Candid comments from Cotic on disks and QRs

[Jasper Janssen]

On Fri, 9 Nov 2007 15:22:32 +0100, "James Thomson" <[email protected]>
wrote:

>I don't know much about marketing, but it seems to me that the way to make
>hay from a of fear of wheel ejection would be to launch the product with
>lots of publicity at a time when the topic was current.

Was it ever a 'hot topic' outside of rbt? Which, let's face it, isn't
nearly large enough to have any influence whatsoever on manufacturers.

Jasper

 

[Jasper Janssen]

On Sat, 10 Nov 2007 10:32:23 -0800, jim beam <[email protected]>
wrote:

>can you guarantee the weld quality? because that is the point of issue.
> poor welds in compression are much safer than poor welds in tension.

Well, as there is now a product in the market that has the welds in
tension, and has been for 18 months, we, (or at least someone) should now
have actual data to support whether or not this is an issue. Has there
been a rash of failures of these forks?

Jasper

 

[Jasper Janssen]

On Wed, 14 Nov 2007 08:55:48 -0000, Mark McNeill
<[email protected]> wrote:

>It's tempting to infer that the much smaller and lower-torque nylocks
>used in skewers are subject to a similar type of degradation in
>performance. Does anybody know? And where nylocks undergo
>tightening/loosening cycles in critical applications in industry, do
>they come with recommendations for their regular replacement?

In aircraft, I believe Nylocks cannot be reused at all.

There are nylocks in skewers? I'd never noticed..

Jasper

 

[[email protected]]

On Nov 14, 10:40 am, Jasper Janssen <[email protected]> wrote:
> On Wed, 14 Nov 2007 08:55:48 -0000, Mark McNeill
>
> <[email protected]> wrote:
> >It's tempting to infer that the much smaller and lower-torque nylocks
> >used in skewers are subject to a similar type of degradation in
> >performance. Does anybody know? And where nylocks undergo
> >tightening/loosening cycles in critical applications in industry, do
> >they come with recommendations for their regular replacement?
>
> In aircraft, I believe Nylocks cannot be reused at all.
>
> There are nylocks in skewers? I'd never noticed..
>

There is a nylon locking mechanism in skewers, but it doesn't qualify
as equivalent to a nylock nut.

In one of the previous incarnations of this debate, I did torque
measurements of a standard commercial nylock nut, and compared to
measurements of a QR nut. I won't dig back to find my numbers, but
the difference was extreme, with the QR nut being much, much weaker.
Think about it! You easily twist the QR nut with your fingers!

The function of a standard nylon insert in a nylock is to prevent
rotation of the nut under conditions of significant, strong lateral
vibration. They work pretty well (at least, for one-time use). The
function of the nylon insert in a QR nut is just to hold your
adjustment for a few seconds while you tighten the clamping lever.
They are NOT the same.

Again, the QR nut's nylon lock is purposely much, much weaker. If
skewers had true nylock nuts to hold their adjustment, they'd need
wrenches to change the adjustment. And at that point, you may as well
use a solid, nutted axle.

- Frank Krygowski

 

[A Muzi]

> Response to Tony Raven
>> Please refer to the mechanism that disables the nylock insert in the QR
>> nut to enable loosening during this phase.

Mark McNeill wrote:
> I remember being curious about this point last time the subject came up,
> and my curiosity wasn't satisfied; which made me more curious ;-).
>
> Nylocks tend to become considerably weaker with use: we have several
> hundred 12mm nylocks in regular use at work, and find that after a
> comparatively small number of cycles, the torque required to take them
> off a bolt will fall from 6-inch-spanner-stylee to being easily turned
> with the fingers: when they reach this state, turning of the instrument
> they're fitted to will routinely unscrew them sufficiently to disengage
> the spring washer they're supposed to keep in compression. [Needless to
> say - and in keeping with most threads on this subject ;-) - this is
> informal observation: no hard numbers.]
>
> It's tempting to infer that the much smaller and lower-torque nylocks
> used in skewers are subject to a similar type of degradation in
> performance. Does anybody know? And where nylocks undergo
> tightening/loosening cycles in critical applications in industry, do
> they come with recommendations for their regular replacement?

