Something being done about the Disc/QR by trek



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M

Mike Jacoubowsk

Guest
> Well, they're investigating at least... what that means is anybody's
guess.

What it means is that TREK is always on the lookout for issues that might affect bicycle safety. The
article references Bob Burns, TREKs chief legal counsel. I've known Bob for a number of years, and
he's definitely one of the reasons TREK does so well in the marketplace. He's constantly on the
lookout for potential product safety (liability) issues, and has the advantage of working for a
company that sells so much product that the sample size is large enough to often determine, on their
own, what works and what doesn't.

I would not make any assumptions about the validity of any claims made by James Annan based upon Bob
Burns investigating the matter. Such things are looked into routinely without any presumption ahead
of time that it's true or not. The point of the investigation, at least initially, isn't to work out
a solution to the problem, but rather to see if it exists in the first place.

--Mike-- Chain Reaction Bicycles http://www.ChainReactionBicycles.com

"Jon Bond" <[email protected]> wrote in message news:[email protected]...
> Well, they're investigating at least... what that means is anybody's
guess.
>
> http://www.singletrackworld.co.uk/article.php?sid=1005
>
> Jon Bond
>
> (thanks Bomba!)
 
J

Jon Bond

Guest
So says the man who's name appears on the Trek custom paint program page as an example ;)
http://projectone.trekbikes.com/mountain/images/paint/bike_for_custom_name.jpg

Either way, I never said that James Annan was right - heck, I'm planning on using XT or XTR quick
releases on my wheel with XT discs - its just a nice reminder to make sure that they're properly
tight. I'm glad they're investigating - it means we'll get an answer either way. Although its 10:1
odds they don't find a problem, and another 10:1 that when they don't, people are still going to say
its the lawyers saying they can just blame people for not "properly tightening their quick
releases". It is nice to know that they at least made an effort to investigate.

Jon Bond knew I recognized that name from somewhere....

"Mike Jacoubowsky" <[email protected]> wrote in message
news:[email protected]...
> > Well, they're investigating at least... what that means is anybody's
> guess.
>
> What it means is that TREK is always on the lookout for issues that might affect bicycle safety.
> The article references Bob Burns, TREKs chief
legal
> counsel. I've known Bob for a number of years, and he's definitely one of the reasons TREK does so
> well in the marketplace. He's constantly on the lookout for potential product safety (liability)
> issues, and has the advantage of working for a company that sells so much product that the sample
> size is large enough to often determine, on their own, what works
and
> what doesn't.
>
> I would not make any assumptions about the validity of any claims made by James Annan based upon
> Bob Burns investigating the matter. Such things
are
> looked into routinely without any presumption ahead of time that it's true or not. The point of
> the investigation, at least initially, isn't to work out a solution to the problem, but rather to
> see if it exists in the first place.
>
> --Mike-- Chain Reaction Bicycles http://www.ChainReactionBicycles.com
>
>
> "Jon Bond" <[email protected]> wrote in message
> news:[email protected]...
> > Well, they're investigating at least... what that means is anybody's
> guess.
> >
> > http://www.singletrackworld.co.uk/article.php?sid=1005
> >
> > Jon Bond
> >
> > (thanks Bomba!)
> >
>
 
M

Mike Jacoubowsk

Guest
> So says the man who's name appears on the Trek custom paint program page
as
> an example ;)
>
http://projectone.trekbikes.com/mountain/images/paint/bike_for_custom_name.jpg

Dang, I'll never be anonymous will I??? :>)

James Annan has definitely given us food for thought. The main problem with his analysis is that, if
true, I would think there'd be more failures than have come to light. The plain simple fact is that
a huge number of people are running around with improperly-adjusted quick releases on front wheels
equipped with disc brakes, and yet the problem as stated appears exceptionally rare.

