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



J

jim beam

Guest
[email protected] wrote:
> On Feb 14, 12:48 am, jim beam <[email protected]> wrote:
>> [email protected] wrote:
>>> EP and jb go on about initial conditions not being verified (or some
>>> such thing) without ever specifying what they'd accept as a standard
>>> for verification. Obviously, the procedures normally used (such as
>>> clamp angle of the QR) don't qualify in their eyes.
>>> They give the impression the only accepted testimony involves QRs
>>> tightened with a torque wrench whose resolution is 0.1 inch-pounds.
>>> Then checked again at the bottom of a suitable descent. With the
>>> entire process done in front of three witnesses. Who sign a document
>>> of testimony. Which is notarized.

>> classic krygowski getting red herringed. torque wrench means nothing
>> across different qr's since friction on each is different.

>
> :) That's even better, jim.
>
> Previously, you've implied gaging proper QR installation by clamp
> angle, as usually advised (90 degrees, 80 degrees, etc.) isn't valid.
> Now you say even the amount of torque applied to the QR can't prove
> it's been properly fastened.


for a mechanical engineering professor, you're either a damned idiot or
you're contributing to mcnamara's gullibility thesis research. and
don't put words in my mouth.

baby steps:
torque is a function of friction. friction is not constant. friction
varies from skewer to skewer, from design to design. torque is
therefore useless.

angle is a function of elasticity. elasticity varies according to
materials and physical dimensions. but angle can be more reliable than
torque for any given skewer since friction is not a factor.

>
> In effect, that means there is _no_ practical way of telling if the QR
> is clamped properly. That's certainly a handy state of affairs for a
> guy who wants to blame all failures on user error!


torque sure isn't the way to do it! and whoops, the engineering
professor needs to clue in on how vehicle head bolts are tightened these
days - final stage is angle tightening. idiot.

>
>> all that matters is indention, since that's what generates retention force.

>
> And how is one to gage "indentation"? Release the QR and look for
> marks? Obviously, that's testing ex post facto. It does nothing for
> a person intending to leave the QR clamped and ride.


do indentations disappear after each fastening? no. do indentations
get "reused"? yes. therefore, apart from the fact that initial
indentations proved the skewer was tightened sufficiently, their
subsequent reuse ensures continued retention. how did you get your job,
idiot?

>
> This doesn't even treat the fact that you've never specified a
> specific depth of indentation. Is 0.010" enough? How about 0.005"?
> How about 0.001"? And how will that be measured in the field?


er, have you never heard about shear? idiot.

>
> Furthermore, any indentation being examined might be from a previous
> installation of the QR, not the current one - which may be adjusted
> differently. (In fact, if a deeper previous indentation exists, the
> current installation may be tightened on flat surfaces adjacent to
> that indentation, but slip into it due to motion induced by impacts.
> When that happens, skewer tension _decreases_.)


my, what a short memory you have - that's been discussed before.
indenter profile ensures the same indent holes get "reused" repeatedly.
and that improves retention over time. idiot.

>
> You've shown your hand. Your standard for disproving user error is
> purposely unattainable. Therefore, you will never accept any failure
> account as anything but user error. Your bias is total and complete.
>

the charitable explanation for your making that statement might be that
you're ignoring many elephants in the room. of course, the other is
that you're an idiot.
 
T

Tim McNamara

Guest
In article <[email protected]>,
jim beam <[email protected]> wrote:

> Tim McNamara wrote:
> > In article <[email protected]>,
> > jim beam <[email protected]> wrote:
> >
> >> dabac wrote:
> >>> jim beam Wrote:
> >>>> ....the real consideration of course is how great the collapsing
> >>>> force is in relation to capacity, not whether a collapsing force
> >>>> exists....
> >>> But you're completely ignoring the different orders of magnitude
> >>> of effort needed to address the different issues. Old school risk
> >>> reduction principles tended to foster a tunnel visioned approach
> >>> like that. Sure, wheel ejection is rare and avoidable through
> >>> known means, and there are other failures that are far more
> >>> common and equally if not more critical. But are there any who
> >>> are as easily corrected and with as little impact on the whole
> >>> concept of bike riding/bike owning as changing dropout angle
> >>> and/or caliper location(even if it only is to top mount and not
> >>> forward mount)?
> >>>
> >>> Of course one could, in the interest of safety, require that all
> >>> bike components should be redesigned with a bigger safety margin
> >>> and with redundancy on critical systems(2-circuit for hydraulic
> >>> brakes, double clamps on wire operated etc), but that would have
> >>> a major impact on just about every aspect on riding, servicing
> >>> and bike ownership. Assuming that fork molds gets changed
> >>> regularly anyhow changing dropout angle and caliper location OTOH
> >>> makes an admittedly small risk go away w/o any rider
> >>> consequences.
> >>>
> >>>
> >> to some extent, and i've said as much before.

> >
> > Oh ********.

>
> you see tim, you huff and you puff, but you don't read the thread.
> other evidence suggests you don't understand much of it even if you
> do.


