"Actually you are the first person to bring up this issue"

Tim McNamara wrote:

"Compelling is in the eye of the beholder" seems to be what you're
suggesting. Fair enough, I think. In the case of the manufacturers,
I suspect that "compelling" is going to be equated with "massive
product liability if we don't immediately fix it" and they don't see
that yet. I think they're burying their heads, but that's between
themselves, their lawyers and their liability insurance carriers. In
the meantime, the users of these products are the ones assuming the
risk.

From the replys and lack of replies I had to the question I asked earlier
"Compelling" would seem to require at least having one person from the many
tens of thousand mountain bikers out there using discs reporting to a
manufacturer that they have experienced a problem of this nature with their
product. So far it looks as if no-one has done that in which case it would
not be unreasonable for them to assume that whatever the theory, across a
large population sample it is not happening in practice.

Have a look at the number of bicycle related CPSC actions and recalls
(http://www.cpsc.gov/cgi-bin/recalldb/prod.asp, choose Bicycles and
Accessories and click Find)and ask why on earth would they ignore this
particular problem when handlebars, forks, stems, helmets, whole bicycles,
disc brake rotors etc are being recalled all the time, sometimes at quite
considerable financial cost to the manufacturer. Either it is a massively
complex and coordinated conspiracy involving multiple companies across the
globe and the US government or there is a simpler answer.

Tony

Mark Hickey wrote in message . ..
(Gary Young) wrote:

Mark Hickey wrote in message . ..
(Gary Young) wrote:

snip
But your attitude seems to be, we could lift a finger, but we
don't want to spend the money. Better that our customers should pay
the price for our stupidity. Isn't that what you're saying? -- we
could fix the problem, but we won't. The only costs will be born by
someone else. We don't mind killing off a few customers as long as it
doesn't hurt our bottom line.
snip
I'm quite surprised to see you pursue this line. All I can say is that
if this is your idea of customer service, then I'll never buy one of
your frames.

Your (il)logical conclusions and inability to understand my position
are astonishing. You really "don't get it", do you?

Well, I should have been more temporate, for civility's sake.
Nonetheless, I think your position is contrary to the law and morally
obtuse. I find it troubling that you haven't responded to a question
I've posed a couple of times: does the industry have a duty to warn
its customers about this problem?

My "position" is that the manufacturers and CPSC probably don't think
there IS a problem, and I'd like to see that remedied by collecting
some data that might influence them (assuming of course that it shows
there IS a problem).

And FWIW, I don't have a "position" on how the rest of the industry
handles potential liability. I have observations, which I shared and
you subsequently ascribed to springing from my own moral code.

Does the industry have a duty to warn customers NOW? I don't know...
it all depends on how compelling the data they have is. I have no
problem at all believing the data they have right now doesn't compel
them to do an expensive recall / or to scare existing customers. I
say that because (as I've said about a hundred times now...) they've
all heard about skewers spontaneously unscrewing themselves, and a few
reports of this happening to customers with disc brakes won't stand
out as anything particularly unusual, barring more data.

I have seen this kind of "filtering effect" at work in other contexts.
For instance, years ago I was prescribed a medication that had a
rather disagreeable side effect for me. I went to my doctor, he
consulted his physicians desk reference, told me, "No one has reported
that side effect," and suggested, ever so gently, that it was all in
my head. Much later I read an article about the medication that
mentioned that side effect.

I don't think the doctor was at fault, or even the manufacturer of the
medication. I suspect that when the manufacturer did its initial run
of tests, it drew up a list of side effects that were prevalent to
show up in their trials. Unfortunately, afterwards such a list can
function as a filter excluding other valid reports of side effects.

But even in that case, my doctor did something about the situation --
switching me to another medication.

Furthermore, I don't think such a filtering effect is at work here.
Let's look at the lawyer from Trek as an example. I find it hard to
believe that a lawyer contacted by the trade press about this problem
would simply write it off as the usual operator error, particularly
after he's informed that it's confined to disc-brake forks. If he went
to one of the engineers at Trek, he would have been told that this is
a different sort of claim and that it merits further study. If he's a
competent attorney, he would know that it's Trek's duty to look into
it or at the very least, pressure the fork suppliers to look into it.

I suppose it's possible that industry lawyers are stone cold stupid,
but I'm not sure that matters. The tort system punishes stupidity as
well as venality.

I suspect that the industry is hoping there are no claims until the
problem can be addressed quietly.

