Carlton Reid on QR safety

On Wed, 08 Feb 2006 07:29:33 +0900, James Annan wrote:

Of course, you know full well that the Velotech lab demonstrated front
wheel slippage under disk braking loads (pictures have been referenced
here and discussed in past threads). In fact, they did it a few years
before I had any interest in the subject.

And their commitment to this cause is such that they no longer have any
web pages in english on the subject. Nor in german, if my rusty command
of the german language is a guide.


If this is sufficiently serious problem that pressure needs to be put on
the manufacturers, then it has got to be done in the english language
using presentation and units that the American public and lawyers can
understand. So calculations in Newtons don't do it, nor do hand-drawn
arrows on a photograph, or vague references to web pages that no longer
exist or are in german if they do.


James, I think that your ideas are sound, although I do have some issues
about details, but the presentation is not good enough to get anywhere.
And the bunker mentality that you and Jobst adopt when questions arise
works against you. For example, /you/ brought uk.rec.cycling into this
discussion for the first time, but treat everyone from there who responds
as if they should have seen all the previous threads wherever they may
have been. Not a good way to gain allies.


TBH, it looks as if this problem is only going to arise in very severe
off-road conditions, and as a mainly roadie this doesn't concern me in
person. If I _were_ going seriously off-road I would not have QRs at
all, or would lockwire the damn things. If thought I'd be falling off
rocks, I'd drill and lockwire every nut and bolt on the bike.



Mike

"Simon Brooke" wrote in message
...
in message a, jtaylor
') wrote:


"Simon Brooke" wrote in message
...




how is it being "badly set up" evidence of design flaw?

I didn't say it was. You said it was impossible. It isn't.

Come on, Simon.

You _know_ jim beam is allowed to change to goal anytime he thinks the
ball is getting close.

I didn't, actually. He must be a rec.bicycles.tech troll; I'm from
uk.rec.cycling.


jim beam is the Matt B. of r.b.t. (except he was frightend by a shift key
when young).

In article 4kfGf.463354$2k.33596@pd7tw1no,
Michael Halliwell wrote:

Personally, I'm more convinced, especially with all the Walmart
incidents, that human error is the more likely culprit in ejections.

The geometry of the disc brakes contributes to ejection;
and is entirely responsible for quick release clamps
loosening in use. Until the geometry of the disc brake is
fixed, there is no such thing as user error.

--
Michael Press

In article ,
Tony Raven wrote:

Michael Press wrote:
In article ,
Tony Raven wrote:

jim beam wrote:
it's nylocked /and/ serrated, therefore it /is/ designed to resist
vibration.
As recommended as two of the three ways to prevent vibration loosening
in the Bolt Science website that JA uses as the basis for his vibration
loosening theory. That bit always seems to be glossed over for some reason.

We know how to secure threaded fasteners against
vibration. The point is that it should never have been
necessary.


But that doesn't answer why two of the recommended anti-vibration
measures which are integral to every Shimano QR are thought to not be
working in this instance.

The mechanism in the Shimano quick release nut is to
prevent the QR nut spinning when the QR is unclamped,
not to prevent loosening with rear mounted disc caliper on
mountain trail descents.

--
Michael Press

"jtaylor" wrote in message
et.ca...

"Simon Brooke" wrote in message
...
in message a, jtaylor
') wrote:


"Simon Brooke" wrote in message
...




how is it being "badly set up" evidence of design flaw?

I didn't say it was. You said it was impossible. It isn't.

Come on, Simon.

You _know_ jim beam is allowed to change to goal anytime he thinks the
ball is getting close.

I didn't, actually. He must be a rec.bicycles.tech troll; I'm from
uk.rec.cycling.


jim beam is the Matt B. of r.b.t. (except he was frightend by a shift key
when young).


There's a MattB here in a.m-b but he sure is a lot more pleasant than jim
beam.

Greg

In article ,
Alex Rodriguez wrote:

In article ,
says...

No, they are not. They are not designed for the conditions
I outlined. Many riders have testified that best quality
quick release systems loosen after one mountain descent.

What brand and model are you describing as best quality?

Those with off center cylinders on the clamping lever that
fits into a machined hole on the skewer, not the cam type
closure mechanisms.

QR's are designed
to hold your wheel in place. What forces does downhill riding present
that a QR can't handle?

Rear mounted disc calipers that induce force on the axle
in the downward direction. This force coupled with the
large forces from rough trail are not forces the quick
release clamp is designed to withstand. In fact the QR
mechanism responds to these forces by the QR nut turning
on the skewer threads and loosening the clamping force.


A sign that you allow your critical faculties to lapse is
your implication that I ride a bicycle where the quick
release clamps spontaneously loosen.

did you write the following?

Yes.


Loosening of the quick release nut from brake forces and
rough terrain vibration. The quick release clamp is not
designed for these conditions.


I ride
over rough roads, NYC, and I also have a disc brake on the front wheel. I
have
never had my QR come loose. The QR on this bike is one of those cheap made
in Taiwan jobs that is not as well made as shimano QR's.

Many qualified riders with best equipment do see the quick
release nuts loosen.

I wonder why this happens to them?

They ride bicycle with rear mounted disc calipers down
mountain trails.


This leads me to
believe that your problem may be associated with user error.