You keep saying that in hopes of it becoming true, jim. Just wishful
thinking on your part.

> >> but q.r. failure, the biggest issue in all this, will still lead
> >> to disaster, angled dropouts or not. all this chicken little b.s.
> >> based on irrational fears created by bad math, with the biggest
> >> adherents being non-engineers that can't grasp the most basic
> >> fundamentals, it beyond bizarre.

> >
> > LOL. Perhaps somehow you keep overlooking the fact that two of the
> > biggest "adherents" *are* mechanical engineers, whereas the biggest
> > opponent *is not.*

>
> one doesn't know the difference between the fatigue characteristics
> of a material that strain ages and one that doesn't. the other
> doesn't know the sense of stress in bending. are they both useful to
> you in this appeal to an authority /you/ don't have?
>
> >
> >> focus on the freakin' q.r., that's the safety issue, not the
> >> dropouts.

> >
> > Duck, weave, circle and dodge.

>
> no tim, /you/ focus on the pertinent facts.


I have all along, jim. You, on the other hand, have employed red
herring, straw men, obfuscation, etc.
 
T

Tim McNamara

Guest
In article <[email protected]>,
jim beam <[email protected]> wrote:

> Tim McNamara wrote:
> > In article <[email protected]>,
> > Ben C <[email protected]> wrote:
> >
> >> On 2007-02-14, [email protected] <[email protected]> wrote:
> >>> On Feb 14, 3:48 am, Ben C <[email protected]> wrote:
> >> [...]
> >>>> The point is that wheel ejection is a molehill of similar
> >>>> proportions.
> >>> If you want to prove the front-mount-fatigue issue is of similar
> >>> importance to the bike wheel ejection issue, it should be easy
> >>> for you to do so. Just post here the tales of motorcycles losing
> >>> their front mount calipers due to fatigue.
> >> If no such tales can be found that just proves that the motorcycle
> >> designers made sufficiently strong or fatigue-resistant caliper
> >> mounts to overcome the problem. I would expect the likes of Honda
> >> to get that right whatever the basic design. It doesn't tell us
> >> anything about the relative importances of fatigue and ejection.
> >>
> >>> My claim is that the fatigue hazard is entirely jim beam's
> >>> invention.
> >> Yes, I also give jim beam the credit for pointing out the fatigue
> >> hazard.

> >
> > Pointing out the *presumed* fatigue hazard and then treating the
> > presumption as fact is more like it. There's no hard evidence to
> > support jim's claim that this is a hazard.

>
> look it up. tables for fatigue strength in castings. it's been
> posted here before.
>
> > And, of course he neglects
> > to mention that existing brake caliper bolts and their mounts are
> > not loaded only in compression.

>
> caliper bolts are mounted in shear. bolts are not cast.
>
> > This varies with the design of the mounts,
> > of course, as there are several in use.

>
> no, /all/ caliper bolts are in shear.
>
> > Hayes makes something like 13
> > different adapters for their brakes!

>
> and /all/ the caliper bolts are in shear.


So then there's no problem with mounting the brake in front of the fork
leg, as all those motorcycle brakes prove.
 
J

jim beam

Guest
Tim McNamara wrote:
> In article <[email protected]>,
> jim beam <[email protected]> wrote:
>
>> Tim McNamara wrote:
>>> In article <[email protected]>,
>>> jim beam <[email protected]> wrote:
>>>
>>>> dabac wrote:
>>>>> jim beam Wrote:
>>>>>> ....the real consideration of course is how great the collapsing
>>>>>> force is in relation to capacity, not whether a collapsing force
>>>>>> exists....
>>>>> But you're completely ignoring the different orders of magnitude
>>>>> of effort needed to address the different issues. Old school risk
>>>>> reduction principles tended to foster a tunnel visioned approach
>>>>> like that. Sure, wheel ejection is rare and avoidable through
>>>>> known means, and there are other failures that are far more
>>>>> common and equally if not more critical. But are there any who
>>>>> are as easily corrected and with as little impact on the whole
>>>>> concept of bike riding/bike owning as changing dropout angle
>>>>> and/or caliper location(even if it only is to top mount and not
>>>>> forward mount)?
>>>>>
>>>>> Of course one could, in the interest of safety, require that all
>>>>> bike components should be redesigned with a bigger safety margin
>>>>> and with redundancy on critical systems(2-circuit for hydraulic
>>>>> brakes, double clamps on wire operated etc), but that would have
>>>>> a major impact on just about every aspect on riding, servicing
>>>>> and bike ownership. Assuming that fork molds gets changed
>>>>> regularly anyhow changing dropout angle and caliper location OTOH
>>>>> makes an admittedly small risk go away w/o any rider
>>>>> consequences.
>>>>>
>>>>>
>>>> to some extent, and i've said as much before.
>>> Oh ********.

>> you see tim, you huff and you puff, but you don't read the thread.
>> other evidence suggests you don't understand much of it even if you
>> do.

