A Cycling & bikes forum. CycleBanter.com

Go Back   Home » CycleBanter.com forum » rec.bicycles » Mountain Biking
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Cannondale's tests of disks and QRs



 
 
Thread Tools Display Modes
  #1  
Old September 15th 04, 12:40 PM
James Annan
external usenet poster
 
Posts: n/a
Default Cannondale's tests of disks and QRs

At last, I've got hold of a report of Cannondale's disk brake/QR test
(you may recall that the CPSC asked them for help last year). It makes
interesting reading.

They tested a single fork/QR/brake combination. None of the components
are named, although the brake seems to be Magura Louise (the brake
_pads_ are described as such). The bicycle was secured in a test rig
with powered rollers under each wheel, rotating at 15.5mph.

I'm not going to type it all in, but this section is taken directly from
the test description:

"A light hand force of 5 lbs was applied to the brake lever every 10
seconds for 3 seconds duration. This caused braking torque to be applied
to the wheel. The drums had 3 equally-spaced cleats (0.5" high the same
as those used on wheel fatigue test T027) to create bumps for the front
wheel to go over."

And then we have:

"Conclusion:

"The conclusion is that the braking action of disc brakes is not causing
the quick release mechanism to unscrew. This test is unable to cause
loosening. At this time there are no reasons to believe that anything is
missing or over constrained in this test."

James
--
If I have seen further than others, it is
by treading on the toes of giants.
http://www.ne.jp/asahi/julesandjames/home/

  #2  
Old September 15th 04, 01:53 PM
Just zis Guy, you know?
external usenet poster
 
Posts: n/a
Default

James Annan wrote:

"The conclusion is that the braking action of disc brakes is not
causing the quick release mechanism to unscrew. This test is unable
to cause loosening. At this time there are no reasons to believe that
anything is missing or over constrained in this test."


See Yellow Pages under "whitewash suppliers"

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington
University


  #3  
Old September 17th 04, 01:17 PM
David E. Belcher
external usenet poster
 
Posts: n/a
Default

"Just zis Guy, you know?" wrote in message ...
James Annan wrote:

"The conclusion is that the braking action of disc brakes is not
causing the quick release mechanism to unscrew. This test is unable
to cause loosening. At this time there are no reasons to believe that
anything is missing or over constrained in this test."


See Yellow Pages under "whitewash suppliers"


I did, and found a firm called Brian Hutton & Co. ;-)

David E. Belcher
  #4  
Old September 15th 04, 02:33 PM
jim beam
external usenet poster
 
Posts: n/a
Default

James Annan wrote:
snip
"The conclusion is that the braking action of disc brakes is not causing
the quick release mechanism to unscrew. This test is unable to cause
loosening. At this time there are no reasons to believe that anything is
missing or over constrained in this test."


james, did you check out the pics i posted of my own disk brakes?

dropout he
http://home.comcast.net/~carlfogel/d...d/Img_3199.jpg

info shot of setup he
http://home.comcast.net/~carlfogel/d...d/Img_3196.jpg

there's no evidence of slippage. there /is/ evidence of indentation
where the axle serrations bite into the fork.

  #5  
Old September 15th 04, 10:16 PM
James Annan
external usenet poster
 
Posts: n/a
Default

jim beam wrote:

James Annan wrote:
snip

"The conclusion is that the braking action of disc brakes is not causing
the quick release mechanism to unscrew. This test is unable to cause
loosening. At this time there are no reasons to believe that anything
is missing or over constrained in this test."


james, did you check out the pics i posted of my own disk brakes?


Yes, but if you thought I'd be interested in a single case of "my wheel
didn't slip" then you have missed the point very very badly indeed.

Now, have you any "reasons to believe that anything is missing or over
constrained in this test"?

Inquiring minds want to know...

James
--
If I have seen further than others, it is
by treading on the toes of giants.
http://www.ne.jp/asahi/julesandjames/home/

  #6  
Old September 16th 04, 03:45 AM
jim beam
external usenet poster
 
Posts: n/a
Default

James Annan wrote:
jim beam wrote:

James Annan wrote:
snip

"The conclusion is that the braking action of disc brakes is not causing
the quick release mechanism to unscrew. This test is unable to cause
loosening. At this time there are no reasons to believe that anything
is missing or over constrained in this test."


james, did you check out the pics i posted of my own disk brakes?



