On Feb 10, 12:18 pm, Gary Young <
[email protected]> wrote:
> On Sat, 10 Feb 2007 11:13:08 -0800, Ed Pirrero wrote:
> > On Feb 10, 11:03 am, Gary Young <[email protected]> wrote:
> >> On Sat, 10 Feb 2007 10:43:57 -0800, Ed Pirrero wrote:
> >> > On Feb 10, 8:47 am, [email protected] wrote:
> >> >> On Feb 9, 11:18 pm, Mark Hickey <[email protected]> wrote:
>
> >> >> > I'm a "skewer skeptic" (sic) based on the following assumptions...
>
> >> >> > 1) A number of people will fail to properly tighten their skewer
> >> >> > before a given ride. This might be from inattention, or could be
> >> >> > because the skewer caught the edge of the lawyer lip or other
> >> >> > debris (preventing it from fully closing).
>
> >> >> > 2) The number of wheel ejections we've heard about (directly and
> >> >> > indirectly) are quite small.
>
> >> >> > 3) I think it's very reasonable to assume that the number of case
> >> >> > number 1 scenarios could eaily exceed the number of case number 2
> >> >> > scenarios. Ipso facto, it's not at all unreasonable to assume
> >> >> > that I've got very little to worry about when I'm riding my MTB.
>
> >> >> While all three of your points are correct, they don't make the
> >> >> problem go away.
>
> >> >> Point 1 is correct, but from the reports we've read, the problem has
> >> >> been demonstrated many times by people who almost certainly did
> >> >> fasten the QR properly.
>
> >> > Without any verification, "almost certainly" is pretty gratuitous.
> >> > Taking data from uncontrolled experiments and using it as evidence is
> >> > normally called "junk science."
>
> >> >> (If j.b. or others say _all_ those people failed to tighten
> >> >> properly, despite pre-knowledge of the problem and lots of prior
> >> >> experience, I expect they'd deny any lab test based on the same
> >> >> criterion!)
>
> >> > That's a strawman, and we both know it. Neither you nor I know the
> >> > conditions under which the QRs in those stories were tightened, and
> >> > have absolutely no clue what the initial conditions were.
>
> >> > If it were an experiment from a grad student, for publication, would
> >> > you let that slide?
>
> >> > Well, *you* might, but the publication wouldn't.
>
> >> >> Point 2 is correct, IMO, simply because the problem is limited
> >> >> almost exclusively to a single riding situation: long, bumpy
> >> >> downhills with hard braking.
>
> >> > We have such conditions out here in the Western U.S. In fact, I
> >> > would suggest that those sorts of conditions prevail in MTB country -
> >> > CO Front Range, Moab area in Utah, Arizona, CA, etc. There are LOTS
> >> > of mountain bikers in those areas, and folks who are pretty serious
> >> > about their riding.
>
> >> > And yet, the stories of loosening don't come from there, but from the
> >> > comparatively flat region of the world known as the United Kingdom.
> >> > This anomaly seems to be ignored by the pro-redesign crowd - for
> >> > reasons I cannot fathom.
>
> >> > I also ride in the West U.S. - ID, to be clear. There are a LOT of
> >> > long, steep, bumpy downhills. In fact, one of my regular rides
> >> > requires me to ride about 5 miles of wide doubletrack and fire road
> >> > so that I can ride down one mile of very bumpy, steep and twisty
> >> > singletrack. Never had any loosening.
>
> >> >> Point 3 is probably correct, since the odds are you "Point 2" type
> >> >> riding fairly infrequently - and because you've read these
> >> >> discussions, you'll be damned sure to watch for the problem!
>
> >> > This is correct. I regularly inspect my front QRs. More now, but I
> >> > did do it before I had disk brakes.
>
> >> >> Still, there are folks who will not have heard of this, who will buy
> >> >> "good" equpment, use it as directed, and put themselves at great
> >> >> risk.
>
> >> > This assumes facts not in evidence.
>
> >> >> That's a description of a faulty design.
>
> >> > Actually, MTBing starts out being kinda risky. I have known a few
> >> > folks who have broken rear triangles on their FS MTBs, and crashed as
> >> > a result. One of those guys had a broken femur, and had to be
> >> > carried 4 miles out. He was using the equipment as designed. And
> >> > yet this brand of MTB and this model is sold a lot. I suppose a
> >> > recall or redesign is in order?
>
> >> If the design could be improved at a reasonable cost, then yes, a
> >> redesign would be in order.