>
> You keep saying that in hopes of it becoming true, jim. Just wishful
> thinking on your part.
>
>>>> but q.r. failure, the biggest issue in all this, will still lead
>>>> to disaster, angled dropouts or not. all this chicken little b.s.
>>>> based on irrational fears created by bad math, with the biggest
>>>> adherents being non-engineers that can't grasp the most basic
>>>> fundamentals, it beyond bizarre.
>>> LOL. Perhaps somehow you keep overlooking the fact that two of the
>>> biggest "adherents" *are* mechanical engineers, whereas the biggest
>>> opponent *is not.*

>> one doesn't know the difference between the fatigue characteristics
>> of a material that strain ages and one that doesn't. the other
>> doesn't know the sense of stress in bending. are they both useful to
>> you in this appeal to an authority /you/ don't have?
>>
>>>> focus on the freakin' q.r., that's the safety issue, not the
>>>> dropouts.
>>> Duck, weave, circle and dodge.

>> no tim, /you/ focus on the pertinent facts.

>
> I have all along, jim. You, on the other hand, have employed red
> herring, straw men, obfuscation, etc.


so why doesn't /your/ math work?
 
J

jim beam

Guest
Tim McNamara wrote:
> In article <[email protected]>,
> jim beam <[email protected]> wrote:
>
>> Tim McNamara wrote:
>>> In article <[email protected]>,
>>> Ben C <[email protected]> wrote:
>>>
>>>> On 2007-02-14, [email protected] <[email protected]> wrote:
>>>>> On Feb 14, 3:48 am, Ben C <[email protected]> wrote:
>>>> [...]
>>>>>> The point is that wheel ejection is a molehill of similar
>>>>>> proportions.
>>>>> If you want to prove the front-mount-fatigue issue is of similar
>>>>> importance to the bike wheel ejection issue, it should be easy
>>>>> for you to do so. Just post here the tales of motorcycles losing
>>>>> their front mount calipers due to fatigue.
>>>> If no such tales can be found that just proves that the motorcycle
>>>> designers made sufficiently strong or fatigue-resistant caliper
>>>> mounts to overcome the problem. I would expect the likes of Honda
>>>> to get that right whatever the basic design. It doesn't tell us
>>>> anything about the relative importances of fatigue and ejection.
>>>>
>>>>> My claim is that the fatigue hazard is entirely jim beam's
>>>>> invention.
>>>> Yes, I also give jim beam the credit for pointing out the fatigue
>>>> hazard.
>>> Pointing out the *presumed* fatigue hazard and then treating the
>>> presumption as fact is more like it. There's no hard evidence to
>>> support jim's claim that this is a hazard.

>> look it up. tables for fatigue strength in castings. it's been
>> posted here before.
>>
>>> And, of course he neglects
>>> to mention that existing brake caliper bolts and their mounts are
>>> not loaded only in compression.

>> caliper bolts are mounted in shear. bolts are not cast.
>>
>>> This varies with the design of the mounts,
>>> of course, as there are several in use.

>> no, /all/ caliper bolts are in shear.
>>
>>> Hayes makes something like 13
>>> different adapters for their brakes!

>> and /all/ the caliper bolts are in shear.

>
> So then there's no problem with mounting the brake in front of the fork
> leg, as all those motorcycle brakes prove.


eh? it's raining wednesday, so i'll paint the house blue? do you even
know what shear /is/??? your cognitive myopia is downright scary.
 
T

Tim McNamara

Guest
In article <[email protected]>,
jim beam <[email protected]> wrote:

> Tim McNamara wrote:
> > In article <[email protected]>,
> > Ben C <[email protected]> wrote:
> >
> >> On 2007-02-14, [email protected] <[email protected]> wrote:
> >>> On Feb 14, 3:48 am, Ben C <[email protected]> wrote:
> >> [...]
> >>>> The point is that wheel ejection is a molehill of similar
> >>>> proportions.
> >>> If you want to prove the front-mount-fatigue issue is of similar
> >>> importance to the bike wheel ejection issue, it should be easy
> >>> for you to do so. Just post here the tales of motorcycles losing
> >>> their front mount calipers due to fatigue.
> >> If no such tales can be found that just proves that the motorcycle
> >> designers made sufficiently strong or fatigue-resistant caliper
> >> mounts to overcome the problem. I would expect the likes of Honda
> >> to get that right whatever the basic design. It doesn't tell us
> >> anything about the relative importances of fatigue and ejection.
> >>
> >>> My claim is that the fatigue hazard is entirely jim beam's
> >>> invention.
> >> Yes, I also give jim beam the credit for pointing out the fatigue
> >> hazard.

> >
> > Pointing out the *presumed* fatigue hazard and then treating the
> > presumption as fact is more like it. There's no hard evidence to
> > support jim's claim that this is a hazard.

>
> whoops, missed that peachy bit! now let me get this straight - a
> presumed hazard cannot be taken as fact? is that correct? a
> presumed hazard like disk ejection? i just want to be sure because
> materials literature is full of data on casting fatigue behavior -
> that's known to most people as "hard evidence".