Furthermore, given the evidence that's already been brought to light,
I don't think the studies you propose would do any good. I'm not
suggesting such studies would necessarily have no scientific validity,
but I suspect that if an industry lawyer doesn't think that the
opinion of a respected engineer like Jobst is reason enough to be
worried, he's not going to change his mind because a bunch of guys on
usenet conducted experiments in their garages. Such a study would have
so little credibility (from a lawyer's perspective) that it would not
be a prod to action.

wrote:


Let's get the caliper in the right place!


Right place for what? It might reverse the ejection force into a holding in
force but OTOH the caliper is out front where it is much more susceptible to
damage and to getting the mounting tabs bent/strained by hitting things. The
mounts would also be under tension under braking, rather than compression
which has an increased chance of failure. Specialized have already had a
recall for mounting tab failures. Don't simply replace one problem with
another and think through all the failure modes of a proposed solution before
implementing it - Design Control 101.

Tony

Tony Raven writes:

If you consider forks without offset at the dropout end, as they
are commonly made today, where offset is achieved at the fork
crown, No change other than placing the mounting lugs for the
disc brake caliper on the front side is required. I think the
same caliper would be adequate for most brands with the distance
between caliper and fork leg remaining as it is today. This
requires a new fork strut anyway.

It might even be possible to simply swap the left and right fork
lowers. Sometimes one sees bikes where the forks have been
installed backwards... usually on eBay.

How long will it take to get the disc caliper ahead of the fork leg?

I wouldn't be surprised to see different wheel attachment instead.
There are already various quick(ish) release 20mm systems that
seem little more trouble than a QR with retention lips. That can
also be sold as an upgrade rather than merely a bug-fix. And you
get to buy a new shiny hub too!

Well that won't do as I already mentioned. The reversing load from
braking and bouncing on the road makes anything but a conical "lug
nut" ineffective to reliably prevent loosening.

Let's get the caliper in the right place!

Right place for what?

The right place to resolve the hazards that have been under discussion
in this thread for more than 500 replies.

It might reverse the ejection force into a holding in force but OTOH
the caliper is out front where it is much more susceptible to damage
and to getting the mounting tabs bent/strained by hitting things.

Yes, and the moon may yet be made of green cheese. This is grasping
at straws to obscure the issue when all else fails. What sort of
damage do you foresee for a metal brake caliper that is far behind the
leading edge of an adjacent wheel? This sounds like the bicycle is
being tossed into a rock crusher. Ejection forces from a rear mounted
caliper are real and undeniable, bending parts of the fork "from
hitting things" is unreal conjecture as is apparent from aluminum
parts of suspension forks that are not full of scrapes and gouges on
their front side "from hitting things".

The mounts would also be under tension under braking, rather than
compression which has an increased chance of failure. Specialized
have already had a recall for mounting tab failures. Don't simply
replace one problem with another and think through all the failure
modes of a proposed solution before implementing it - Design Control
101.

There is nothing wrong with tension. If it were we couldn't ride
spoked wheels that have plenty of tension. In fact, no matter how you
make it, the bicycle (and n=most machines) are full of tension and
compression stresses. That is what bending is.

Jobst Brandt

Tony Raven wrote:

Benjamin Lewis wrote:

I see -- your question was a little unspecific. It would surprise me to
find that disc brakes were less prone to fade, since they appear to have
much less surface area available for heat dissipation, but there may be
other factors I'm overlooking. They certainly must reduce the chances
of tire blow-off due to heating of rims, but this is a different
question.

That's certainly my experience. Because you have much more discretion in
the choice of disc material and brake pad material than you do with rim
brakes you can chose arrangements that are less prone to fade. Heat is
not an issue - remember Formula One brakes work best when they are
glowing red hot - with the right materials choices.

Ah, that makes sense, although I'm not sure it's a problem with all rim
brake pad materials either.

--
Benjamin Lewis

Don't take life so serious, son, it ain't nohow permanent.
-- Walt Kelly

Tony Raven wrote:


Specialized have already had a
recall for mounting tab failures.

When?

If you mean the recent recall of bikes with too large a rotor installed,
there were NO failures and no evidence that there ever would be any
failures. The problem was merely that the combination had not been
properly checked.

Puts the current situation regarding disks and QRs into context, don't
you think?

James

"Tony Raven" wrote in message
...
Tim McNamara wrote:

"Compelling is in the eye of the beholder" seems to be what
you're
suggesting. Fair enough, I think. In the case of the
manufacturers,
I suspect that "compelling" is going to be equated with
"massive
product liability if we don't immediately fix it" and they
don't see
that yet. I think they're burying their heads, but that's
between
themselves, their lawyers and their liability insurance
carriers. In
the meantime, the users of these products are the ones
assuming the
risk.

