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



"tcmedara" <[email protected]> wrote in message news:<xfr9c.15168$oH2.12284@lakeread01>...

[snip]

[snip]

Dear Tom,

Wasn't that how Pope Leo X invited Martin Luther to Rome
after he heard about the convenient new Wittenberg wallpaper
that could be nailed to a church door?

Nostalgically,

Carl Fogel
 
Tim McNamara wrote:

> ... Name calling doesn't change the facts, BTW. Neither
> does your anger nor your emotional reasoning. Everybody
> that has disk brakes may just have been hoodwinked by the
> companies that made them- those are the people you should
> be challenging.

Should not the criticism be leveled at the fork
manufacturers and not the brake manufacturers?

--
Tom Sherman - Quad Cities (Illinois Side)
 
Mike Jacoubowsky/Chain Reaction Bicycles wrote:

> I relayed reports of this issue, several months ago (when
> it first appeared here), to a major manufacturer. Just
> because one of my customers hasn't had the issue doesn't
> mean it doesn't exist, and it would be irresponsible not
> to tell them about this thread. So, of course, you're
> wondering what they said, yada yada yada. In a nutshell,
> if there is an issue, it hasn't risen about the noise
> level (meaning that it hasn't called attention to itself).
> If you're a manufacturer, you have to prioritize your
> efforts and deal with what's in front of you.

Actually they did spend a fair bit of time looking in to
this "theoretical" problem. Trek certainly promised to look
into it (but we only ever heard from their lawyer). LaPlante
looked into it long enough to produce a report "proving"
that it is impossible, and the ASTM promised a "simulation
exercise" testing QR retention and had a whole meeting
discussing it. Velotech managed to find a problem, so did
Ben Cooper in his back garden, but the engineering might of
Rockshox, Marzocchi, Manitou, Fox and the rest were baffled
as to what all the fuss was about.

Given this apparent chasm between their experiences, and the
substantial number of independent experts who appear to be
convinced of the problem, what would a reasonable person do?
Would they actually try to find anyone who had experienced
the problem, like the people I quote on my website, or
Lennard Zinn in Velonews who describes his own experiences
of a slipping QR, or the author of that MBR article who had
a QR come loose no fewer than 6 times? Would they talk with
the Velotech lab, or even stoop to the plebeian level of
looking at the singletrackworld website, and doing a search
for "loose qr" on the forum? What do you think?

I haven't told you yet about the USA bike shop owner who
told me last summer that he had seen the problem himself
regularly in his own stock, and would raise it with the
manufacturers. I never heard from him again, and I'm not
surprised that he is more than a little worried about
"coming out" in public. He told me:

"I can't believe that someone at a magazine, or company has
not seen a front wheel on a single bike turn just a little
crooked while out on a ride when using a disc brake system.
I see it often enough."

"Most all of the forks, discs I deal with have deep lawyer
tabs, and so far have been used by riders that will out of
habit check and reposition the front QR after a long or
steep descent, if the group gathers up to chit chat, etc it
just seems to be habit to check the QR on disc bikes, in my
group. The concerning thing is that there usually is at
least one person in the group that needs the QR
adjusted/tightened."

And what did the manufacturers do when someone popped up
last month, saying "hey, I've got this problem you've been
unable to find for the last year"? A problem, you may
recall, that was immediately characterised as too dangerous
to ride (by Avid). Did they jump at the chance of examining
this curiosity? Did they hell. They said they had never
heard of it, told him no-one ever had that problem round
their parts.

I'm astonished that you still claim that this state of
affairs is all _my_ fault for not generating yet more data.
You are bending over backwards to defend the indefensible in
their case, and pick the most insignificant of nits in mine.
They have not seen the data because they are holding up
their telescopes to blind eyes.

James
 
Tim McNamara <[email protected]> wrote in message news:<[email protected]>...
> [email protected] (Dave Kahn) writes:

> > In British English "pavement" is usually used to mean
> > "sidewalk", hence the derogatory term "pavement
> > cyclist".
>
> Well, I wondered if it was something like that (I was
> aware of the terminology, being a hostage of public
> television), but the poster's e-mail address gives no
> indication of nationality.

The clue is that this thread is cross-posted to u.r.c.

--
Dave...
 