The ejection force is a demonstrable fact. You've stipulated to that
already, unless you are (once again) changing your position. The
presumed catastrophic failures that you are treating as fact has not
been demonstrated. Indeed, since perfectly workable forks with the
calipers in front exist, your claim seems rather specious.
 
T

Tim McNamara

Guest
In article <[email protected]>,
jim beam <[email protected]> wrote:

> [email protected] wrote:
> > On Feb 14, 3:48 am, Ben C <[email protected]> wrote:
> >> On 2007-02-14, [email protected] <[email protected]> wrote:
> >>
> >>> But third (and perhaps easiest to understand) is that the
> >>> specific thing jim beam warns about - front mounting of disk
> >>> brakes - has been employed on multi-hundred-pound motorcycles for
> >>> many decades. The direct tensile stresses that come from such
> >>> mounting are small, and very easily accommodated. If they were
> >>> not, NHTSA and CPSC would have told you about it in the recall
> >>> documents for those motorcycles.
> >> Noone's disputed that a front caliper is possible, but motorbikes
> >> are not bicycles.

> >
> > True. They're much more massive, travel at much higher speeds, and
> > impose much higher forces on their caliper attachements.
> >
> >> All the relative pros and cons are different, which makes it a
> >> different optimization problem and we should not be surprised if
> >> it has a different solution. Lots of motorbikes do have rear
> >> calipers anyway.

> >
> > Do you know of any motorcycle with a rear caliper and a quick
> > release front axle? I don't believe they exist. Every motorcycle
> > I've owned or seen had a through-axle. Thus, the hazard imposed by
> > a rear caliper was removed by other means.

>
> conversely, why aren't /all/ motorcycles front caliper? idiot.


Who's the idiot, jim? Frank? Or you with your obstinate denial of
reality? If he's an idiot, you're a pathetic muppet.

Through axles. No QRs. Ejection force not an issue.

> >>> So yes, there's a grain of metallurgical truth in what j.b. says.
> >>> But the design proclamations he derives from it are nonsense.
> >>> He's making a mountain out of a molehill for reasons of his own.
> >> The point is that wheel ejection is a molehill of similar
> >> proportions.

> >
> > If you want to prove the front-mount-fatigue issue is of similar
> > importance to the bike wheel ejection issue, it should be easy for
> > you to do so. Just post here the tales of motorcycles losing their
> > front mount calipers due to fatigue. Carl has posted several
> > examples of candidate motorcycles to check. If you find enough
> > such tales, I'll believe the hazards are similar.

>
> post front wheel ejections where it's proven not to be user error!
> idiot.


Post wheel ejections where it's proven to be user error! Muppet.

> > My claim is that the fatigue hazard is entirely jim beam's
> > invention.

>
> i invented inferior fatigue properties for castings??? you don't
> even know what a casting is! idiot.
>
> > You have an opportunity to prove me wrong.

>
> no, you do that on your own. idiot.


ROTFL! jim, do you get spittle all over your keyboard when you are
posting this drivel?
 
T

Tim McNamara

Guest
In article <[email protected]>,
jim beam <[email protected]> wrote:

> Tim McNamara wrote:
> > In article <[email protected]>,
> > jim beam <[email protected]> wrote:
> >
> >> Tim McNamara wrote:
> >>> In article <[email protected]>,
> >>> jim beam <[email protected]> wrote:
> >>>
> >>>> Tim McNamara wrote: <snip ****>
> >>>>
> >>>>> The simple truth, jim, which you have been fending off for
> >>>>> years is that there is no necessity to have a design that
> >>>>> results in an ejection force on the front wheel. It can be
> >>>>> readily remedied and- since it appears that several
> >>>>> manufacturers have made adjustments in their design to result
> >>>>> in a safer product- it has been. You've spent all this time
> >>>>> and effort trying to disparage and defeat and even humiliate-
> >>>>> how many posts in this thread alone?- and yet your position is
> >>>>> still one of senseless denial.
> >>>> oh the irony. it would be funny if you understood it.
> >>> I do understand the point you are trying to make.
> >> no you don't. you think you do, but you don't know what you don't
> >> know. even when presented with the answers, your ability to
> >> connect them with fundamental principals is repeatedly shown to be
> >> non existent. add a generous dose of stubbornness, and a research
> >> thesis presents itself.

> >
> > LOL. Pot, kettle, black, dude. Jeez, you are such a riot to read.

>
> that's just pissing.


Yes. Just pointing out to you that pissing is all you have left in this
argument.

> >>> And I think you're- once again- just plain wrong.
> >> you don't understand basic math tim.

> >
> > LOL. Fortunately my puny math skills are adequate to the task.

>
> so why can't you grasp the fact that if x>y, y!>x?


Because it has been demonstrated that y can be > x. Your waffling
lunacy does not withstand this.

> > It would seem, jim, that you are unable to comprehend the simple
> > fact that I can understand your position and still disagree with
> > it. You appear so convinced of your rightness, and so committed to
> > your conviction, that you can't see the forest for the trees.

>
> no, you just won't accept that there's massive gaps in your
> understanding - a gap of a size that you don't know what you don't
> know.