_My_ problem?

???

What do you mean when you say `This leads me to believe
that your problem may be associated with user error. '

--
Michael Press

Michael Press wrote:
In article 4kfGf.463354$2k.33596@pd7tw1no,
Michael Halliwell wrote:


Personally, I'm more convinced, especially with all the Walmart
incidents, that human error is the more likely culprit in ejections.


The geometry of the disc brakes contributes to ejection;
and is entirely responsible for quick release clamps
loosening in use. Until the geometry of the disc brake is
fixed, there is no such thing as user error.


Oh, that's right....it has to be a flaw in the design....after all, I
recall seeing a post about walmart bikes without discs experiencing this
"non user error" problem.

Don't get me wrong....I can see where the idea behind this debate is
coming from....especially with larger calipers and larger drop out
notches bringing the contact area of the brake pads further from the
vertical axis of the fork and axle (and hence generating a larger
vertical force due to the resistance to the moment created by
braking)....but from what I've seen, the design appears sufficient to
the task at hand. In order to get sufficient downward force (at least
on the bikes I have to compare to), the moment created on the wheel
would tend to either an endo or overcoming the friction of the front
wheel (skid) long before an ejection would take place.

Psycho Mike

Benjamin Lewis wrote:


What if you take a rest stop while riding? Do you check the QR when you
resume? How long to you have to stop before you have to do another check?

From this behaviour, one would think QRs regularly loosened themselves on
stationary unridden bicycles, but always stayed put while riding. Or
perhaps those of us that participate in longer rides should also check
periodically while on the road.

The "I live in a location rife with vandals" excuse aside, I can think of
no explanation for this.


A pre-ride check isn't based on vandals or some spontaneous loosening of
a QR on a stationary bike... but it does have several good reasons.

1) I have a tendancy of riding then parking. Where I park, there is the
possibility of snagging a variety of obstacles that could catch a QR
lever, zipper on a tool kit, pull a cable etc. I'd rather check before
I ride off to make sure I'm not going to lose something.

2) When do you notice regular wear and tear if you don't do an
inspection? I'd rather catch something early (like a loose bolt
someplace) than have a failure on a stretch of singletrack someplace at
dusk.

3) Off-roading can be a demanding and dangerous past-time...I check
diving gear before I dive, my chute before I jump out of a plane...why
would I not check my bike before hopping on to go for a ride in the bush?

and

4) It forces me to make sure I have what I need for the ride du jour
(like batteries charged for a night ride).

I'm not talking excessive checks here, Ben....once per day unless I
notice something in the feel/sound of the bike that makes me wonder if
something is going on. Hell, I'm like every other average biker out
the I'd rather be riding than doing checks or maintenance...but I
don't see it as a waste to spend a minute to be sure that my bike is as
ready to go as I am.

Psycho Mike

In article
pan.2006.02.08.23.40.57.384584@firstnamelastname. com.inva
lid,
Mike Causer wrote:

TBH, it looks as if this problem is only going to arise in very severe
off-road conditions, and as a mainly roadie this doesn't concern me in
person. If I _were_ going seriously off-road I would not have QRs at
all, or would lockwire the damn things. If thought I'd be falling off
rocks, I'd drill and lockwire every nut and bolt on the bike.

To lock wire the quick release lever will not prevent
quick release nut loosening. This processes have been
described many times. Please make the problem clear to
yourself. At some point spoon feeding reaches the limits
of effectiveness and the student must buckle down and work
out the details for himself.

--
Michael Press

James Annan wrote:
jim beam wrote:

James Annan wrote:

jim beam wrote:

James Annan wrote:

jim beam wrote:


James Annan wrote:




Of course, you know full well that the Velotech lab demonstrated
front
wheel slippage under disk braking loads (pictures have been
referenced
here and discussed in past threads). In fact, they did it a few
years
before I had any interest in the subject.

James



what exactly does that do to show that you didn't omit to do a
pullout
force calculation? all i see is you grasping at straws and citing a
conveniently hard to check "source", without context or content.




What do you mean "hard to check"? I've already given you the full URL,
and you've given feeble excuses as to why you couldn't possibly
look at
or comment on it. You should really x-no-archive your posts, or change
your handle, if you don't want your embarrassing past to stick to you.

James


post it here.




http://tinyurl.com/dydby

James


1. that kind of linkage is juvenile. you want people to take you
seriously? link direct.
2. when we finally get there, you obliquely reference that old
chestnut? nested deep in a thread where it's been discussed to death
before?



Actually, you previously said:

"i don't have either the time or the ax to grind to look for this
stuff."

which is hardly what I would describe as "discussed to death".

I must admit that I was naive enough to consider the possibility, based
on your request for me to post the reference (your "post it here")
comment above) that you might actually have a look at it this time.

My mistake, obviously. You're too scared to even click on the link
provided.

But this post will be in the Google cache in a couple of years when you
next deny that such evidence exists.

James

what a jerk. you post some asinine link with a juvenile cartoon, that
then links into the the top of a long tortuous thread, not a direct link
to the article i asked you to cite. and now you're bleating like you're
the injured party? no wonder you had to flee to japan - refuge among
foreigners that don't understand you is the only way i can imagine you
not getting regularly slapped.