On Sun, 21 Mar 2004 23:10:23 -0600,
Tim McNamara <[email protected]> wrote:
> "Mike Jacoubowsky" <[email protected]> writes:
>
>> Sorry, that doesn't fly with me. Nor can a Bumblebee,
>> according those with a basic knowledge of mechanics &
>> physics (at least if I remember that correctly... maybe
>> it was a hummingbird?).
>
> Those who claimed that the bumblebee couldn't fly were
> wrong, mainly

IIRC this "myth" came about because someone decided to apply
the then known aerodynamics to a bumblebee and discovered
that it's weight to wingspan meant it couldn't fly. This was
immediately seen to be absurd and it was realized that
perhaps the assumption that the bumblebee was a fixed wing
aircraft was a slight oversimplification.

Tim.
--
God said, "div D = rho, div B = 0, curl E = - @B/@t, curl H
= J + @D/@t," and there was light.

http://tjw.hn.org/
http://www.locofungus.btinternet.co.uk/
 
[email protected] (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?

Mark Hickey Habanero Cycles http://www.habcycles.com Home of
the $695 ti frame
 
Carl Fogel <[email protected]> wrote:
> "tcmedara" <[email protected]> wrote in message
> news:<xfr9c.15168$oH2.12284@lakeread01>...
>
> [snip]
>

>
> [snip]
>
> Dear Tom,
>
> Wasn't that how Pope Leo X invited Martin Luther to Rome
> after he heard about the convenient new Wittenberg
> wallpaper that could be nailed to a church door?
>
> Nostalgically,
>
> Carl Fogel

Dear Carl,

As a Catholic, I'd hope the late Bishop of Rome would have
used more ecumenically appropriate language albeit with
similar sentiments. I do appreciate the analogy, however,
particularly the tone religious fervor it implies.
Unfortunately, neither the Church nor it's Heretic in Chief
had resort to governmental protective agencies or empirical
data collection. God only knows how much turmoil could have
been avoided had that been the case.

Your on a Sunday,

Tom
 
Tim McNamara <[email protected]> wrote:
>
> Easy there, Buckwheat. It's obvious that James Annan's
> research into the design flaw of disk brakes and forks has
> threatened your world dramatically, and that you must lash
> out at him to regain your sense of order and control. It's
> pathetic to watch.

That's funny, really, to think that my world has anything to
do with disk brakes. My sense of order and control have very
little to do with the silliness of USENET. What's really
funny is that both my bikes have rim brakes! I would say
that your boy James is the one who leads the "church of
ejection force" true believers and feels threatened by the
potential for empirical information. I guess a FOIA request
runs the risk of uncovering some contradictory scripture.
That's my point, and that's what is pathetic. He's like the
guy who stands outside a movie theater protesting the film
but refuses to go in and watch it.

> You and everyone else who thinks that Annan should set up
> some kind of research laboratory should stop hiding your
> heads in the sand, and step up to the plate yourselves.

I'm not saying he should do anything of the sort, however
the good Mr Annan has shown a remarkable propensity to argue
his case. It's an absolute non sequiter at this point. Lab
testing takes resources and expertise. A simple FOIA means
you write a letter and perhaps fill out a form or two. Big
difference there. This perhaps shows that the propensity to
support the case stops when it is confronted with cold, hard
reality. Why does he choose to retire from the discussion
when he has the opportunity to prove one of the key
linchpins of his manufacturer/CPSC conspiricy? He is the one
who's made claims of stonewalling at the CPSC. It's all over
his web site. As I said previously, why does he avoid the
opportunity to breach that wall?

>Stop being a lazy ****** taking potshots at the guy who
>pointed out the problem, and turn your attentions instead
>to the people who *created* the problem- and have possibly
>put your lives and health at risk. Perhaps, while you're
>at it, you should read Ibsen's "Enemy of the People" or
>watch the movie.

