CPSC judgement on disk brakes and QR forks

wrote:

Not so. Even on fairly loose but uneven ground deceleration of 1g is
likely. Average loadings are fine, but this action responds to impact
forces.

That is only in so much as it confuses the issue. That peak brake
forces are at the level of 1g is adequate for solving the problem,
trying to reduce that is only a cover-up of the problem.

I agree with this, and the likelihood of higher peak loading has come up
a few times previously. Nevertheless, I think it helps most people to
understand if they can actually 'see the numbers' on this issue, and can
you imagine the consternation if I had used a figure of 1g? I shudder to
think of it.

It's quite fortunate in that respect that the 0.6g figure can actually
exceed the ISO standard, even though neither is of great importance to
the problem other than as a rough indicator of real-world applicability.

James

In article ,
(Spider) wrote:

Tim McNamara wrote in message
...

This seems altogether different than your previous posts on the
matter.

Then you have not read them carefully.

There's the "if you disagree with me then you haven't read carefully"
strategem. Which is usually shortly followed (as in your last
paragraph) by the "you must be a moron so I'll spell it out in baby
talk for you."

Part of my concern *all along* was the manner in which questions
were answered. If one desires to make a favorable impression, it
behooves that person to try and avoid being a complete asshole.
Now, that's just my opinion, of course. Maybe out there in the
great wide world, this is SOP to treat everybody without the
keenest of insight as a complete moron. I've never come up against
that myself, but I work in the sheltered community of a research
university.

And of course you are not at all guilty of doing exactly the same
thing from your earliest posts on the subject. /sarcasm Perhaps
you haven't noticed that "treat(ing) everybody without the keenest of
insight as a complete moron" *is* SOP in the research university
world. And you've learned your lessons well.

The other part of my concern was about the actual questions
themselves. The fact that I had to wait so long for such a simple
answer speaks volumes toward the other part of my concern.

The question was answered a number of times by Annan, Brandt and
Dammerell, but you didn't seem to notice. And, now that I think of
it, you've yet to acknowledge that the question was answered.

Now, Tim, if you would like, I'll go back and start from the beginning
and quote my style objections on a post-by-post basis.

Thanks for showing that you're just as human and concescending as
anyone else in this newsgroup. Irritation and frustration are
universal human characteristics.

Spider wrote:
Maybe out there in the great wide world, this is SOP to treat
everybody without the keenest of insight as a complete moron.

So who was telling me to review my "freshman physics" (of something I
learned at around age fifteen, no less) while in fact talking rubbish
himself?

This holier-than-thou attitude won't wash; you've been just as
condescending, with the additional drawback that you don't know what
you're talking about.

--
David Damerell Distortion Field!

(James Annan) writes:

"Doug Taylor" wrote in message ...

As for you, please supply the name, date and place for *any* cyclist who has
been severly injured, paralyzed or killed due to your pet problem. Bet you
can't find one.

www.russ-appeal.org.uk is perhaps the most well-known, and provided
much of the motivation for my research.

I've heard of about 20 cases of actual wheel loss, roughly half of
which have resulted in overnight (or longer) hospital stays - in the
cash-strapped UK National Health Service, this is something that is
far from routine and indicates that there were severe head and neck
injuries.

There's serious misinformation here. The UK health system, like any
other, could do with more money than it has, but this doesn't limit
overnight stays. In June of this year I was kept in for five days for
observation because of a blood clot in my leg. People with suspected
concussion are almost always kept in hospital at least twenty four
hours for observation, so an overnight stay is no indication of
anything more than a minor bump on the head.

This isn't to say I have any opinion one way or the other regarding
ejecting front wheels; merely that the paragraph quoted doesn't
provide any evidence of repeated serious injuries. Nor, on the
evidence I can find on the Russ Appeal site, is there conclusive
evidence that the disk brake caused the wheel to eject in Russell
Pinder's accident - again, there may be evidence I don't know about -
but you have to remember that front wheels have been falling off bikes
for a lot longer than we've been using disk brakes.


--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

;; I'll have a proper rant later, when I get the time.

Simon Brooke wrote in message .uk...
(James Annan) writes:

I've heard of about 20 cases of actual wheel loss, roughly half of
which have resulted in overnight (or longer) hospital stays - in the
cash-strapped UK National Health Service, this is something that is
far from routine and indicates that there were severe head and neck
injuries.

There's serious misinformation here. The UK health system, like any
other, could do with more money than it has, but this doesn't limit
overnight stays. In June of this year I was kept in for five days for
observation because of a blood clot in my leg. People with suspected
concussion are almost always kept in hospital at least twenty four
hours for observation, so an overnight stay is no indication of
anything more than a minor bump on the head.

Good grief, hasn't everyone on this thread packed up and gone home
long ago?

Ok, I agree that the mere fact of an overnight stay does not in itself
prove beyond any doubt that the injuries were very serious.
Nevertheless, many of the injuries _were_ very serious, I just
couldn't be bothered listing them all. They are not just a handful of
the comedy over-the-bar moments that most MTB riders will have learnt
to love.

As an aside, I didn't think that an overnight stay was routine for
mere concussion, let alone `suspected concussion'. But I'll take your
word for it, and it may even apply to one of the cases I have heard
about.

James

James Annan wrote in message ...
This is not actually the 'official' signed letter which is in the post,
but I received the following via email recently:

"Based upon the information currently available, the staff does not
believe the problem identified necessitates further action by the
Commission under Section 15 of the CPSA. However, the Commission has
recommended that the ASTM Bicycle Committee, which meets in October
2003, take this matter under advisement for further discussion,
additional testing and problem examination."

Section 15 of the CPSA can be found at
https://www.cpsc.gov/businfo/cpsa15b.html

I thought the following article might be pertinent to this discussion:

http://seattlepi.nwsource.com/business/apbiz_story.asp?category=1310&slug=Bicycle%20Defec ts%20Fine

In a nutshell: a manufacturer of cheap department store bikes was
fined US $1 million by the CPSC for failing to report injuries caused
by defective forks. I suppose it's reassuring to know the CPSC is
capable of taking strong action, even if it is after the fact. Perhaps
that will motivate fork makers to address the problem with disk
brakes.