Over and over and over you say this. You still can't conceive that
someone might possibly understand your position and *still* think that
you are a moron using insane troll logic.

I've been trying to cut you some slack and just figured that your
obvious personal vendetta against Jobst distorts your thinking. But you
know what? I was wrong. You're the idiot that you claim others are.

> >>> Since you are reduced to "am not" and "are too" type arguments,
> >>> and have already called Frank an idiot twice in this thread,
> >> that's because he /is/ an idiot.

> >
> > And yet he is a mechanical engineer, and you are not. Hmmm. In
> > fact, it appears that all the mechanical engineers in this thread
> > disagree with you. Hmmm.

>
> and there's "mechanical engineers" that think castings are just as
> good in tension as they are in compression. it's those kind of
> "mechanical engineers" that are responsible for failures.


Or former metallurgists arrogant enough to be oblivious to the grievous
errors in their thinking, promoting a status quo that is flawed.
 
J

jim beam

Guest
Tim McNamara wrote:
> In article <[email protected]>,
> jim beam <[email protected]> wrote:
>
>> Tim McNamara wrote:
>>> In article <[email protected]>,
>>> Ben C <[email protected]> wrote:
>>>
>>>> On 2007-02-14, [email protected] <[email protected]> wrote:
>>>>> On Feb 14, 3:48 am, Ben C <[email protected]> wrote:
>>>> [...]
>>>>>> The point is that wheel ejection is a molehill of similar
>>>>>> proportions.
>>>>> If you want to prove the front-mount-fatigue issue is of similar
>>>>> importance to the bike wheel ejection issue, it should be easy
>>>>> for you to do so. Just post here the tales of motorcycles losing
>>>>> their front mount calipers due to fatigue.
>>>> If no such tales can be found that just proves that the motorcycle
>>>> designers made sufficiently strong or fatigue-resistant caliper
>>>> mounts to overcome the problem. I would expect the likes of Honda
>>>> to get that right whatever the basic design. It doesn't tell us
>>>> anything about the relative importances of fatigue and ejection.
>>>>
>>>>> My claim is that the fatigue hazard is entirely jim beam's
>>>>> invention.
>>>> Yes, I also give jim beam the credit for pointing out the fatigue
>>>> hazard.
>>> Pointing out the *presumed* fatigue hazard and then treating the
>>> presumption as fact is more like it. There's no hard evidence to
>>> support jim's claim that this is a hazard.

>> whoops, missed that peachy bit! now let me get this straight - a
>> presumed hazard cannot be taken as fact? is that correct? a
>> presumed hazard like disk ejection? i just want to be sure because
>> materials literature is full of data on casting fatigue behavior -
>> that's known to most people as "hard evidence".

>
> The ejection force is a demonstrable fact. You've stipulated to that
> already, unless you are (once again) changing your position.


the presumption is that it exceeds retention force!!! jeepers.

> The
> presumed catastrophic failures that you are treating as fact has not
> been demonstrated.


but there's extensive lit on it! what more do you want?

> Indeed, since perfectly workable forks with the
> calipers in front exist, your claim seems rather specious.


on [a very small minority of] motorcycles with somewhat different
design. cheap lightweight castings are not the place for tension, for
reasons detailed in material lit at great length. and the angled fork
design is useless against a failed q.r!
 
J

jim beam

Guest
Tim McNamara wrote:
> In article <[email protected]>,
> jim beam <[email protected]> wrote:
>
>> [email protected] wrote:
>>> On Feb 14, 3:48 am, Ben C <[email protected]> wrote:
>>>> On 2007-02-14, [email protected] <[email protected]> wrote:
>>>>
>>>>> But third (and perhaps easiest to understand) is that the
>>>>> specific thing jim beam warns about - front mounting of disk
>>>>> brakes - has been employed on multi-hundred-pound motorcycles for
>>>>> many decades. The direct tensile stresses that come from such
>>>>> mounting are small, and very easily accommodated. If they were
>>>>> not, NHTSA and CPSC would have told you about it in the recall
>>>>> documents for those motorcycles.
>>>> Noone's disputed that a front caliper is possible, but motorbikes
>>>> are not bicycles.
>>> True. They're much more massive, travel at much higher speeds, and
>>> impose much higher forces on their caliper attachements.
>>>
>>>> All the relative pros and cons are different, which makes it a
>>>> different optimization problem and we should not be surprised if
>>>> it has a different solution. Lots of motorbikes do have rear
>>>> calipers anyway.
>>> Do you know of any motorcycle with a rear caliper and a quick
>>> release front axle? I don't believe they exist. Every motorcycle
>>> I've owned or seen had a through-axle. Thus, the hazard imposed by
>>> a rear caliper was removed by other means.

>> conversely, why aren't /all/ motorcycles front caliper? idiot.

>
> Who's the idiot, jim? Frank? Or you with your obstinate denial of
> reality? If he's an idiot, you're a pathetic muppet.
>
> Through axles. No QRs. Ejection force not an issue.


but you can already buy one. that's not a "design change"!!!