Lazy ******? I don't think that posts in a NG or on a
website impart any sort of an obligation on me That's the
flaw in Annan's whole approach. What he's saying is that
he's opened the disucussion, posted what he knows, draws
conlusions and asserts that it's up to others to disprove
him. That's nice if it worked that way, but it doesn't.
Again, rather than assert the case against the CPSC, he's
been offered an avenue to obtain the information he claims
has been withheld. He's so convinced the report is flawed,
but hasn't seen it. It strikes me that it would go a long
way to bolster his case. He's shown a marked propensity to
engage in the debate, why does he now refuse the opportunity
to substantiate his claims. Are they perhaps not as strong
as he'd have us believe? What's the rest of the story?
Having been shown the door, he refuses to go through it,
citing a desire to avoid being a "performing bear." More
indication -- much like his rejection of empirical data
collection -- that he's mind's made up and he doesn't want
to be confused with the facts.
>
> This is not some ersatz court where the onus is on the
> accuser. Stop treating it like one, since that doesn't
> further the discussion or the remediation of the problem.
> Instead, hold accountable the makers of the brakes and the
> forks since they have the ethical obligation to ensure
> that their products are not inherently flawed or
> dangerous.

Nor is it some kangaroo court where every wild-eyed zealot
can throw assertions on the table and then challenge others
to disprove them. I'm all for holding the industry
accountable, and if I was convinced of the dire nature of
the problem I'd be at the front of line. The FOIA request to
the CPSC is a step in that accounatability process. I
mentioned that avenue to Annan several days ago and it was
ignored. Now the actual process has been spelled out in this
forum and Annan refuses to follow them. Why is that? He
accuses the CPSC of ignoring him and denying him information
then refuses

weasel would do such a thing.
>
> Annan has identified the problem, has gathered evidence
> and has done the math. Several mechanical engineers with
> decades of experience with bicycle design have verified
> Annan's analysis of the primary problem- the existence of
> the ejection force. The other problem identified by Annan,
> that of loosening nuts, was identified and verified long
> before Annan ever raised this issue. This too has been
> verified by several mechanical engineers. The problem has
> been presented and the next step now lies with the
> manufacturers and the various regulatory bodies.

And now is his chance to find out what the US Government's
own consumer protection agency has to say on the matter and
he avoids the topic. Why go through all the trouble to
compile the evidence you cite and then claim the "performing
bear" defense when pressed to substantiate some of his
claims that perhaps aren't so well supported?
>
> Name calling doesn't change the facts, BTW. Neither does
> your anger nor your emotional reasoning. Everybody that
> has disk brakes may just have been hoodwinked by the
> companies that made them- those are the people you should
> be challenging.

Don't mistake language for emotion. I don't get angry or
emotional over posts in a NG. I occasionally laugh at the
sillines and enjoy the debate. I'm also not afraid to call a
weasel a weasel when I think its warrented. You can call it
"emotional reasoning" if you'd like, I call it on target. Ah
the beauty of free and unencumbered exchange of ideas. And
as far as being "hoodwinked" -- that's just the sort of
conspiricy theory BS that the FOIA request could help
confirm.....or refute (oh my!). Rather than assert, why
doesn't Annan or one of his many sock puppets submit the
request? Or is that too close to reality?

Annan's the one who's heaped scorn on the CPSC. He either
wants to support his case or not, that's the whole issue.
You accuse me of being a "lazy ******", but that cuts both
ways. He can either engage and support his position or
continue to wallow in the intellectual masturbation that
USENET offers. He's convinced there's a dangerous product
out there and implies a conspiricy to avoid the topic on the
part of manufacturers and the US Gov't. FOIA is a tool to
gather infomation to support that allegation. Why is that a
problem? Hell, I'm tempted to submit the damn request myself
just to make the point. But that would require some minimal
effort, and I'm not the one with the axe to grind.

Tom
 
[email protected] (Carl Fogel) wrote in message news:<[email protected]>...
> Tim McNamara <[email protected]> wrote in message news:<m2smft29z2.fsf@Stella-
> Blue.local>...
> > Simon Brooke <[email protected]> writes:
> >
> > > in message <[email protected]>, Tim
> > > McNamara ('[email protected]') wrote:
> > >
> > >> Mark Thompson <[email protected]>
> > >> writes:
> > >>
> > >>>> perhaps pumice or slickrock might equal or exceed
> > >>>> cement pavement.
> > >>>
> > >>> <ahem> pavement? :)
> > >>
> > >> Hmm. Some attempt at humor that's escaping the
> > >> American? :)
> > >
> > > Failure of translation, I expect. The word 'pavement'
> > > in British English translates to 'sidewalk' in
> > > American English. Riding a bicycle on the pavement is
> > > illegal in Britain.
> >
> > I rather thought that might have been the case, although
> > the poster's e-mail address didn't give away his
> > nationality so I wasn't sure. This side o' the pond,
> > "pavement" is generic term for "artificial surface" for
> > roadways, sidewalks, patios, driveways and usually
> > refers to concrete (or cement, often used
> > interchangeably) or asphalt. The UK "metalled" road
> > would be "gravel" here, "metalled" bringing to mind a
> > road covered is some sort of sheet metal like tin or
> > corrugated iron or something.
> >
> > So, rather than "pavement" to describe an artificially
> > surfaced road, what would the usual term in the UK be?
>
> Dear Tim,
>
> Street? Road? Tarmac? Pothole incubator?
>
> Here's a page that blathers hopefully about it all. I
> liked the explanation about "metalled roads."
>
> Carl Fogel

