations
> on a QR nut? Wouldn't he then figure a theoretical pullout force? And
> wouldn't he then say "The theoetical pullout force should handle the
> 'g's of an impact' so my upward facing dropouts are perfectly fine,
> provided the installation meets my ideal case"?
>
> After all, your entire argument has been that we need no metal in the
> way of the ejecting force. Friction, perhaps with a little help from
> indentations, ought to do it.
>
> Isn't it odd that in 150 years of bicycle design, nobody's used your
> logic to design and defend upward facing front dropouts?
>
> - Frank Krygowski
>
/my/ design??? trying to put words in someone's mouth like that is so
weak, it's just shameful. does ysu know you disgrace them in this way?
jim beam
>>>meshing, but not quite meshing, they _would_ clamp tightly.
>>
>>"not quite meshing"??? so how come i can so unerringly and completely
>>manage to get such consistently comlete repetition over 100
>>insertions??? am i secretly using some precision alignment device that
>>micro-rotates my axle to an exactly pre-determined position as i throw
>>it in from the trunk of my car?
>
>
> I don't know what you're doing. I don't know the history of the bike
> in the photograph.
>
> What's your theory for the precise duplication of the circumferential
> position of the indentations? Do you disagree that random positioning
> would mean they usually _wouldn't_ match from one insertion to the
> next? Is there not twice as much space between dents as the width of
> the dents themselves?
>
> What's your explanation?
why don't /you/ tell me frank? i'm just a materials guy. i'm not an
engineer. you're an engineering professor for the love of mike. i'm
not playing a stupid game with you just so you can have some sicko fun.
>
>
>
>>>>pictorial evidence shows no attrition that
>>>>would be caused by the description you're desperately trying to
>>>>artificially manufacture.
>>>
>>>
>>>One picture shows something different, and we don't know what makes it
>>>different. My dropouts don't show any serrations at all. (Sorry, no
>>>digital camera lives here.) By my count, you're one-for-two.
>>
>>how damned convenient. and you /dare/ you trot out a smooth faced
>>non-disk axle in this debate? you got chutzpah frank.
>
>
> ?? I'm looking at a quick release, not an axle. The face of the quick
> release nut is not smooth, it's serrated. And it's steel, chrome
> plated. The dropout it's clamping into is aluminum.
>
> The bike is old, and that axle has been clamped many, many times. But
> I saw nothing that looked like your indentations. Harder aluminum
> alloy? Weaker quick release? Completely random serration positioning
> causing no easily visible dents? I can't say.
>
> All I can say is your picture looked completely different from my
> dropout - and simple probability says your serrations would not grip in
> exactly the same circumferential position each time by random chance.
you shamelessly say that because it suits your weak little trumped-up
argument - but as i told you before, that pic is where the wheel had
been inserted and clamped approximately 100 times. it shows
extroardinarily clear repetition of indentation position. now frank, go
ahead and demonstrate your engineering prowess rather than your desire
to propagate a pissing contest.
>
> Possibilities that occur to me are these: Perhaps you're in the habit
> of feeling for those dents, rotating the nut and lever so they mesh.
> That would be extraordinary. I know of nobody else that does that.
unbefuckinleivable. where do you get this stuff from? i couldn't make
up fantasies like this if i tried.
>
> Perhaps you're hiding something from us. That is, perhaps those dents
> are the result of ONE very large clamping force. That sounds harsh,
> but no more than your (and "gmschemist's") claim that all the reporters
> of problems are lying incompetents.
yeah, sure. i carefully applied the mud and the scrapes and wore the
disk down just for that one photo. why not accuse me of photoshopping
it instead?
>
> Or perhaps you really did position that QR mechanism completely
> randomly, and a one-out-of-three chance came true over 100 times in a
> row. That's not impossible. There's a one in 2E-48 chance it can
> happen.
>
> At this point, you really need to give us the details. Is one of my
> guesses correct? If not, what _is_ the explanation for the
> improbability? IOW, what exactly happens when the teeth on your QR
> land between those grooves as you're clamping?
but frank, you're the engineering professor...
>
> No that this is the most important point in this debate, of course.
eh??? frank, it /is/ the whole crux of the argument. indentations
prevent slippage. period.
>
> - Frank Krygowski
>
jim beam
i forgot - haven't been able to locate the pdf so haven't been able to
email it, but iirc, it basically just showed skewer clamping force was a
function of cam displacement, and went on to prove it for a bunch of
different skewers. not a pivotal piece.
jobst....@stanfordalumni.org
>> As I peruse these postings, the rudeness of anonymous writers while
>> attacking logical presentation with which they disagree, is
>> striking. Beyond that they give no explanation other than calling
>> the author with whom they disagree insulting names and citing
>> articles that no one can find.
>> This immediately reduces these respondents credibility to near zero
>> for such a public debate.