We're also dealing with one of the interesting paradoxes brought upon us by our legal system.
Anybody who tries to engineer something that provides greater safety than what's been previously
available puts themselves at great legal risk, since it implies that their previous product wasn't
as safe as it could have been, which provides a potential gold mine for lawyers. Thus the irony... a
strong disincentive to improve safety. Better to go with the flow.

--Mike-- Chain Reaction Bicycles http://www.ChainReactionBicycles.com

"Jon Bond" <[email protected]> wrote in message
news:[email protected]...
> So says the man who's name appears on the Trek custom paint program page
as
> an example ;)
>
http://projectone.trekbikes.com/mountain/images/paint/bike_for_custom_name.jpg
>
> Either way, I never said that James Annan was right - heck, I'm planning
on
> using XT or XTR quick releases on my wheel with XT discs - its just a nice reminder to make sure
> that they're properly tight. I'm glad they're investigating - it means we'll get an answer either
> way. Although its
10:1
> odds they don't find a problem, and another 10:1 that when they don't, people are still going to
> say its the lawyers saying they can just blame people for not "properly tightening their quick
> releases". It is nice to know that they at least made an effort to investigate.
>
> Jon Bond knew I recognized that name from somewhere....
>
>
> "Mike Jacoubowsky" <[email protected]> wrote in message
> news:[email protected]...
> > > Well, they're investigating at least... what that means is anybody's
> > guess.
> >
> > What it means is that TREK is always on the lookout for issues that
might
> > affect bicycle safety. The article references Bob Burns, TREKs chief
> legal
> > counsel. I've known Bob for a number of years, and he's definitely one
of
> > the reasons TREK does so well in the marketplace. He's constantly on
the
> > lookout for potential product safety (liability) issues, and has the advantage of working for a
> > company that sells so much product that the sample size is large enough to often determine, on
> > their own, what works
> and
> > what doesn't.
> >
> > I would not make any assumptions about the validity of any claims made
by
> > James Annan based upon Bob Burns investigating the matter. Such things
> are
> > looked into routinely without any presumption ahead of time that it's
true
> > or not. The point of the investigation, at least initially, isn't to
work
> > out a solution to the problem, but rather to see if it exists in the
first
> > place.
> >
> > --Mike-- Chain Reaction Bicycles http://www.ChainReactionBicycles.com
> >
> >
> > "Jon Bond" <[email protected]> wrote in message
> > news:[email protected]...
> > > Well, they're investigating at least... what that means is anybody's
> > guess.
> > >
> > > http://www.singletrackworld.co.uk/article.php?sid=1005
> > >
> > > Jon Bond
> > >
> > > (thanks Bomba!)
> > >
> > >
> >
>
 
J

James Annan

Guest
Mike Jacoubowsky wrote:

> James Annan has definitely given us food for thought. The main
problem with
> his analysis is that, if true, I would think there'd be more failures
than
> have come to light.

Well, I haven't said too much about the probability of failure, because I really don't know what it
is. As others have said, some skewers seem to do a lot better than others, but I have heard one
story relating to a Shimano skewer. I was looking more for an explanation for the number of failures
that we do see, rather than the probability of failure.

It also depends a lot on what you define as a 'failure'.

At the bottom of the pyramid, we have huge numbers of people who have experienced some slippage of a
well-fastened QR, even if only occasionally. Even though some might never have had a problem, I
don't think that even the most ardent sceptic would deny that this much of a problem exists widely.
Most riders cope with it somewhat by cranking up the tension, switching skewers until they find one
that works, or just putting up with it.

Of the skewers that slip, a proportion may unscrew slightly. If the threads are stiff enough, or the
slippage is very minor, it might never happen, and people who remove the wheel regularly for
transport might not notice anyway. But certainly many people have mentioned some loosening of the
QR, that until recently they couldn't really explain.