>
>>>>> So yes, there's a grain of metallurgical truth in what j.b. says.
>>>>> But the design proclamations he derives from it are nonsense.
>>>>> He's making a mountain out of a molehill for reasons of his own.
>>>> The point is that wheel ejection is a molehill of similar
>>>> proportions.
>>> If you want to prove the front-mount-fatigue issue is of similar
>>> importance to the bike wheel ejection issue, it should be easy for
>>> you to do so. Just post here the tales of motorcycles losing their
>>> front mount calipers due to fatigue. Carl has posted several
>>> examples of candidate motorcycles to check. If you find enough
>>> such tales, I'll believe the hazards are similar.

>> post front wheel ejections where it's proven not to be user error!
>> idiot.

>
> Post wheel ejections where it's proven to be user error! Muppet.


oh, wait, circular argument based on supposition. surely not part of
the research thesis is it?

[p.s. don't let lack of ejection data get in the way of that one tim.]

>
>>> My claim is that the fatigue hazard is entirely jim beam's
>>> invention.

>> i invented inferior fatigue properties for castings??? you don't
>> even know what a casting is! idiot.
>>
>>> You have an opportunity to prove me wrong.

>> no, you do that on your own. idiot.

>
> ROTFL! jim, do you get spittle all over your keyboard when you are
> posting this drivel?


eh? krygowski proves he knows nothing about castings and can't think
through a simple stress sense scenario correctly? but pointing that out
is drivel? get a grip on yourself man.
 
B

Ben C

Guest
On 2007-02-15, Tim McNamara <[email protected]> wrote:
[...]
> The ejection force is a demonstrable fact.


Yes, but isn't the existence of a tensile fatigue cycle for a
front-mounted caliper also a demonstrable fact?

> You've stipulated to that already, unless you are (once again)
> changing your position. The presumed catastrophic failures that you
> are treating as fact has not been demonstrated.


There's precious little evidence of catastrophic failures due to
_either_ demonstrable fact (ejection force or tensile fatigue).

Back to your "absence of evidence != evidence of absence" idea-- we
would expect to see frequent ejections, if they are a problem, since
rear calipers are out there in the wild in their tens of thousands.
Front calipers on bicycles are rare.

There is more evidence that ejection is not a problem in practice than
there is that tensile fatigue is not a problem.

> Indeed, since perfectly workable forks with the calipers in front
> exist.


On a minority of motorbikes.
 
B

Ben C

Guest
On 2007-02-15, [email protected] <[email protected]> wrote:
[...]
> Dear Frank & Ben,
>
> To clarify things, disk brakes first appeared on large, heavy street
> motorcycles--and were originally mounted with high leading calipers by
> Honda.
>
> In ten years or less, the industry (including Honda) had switched to
> overwhelmingly to low trailing calipers.
>
> The only modern leading calipers that I know of are found on trials
> machines, where the high leading position helps avoid damaging
> calipers when the bikes are dropped to one side or the other in rocks,
> a routine hazard.
>
> Trials machines are not designed or certified for road use and
> nowadays weigh under 170 pounds. Their braking can be quite savage at
> low speeds in stunt-riding maneuvers, with the contact patches at
> absurd angles.
>
> I don't know why all other machines switched to low trailing calipers
> after the first high leading calipers, but I doubt that it had
> anything to do with failures. More likely, the lower trailing caliper
> improves handling at normal speeds--the motorcycle calipers and disks
> are much larger and heavier than what's found on bicycles.


Possibly there are aerodynamic advantages as well.

[...]
> Any RBT poster interested in such things should stop by a motorcycle
> shop or just peek at a parked machine and see how much thicker,
> heavier, and stronger motorcycle parts are.


I have been getting funny looks recently as I scrutinize the caliper
placement of every parked vehicle I walk past. All the motorbikes I've
seen had them low and rear.

Most cars I saw had them front mounted, but some were rear mounted.

I saw a couple of Porsche 911s with cross-drilled discs. Grrr.
 
B

Ben C

Guest
On 2007-02-15, jim beam <[email protected]> wrote:
[...]
> question: in a situation where there is a known risk, but another known
> benefit with a certain design, then what happens? example: most modern
> cars have negative scrub radius for their steering. it's "safe" because
> it tends to counteract the steering effect of a front tire flat at speed
> thereby allowing an unskilled driver more chance of retaining control
> and bringing the vehicle to a halt in a controlled manner. but the
> danger is that it makes steering feel light [and therefore "safe"] when
> braking /through/ corners, thereby encouraging that unsafe habit.


I used to drive a Mini which I believe had a zero scrub radius. I braked
deep into corners (risk of a spin but the technique, once mastered,
neutralized understeer and I felt allowed you to carry more speed
through the corners). The car felt good doing that, I didn't notice the
steering getting heavy or uncertain, although perhaps I was just used to
it.

I read in a book at the time that negative scrub radius made steering
slightly vague around the centre position, but made motorway/freeway
driving easier as constant steering correction was not required. I
thought that was the purpose of it.