Oops.

http://en.wikipedia.org/wiki/Pavement_(roads)
 
"Tim McNamara" <[email protected]> wrote in message
news:[email protected]...
> Not much of a clue, that, since the thread is also cross-
> posted to rec.bicycles.tech which has an international
> audience as a matter of course (although seems largely
> American) and alt.mountain-bike which has an audience of
> who-knows-what.

People who know and ride the bikes that are being discussed.
Unlike you.
 
tcmedara wrote:

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

1. There's nothing interesting in the CPSC files, we all
know that the manufacturers claim to have never heard of
the problem.

2. If there was any evidence of a safety flaw, it would in
any case be prohibited from release by Section 6(b)(5) of
the CPSA. Of course if Tony had realised this he would
not have been so mischievous as to say "You should be
able to request all the information they hold on the
subject". Perhaps you should do a little homework before
being quite so free with your insults.

3. The only interest in LaPlante's report is that he is so
embarrassed at its inadequacy that he is not prepared to
release it. The whole point is that there _is_ nothing of
interest in it. I've already got the CPSC letter (both
versions) if I want to read a bland whitewash.

4. The fact that that manufacturers are holding up
telescopes to their blind eyes and saying "we see no
danger" is clear enough. Did they report the slippping
front wheel (that started this thread) to the CPSC? Well,
we cannot check for sure, but since they did not even ask
to see it, or seem in any way concerned, it should not be
too hard to guess the answer.

James
 
James Annan <[email protected]> wrote:
> tcmedara wrote:
>

>
> 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.
>
> 1. There's nothing interesting in the CPSC files, we all
> know that the manufacturers claim to have never heard
> of the problem.

How do you know what's in the CPSC files if you haven't seen
them? You claimed the CPSC was being "deliberately
obstructive", but now claim you have no interest in what
they know or don't know? And why do you really mean every
bike fork manufacturer is lying about the problem. Have you
contacted them all? Or are you making that statement merely
because they've failed to respond to your cries?
>
> 2. If there was any evidence of a safety flaw, it would in
> any case be prohibited from release by Section 6(b)(5)
> of the CPSA. Of course if Tony had realised this he
> would not have been so mischievous as to say "You
> should be able to request all the information they hold
> on the subject". Perhaps you should do a little
> homework before being quite so free with your insults.

You're the one who doesn't want to do the homework. You
should be able to request all the information they hold.
Doesn't mean you'll get it, but that's a far cry from not
asking for it at all. You don't know what you'll get out of
a FOIA request, because you haven't tried it yet. You've
given lots of reasons why you won't try, but then stick to
your story line that the CPSC is stonewalling you. You can't
have it both ways in real life.
>
> 3. The only interest in LaPlante's report is that he is so
> embarrassed at its inadequacy that he is not prepared
> to release it. The whole point is that there _is_
> nothing of interest in it. I've already got the CPSC
> letter (both versions) if I want to read a bland
> whitewash.

You claim frustration that LaPlante's report wasn't released
and now say there's nothing of interest in it? What makes
you so sure that he's "embarrassed". Maybe he just doesn't
feel like dealing with you personally, knowing that whatever
is in his report isn't going to sway your opinion either
way. You easily assert it's a whitewash, but I guess that's
easier than having to actually read it and trying to refute
it on it's merits.
>
> 4. The fact that that manufacturers are holding up
> telescopes to their blind eyes and saying "we see no
> danger" is clear enough. Did they report the slippping
> front wheel (that started this thread) to the CPSC?
> Well, we cannot check for sure, but since they did not
> even ask to see it, or seem in any way concerned, it
> should not be too hard to guess the answer.