Of those that loosen a bit, some will loosen substantially. A typical report from these riders is
that they notice the completely loose QR in the middle of a big ride, and have absolutely no idea
how it can have happened but convince themselves that they simply didn't fasten it up at the start
of the day, however implausible that seems. After all, until last month, if they suggested it might
have some undone during the ride they were labelled as liars or insane.

Then you get those who don't notice until they hit the ground. Again, they have always been bullied
into believing that it was their fault all along. After all, we know that the QR doesn't unscrew.
Except when it does.

The number of people at the top of the pyramid is certainly quite small, but it seems to me that
even the bottom level is in principle a failure. The wheel isn't supposed to move! I've heard enough
stories from people in all categories to convince me, it all fits together far too neatly to be a
coincidence.

> We're also dealing with one of the interesting paradoxes brought upon
us by
> our legal system. Anybody who tries to engineer something that provides greater safety than
> what's been previously available puts themselves at great legal risk, since it implies that their
> previous product wasn't as safe as it could have been, which provides a potential gold mine for
> lawyers. Thus the irony... a strong disincentive to improve safety.
Better
> to go with the flow.

Three tandem manufacturers have already changed their fork designs. There's only one way the
flow is going.

James
 
J

Jobst Brandt

Guest
James Annan writes:

> Of those that loosen a bit, some will loosen substantially. A typical report from these riders is
> that they notice the completely loose QR in the middle of a big ride, and have absolutely no idea
> how it can have happened but convince themselves that they simply didn't fasten it up at the start
> of the day, however implausible that seems. After all, until last month, if they suggested it
> might have some undone during the ride they were labelled as liars or insane.

> Then you get those who don't notice until they hit the ground. Again, they have always been
> bullied into believing that it was their fault all along. After all, we know that the QR doesn't
> unscrew. Except when it does.

> The number of people at the top of the pyramid is certainly quite small, but it seems to me that
> even the bottom level is in principle a failure. The wheel isn't supposed to move! I've heard
> enough stories from people in all categories to convince me, it all fits together far too neatly
> to be a coincidence.

In the days when Sturmey Archer 3-Speed hubs were common on bicycles, riders went over the bars
while sprinting in top gear and were also dismissed as having adjusted the shift chain improperly.
Just the fact that this was a common among those who accelerated standing in top gear should have
been enough to bring suit against a company that produced a product that required unattainably
precise adjustment in order to be used safely.

However, adjustment was not the problem. There is no correct adjustment while dropping into forward
free-wheeling under heavy load is guaranteed by the design. Disengagement occurs even with the shift
chain in optimal adjustment... with the shift chain removed. With no shift chain, the driver
"clutch" is as fully and forcefully engaged with the planet pins as can be, in spite of which
disengagement occurs. SA got away with this because... "we've always done it that way" and
"thousands of riders have ridden thousands of miles with no problem" as an excuse.

I think I'm hearing echos! It's deja-vu all over again.

Jobst Brandt [email protected] Palo Alto CA
 
J

Jobst Brandt

Guest
James Annan writes:

> Of those that loosen a bit, some will loosen substantially. A typical report from these riders is
> that they notice the completely loose QR in the middle of a big ride, and have absolutely no idea
> how it can have happened but convince themselves that they simply didn't fasten it up at the start
> of the day, however implausible that seems. After all, until last month, if they suggested it
> might have some undone during the ride they were labelled as liars or insane.

> Then you get those who don't notice until they hit the ground. Again, they have always been
> bullied into believing that it was their fault all along. After all, we know that the QR doesn't
> unscrew. Except when it does.

> The number of people at the top of the pyramid is certainly quite small, but it seems to me that
> even the bottom level is in principle a failure. The wheel isn't supposed to move! I've heard
> enough stories from people in all categories to convince me, it all fits together far too neatly
> to be a coincidence.

In the days when Sturmey Archer 3-Speed hubs were common on bicycles, riders went over the bars
while sprinting in top gear and were also dismissed as having adjusted the shift chain improperly.
Just the fact that this was common among those who accelerated standing in top gear should have been
enough to bring suit against a company that produced a product that required unattainably precise
adjustment to be used safely.