The Mini was designed in 1959 (before motorways), had very precise
steering (low-geared, light, and the steering wheel was connected
directly to the rack with no UJs in between), but did require more
correction when cruising on motorways than the average 1980s shopping
car.

> physics will tell you that braking through corners is a bad thing, and
> positive scrub makes braking through feel heavy and uncertain, thereby
> discouraging that kind of bad behavior. how might a legal test be
> applied to that?
 
B

Ben C

Guest
On 2007-02-14, [email protected] <[email protected]> wrote:
> On Feb 14, 3:11 am, Ben C <[email protected]> wrote:
>
>> > [J.B.] I think this is not the place to learn about material science.

>>
>> It's better than nothing.

>
> Actually, it goes beyond that. This is also not the place to learn
> about mechanical design to resist fatigue failure, and that's really
> what we're discussing at the moment. j.b. appears to know something
> about metallurgy, but he knows too little about mechanical design.
> It's principles are by no means obvious.


So explain them, or suggest a link.

> You won't learn them here, and certainly not from jim beam.


In my salad days I attended a top university myself, and learnt many
things there. Almost to a man the tutors were as opinionated,
egotistical, informative and full of **** as the best usenet cranks. The
learning process consisted of filtering and thinking for yourself, no
different to r.b.t. or life in general.
 
M

Mike Causer

Guest
On Wed, 14 Feb 2007 19:26:56 -0800, jim beam wrote:

> no, /all/ caliper bolts are in shear.


Except for the maybe 50% that aren't. Data obtained by examining the
attachment of every disc brake on the stock of new bikes in Moon's Cycle
Centre, Newmarket, England, yesterday afternoon.

What I saw removed any doubts about front mounting, the weediness of some
of the rear mounted setups has further convinced me that the load, and
service life, would be very easily handled with a properly made front
attachment.


Mike
 
J

jim beam

Guest
Mike Causer wrote:
> On Wed, 14 Feb 2007 19:26:56 -0800, jim beam wrote:
>
>> no, /all/ caliper bolts are in shear.

>
> Except for the maybe 50% that aren't. Data obtained by examining the
> attachment of every disc brake on the stock of new bikes in Moon's Cycle
> Centre, Newmarket, England, yesterday afternoon.
>
> What I saw removed any doubts about front mounting, the weediness of some
> of the rear mounted setups has further convinced me that the load, and
> service life, would be very easily handled with a properly made front
> attachment.
>
>
> Mike


unless you're looking at old stock or something custom, brake tabs are
"international". mounting bolts for this standard are perpendicular to
the wheel, i.e. they're loaded in shear mode. even old stock mountings
with the other type of mounting [whatever it's called] have bolts in
compression mode, not tension, the undesirable mode.
 
J

jim beam

Guest
Ben C wrote:
> On 2007-02-15, jim beam <[email protected]> wrote:
> [...]
>> question: in a situation where there is a known risk, but another known
>> benefit with a certain design, then what happens? example: most modern
>> cars have negative scrub radius for their steering. it's "safe" because
>> it tends to counteract the steering effect of a front tire flat at speed
>> thereby allowing an unskilled driver more chance of retaining control
>> and bringing the vehicle to a halt in a controlled manner. but the
>> danger is that it makes steering feel light [and therefore "safe"] when
>> braking /through/ corners, thereby encouraging that unsafe habit.

>
> I used to drive a Mini which I believe had a zero scrub radius. I braked
> deep into corners (risk of a spin but the technique, once mastered,
> neutralized understeer and I felt allowed you to carry more speed
> through the corners). The car felt good doing that, I didn't notice the
> steering getting heavy or uncertain, although perhaps I was just used to
> it.
>
> I read in a book at the time that negative scrub radius made steering
> slightly vague around the centre position,


negative scrub tends to be small - that's what makes it vague. that and
the fact that it's usually married to macpherson...

> but made motorway/freeway
> driving easier as constant steering correction was not required. I
> thought that was the purpose of it.


it's about flats. in positive scrub, a flat will drag you off to the
side of the flat, possibly into oncoming traffic if you're not alert.
negative, and if you think about it this makes sense, has the drag force
in the steering acting counter to the drag force on that corner of the car.

>
> The Mini was designed in 1959 (before motorways), had very precise
> steering (low-geared, light, and the steering wheel was connected
> directly to the rack with no UJs in between), but did require more
> correction when cruising on motorways than the average 1980s shopping
> car.
>
>> physics will tell you that braking through corners is a bad thing, and
>> positive scrub makes braking through feel heavy and uncertain, thereby
>> discouraging that kind of bad behavior. how might a legal test be
>> applied to that?
 
M

Mike Causer

Guest
On Thu, 15 Feb 2007 06:13:44 -0800, jim beam wrote:

> Mike Causer wrote:
>> On Wed, 14 Feb 2007 19:26:56 -0800, jim beam wrote:
>>
>>> no, /all/ caliper bolts are in shear.

>>
>> Except for the maybe 50% that aren't. Data obtained by examining the
>> attachment of every disc brake on the stock of new bikes in Moon's
>> Cycle Centre, Newmarket, England, yesterday afternoon.


