Sobering thoughts on disk brakes.



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Spider

Guest
Dave W <[email protected]> wrote in message news:<[email protected]>...
> On 20 Apr 2003 13:04:00 -0700, [email protected] (Spider) wrote:
>
> >Dave W <[email protected]> wrote in message news:<[email protected]>...
> >> On 18 Apr 2003 20:25:43 -0700, [email protected] (Spider) wrote:
> >>
> >> >Dave W <[email protected]> wrote in message
> >> >news:<[email protected]>...
> >> >> On 18 Apr 2003 09:08:15 -0700, [email protected] (Spider) wrote:
> >> >>
> >> >> >Bill Wheeler <[email protected]> wrote in message
> >> >> >news:<[email protected]>...
> >> >> >> On 17 Apr 2003 09:19:17 -0700, [email protected] (Spider) wrote:
> >> >> >>
> >> >> He can talk engineer pretty goodly.
> >> >>
> >> >> >:)
> >> >> >
> >> >> >Spider
> >> >>
> >> >> What amazes me is that YOU can actually understand it.
> >> >
> >> >From the likes of you, that comment is particularly hilarious.
> >> >
> >> >Spider
> >>
> >>
> >> Glad to help the less fortunate in the brain area anytime.
> >
> >There *are* none less fortunate than you in that regard.
>
> yes you are, admit it.

Clever. The "I know you are but what am I" retort. Just learned that one, eh?

:)

> >But please, continue - it amuses me to no end.
>
> No, now back in your box.

Aww, how disappointing. And you were doing so well. *snork*

Spider
 
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Shaun Rimmer

Guest
Spider <[email protected]> wrote in message
news:[email protected]...

> But it is incorrect to say that the QR doesn't have a "screwing component" (shut up, Rimmer.)

Screw you Spider - where screwing components are concerned, I'm a slow release man.

> And the forces discussed on James' website do seem to bear this out.
>
> Rigorous, controlled experimentation needs to be done. And you can bet your ass that the fork
> manufacturers probably won't be doing it.
>
> I would hope that the takeaway message is to be careful when you do up your fork QR if you have
> disk brakes. And check the thing in the ride somewhere, just to make sure. Sorta like a helmet -
> it may not help, but it probably won't hurt. But if you want to shout "B.S." on it, talk to Jobst.
> He can talk engineer pretty goodly.

Someone posted here recently about this same problem. Also, wasn't this what is said to have caused
Russ' accident?

Shaun aRe - Think he knows better that to poorly tighten a QR.
 
S

Spider

Guest
"Shaun Rimmer" <[email protected]> wrote in message
news:<[email protected]>...
> Spider <[email protected]> wrote in message
> news:[email protected]...
>
>
> > But it is incorrect to say that the QR doesn't have a "screwing component" (shut up, Rimmer.)
>
> Screw you Spider - where screwing components are concerned, I'm a slow release man.
>
> > And the forces discussed on James' website do seem to bear this out.
> >
> > Rigorous, controlled experimentation needs to be done. And you can bet your ass that the fork
> > manufacturers probably won't be doing it.
> >
> > I would hope that the takeaway message is to be careful when you do up your fork QR if you have
> > disk brakes. And check the thing in the ride somewhere, just to make sure. Sorta like a helmet -
> > it may not help, but it probably won't hurt. But if you want to shout "B.S." on it, talk to
> > Jobst. He can talk engineer pretty goodly.
>
> Someone posted here recently about this same problem. Also, wasn't this what is said to have
> caused Russ' accident?

Yes, Carla. And yes to the second one as well. :(

Spider
 
S

Shaun Rimmer

Guest
Spider <[email protected]> wrote in message
news:[email protected]...
> "Shaun Rimmer" <[email protected]> wrote in message
news:<[email protected]>...
> > Spider <[email protected]> wrote in message
> > news:[email protected]...
> >
> >
> > > But it is incorrect to say that the QR doesn't have a "screwing component" (shut up, Rimmer.)
> >
> > Screw you Spider - where screwing components are concerned, I'm a slow release man.
> >
> > > And the forces discussed on James' website do seem to bear this out.
> > >
> > > Rigorous, controlled experimentation needs to be done. And you can bet your ass that the fork
> > > manufacturers probably won't be doing it.
> > >
> > > I would hope that the takeaway message is to be careful when you do up your fork QR if you
> > > have disk brakes. And check the thing in the ride somewhere, just to make sure. Sorta like a
> > > helmet - it may not help, but it probably won't hurt. But if you want to shout "B.S." on it,
> > > talk to Jobst. He can talk engineer pretty goodly.
> >
> > Someone posted here recently about this same problem. Also, wasn't this
what
> > is said to have caused Russ' accident?
>
> Yes, Carla. And yes to the second one as well. :(
>
> Spider

Sucks dunnit ;-(

Shaun aRe
 
P

Pete Jones

Guest
On Fri, 25 Apr 2003 13:42:51 +0100, "Shaun Rimmer" <[email protected]> blathered:

