Cannondale's tests of disks and QRs

SuperSlinky wrote:

In the very beginning, he had an interesting story to tell. Now he is
like Don Quixote, trying to create a reality that never existed.

I even forge emails to myself about it, like this one that appeared in
my inbox at the end of last month.

Date: Tue, 31 Aug 2004 00:12:15 -0700 (PDT)

I am recovering from a
serious mountain biking accident in which my front
wheel flew off my bike after 45 minutes of
riding(including multiple climbs and descents). I
suffered a broken jaw in 4 places, and have over 50
stitches on my face and tongue. I had emergency
surgery the same day as the accident and spent 2 days
in the hospital, one in Intensive Care.

The bike is a xxxxxxxxxxxxxxx with front disk brakes
and your standard quick release. I've been a pretty
consistent rider for over 12 years and this is my
first accident. I can say with 100% confidence that I
properly attached the front wheel prior to starting
the ride(though new to disk brakes, I'd used quick
release for over 12 years without incident).

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

Paul - xxx wrote:

How was the 5 lbs measured ?

A weight hung directly on the lever, which was not actually mounted on
the bike but separately to one side.

Maybe they are running more tests and you have interim
results ?

One might hope so, but no, this single experiment is the only test that
any manufacturer has performed (and communicated to the CPSC) concerning
this problem. There are no plans to perfom any more, indeed it appears
that there is no justification for doing so, since there was no
conceivable weakness in this one.

Did they have a specification to work to for the tests ?

I don't believe the CPSC has the engineering nous to specify a suitable
test all on its own, they just asked Cannondale to investigate if there
could be a problem.

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

Tony Raven wrote:

I'm staying out of this.

But Tony, you said back in March that you were looking forward to
hearing about the test. I was looking forward to hearing of your
reaction to it!

My views are well known and there is not a lot
of point repeating them in the church of the faith.

Are really you so ideologically driven that this new evidence - the only
manufacturer's test data that has been released to the public - is
incapable of influencing you, in principle? What a shame. If that really
is the case, then I agree you have little to offer and might as well
shut up.

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

I will post my assessment in a few days. I want to give other posters a
free hand in forming their own judgements first.

So far all jim beam can bring himself to say is that it is is "carefully
guarded, but i fail to see how you'd expect anything else". Actually, it
seems to me that his comment is even more guarded, but I must admit I
did not expect anything else from him. I can see how he might find it
extremely difficult to say anything meaningful about the test.

However, Super Slinky tells us that 5 pound lever force and 0.5" bumps
is plenty radical enough for him. Phat, dude. Bet you catch wikkid air.

ridiculing the figure absent realistic reference points is conviction not scientific enquiry.

Well, it certainly does appear that most responses are ridiculing it.
But OTOH, we have the might of Cannondale's engineering department
unable to conceive of any possible weakness in the test.

I'll give you another few days to ponder it further.

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

James Annan wrote:
Tony Raven wrote:

I'm staying out of this.

But Tony, you said back in March that you were looking forward to
hearing about the test. I was looking forward to hearing of your
reaction to it!


There are I guess two possible outcomes. One is that the test is
totally unrealistic and does nothing to clarify the situation. The
other is that it is realistic in terms of brake pressures being
representative in which case we have one repeatable experiment which has
failed to produce the sort of QR loosening you have predicted. That
does not mean it invalidates your theory because it did not test all
combinations but at best it is neutral to your theory and at worst it is
some evidence counter to your theory. Until I have read the report in
detail and assessed how realistic 5lbs is I cannot comment which of
these it is. If it had shown QR slipping and loosening it would have
clearly shown strong support for your theory but it didn't.

I would be interested to know what your critique of the test is as you
clearly have reached a conclusion that it is unrealistic and the basis
on which you reached that conclusion would be interesting to know.

Tony

I don't believe the CPSC has the engineering nous to specify a suitabl=
e =

test all on its own, they just asked Cannondale to investigate if ther=
e =

could be a problem.

James


Did C-Dale's test do anything to change your mind on the matter?

-- =

Slacker

"James Annan" wrote in message
...
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.
"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
--

Oh lord, here we go again

Nelson--who has to date only seen pictures that look *a lot* like bad
skewer installations.


---
__o
_`\(,_ Cycling is life,
(_)/ (_) all the rest, just details.
The Nelson Paradigm =^o.o^=
http://intergalax.com
http://intbike.com
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.760 / Virus Database: 509 - Release Date: 9/10/2004

Peter Clinch said...

It probably was a perfect storm of bad ingredients, but perfect storms
of bad ingredients can happen, and if they can still be avoided without
too much extra trouble then there's no good reason not to avoid them.
Unless you think complacency is a good reason.

Or you could just bluster about saying it hardly ever happens, so it's
not a problem. Like Chernobyl, for example...

Pete.

Bull****. The perfect storm was his particular bike. What part of that
didn't you understand? Take it up with that manufacturer. In particular,
lack of retention lips seems to be typical of UK made forks. Last I
checked, neither Pace nor Planet X forks had them. Every MTB fork I have
owned on this side of the pond has had them, even my full rigid '98 GT.
That alone would have stopped this silliness from ever happening. Then
there is the fact that almost none of us ride off-road tandems. I will
admit that it is a cute idea, but one that brings with it some extra
equipment demands, one of which James discovered the hard way. Glad he
wasn't seriously injured, but spread the warning to owners of disc
equipped tandem forks without retention lips. The rest of don't have
that problem.

Simon Brooke wrote in message ...

Of course by exerting more force you can lock the front wheel. But the
injury consequent on locking the front wheel at speed is not greatly
different from the injury consequent on the wheel ejecting at speed.

I don't think Russ would agree with you there. Going over the top is
bad, but you at least have a split second to react. Wheel ejection
under braking slams you straight into the ground.

--
Dave...

Although I believe my original post already contained ample information
with which to come to a judgement about the validity of Cannondale's
test, I think it may be worth mentioning one more detail. I've added the
immediately preceding sentence from the report. The amended description
follows:


"There is an air cylinder pushing forward and downward on the handlebar
stem area with 275lbs. 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/

James Annan wrote:
Although I believe my original post already contained ample information
with which to come to a judgement about the validity of Cannondale's
test, I think it may be worth mentioning one more detail.

Haven't had the time to check whether you've already done it but would
be useful to have the whole report posted on your website so we can read
it all. Is there any reference to how they come to these figures? I
would think that Cannondale have the benefit of having instrumented
their bikes in development and testing including their sponsored team
bikes and would have access to real life figures up to and including
international standard competition to guide their test set up.

Tony