> unless you're looking at old stock or something custom,


Many of them said "Shimano" on the side, and they were being sold as
"2007" stock. Bike makes were Raleigh, Marin and a couple of others.


> brake tabs are "international". mounting bolts for this standard are
> perpendicular to the wheel, i.e. they're loaded in shear mode.


Some were as you say, but many had the bolts in the plane of wheel which
would load them mostly in tension, and presumably are intended to take the
braking load out through friction between the clamped faces. I believe
this is called "post mount" by the fork and brake manufacturers.


Mike
 
T

Tim McNamara

Guest
In article <[email protected]>,
jim beam <[email protected]> wrote:

> Tim McNamara wrote:
> > In article <[email protected]>,
> > jim beam <[email protected]> wrote:
> >
> >> Tim McNamara wrote:
> >>> In article <[email protected]>,
> >>> Ben C <[email protected]> wrote:
> >>>
> >>>> On 2007-02-14, [email protected] <[email protected]> wrote:
> >>>>> On Feb 14, 3:48 am, Ben C <[email protected]> wrote:
> >>>> [...]
> >>>>>> The point is that wheel ejection is a molehill of similar
> >>>>>> proportions.
> >>>>> If you want to prove the front-mount-fatigue issue is of
> >>>>> similar importance to the bike wheel ejection issue, it should
> >>>>> be easy for you to do so. Just post here the tales of
> >>>>> motorcycles losing their front mount calipers due to fatigue.
> >>>> If no such tales can be found that just proves that the
> >>>> motorcycle designers made sufficiently strong or
> >>>> fatigue-resistant caliper mounts to overcome the problem. I
> >>>> would expect the likes of Honda to get that right whatever the
> >>>> basic design. It doesn't tell us anything about the relative
> >>>> importances of fatigue and ejection.
> >>>>
> >>>>> My claim is that the fatigue hazard is entirely jim beam's
> >>>>> invention.
> >>>> Yes, I also give jim beam the credit for pointing out the
> >>>> fatigue hazard.
> >>> Pointing out the *presumed* fatigue hazard and then treating the
> >>> presumption as fact is more like it. There's no hard evidence to
> >>> support jim's claim that this is a hazard.
> >> whoops, missed that peachy bit! now let me get this straight - a
> >> presumed hazard cannot be taken as fact? is that correct? a
> >> presumed hazard like disk ejection? i just want to be sure
> >> because materials literature is full of data on casting fatigue
> >> behavior - that's known to most people as "hard evidence".

> >
> > The ejection force is a demonstrable fact. You've stipulated to
> > that already, unless you are (once again) changing your position.

>
> the presumption is that it exceeds retention force!!! jeepers.


And it's been shown to you over and over again that the ejection force
can exceed the retention force.

> > The presumed catastrophic failures that you are treating as fact
> > has not been demonstrated.

>
> but there's extensive lit on it! what more do you want?


There's extensive literature on reaction forces, there's extensive
literature on threaded fasteners unscrewing, etc. Now what? Is it time
for the various participant to start throwing citations at each others?

> > Indeed, since perfectly workable forks with the calipers in front
> > exist, your claim seems rather specious.

>
> on [a very small minority of] motorcycles with somewhat different
> design.


So, as you now stipulate, it can be done successfully.

> cheap lightweight castings are not the place for tension, for reasons
> detailed in material lit at great length. and the angled fork design
> is useless against a failed q.r!


I'm sure the fork industry- and their customers- would appreciate your
characterization of their products as "cheap lightweight castings."
It's lovely how in one breath you staunchly defend them and in the next
impugn them. Hilarious!

If you're so worried about failed QRs, then go to a through-axle design.
Not going to be very popular with the average buyer, though. That would
solve the problem and allow you to retain your precious
caliper-behind-the-fork design that you love so well and defend so
passionately, blindly ignoring the major design flaw.

How often do QR failures happen, do you think? And why? I have seen
one broken QR in 40 years of riding bikes. Close examination suggested
that the skewer had been slightly bent, although whether prior to the
fracture or as a result of it, I don't know.

Mountain bike suspension forks- except the Headshock design- subject QRs
to unusual forces for which they were not designed. The forklegs can
have a degree of independent movement which the skewer must resist.
Then you add the ejection force from a disk brake, and you have added a
lot of forces on the QR which were not envisioned when Tullio Campagnolo
came up with the design. All the more reason to eliminate the
unnecessary ejection force.
 
B

Ben C

Guest
On 2007-02-15, Mike Causer <[email protected]> wrote:
> On Thu, 15 Feb 2007 06:13:44 -0800, jim beam wrote:

[...]
>> brake tabs are "international". mounting bolts for this standard are
>> perpendicular to the wheel, i.e. they're loaded in shear mode.

>
> Some were as you say, but many had the bolts in the plane of wheel which
> would load them mostly in tension


So were they also front-mounted?

> and presumably are intended to take the braking load out through
> friction between the clamped faces. I believe this is called "post
> mount" by the fork and brake manufacturers.