Carlton Reid on QR safety

David Damerell wrote:
Quoting Tony Raven :
Try it. Undo your quick release until it just releases over the lawyers
lips and then do it up just enough to marginally retain the axle. Go
test ride the bike carefully. Then tell me that it is not very obvious
that the QR is undone.

OK, I will; the local chavs periodically undo front QRs, so - back when I
had a front QR hub - I've found myself riding with a loose one once or
twice (lucky me, I don't have a disc brake). No, it's not necessarily
obvious; and that's on smooth flat pavement, not rattling about like crazy
down a hill offroad. The axle is retained in its normal position in the
dropouts by the weight of the rider.

I recall an internet video clip whose link was (IIRC) posted on this
group. It showed about four mountain bikers starting a ride in a
parking lot. One guy tried to wheelie over a speed bump (or some such
thing) and lost his front wheel completely. He apparently hadn't
fastened his QR at all.

This shows that, at least for some distances on certain terrains, a
completely loose QR isn't necessarily obvious. I'd assume that for
shorter distances in somewhat rougher terrain, a partially loose QR is
also not obvious.

This is not a major problem for the rider as long as the force on the
axle is not toward the dropout opening. But if a disk brake is trying
to eject the wheel, it's a problem.

And that's the problem we're discussing. The cam lock QR was never
intended to provide the primary retention force. Instead, that primary
retention force was intended to be provided by the direct
metal-to-metal compressive contact between the dropout metal and the
top of the axle. IOW, you have the closed end of the dropout slot
blocking the axle from moving.

A rear-mounted disk caliper asks the QR to do something it was never
intended to do.

- Frank Krygowski

Michael Halliwell wrote:
wrote:

Anyways, I think that checking the front quick release before each
ride might be a good idea. In fact, I think I'll go check it right
now...


You mean, like most manufacturers recommend before each ride in thier
owners manuals?

What a novel concept!

Do you _seriously_ open and shut your front QR before every ride??

I've been riding bikes with QR wheels since the early 1970s. I never
check my QR if I'm not in the process of removing or installing the
wheel, and I've never needed to. On bikes with caliper brakes, they
simply do not loosen.

Why? Because there is other metal-to-metal contact resisting any force
that would try to shift the axle in the dropout. There is no
possibility of lateral motion within QR adjusting threads. There are
no influences that would cause loosening.

For a disk brake bike with rear mount calipers and downward facing
dropouts, this is not true.

And by now, we've seen enough reports from mountain bikers who checked
their QR at the top of a long, rocky descent, found them looser at the
bottom, and gave us the difference measured in degrees of swing of the
QR lever. Seems unrealistic to pretend these guys are lying. Why
would they?

- Frank Krygowski

wrote:


Do you _seriously_ open and shut your front QR before every ride??

I've been riding bikes with QR wheels since the early 1970s. I never
check my QR if I'm not in the process of removing or installing the
wheel, and I've never needed to.

If you have properly adjusted cup and cone bearings, the bearings will
develop play with a loose skewer long before the wheels drop out. This
is very audible if you pick up the bike, provided the bike is well cared
for and not a ratling heap of misery. But if you don't want to listen....


--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

Michael Halliwell writes:

Anyways, I think that checking the front quick release before
each ride might be a good idea. In fact, I think I'll go check it
right now...

You mean, like most manufacturers recommend before each ride in
their owners manuals?

What a novel concept!

That is "novel" if you mean that literally, as in "new". In the
many years I have ridden bikes with QR hubs, I have not done that
and also never found a loose QR when taking a wheel out for, for
instance repairing a flat on the road. Maybe the QR's of today are
no good and open themselves, as John Howard claimed in his now
famous testimony that brought us lawyer lips.

This is all so reminiscent of AUDI unwanted acceleration, that was
an old story long before because AARP folks driving Cadillacs had a
history of stepping on the gas when they meant the brake... so
today we must push the brake pedal before engaging the automatic
transmission. Not a bad idea, but useless for drivers with good
habits. Jobst Brandt

Funny, in all the time I've been riding with quick releases, it has
been a recommendation in the owners manual (even with v-brakes /
cantilever brakes) to check the QR's before each ride.

You haven't been riding bike very long. Those admonitions arose after
John Howard's testimony. After all, he was a professional bicycle
racer and Bonneville speed record setter. Who knows more about
mechanics of QR's, an engineer or a bicycle racer anyhow? At least
that was the emphasis at the time of the trial.

Forgive me for stating the obvious, but if something is designed to
be quickly removable, shouldn't it be checked periodically to ensure
that when you don't want it to be quickly removed, it won't come
out?

Not if properly designed. Do you check to see if the door on your car
is still closed after driving awhile? There are many QR type devices
that remain reliably secure. Only when disk brakes were introduced,
as they were, did this problem arise. Reversing axle loads are a new
condition that the classic front wheel dropout and QR were not
designed for. In such a design the forces should have been analyzed
so the design made insure unidirectional loading. Had that been done
there would be no problem with friction retention of the wheel. That
can still be accomplished.