However, adjustment was not the problem. There is no correct adjustment to prevent dropping into
forward free-wheeling under heavy load because it is guaranteed by the design. Disengagement occurs
even with the shift chain in optimal adjustment... with the shift chain removed. With no shift
chain, the driver "clutch" is as fully and forcefully engaged with the planet pins as possible, in
spite of which disengagement occurs. SA got away with this because... "we've always done it that
way" and "thousands of riders have ridden thousands of miles with no problem" as an excuse.

The cause and details of the design have been presented here years ago.

I think I'm hearing echos! It's deja-vu all over again.

Jobst Brandt [email protected] Palo Alto CA
 
J

Jon Isaacs

Guest
>I would not make any assumptions about the validity of any claims made by James Annan based upon
>Bob Burns investigating the matter. Such things are looked into routinely without any presumption
>ahead of time that it's true or not. The point of the investigation, at least initially, isn't to
>work out a solution to the problem, but rather to see if it exists in the first place.
>

In my mind, James Annan has pointed out a design flaw. I believe that everyone would agree that
given a loose QR or improperly installed QR, applying the brakes will cause the wheel to pop out.

This need not be, proper placement of the brake caliper can push the wheel into the dropout rather
than pop it out, thus making it more secure rather than less secure than traditional brake designs.

What the exact mechanism that causes the QR to loosen is not as important as recognizing that
putting the caliper behind the fork is a design flaw.

We all know that QRs can be loose, Missy Giove's relevation after her bike had been checked by
mechanics is a real indication that James is really on to something with his mechanism to explain
how QR with disk brakes can loosen. But they can also loosen simply because they were improperly
installed or if the jam nuts on the axle walk.

As an engineer, when I design something, I look at the problems and possible potential difficulties.
A loose QR is a big problem on a disk brake fork if the caliper is mounted behind the fork, it is
not a big problem if it is mounted in front of the fork.

(Other designs of the dropout can also address this problem.)

So the question has to be, "Why mount the brake behind the fork?"

--------

Some side comments.

1.The article mentioned giving the calculations to a mathamatics professor. This is not a math
problem, the math that is required is simply addition, subtraction, multiplication and division.

Most appropriate would have been an engineering professor but a physic professor would have been
equally adept.

This problem starts with a free body diagram, draw the correct freebody diagram and the solution
is obvious.

2. The basic test required here is very simple. Loosen the QR, ride the bike, apply the brake hard.
Does the wheel come out or doesn't it.

As a pointed out earlier, why the QR is loose is of secondary importance, once it is established if
the QR is loose that wheel will pop out when the brakes are applied, the design is shown to be weak.

3. I hope that this does not end up with the bicycle manufacturers going on the defensive. The
issue of a loose QR has always been placed on the rider and yet QRs are a flaky design. The
industry ought to sit up and take note and look at the big picture instead of trying to defend
past practices.

4. Take this Email, include the link to James Annan's site and send a private Email to Damon Rinard
and ask him what he thinks.

Then read what Damon has to say, don't share it with me or anyone else, but just think about what
Damon has to say to you privately.

Jon Isaacs
 
M

Maki

Guest
In article <[email protected]>, [email protected] (Jon Isaacs) wrote:

> 2. The basic test required here is very simple. Loosen the QR, ride the bike, apply the brake
> hard. Does the wheel come out or doesn't
> it.

A fellow on an italian newsgroup reported that it doesn't. He didn't do it by intention, he just
forgot to lock the QR and started. When he realized that the wheel was loose he instinctively
braked, felt vibrations, but the axle didn't go out of place. It should be noted that, unless the
deceleration is quite high, gravity is bigger than the reaction to the braking force. So, if you
feel the wheel loose, brake, but kindly. :)

--
Fact of life #15: Heads bleed, walls don't.
 
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