> hey pot, let me introduce you to kettle; kettle, here's pot.
Before you write so self assuredly, would you cite an instance of four
letter words and insulting names you seem to believe I have used. If
I did, you can surely find them on the net. I disagree with your
assessment of mechanical designs in bicycles but that's what this
forum is about, presenting credible events and discoveries of the
equipment we ride. What I see from you is that most new things
presented here must be wrong and the person who wrote it a target for
rude ridicule. You could write something about the discoveries you
have made that might help the readers and get on the positive side of
discussions.
Jobst Brandt
jim beam
discoveries? you credit yourself with discoveries?
* like non-brinelling headsets?
* like sweeping away all distinction between a journal bearing and a
rolling element bearing?
* like elasto-hydrodynamically separated rolling element bearings on bikes?
* like fatigue-proof stainless steel?
* like j-type spokes that don't bend at the elbow when loaded?
* like suddenly re-defining the word "swaging" to include a bunch of
metal processing techniques that are otherwise perfectly adequately and
distinctly defined?
* like wheels that get stronger as their spoke tension increases?
* like wheels that collapse in the absence of bottom spokes?
* like tensiometers that measure tension without regard to spoke thickness?
* like using a dye penetrant test to conclude that anodizing is
responsible for rim cracking?
jobst, you endlessly promote yourself as some form of expert. and some
people even believe you. but the truth is, you don't know half the
things you claim. all the above examples, and it's not an exhaustive
list, merely expose your shallowness. and yet you shamelessly plow on
as if there's nothing wrong, all at a time when unprecidented access to
information on the internet shows just how contemptuous you are by not
even being bothered to look anything up.
it's a disgrace. frankly, i'm surprised stanford allow you to use an
alumni address - you single handedly do more damage to the credit of
their engineering department than they can possibly hope to redeem in a
generation. i'd never hire a stanford engineering grad based on you as
an example of their output.
frkr...@yahoo.com
> weak, it's just shameful. does ysu know you disgrace them in this way?
:-) Hilarious!
Looks like you need to read more slowly, Jim. I didn't say the
_design_ was yours. I said the LOGIC was. (Although I really should
have put "logic" in quotes.)
See what happens when you let your spittle cover the screen? ;-)
- Frank Krygowski
James Annan
> James Annan wrote:
> > After all, he's been give ample opportunity to justify it, and
> > ducked and weaved in the style we all know and love.
>
> He *did* provide a URL, which turned out to be dead. That's pretty
> long way to go to merely bluster. He offered to send me the data via
> e-mail, if he had it on his hard drive. I will allow the benefit of
> the doubt - after all, he implies that the calculations are
> straightforward. I await them, as do you.
Oh, are you under the illusion that the pdf had any relevance to his
estimate? I can see how in that case, you might assume that his figure
has a plausible basis in reality. However, he described his estimate as
"a rough calc", and has so far provided no support for it.
Unfortunately for him, the pdf was describing real experiments which
flatly contradict him, as does every source I bothered to look into via
google.
> > I have stated the facts as clearly as I can on my website and previously
> > many times here.
>
> And if you stopped right there, I'd have more respect for you and your
> conclusions. But because of snide and snotty comments, I assume that
> there's some kind of smokescreen being generated.
Assume what you like a priori, but think about the evidence for
yourself.
> As soon as I assemble my rig, and get all the necessary bits, I am
> going to perform experiments. They will be written in such a way that
> anyone could repeat them if they desired. Such is the way of science -
> hypothesis, testing, lather, rinse, repeat. After all is said and
> done, Conclusion, with experimental and theoretical support. And a
> nice paper in some obscure journal. :)
I hope you will have a look at Cannondale's version of the same, and
consider if you could improve on the rigour of their testing in any way
:-)
http://www.ne.jp/asahi/julesandjames/home/disk_and_quick_release/cannondale.html
James
frkr...@yahoo.com
John Red-Horse wrote:
> In article <1129134291....@g14g2000cwa.googlegroups.com>,
> frkr...@yahoo.com wrote:
> >
> >:-) Oh? When we're dealing with a design that has generated many
> >accounts of front axles slipping loose, and at least one of a wheel
> >ejection and consequent paralysis, then wheel ejection isn't relevant?
> >
>
> Why do you think lawyer lips were dreamt up in the first place? Hint: it
> was prior to the introduction of bike disk brakes. How is that relevant?
> Wheel ejection was a problem *before* the whole disk brake topic ever
> arose.
Which makes it even more foolish to design a brake to exacerbate the
problem - to actually try to force the axle out of the dropouts.
>
> I've both heard of and personally observed far more cases where user-error
> resulted in loose QR's, which later resulted in crashes or near-crashes,
> on bikes without disks than with...
Of course! Dick brakes are present on fewer than 1% of the QR bikes in
the world.
