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

"tcmedara" writes:

James Annan wrote:
tcmedara wrote:

You ****ing hypocritical little weasel.

Easy tiger, it's only "fun and amusement", remember? I already
explained why there was not much point:

Watching you twist and turn amidst your own contradictions is quite
fun and amusing. You've explained away alot of things, but that
doesn't mean they just don't exist any more. Why you steadfastly
refuse to submit a FOIA request to support your allegations is the
point of the moment.

No, the point- despite your many valiant attempts at obfuscation and
distraction- is that front disk brakes create an ejection force in
normal use. That's certainly simple enough for you to grasp, I
trust.

Tim McNamara wrote:

writes:

Changing the dropout is not a reasonable option because the dropout
would need to face upward, which would release the wheel on normal
wheel loads, while reversing loads of rider and brake force, being
opposite, could still cause QR loosening. The dropout should be
loaded in the same direction at all times as it is with rim brakes.


I was thinking of facing the open end of the dropouts forward, so
that the normal load would be directed into the end of the fork leg,
and the lower "jaw" of the dropout would constrain the braking
force. This wouldn't be suitable?

It would still leave the alternating up/down forcing. Bolts don't need
to have a massively elongated slot to loosen in. Probably it would
reduce the magnitude of the problem, but there is a simple solution that
eliminates it.

James

"tcmedara" writes:

Call me a "head-in-the-sand advocate" if you choose, but that does
nothing to cover the otherwise obvious holes in your whole theory.
No need to rehash those now, they're all over the thread.

Which holes are those? That the currect design of disk brakes
creates an ejection force? Nope, that's been verified. That cyclic
forces normal to the axis of a bolt result in loosening? Nope,
that's been verified. That... wait, that is the theory. No holes,
both parts have been verified.

My biggest beef with you James isn't with the issue of disks and
qr's. You've gathered a pretty serious pile of evidence. My
problem here is that you (and many others) fail to acknowledge that
there's lots of unanswered questions remaining.

There is only one question remaining. Just one. How often does this
happen? That's not one that Annan has any hope of being able to
answer, and you'll have to address your comments to more appropriate
parties. Since you're so familiar with the CPSC and FOIA stuff, I
suggest you start there.

Tim McNamara writes:

I don't know but do suspect that changing the dropout design might
be the easier solution, and I don't know but do suspect that
changing the location of the brake would be the better solution.

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.

Changing the dropout is not a reasonable option because the dropout
would need to face upward, which would release the wheel on normal
wheel loads, while reversing loads of rider and brake force, being
opposite, could still cause QR loosening. The dropout should be
loaded in the same direction at all times as it is with rim brakes.

I was thinking of facing the open end of the dropouts forward, so
that the normal load would be directed into the end of the fork leg,
and the lower "jaw" of the dropout would constrain the braking
force. This wouldn't be suitable?

As I said, I believe that as long as there is a large reversing load
on that joint it has the ability to loosen a threaded fastener. Now
is not the time to introduce half baked solutions, especially if it
requires changing the fork anyway.

Besides, I like QR's and they are not in contention with any solution
other than positioning the caliper ahead of the fork.

Jobst Brandt

(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.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

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.

Tony

"Chris B." wrote in message
...

Since most bike brakes are capable of skidding the front wheel in most
circs, all that better brakes give you is finer control of braking
force and less grip effort.

And less fade.

Why?

Pad compounds and steel rotors is my guess. The steel rotor means you can
use a much more aggressive compound without worrying about wear. But it
works: braking at 40mph on rim brakes produces a lovely smell of melting
phenolic resins and no noticeable deceleration, same with discs results in
Major Stopping Power.

--
Guy
===
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington University

"Just zis Guy, you know?" wrote in message
...

braking at 40mph on rim brakes produces a lovely smell of melting
phenolic resins and no noticeable deceleration

You're doing it wrong then. The rim brakes on our tandem have done hard
stops from 50mph more than once (feature of having steep hills with a
nasty sharp corner at the bottom!)

(maguras, black or red compound - the latter is the same as the koolstop
salmon and is what's on it at the moment).

cheers,
clive

Tim McNamara wrote:

Well, now, that was certainly a charming response. It's unclear on
what grounds you think this to be the case, nor why you felt the need
for spurious invective. Ah, well, like many mysteries it will no
doubt remain unexplained.

Au contraire.

This from you:

"I too have been told by mountain bikers "dude, you've got no business
being out here on that road bike" on trails that are easily negotiated
on a "road" bike (although the bike in question was a cyclo-cross
bike), especially evidence by the fact that I was passing some of
them. Many mountain bikers have an exaggerated view of what equipment
is necessary to ride through a given terrain."

Gag me with a spoon. Maybe a trifle self important and sanctimonious?

Sorry, but for the people who post in alt.mountain-bike, and who ride
mountain bikes frequently and in some cases exclusively, you clearly
have only a passing acquaintance with the sport, if that. The bikes
under discussions are mountain bikes. Nor are you an engineer. Your
observations on that subject simply parrot your idol, Brandt. You are
really nothing more than a dilettante.

Why not let the mountain bikers who know WTF they are talking about
(e.g. Hickey, Raven, Superslinky, Spider) discuss mountain bikes, and
the engineers who know WTF they are talking (e.g. Jobst; maybe Annan)
about discuss physics and engineering, and YOU get over yourself?

Clearly you are entitled to your opinion, but the officious manner in
which you express it is offensive and nauseating .

--dt

Mark Hickey writes:

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.

"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.