>> > > Rigorous, controlled experimentation needs to be done. And you can bet your ass that the fork
>> > > manufacturers probably won't be doing it.
>> > >
>> > > I would hope that the takeaway message is to be careful when you do up your fork QR if you
>> > > have disk brakes. And check the thing in the ride somewhere, just to make sure. Sorta like a
>> > > helmet - it may not help, but it probably won't hurt. But if you want to shout "B.S." on it,
>> > > talk to Jobst. He can talk engineer pretty goodly.
>> >
>> > Someone posted here recently about this same problem. Also, wasn't this
>what
>> > is said to have caused Russ' accident?

http://www.singletrackworld.com/forum/read.php?f=2&i=370832&t=370832

Pete
----
http://www.btinternet.com/~peteajones/
 
X

x

Guest
RE/
>So I did a quick full stop causing my rear to lift. I felt and saw the front wheel move.....holy
>sh!t it's amazing what a loose QR can cause.
>
>People tighten you QR's discs or no dics and do it properly.

Maybe an engineer can comment on this.

My seatpost had been slipping slightly ever since I started greasing it.

Tightend the QR that held that sucker until my knuckles couldn't take it anymore and I had to be
feeling pretty strong to unfasten the thing.

It still slipped.

Then I read a suggestion in another thread about replacing the QR seatpost binder with a regular
allen-key binder. "Riiiiitttte..." I thought. "Howinthehick is that gonna make any diff when I
already have that sucker as tight as humanly possible?".

Bottom line: I replaced it with an allen key binder, didn't tighten it *all* that tight - for fear
of stripping something - and it hasn't slipped since.

From that, I extrapolate that somehow it's possible to get a lot more tightness from an allen-key
bolt than a QR.

Funny thing: the QR on my seatpost binder looks an awful lot like the QR on my front wheel's skewer.

What about replacing QR on the skewer with some sort of deep-hole, conical-shaped 5 mm socket nut?
The hand-adjustable nut on the far end could still give/take up the slack for the lawyer lips and it
would *seem* that the wheel would be held in place a *lot* tighter.... and it would probably be
almost as fast/convenient to remove/install given that most people probably have a 5mm allen key
readily available for adjusting handlebars, stems, v-brake mounts, caliper mounts, seatpost binders,
saddle clips, and so-forth.
-----------------------
PeteCresswell
 
J

James Annan

Guest
"Shaun Rimmer" <[email protected]> wrote in message
news:<[email protected]>...
> Spider <[email protected]> wrote in message
> news:[email protected]...
>

> > Rigorous, controlled experimentation needs to be done. And you can bet your ass that the fork
> > manufacturers probably won't be doing it.

The fork manufacturers appear sticking their heads in the sand hoping the problem will go away. Pace
recently issued an 'open letter' which serves only to confirm their lack of understanding of the
problem. Perhaps I shouldn't be too harsh on them, since none of the other manufacturers have been
prepared to comment other than the Director of R+D at Rockshox saying that since the lawyers had
decided it was all user error, he sees no reason to worry about it.

> Someone posted here recently about this same problem. Also, wasn't this what is said to have
> caused Russ' accident?

Yes it is. Since posting the explanation of failure I have heard many anecdotes which fit the
description very closely. Here is the latest one, quoted from

http://www.singletrackworld.com/forum/read.php?f=2&i=369911&t=369911

I have marginally edited the text to clarify a few points.

begin quote:
---------------------------------------------------------

Following my mates accident and the forum discussions of the previous week, I marked my skewers and
kept an eye on QR's during my merry adventures.

['marked my skewers' - following Russ's crash, some people decided to mark the position of the
skewer and check carefully for any sign of movement]

Having gone for a tootle round the Peaks, I arrived at the top of the first hill- I sat down to take
in the view and sunshine...and looked at my QR - no movement, tight as a bell.

['looked at' clarified as 'I physically checked as well as visually checked the QR at the top - no
rotation, tightly done up'.]

Rattle rattle rattle down a Peak rockfest - and I had a strange feeling to the front of the
bike(clunk). - I glanced down and the QR was rotating slowly forward! Splash into stream...bugger,
stop quickly
- look down and QR was now completely undone - i.e. unlocked! Wheel was loose, but wouldn't drop out
because of the dropout shape...

A few of points:-

1. QR WAS done up - I had checked it at the top and had not stopped, crashed or clipped anything
that may have undone it.

2. I could see the QR lever had rotated forward when I glanced down.

3.QR was hot to touch - not red hot but hot. Disc was the usual hot, hot, hot.

4. Was a descent that meant often trailing brakes, followed by hard braking for around 10 minutes.

5. 'Twas a Rocky descent in places. (Whinstone Lee Tor to Ladybower)

mmm more food for thoughts. Its making me think about bolt up axles....

--------------------------------------------------------
end quote

> > I would hope that the takeaway message is to be careful when you do up your fork QR if you have
> > disk brakes. And check the thing in the ride somewhere, just to make sure.

I would hope that the takeway message is that the design is faulty, and no amount of skewer
tightening and checking is guaranteed to stop it unscrewing.

> Shaun aRe - Think he knows better that to poorly tighten a QR.