I don't know about you, but I'm going to continue to check my QR's,
headset and any other component that are vital to my bike's
components before I ride, just like I do a walk around on the car so
I don't drive on a flat if some punk slashed my tire.

You need to move to better real estate. Location, location, location.

Jobst Brandt

On Mon, 06 Feb 2006 21:15:42 -0800, jim beam
wrote:




so james, are you able to differentiate between someone that doesn't
operate their qr correctly [user error] and design flaw? no? are you
going to keep on ignoring the FACT that correctly fastened qr's retain
wheels with a significant safety margin? [also ignoring the efficacy of
lawyer lips of course.] until you can, you're simply the lunatic the
industry is going to ignore.

I resent the idea that I do not know how to tighten a QR on the front
wheel of one of my bicycles but a capable of tightening the other
five.

My case

I ride my disc equipped bike for a year with no problem at all. As
something ages the problems start. I do not suffer ejection despite
the absence of 'lawyers lips'. However occasionally after sharp
braking the wheel would move in the drop out causing the disc to rub
against the brake. So I would need to stop, reset the wheel and
tighten the QR. I conclude that maybe the problem is with the X-Lite
QR so I swap in a Shimano one from my bits box. The problem ceases
for a while but eventually the problem returns.

Unfortunately I no longer have that fork. When I needed to replace it
I specified that the brake is mounted on the front of the right hand
fork. Problem solved.

Your assertion that the problem does not exist is false. Although
thankfully like cancer the condition is rare. However you seem to be
claiming 'None of my friends and family have cancer therefore nobody
has cancer' I apologise if anyone you know does. It remains correct
that we find solution to problems even if they do not apply to you.

In article ,
says...

That is "novel" if you mean that literally, as in "new". In the many
years I have ridden bikes with QR hubs, I have not done that and also
never found a loose QR when taking a wheel out for, for instance
repairing a flat on the road. Maybe the QR's of today are no good and
open themselves, as John Howard claimed in his now famous testimony
that brought us lawyer lips.

Me too. I've never had a QR mysteriously loosen itself. I mostly use
Shimano QR's, but I have used a few of the cheapo units at times. Neither
had problems when properly used.


This is all so reminiscent of AUDI unwanted acceleration, that was an
old story long before because AARP folks driving Cadillacs had a
history of stepping on the gas when they meant the brake... so today
we must push the brake pedal before engaging the automatic
transmission. Not a bad idea, but useless for drivers with good
habits.

More importantly those of us with good habits have to pay for what amounts
to a useless feature.
-------------
Alex

In article vD2Gf.580573$ki.373250@pd7tw2no, says...

Funny, in all the time I've been riding with quick releases, it has been
a recommendation in the owners manual (even with v-brakes / cantilever
brakes) to check the QR's before each ride.
Forgive me for stating the obvious, but if something is designed to be
quickly removable, shouldn't it be checked periodically to ensure that
when you don't want it to be quickly removed, it won't come out?

If it requires more than a quick visual inspection, it is crap.

I don't know about you, but I'm going to continute to check my QR's,
headset and any other component that are vital to my bike's components
before I ride, just like I do a walk around on the car so I don't drive
on a flat if some punk slashed my tire.

If your QR's or headset are coming loose on there own, there is something wrong
with those parts. You should consider replacing them with something decent
that works properly.
---------------
Alex

In article ,
says...

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

You either have a defective design or improplery tightened QR's. QR's are
designed to hold your wheel in place under all riding 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. This leads me to
believe that your problem may be associated with user error.
--------------
Alex

in message , jim beam
') wrote:

Try it. Undo your quick release until it just releases over the
lawyers lips and then do it up just enough to marginally retain the
axle. Go test ride the bike carefully. Then tell me that it is not
very obvious that the QR is undone. I know, I've forgotten to do up
the QR on occasions when setting off and I have never got more than a
few yard before it is very obvious something is wrong.

So what? Even you can't deny that this wheel loss actually happens.

i'll deny it for you james. wheel loss CANNOT happen on a fork with
lawyer lips. sorry to point out something so fundamentally obvious and
painful for you, but reality has to slap you in the face some day.

It can, and I've seen it. It happened to my next-door neighbour's eleven
year old son. The bike had V brakes, quick release and lawyer lips - but
was so badly set up that he /still/ managed to lose the front wheel when
pulling a wheelie to impress school friends. How he managed to lose a
front wheel on a fat tyre bike with V brakes amazed me, but he did it.

Result: broken elbow, broken jaw. He's given up on mountain bikes and now
rides BMX(!).

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

The trouble with Simon is that he only opens his mouth to change feet.
;; of me, by a 'friend'

in message , jim beam
') wrote:


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

it's nylocked and serrated, therefore it is designed to resist
vibration.

Uhhhmmm... walk that by me again. Are you saying that all mountain bike
quick release skewers are nylocked? Or have I misunderstood you?

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/
;; Generally Not Used
;; Except by Middle Aged Computer Scientists