I would suggest that there are more manufacturers beyond
just those you cite, but that's just pointless nit-picking
really. My guess is that the issue hasn't made it out of the
corporate noise level. Now you can attack that angle too,
but that's much different from them intentionally avoiding
the issue. Failure of the corporations to act as you demand
is not prima facia evidence of conspiricy to cover-up the
issue. Get some hard facts rather than innuendo and you
might have a case.

You see James, asserting obstruction on the part of the
government and fork makers and then failing to avail
yourself of the tools to prove it really suggests something
other than rational thought is afoot. Using your website to
suggest others contact the CPSC with email but then refusing
to attempt what is ostensibly a more effective approach is
--dare I say it?-- hypocritcal. Your lame dodge of not
wanting to to be a "dancing bear" is what earned the
"weasel" moniker -- as in "weasel out of a dilemma". The

In reality, I'm quite curious about the real impact of the
infamous ejection force. I wonder if it's really something
to worry about, or is it something that can be mitigated by
proper use of the QR (I know your answer James, so just
leave that alone). Anecdotes aside, the question is yet to
be answered. I manage the "gravity/fat ass force" on my
seatpost with a QR despite the inherent design flaw that
forces it into the seat tube even with constant loading and
unloading, so I wonder if the same can be done with the
fork. That said, your religious zealotry, artful dodges, and
downright obfuscation unfortunately cloud any meaningful
weight you bring to solving the issue. It keeps the NG
interesting though...keep it up!

......and for $20.00 and your old QRs I'll submit the FOIA
request for you.

Tom
 
"Simon Brooke" <[email protected]> wrote in message
news:[email protected]...
> in message <[email protected]>,
> [email protected]
> ('[email protected]') wrote:
>
> > The greatest retardation (negative acceleration) is
> > limited by overturning the bicycle forward, regardless
> > of tire grip, soft ground, or dry pavement. people talk
> > of hanging off the back of the saddle to achieve a lower
> > center of gravity, but that cannot be done except on a
> > long sooth surface or the saddle will give the rider a
> > painful kick in the belly. Besides, this is not a
> > position that is easily entered or left in situations
> > where hard braking is demanded.
>
> Rubbish. I often go down steep and difficult sections with
> my sternum resting on the back of the saddle.

Jobst has a history of pontificating about the way things
are in the mountain biking world and making himself look
like a fool.

He should stick to what he knows best and resist the
apparently overwhelming urge that he has to fantasize about
riding that is beyond his experience.
 
"tcmedara" <[email protected]> wrote in message news:<mXI9c.20940$oH2.4343@lakeread01>...
> Why you steadfastly refuse to submit a FOIA request to
> support your allegations is the point of the moment.

I haven't "steadfastly refused" to do anything. I merely
said it would not achieve anything, and explained why. Maybe
I will after all? I suppose it would be amusing to see what
sort of analysis (if any) was presented to them. Perhaps
your encouragement has helped, wouldn't that be a delicious
irony if one of the head-in-the-sand advocates was the one
who actually precipitated the critical step? Don't worry,
there's little chance of that, since this problem will only
be solved when a significant number of cyclists bother to
report their slipping wheels (or worse).

James
 
James Annan <[email protected]> wrote:
> "tcmedara" <[email protected]> wrote in message
> news:<mXI9c.20940$oH2.4343@lakeread01>...
>> Why you steadfastly refuse to submit a FOIA request to
>> support your allegations is the point of the moment.
>
> I haven't "steadfastly refused" to do anything. I merely
> said it would not achieve anything, and explained why.
> Maybe I will after all? I suppose it would be amusing to
> see what sort of analysis (if any) was presented to
> them. Perhaps your encouragement has helped, wouldn't
> that be a delicious irony if one of the head-in-the-sand
> advocates was the one who actually precipitated the
> critical step? Don't worry, there's little chance of
> that, since this problem will only be solved when a
> significant number of cyclists bother to report their
> slipping wheels (or worse).
>
> James

It wouldn't be ironic at all, it would be quite rational.
Rather than mere assertion regarding the CPSC, a FOIA
request might actually provide some real documentation about
the role of the CPSC, the actions of fork manufacturers, and
the contents of the infamous LaPlante report. Wouldn't it be
absolutely amazing if it turned out you had it all wrong?
Now that would be irony. And if the FOIA request results in
the release of information that supports your whole
construct, I'll be the first to take credit for the guy that
goaded you into it. Now that would be some irony too.