Yes, but if you thought I'd be interested in a single case of "my wheel
didn't slip" then you have missed the point very very badly indeed.


polite as always. james, the point is not my "single case" but the lack
of cases that you present to the contrary. post some pics of forks
evidencing slippage if you please. dismissal of evidence that
contradicts your accusations does not add credibility to your case.

bottom line is this; put yourself in the position of a manufacturer.
are you going to pay attention to a guy on the net who, with respect,
misses a vital part of their analysis, then descends to personal attack
when challenged, or are you going to rely on your distributor network's
return data?

trust me, i have been carefully on the lookout for potential ejection
problems among all the people i've ridden mountain with since you raised
this issue, and you may be interested to learn that i have actually seen
one case of slip! but problem is, there was no ejection and it was
clearly attributable to an open cam skewer, badly crudded up, that the
rider couldn't be bothered to close properly. so, like a broken chain
that's attributable to it not being fitted correctly or an under-clamped
brake cable slipping and causing brake failure, the only disk wheel
slippage i've seen was due to incorrect skewer deployment. and even
then, if i hadn't been specifically looking for the slippage, the rider
would never have known because he hadn't, nor had he /ever/ had, any
problems! certainly not anything as serious as ejection.

now, to address your cannondale point, it is clearly a carefully guarded
response, but i fail to see how you'd expect anything else in the face
of a serious liability threat that's not supported by any statistical
evidence. mtb brakes changed from cantilever to linear p.d.q. once it
was established that incorrect usage combined with fouling could send a
rider over the bar. i don't know the numbers, but i'll wager there were
not many o.t.b's before manufacturers made the switch, however
statistically unlikely. unless disk brake ejection is actually
evidenced, then who is going to fix a problem that doesn't exist?


Now, have you any "reasons to believe that anything is missing or over
constrained in this test"?

Inquiring minds want to know...

James


  #7  
Old September 16th 04, 08:13 AM
James Annan
external usenet poster
 
Posts: n/a
Default

jim beam wrote in message ...

polite as always. james, the point is not my "single case" but the lack
of cases that you present to the contrary. post some pics of forks
evidencing slippage if you please.


http://www.velotech.de/saz_12_-_03_-_05.pdf

which I found by googling a previous post of mine in r.b.t, so don't
pretend you haven't seen it before. Unfortunately, I can't find the
rebuttal that you presumably offered, so I'd be grateful for a
reminder.

now, to address your cannondale point, it is clearly a carefully guarded
response, but i fail to see how you'd expect anything else


Is this really all you can bring yourself to say about it?

Let me remind you of their test:

"A light hand force of 5 lbs was applied to the brake lever every 10
seconds for 3 seconds duration. This caused braking torque to be applied
to the wheel. The drums had 3 equally-spaced cleats (0.5" high the same
as those used on wheel fatigue test T027) to create bumps for the front
wheel to go over."

And then we have:

"Conclusion:

"The conclusion is that the braking action of disc brakes is not causing
the quick release mechanism to unscrew. This test is unable to cause
loosening. At this time there are no reasons to believe that anything is
missing or over constrained in this test."


You describe that as "carefully guarded, but i fail to see how you'd
expect anything else"!

Remember that this is not just something they happened to have done
and offered to throw into the ring, but a piece of work they were
specifically commissioned to do by the CPSC in order to investigate
whether there was a potential danger.

Have you really no "reasons to believe that anything is missing or
over constrained in this test"? You have no opinion beyond "carefully
guarded, but i fail to see how you'd expect anything else"?

I would be equally amused to hear Mark Hickey's assessment of this
test, and Tony Raven's, too.