Real skewer nuts have brass inserts which press on the thread with a
spring loop.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

 

[James Thomson]

"Jasper Janssen" <[email protected]> a écrit:

> Was it ever a 'hot topic' outside of rbt? Which, let's face it,
> isn't nearly large enough to have any influence whatsoever
> on manufacturers.

The issue was known to the UK-based online magazines (Bikemagic,
Singletrackworld, Bikebiz), and the online community is an important source
of sales for small, web-based companies like Cotic.

James Thomson

 

[Steve Gravrock]

On 2007-11-14, Tony Raven <[email protected]> wrote:

> If it is the QR continues to loosen until it is loose enough to eject
> why is it that nobody notices the wheel canting over and rubbing against
> the disk pads after the initial loosening but before its loosened enough
> to get over the lawyers lips ? Bikers are very sensitive to their disk
> brakes rubbing IME.

Mountain bikers using disc brakes on long descents are less so. Rotors
tend to warp under heavy sustained braking, and the effects of loosening
could be lost in that noise.

 

[jim beam]

Jasper Janssen wrote:
> On Sat, 10 Nov 2007 10:32:23 -0800, jim beam <[email protected]>
> wrote:
>
>> can you guarantee the weld quality? because that is the point of issue.
>> poor welds in compression are much safer than poor welds in tension.
>
> Well, as there is now a product in the market that has the welds in
> tension, and has been for 18 months, we, (or at least someone) should now
> have actual data to support whether or not this is an issue. Has there
> been a rash of failures of these forks?

the more rational [not rationale] question to ask would be whether they
used a rear-mounting tab and put it on the front without proper
redesign, or whether they knew what they were doing and attempted to
address the tension fatigue issue properly.

 

[[email protected]]

On Nov 15, 12:57 pm, jim beam <[email protected]> wrote:
>
> the more rational [not rationale] question to ask would be whether they
> used a rear-mounting tab and put it on the front without proper
> redesign, or whether they knew what they were doing and attempted to
> address the tension fatigue issue properly.

It might also be rational to ask whether fork manufacturers changed
from rim brakes to disk brakes without doing proper redesign of the
wheel attachment, or whether they knew what they were doing and
attempted to address the ejection force issue properly.

Of course, Cannondale did do some testing:

<http://www.ne.jp/asahi/julesandjames/home/disk_and_quick_release/
cannondale.html>

Hands up those who think they did
(A) a competent job as one might expect of a major manufacturer
(B) a laughably inadequate test which was so utterly useless that the
person who designed it must either be grossly incompetent or
fraudulent

James

 

[Tony Raven]

In article <dcf8681a-2a31-46e5-a10c-
[email protected]>, [email protected]
says...
>

I see the BBC now has you down as a Climate Change Sceptic ;-)
http://news.bbc.co.uk/1/hi/sci/tech/7092614.stm

--
Tony

"The single biggest problem in communication is the illusion that it has
taken place"
George Bernard Shaw

 

[jim beam]

[email protected] wrote:
> On Nov 15, 12:57 pm, jim beam <[email protected]> wrote:
>> the more rational [not rationale] question to ask would be whether they
>> used a rear-mounting tab and put it on the front without proper
>> redesign, or whether they knew what they were doing and attempted to
>> address the tension fatigue issue properly.
>
> It might also be rational to ask whether fork manufacturers changed
> from rim brakes to disk brakes without doing proper redesign of the
> wheel attachment, or whether they knew what they were doing and
> attempted to address the ejection force issue properly.
>
> Of course, Cannondale did do some testing:
>
> <http://www.ne.jp/asahi/julesandjames/home/disk_and_quick_release/
> cannondale.html>
>
> Hands up those who think they did
> (A) a competent job as one might expect of a major manufacturer
> (B) a laughably inadequate test which was so utterly useless that the
> person who designed it must either be grossly incompetent or
> fraudulent
>

you're priceless.