> ---the latter of which, I've known of zero save for these arguments on
> Usenet.
This is why the acronym "YMMV" was invented, isn't it? IOW, your
sample is not necessarily a statistically valid one.
I'll also remind you, nobody is saying this problem happens to everyone
with such a setup. It's apparently more likely if certain conditions
exist: non-ferrous skewers, external cam QR, lots of very hard
braking, and long periods of time between front wheel installations.
Oh, and tandem usage makes it more likely too.
We know the vast majority of mountain bikes seldom see dirt, and
likewise, seldom see extreme conditions of any kind. Those riders,
esp. with steel skewers, can probably get away with using this design.
But why not use a design that would be much safer for the hard-charging
type of mountain biker? What is the downside?
- Frank Krygowski
gcmsc...@gmail.com
James Annan wrote:
> gcmsc...@gmail.com wrote:
> > James Annan wrote:
>
> > > After all, he's been give ample opportunity to justify it, and
> > > ducked and weaved in the style we all know and love.
> >
> > He *did* provide a URL, which turned out to be dead. That's pretty
> > long way to go to merely bluster. He offered to send me the data via
> > e-mail, if he had it on his hard drive. I will allow the benefit of
> > the doubt - after all, he implies that the calculations are
> > straightforward. I await them, as do you.
>
> Oh, are you under the illusion that the pdf had any relevance to his
> estimate? I can see how in that case, you might assume that his figure
> has a plausible basis in reality.
Knock off the snide bullshit. It does not help your position or
credibility.
> However, he described his estimate as
> "a rough calc", and has so far provided no support for it.
Actually he has. Read further in the thread.
> Unfortunately for him, the pdf was describing real experiments which
> flatly contradict him, as does every source I bothered to look into via
> google.
Provide a copy of the .pdf, and a list of references, please. Sauce
for the goose and all that...
> > > I have stated the facts as clearly as I can on my website and previously
> > > many times here.
> >
> > And if you stopped right there, I'd have more respect for you and your
> > conclusions. But because of snide and snotty comments, I assume that
> > there's some kind of smokescreen being generated.
>
> Assume what you like a priori, but think about the evidence for
> yourself.
You have no idea what "a priori" means, I take it? I did not come to
any conclusion without a data review, James.
I see the evidence, and give it *exactly* the weight it deserves, in a
scientific sense. And I see your snide attitude, and wonder what
you're covering...
> > As soon as I assemble my rig, and get all the necessary bits, I am
> > going to perform experiments. They will be written in such a way that
> > anyone could repeat them if they desired. Such is the way of science -
> > hypothesis, testing, lather, rinse, repeat. After all is said and
> > done, Conclusion, with experimental and theoretical support. And a
> > nice paper in some obscure journal. :)
>
> I hope you will have a look at Cannondale's version of the same, and
> consider if you could improve on the rigour of their testing in any way
> :-)
I've seen it, and I'm not at all impressed. But that test is nothing
like my design. I have no money to duplicate their effort in a more
realistic way - that would take at least an order of magnitude more
cash. At least.
Your derision of their test isn't convincing, however - they actual did
*something.*
You've done how many experiments again? None? I wouldn't be so damn
smug, if I were you. Your hypothesis still requires *some*
experimental verification, you know. I am holding both you and Jim to
exactly the same standard on this. So far, you have a drawing and
calculations. When Jim comes up with his, assuming they check out,
then you'll be on equal footing, as far as I'm concerned.
frkr...@yahoo.com
jim beam wrote:
> jobst....@stanfordalumni.org wrote:
>
> > You could write something about the discoveries you
> > have made that might help the readers and get on the positive side of
> > discussions.
>
>
> * like non-brinelling headsets?
> * like sweeping away all distinction between a journal bearing and a
> rolling element bearing?
> * like elasto-hydrodynamically separated rolling element bearings on bikes?
> * like fatigue-proof stainless steel?
> * like j-type spokes that don't bend at the elbow when loaded?
> * like suddenly re-defining the word "swaging" to include a bunch of
> metal processing techniques that are otherwise perfectly adequately and
> distinctly defined?
> * like wheels that get stronger as their spoke tension increases?
> * like wheels that collapse in the absence of bottom spokes?
> * like tensiometers that measure tension without regard to spoke thickness?
> * like using a dye penetrant test to conclude that anodizing is
> responsible for rim cracking?
>
> jobst, you endlessly promote yourself as some form of expert. and some
> people even believe you. but the truth is, you don't know half the
> things you claim. all the above examples, and it's not an exhaustive
> list, merely expose your shallowness.
Jim, why don't you just run a separate thread titled "I'm really much
smarter than Jobst." Put all such posts in it, not in other threads.
It really _would_ be a great place to list your contributions to the
world of cycling, you know!
- Frank Krygowski