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. I've said it before, I don't reject the
notion, I just don't think it's a certain as you make it out
to be. I'm sure that looks like a "head-in-the-sand"
approach to you and the rest of the true believers, and
that's too bad. That precludes you from seeing the flaws in
your own construct and diminishes whatever credibility you
could have brough to bear. This "with us or against us"
approach to a serious question of safety is really counter-
productive. It's absolutely naive to assume you've got the
whole thing sewed up tight and suggest that anyone who might
challenge that is either ignorant or criminally negligent.

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. You might not care for the answers,
but impinging the motives and intelligence of those who do
suggests a faith-based crusade rather than a rational
desire to know the facts.

Tom
 
Tim McNamara writes:

>>> Name calling doesn't change the facts, BTW. Neither does
>>> your anger nor your emotional reasoning. Everybody that
>>> has disk brakes may just have been hoodwinked by the
>>> companies that made them- those are the people you
>>> should be challenging.

>> Should not the criticism be leveled at the fork
>> manufacturers and not the brake manufacturers?

> IMHO both, since they are equal parts of the system. The
> brake is designed by its maker to be mounted behind the
> fork leg, and the fork is designed to put it there by its
> maker. Both are equal contributors to the problem.

> 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.

That stress reversals cause unanticipated failures was
evident in the old Shimano short splined hollow BB axles.
Riders who descended standing, right foot forward, had crank
loosening and spline failures as I predicted. We had a
similar thread to this one on that issue as well as one on
the progressive ratio Campagnolo Delta brake. Both products
are no longer made for practical and safety reasons.

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

Jobst Brandt [email protected]
 
Tom Sherman wrote:
>> You could make it quite exciting by locking your brakes
>> and launching yourself forwards into an upright position
>> to continue on foot.
>
>
> I have locked both front brakes on my Dragonflyer trike on
> broom finished Portland cement concrete surfaces and on
> unworn (no significant aggregate polishing has occurred)
> asphalt cement concrete surfaces. In neither case did I
> even come close to flying forward off the bike.
>
> Consider this; if I am able to decelerate at 1-G on my
> trike, the force that I will have to resist with my legs
> is the same magnitude as the force that I have to exert to
> stand upright. This obviously is not much of an issue for
> a person without a physical handicap.

I was not quibbling with your leg strength. It is now clear
to me that the centre of mass of you and your recumbent is
low enough that you can break the traction with your front
wheels (skid) rather than pivoting on the contact patch as
can happen with an upright (endo).

In the case of an endo, bracing against the bars stops you
moving with respect to the bars, but does not prevent the
pivoting at the contact patch. I was wondering (half
jokingly) that the same effect might work on a recumbent and
be an interesting circus trick.

--
R.

<> Richard Brockie "Categorical statements <> The tall
blond one. always cause trouble." <>
[email protected]
 
Richard Brockie writes:

>>> You could make it quite exciting by locking your brakes
>>> and launching yourself forwards into an upright position
>>> to continue on foot.

>> I have locked both front brakes on my Dragonflyer
>> trike on broom finished Portland cement concrete
>> surfaces and on unworn (no significant aggregate
>> polishing has occurred) asphalt cement concrete
>> surfaces. In neither case did I even come close to
>> flying forward off the bike.

>> Consider this; if I am able to decelerate at 1-G on my
>> trike, the force that I will have to resist with my legs
>> is the same magnitude as the force that I have to exert
>> to stand upright. This obviously is not much of an issue
>> for a person without a physical handicap.

> I was not quibbling with your leg strength. It is now
> clear to me that the centre of mass of you and your
> recumbent is low enough that you can break the traction
> with your front wheels (skid) rather than pivoting on the
> contact patch as can happen with an upright (endo).

> In the case of an endo, bracing against the bars stops you
> moving with respect to the bars, but does not prevent the
> pivoting at the contact patch. I was wondering (half
> jokingly) that the same effect might work on a recumbent
> and be an interesting circus trick.