disk hub axles are serrated, unlike their non-disk predecessors. this
means they need to physically shear through the metal into which they
are clamped if they are to be ejected. the force necessary to do that
exceeds "ejection" force many fold. i don't know how many more times
you need to be reminded of this before you finally start to correlate
the math with reality, but hey, you're james annan.

oh, i forgot lawyer lips. well, i didn't really, but why let the
obvious get in the way of your ability to omit any details that show you
to be such a bullshitter?

 

[Michael Press]

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

> [email protected] wrote:
> > On Nov 15, 12:57 pm, jim beam <[email protected]> wrote:
> >> the more rational [not rationale] question to ask would be whether they
> >> used a rear-mounting tab and put it on the front without proper
> >> redesign, or whether they knew what they were doing and attempted to
> >> address the tension fatigue issue properly.
> >
> > It might also be rational to ask whether fork manufacturers changed
> > from rim brakes to disk brakes without doing proper redesign of the
> > wheel attachment, or whether they knew what they were doing and
> > attempted to address the ejection force issue properly.
> >
> > Of course, Cannondale did do some testing:
> >
> > <http://www.ne.jp/asahi/julesandjames/home/disk_and_quick_release/
> > cannondale.html>
> >
> > Hands up those who think they did
> > (A) a competent job as one might expect of a major manufacturer
> > (B) a laughably inadequate test which was so utterly useless that the
> > person who designed it must either be grossly incompetent or
> > fraudulent
> >
>
> you're priceless.

And a good think too, because you do not
have the price of admission.

[...]

--
Michael Press

 

[Jasper Janssen]

On Wed, 14 Nov 2007 19:57:35 -0800, jim beam <[email protected]>
wrote:
>Jasper Janssen wrote:
>> On Sat, 10 Nov 2007 10:32:23 -0800, jim beam <[email protected]>
>> wrote:
>>
>>> can you guarantee the weld quality? because that is the point of issue.
>>> poor welds in compression are much safer than poor welds in tension.
>>
>> Well, as there is now a product in the market that has the welds in
>> tension, and has been for 18 months, we, (or at least someone) should now
>> have actual data to support whether or not this is an issue. Has there
>> been a rash of failures of these forks?
>
>the more rational [not rationale] question to ask would be whether they
>used a rear-mounting tab and put it on the front without proper
>redesign, or whether they knew what they were doing and attempted to
>address the tension fatigue issue properly.

They said up above in the thread that it wasn't hard to redesign the mount
for those stresses, so I would assume they'd actually done that.

Jasper

 

[Ed Pirrero]

On Nov 15, 12:02 am, "[email protected]" <[email protected]>
wrote:
> On Nov 15, 12:57 pm, jim beam <[email protected]> wrote:
>
>
>
> > the more rational [not rationale] question to ask would be whether they
> > used a rear-mounting tab and put it on the front without proper
> > redesign, or whether they knew what they were doing and attempted to
> > address the tension fatigue issue properly.
>
> It might also be rational to ask whether fork manufacturers changed
> from rim brakes to disk brakes without doing proper redesign of the
> wheel attachment, or whether they knew what they were doing and
> attempted to address the ejection force issue properly.
>
> Of course, Cannondale did do some testing:
>
> <http://www.ne.jp/asahi/julesandjames/home/disk_and_quick_release/
> cannondale.html>
>
> Hands up those who think they did
> (A) a competent job as one might expect of a major manufacturer
> (B) a laughably inadequate test which was so utterly useless that the
> person who designed it must either be grossly incompetent or
> fraudulent

Interesting, isn't it - no countering data, no experimentation done to
show that the methodology was flawed - just a flip comment that
supposed to cast doubt on the only real data collection that's been
done to date.

You sound a lot like Mike Vandeman.

E.P.