>
> > Because ONE guy got hurt? That's pretty knee-jerk...
>
> >> If some failure is inevitable given even the best in design, then no, a
> >> redesign would not be in order.
>
> > I think this would be the case with EVERY mechanical item. And
> > sometimes "best" is not cost-effective.
>
> Agreed. That's why I said the change should be made if it can be done at
> reasonable cost. It may be hard to quantify what's reasonable, but the law
> generally asks juries to look at what an average consumer would expect for
> his money. If informed consumers are generally willing to accept a certain
> tradeoff between cost and safety, then that's generally deemed reasonable.
> (while I think that's an accurate overview, the case at hand might be
> treated differently because the brake placement might be considered a
> design defect triggering strict liability -- I'm sure JayBeattie, if he's
> following this thread, could give a more accurate picture.) You can't just
> look at the costs to the manufacturers, because they have an interest in
> imposing their costs onto the consumer (that is, refusing to pay the price
> for externalities).
>
> One of the ways that manufacturers get away with imposing externalities on
> consumers without compensation is by failing to disclose defects. If
> consumers don't know about a defect, they are likely to chalk up failures
> to other factors -- user error, unavoidable fatigue, etc.
>
> To me, that means that at the very least manufacturers should be required
> to disclose this problem to their consumers. Suppose, for instance, that
> fork makers were required to include with their forks and in
> advertisements the following message:
>
> Dear consumer:
> Applying your front disk brake creates a force that tends to eject the
> wheel from the dropouts. Our research leads us to believe that this is not
> a problem in practice if you use your quick release in the proper fashion.
> Please follow carefully our instructions regarding quick releases.
>
> What would be your objections to that? I know why manufacturers would fear
> that, though they might not say it out loud -- a lot of consumers would be
> leery of buying a fork from someone boneheaded enough to place the brake
> in a way that tends to eject the wheel.
>
> >> After all, if it's possible to get hurt, a> redesign is
> necessary,
> >> right?
>
> >> No one is saying anything that silly.
>
> > Actually, they are. AFAIK, there are zero proven disk-ejection
> > injuries. There have been a lot of assumptions made, but very little
> > proof.
>
> So we have to wait for someone to get killed or seriously injured before
> we take action? Why? Why not no killings or serious injuries from this
> cause?
>
> Given what you've said above, one indisputable case still wouldn't be
> enough for you: "Because ONE guy got hurt? That's pretty knee-jerk..."
> How many bodies have to pile up before you'd think action is necessary?
>
>
>
> > And yet, on the basis of assumption, and no real data, people are crying
> > for a redesign. Because of the possibility that someone might get hurt,
> > when all the assumptions line up in a specific way.
>
> > E.P.- Hide quoted text -
>
> - Show quoted text -- Hide quoted text -
>
> - Show quoted text -
I've been busy doing the dirty-work of evil manufacturers, so I
haven't followed along much. Anyway, under a strict "consumer
expectation" test, a bicycle or component manufacturer is subject to
liability if a design or manufacturing defect makes a product more
dangerous than expected by a reasonable consumer -- this is the so-
called "consumer expectation" test. So, if a reasonable consumer
does not expect his/her front wheel to be ejected by braking forces,
and the wheel does eject, then the wheel/brake/bike (whatever part is
the culprit) is dangerously defective, and the manufacturer is subject
to liability (with the usual comparative fault/misuse/modification
defenses).
California came up with a "risk-utility test" to supplement the
consumer expectation test maybe 40 years ago to deal with products
that were obviously dangerous (and were expected to cause injury) or
which were so complicated that no consumer had an expectation
concerning safety. Cigarettes, for example, are not unreasonably
dangerous under the consumer expectation test because everyone knows
they will kill you. They flunk the risk-utility test, though because
they have no utility. You don't even need to use the risk-utility
test with front brakes, though, since they are not obviously dangerous
and we do not expect them to eject the front wheel. All you need to
do is tie the ejection to a "defect" (the placement of the caliper)
and not to some schmuck failing to tighten a quick release.
I represent some big bicycle manufacturers and have not seen a disc
brake wheel ejection case in Oregon. In fact, I wish they would
start ejecting so I could get some more bicycle work. Anyone in
Oregon who is considering getting injured, please do so in the Bend
are during winter so I can work in some skiing on Batchelor. Nobody
should get injured in Lakeview, ever, since it is a gawdawful long
drive through endless scrub. Thank you. -- Jay Beattie.