James
  #8  
Old September 16th 04, 02:55 PM
jim beam
external usenet poster
 
Posts: n/a
Default

James Annan wrote:
jim beam wrote in message ...


polite as always. james, the point is not my "single case" but the lack
of cases that you present to the contrary. post some pics of forks
evidencing slippage if you please.



http://www.velotech.de/saz_12_-_03_-_05.pdf

which I found by googling a previous post of mine in r.b.t, so don't
pretend you haven't seen it before. Unfortunately, I can't find the
rebuttal that you presumably offered, so I'd be grateful for a
reminder.


i have deep regret that

1. my german is not strong enough to follow all of the text
2. that i don't have either the time or the ax to grind to look for this
stuff.

only when i show up on r.b.t. do i ever get to see articles like that,
so please james, emotive language like "don't pretend you've never seen
it before" merely serves as antagonism.



now, to address your cannondale point, it is clearly a carefully guarded
response, but i fail to see how you'd expect anything else



Is this really all you can bring yourself to say about it?

Let me remind you of their test:


"A light hand force of 5 lbs was applied to the brake lever every 10
seconds for 3 seconds duration. This caused braking torque to be applied
to the wheel. The drums had 3 equally-spaced cleats (0.5" high the same
as those used on wheel fatigue test T027) to create bumps for the front
wheel to go over."

And then we have:

"Conclusion:

"The conclusion is that the braking action of disc brakes is not causing
the quick release mechanism to unscrew. This test is unable to cause
loosening. At this time there are no reasons to believe that anything is
missing or over constrained in this test."


i did read it, thanks. what is restatement trying to achieve?



You describe that as "carefully guarded, but i fail to see how you'd
expect anything else"!

Remember that this is not just something they happened to have done
and offered to throw into the ring, but a piece of work they were
specifically commissioned to do by the CPSC in order to investigate
whether there was a potential danger.

Have you really no "reasons to believe that anything is missing or
over constrained in this test"? You have no opinion beyond "carefully
guarded, but i fail to see how you'd expect anything else"?

I would be equally amused to hear Mark Hickey's assessment of this
test, and Tony Raven's, too.


you're just too busy being a victim to make progress in this. if you're
serious about getting traction, why don't /you/ commission an
independent test from a reputable third party and have your attorney
submit it? habeus corpus. any attorneys here want to represent james?

  #9  
Old September 16th 04, 03:17 PM
Tony Raven
external usenet poster
 
Posts: n/a
Default

James Annan wrote:


I would be equally amused to hear Mark Hickey's assessment of this
test, and Tony Raven's, too.


I'm staying out of this. My views are well known and there is not a lot
of point repeating them in the church of the faith. I did plan to do
what no-one seems to have done and go and find out what 5lbs force on
the brake lever was like. I know I don't squeeze my brakes as hard as I
possibly can so I know 100lbs is not realistic. However I have no idea
at present what 5lbs represents in my normal range of braking. Is it
top end, bottom end, middling? Can anyone here say yet because until
they can then ridiculing the figure absent realistic reference points is
conviction not scientific enquiry.

Damn, I just got sucked in.

Tony

  #10  
Old September 16th 04, 10:05 AM
Simon Brooke
external usenet poster
 
Posts: n/a
Default

in message , jim beam
') wrote:

James Annan wrote:
jim beam wrote:

James Annan wrote:
snip

"The conclusion is that the braking action of disc brakes is not
causing the quick release mechanism to unscrew. This test is unable
to cause loosening. At this time there are no reasons to believe
that anything is missing or over constrained in this test."

james, did you check out the pics i posted of my own disk brakes?


Yes, but if you thought I'd be interested in a single case of "my
wheel didn't slip" then you have missed the point very very badly
indeed.


polite as always. james, the point is not my "single case" but the
lack
of cases that you present to the contrary. post some pics of forks
evidencing slippage if you please. dismissal of evidence that
contradicts your accusations does not add credibility to your case.


Darth Ben of Kinetics carried out his own independent tests and observed
slippage under braking, with properly tightened skewers; and published
his results on the net. If this happens in 0.01% of bicycles that's
still an awful lot of very nasty crashes. The fact that it doesn't
happen in 99.9% of bicycles is good news but does not prove there is no
problem.

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

;; better than your average performing pineapple

 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT +1. The time now is 01:26 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 CycleBanter.com.
The comments are property of their posters.