From the replys and lack of replies I had to the question I
asked earlier
"Compelling" would seem to require at least having one person
from the many
tens of thousand mountain bikers out there using discs
reporting to a
manufacturer that they have experienced a problem of this
nature with their
product. So far it looks as if no-one has done that in which
case it would
not be unreasonable for them to assume that whatever the
theory, across a
large population sample it is not happening in practice.

Have a look at the number of bicycle related CPSC actions and
recalls
(http://www.cpsc.gov/cgi-bin/recalldb/prod.asp, choose Bicycles
and
Accessories and click Find)and ask why on earth would they
ignore this
particular problem when handlebars, forks, stems, helmets,
whole bicycles,
disc brake rotors etc are being recalled all the time,
sometimes at quite
considerable financial cost to the manufacturer. Either it is
a massively
complex and coordinated conspiracy involving multiple companies
across the
globe and the US government or there is a simpler answer.


Right on. Maybe there is a problem, but I have not seen the mass
of injuries or lawsuits everybody is talking about.
Manufacturers of problem components commonly launch voluntary
recalls -- especially since much of the economic burden is shared
by the retailers who signed-up to do warranty/recall work. I
feel sorry for those guys. Recalls are a good reason for a LBS
not to be a dealer for anyone. -- Jay Beattie.

Tony Raven wrote:



From the replys and lack of replies I had to the question I asked earlier
"Compelling" would seem to require at least having one person from the many
tens of thousand mountain bikers out there using discs reporting to a
manufacturer that they have experienced a problem of this nature with their
product. So far it looks as if no-one has done that in which case it would
not be unreasonable for them to assume that whatever the theory, across a
large population sample it is not happening in practice.

But surely you have to agree that it _does_ happen in practice (where
"it" means at a minimum a failure of indeterminate cause with the front
wheel attachment, even if you dispute the design fault). You only have
to follow the links on my web page to see that (and don't pretend you do
not read STW yourself). Further, it is also clear to anyone who had not
closed their eyes that the number of failures whatevver the cause is
much much higher with disk brakes (3 times in a group ride, and no fewer
than 6 times for a journalist testing a bike!)

It's true that mountainbikers have in the main not helped themselves by
their unwillingness to mention failures to the manufacturers. There are
a number of reasons which may explain this. There is also clear evidence
that the manufacturers are ignoring any failures that they are informed
of (see the subject line).

I have also heard privately of other complaints that were conveyed to
the mnufacturers. There is more to this than you are aware of, however
much you try to put a reasonable spin on their behaviour.

James

Gary Young wrote:

I suspect that the industry is hoping there are no claims until the
problem can be addressed quietly.

This is not so much a suspicion as an openly stated fact within the
industry.

James

"Tony Raven" writes:

Tim McNamara wrote:

"Compelling is in the eye of the beholder" seems to be what you're
suggesting. Fair enough, I think. In the case of the
manufacturers, I suspect that "compelling" is going to be equated
with "massive product liability if we don't immediately fix it" and
they don't see that yet. I think they're burying their heads, but
that's between themselves, their lawyers and their liability
insurance carriers. In the meantime, the users of these products
are the ones assuming the risk.

From the replys and lack of replies I had to the question I asked
earlier "Compelling" would seem to require at least having one
person from the many tens of thousand mountain bikers out there
using discs reporting to a manufacturer that they have experienced a
problem of this nature with their product. So far it looks as if
no-one has done that in which case it would not be unreasonable for
them to assume that whatever the theory, across a large population
sample it is not happening in practice.

Well, presumably James has repored his experience, and Russ who will
also be going to court.

Have a look at the number of bicycle related CPSC actions and
recalls (http://www.cpsc.gov/cgi-bin/recalldb/prod.asp, choose
Bicycles and Accessories and click Find)and ask why on earth would
they ignore this particular problem when handlebars, forks, stems,
helmets, whole bicycles, disc brake rotors etc are being recalled
all the time, sometimes at quite considerable financial cost to the
manufacturer. Either it is a massively complex and coordinated
conspiracy involving multiple companies across the globe and the US
government or there is a simpler answer.

I think the simplest answer is that the CPSC has not yet realized that
this can happen, and without a flood of complaints they won't. Of
course, riders will tend to think "wow, I must not have done up my QR
tight enough, because everybody knows QRs never loosen up if they're
used properly." So they wouldn't actually realize that it's a design
problem.