I didn't see a picture of this tricycle but short wheelbase
recumbent bicycles, ones where pedal cranks are ahead of the
front wheel, do endo's more easily than a conventional
bicycle. Drawing a visual line from the rider's belly button
(rider CG) to the contact patch of the front wheel shows
that the CG is no better positioned than that of a
conventional bicycle and usually worse.

I don't think trikes work well on MTB trails any more than
recumbent bicycles do, the ability to rise off the saddle
being absent and with more than a single track vehicle,
most trails are impassable quite aside from the sudden
drops and obstacles that usually abound. In any case, I
have never seen a recumbent on any of the trails in the
Santa Cruz Mountains nor in the Alps in the many years that
I have ridden.

Jobst Brandt [email protected]
 
Originally posted by Jobst Brandt
Richard Brockie writes:

>>> You could make it quite exciting by locking your brakes
>>> and launching yourself forwards into an upright position
>>> to continue on foot.

>> I have locked both front brakes on my Dragonflyer
>> trike on broom finished Portland cement concrete
>> surfaces and on unworn (no significant aggregate
>> polishing has occurred) asphalt cement concrete
>> surfaces. In neither case did I even come close to
>> flying forward off the bike.

>> Consider this; if I am able to decelerate at 1-G on my
>> trike, the force that I will have to resist with my legs
>> is the same magnitude as the force that I have to exert
>> to stand upright. This obviously is not much of an issue
>> for a person without a physical handicap.

> I was not quibbling with your leg strength. It is now
> clear to me that the centre of mass of you and your
> recumbent is low enough that you can break the traction
> with your front wheels (skid) rather than pivoting on the
> contact patch as can happen with an upright (endo).

> In the case of an endo, bracing against the bars stops you
> moving with respect to the bars, but does not prevent the
> pivoting at the contact patch. I was wondering (half
> jokingly) that the same effect might work on a recumbent
> and be an interesting circus trick.

I didn't see a picture of this tricycle but short wheelbase
recumbent bicycles, ones where pedal cranks are ahead of the
front wheel, do endo's more easily than a conventional
bicycle. Drawing a visual line from the rider's belly button
(rider CG) to the contact patch of the front wheel shows
that the CG is no better positioned than that of a
conventional bicycle and usually worse.

[snip]

Jobst Brandt [email protected]

Dear Jobst,

Here are some mug shots of the rather handsome
blue contraption in question:

http://www.ihpva.org/incoming/2002/Dragonflyer/df1a.jpg

http://www.ihpva.org/incoming/2002/Dragonflyer

Given that the backward-reclining owner's hips would
be below the tops of what I suspect are small wheel
rims, I expect that it might stop a bit faster than my
more traditional Fury Roadmaster.

Carl Fogel
 
[email protected] wrote:

> ... I didn't see a picture of this tricycle but short
> wheelbase recumbent bicycles, ones where pedal cranks are
> ahead of the front wheel, do endo's more easily than a
> conventional bicycle. Drawing a visual line from the
> rider's belly button (rider CG) to the contact patch of
> the front wheel shows that the CG is no better positioned
> than that of a conventional bicycle and usually worse....

Picture of my trike. <
http://www.ihpva.org/incoming/2002/df1a.jpg >.

Mr. Brandt's comments on short wheelbase (SWB) recumbents
indicate outdated and/or incomplete knowledge. The first
regular production SWB recumbent was the Hypercycle.
Among other design defects, the Hypercycle had a very
long pedal boom, which meant that the rear wheel would
lift easily when the front brake was applied, and hard
braking could well launch the rider off the front of the
bike in a near standing position and/or put the
chainring into the ground.

Better designed (not all, by any means) modern SWB
recumbents have a static weight distribution of
approximately 40%/60% front/rear and will not lift the rear
wheel under hard braking. Here is one such common design
that I have ridden extensively (including emergency braking)
without ever lifting the rear wheel. <
http://www.ransbikes.com/2004Bikes/Rocket.htm >.

Here is a picture of the SWB recumbent I regularly use for
longer rides. <
http://www.ihpva.org/incoming/2002/sunset/Sunset001.jpg >.
With the low seat height and short pedal boom, the angle
formed by the ground, front tire contact patch, and
combined bike/rider center of mass is very small. It would
take sudden stoppage of the front wheel (e.g., wedged in a
storm sewer inlet grating) for the rear wheel to lift off
of the ground.

--
Tom Sherman - Quad Cities (Illinois Side)
 

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