James - who thinks he knows better than to trust a faulty design with a substantial number
of failures.
 
P

Pete Jones

Guest
On 25 Apr 2003 20:09:15 -0700, [email protected] (James Annan) blathered:

>> > Rigorous, controlled experimentation needs to be done. And you can bet your ass that the fork
>> > manufacturers probably won't be doing it.

http://www.singletrackworld.com/forum/read.php?f=2&i=370832&t=370832

>Since posting the explanation of failure I have heard many anecdotes which fit the description
>very closely.

So have I. The one common factor seems to be the use of lightweight QRs, of both cheapo & boutique
origin. I had one incident where I pulled the rear wheel from its dropouts (on Porcupine Rim)
using...yup, a cheap lightweight skewer (a Ritchey, I think).

I now use stock Shimano skewers, and get medieval on their ass when I'm locking them down (as I
always have). I think there is certainly a phenomonen here that needs looking at, but it's not
simply a case of QR + disk = death.

When installing the CP125s yesterday I quickly discovered that, due to the design of the dropouts,
it's impossible to get the QR nuts out without loosening them off A LOT. Pic -
http://www.btinternet.com/~peteajones/temp/cp125-dropout.jpg It was a bloody nuisance while I was
setting up the disk caliper, but I'm not too worried about my wheels popping out...

Pete
----
http://www.btinternet.com/~peteajones/
 
J

James Annan

Guest
Pete Jones wrote:

> So have I. The one common factor seems to be the use of lightweight QRs, of both cheapo &
> boutique origin. I had one incident where I pulled the rear wheel from its dropouts (on Porcupine
> Rim) using...yup, a cheap lightweight skewer (a Ritchey, I think).
>
> I now use stock Shimano skewers, and get medieval on their ass when I'm locking them down (as I
> always have). I think there is certainly a phenomonen here that needs looking at, but it's not
> simply a case of QR + disk = death.

No, it's an intermittent problem and surely the frequency will vary with equipment. Probably many
people will never experience the problem, but I've had at least one report of a Shimano skewer
coming loose, so I think it is foolish for anyone to assume that they are immune.

Of course, statistically speaking, it generally "won't happen to me" but the same could be said
about head injury, and most MTBers still seem to agree that a helmet is a reasonable safety
precaution.

James
 
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Shaun Rimmer

Guest
James Annan <[email protected]> wrote in message
news:[email protected]...
> "Shaun Rimmer" <[email protected]> wrote in message
news:<[email protected]>...

> > Someone posted here recently about this same problem. Also, wasn't this
what
> > is said to have caused Russ' accident?
>
> Yes it is. Since posting the explanation of failure I have heard many anecdotes which fit the
> description very closely. Here is the latest one, quoted from
>
> http://www.singletrackworld.com/forum/read.php?f=2&i=369911&t=369911

> end quote

Thanks.

> > Shaun aRe - Think he knows better that to poorly tighten a QR.
>
> James - who thinks he knows better than to trust a faulty design with a substantial number of
> failures.

Yes, I was meaning to say 'I think Russ knows better' (etc.), in response to the other poster's
insinuation that it was operator error that caused the problem, and intending to infer there was an
inherent design oversight at the root of it.

Shaun aRe
 
J

James Annan

Guest
Shaun Rimmer wrote:

>
> Yes, I was meaning to say 'I think Russ knows better' (etc.), in response to the other poster's
> insinuation that it was operator error that caused the problem, and intending to infer there was
> an inherent design oversight at the root of it.

Ah, ok, that makes sense.

Interestingly, this part of the thread seems to have vanished from the Google Groups archive, along
with recent postings in rec.bicycles.tech on the same subject (there are other recent postings in
the groups, so it's not a widespread failure). I'm not one for conspiracy theories, but it's not
happened to me before. I'll assume it is just a technical ****-up for now...

James
 
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Shaun Rimmer

Guest
James Annan <[email protected]> wrote in message news:[email protected]...
> Shaun Rimmer wrote:
>
> >
> > Yes, I was meaning to say 'I think Russ knows better' (etc.), in
response to
> > the other poster's insinuation that it was operator error that caused
the
> > problem, and intending to infer there was an inherent design oversight
at
> > the root of it.
>
> Ah, ok, that makes sense.

I wrote it, it's bound to ',;~}~

<chortle!>

> Interestingly, this part of the thread seems to have vanished from the Google Groups archive,
> along with recent postings in rec.bicycles.tech on the same subject (there are other recent
> postings in the groups, so it's not a widespread failure). I'm not one for conspiracy theories,
> but it's not happened to me before. I'll assume it is just a technical ****-up for now...
>
> James

It's them Jupiterians in the Guvmint again. Look just like politicians they do, but they got a
finger in every pie. Always up to summat.......

Shaun aRe
 
J

James Annan

Guest
"Shaun Rimmer" <[email protected]> wrote in message
news:<[email protected]>...

> It's them Jupiterians in the Guvmint again. Look just like politicians they do, but they got a
> finger in every pie. Always up to summat.......

Panic over, it seems to have all come back now...all's right with the world and it's time for bed
(over here at least).

James
 
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