x-post: Bike Biz: Wheel ejection theory goes legal

"Ed Pirrero" wrote in message
ups.com...
On Feb 11, 7:54 pm, Gary Young wrote:


This is a variant of the my-uncle-was-a-smoker-and-he-lived-until-95
argument.

Except for the small details that smoking will most definitely cause
some harm, and, so far, disk brakes have caused none due to the
ejection force being present.

None? You're sure about that?

Greg

On 2007-02-12, wrote:

Ben C? writes:

But moving the dropout angle forwards and the caliper upwards a bit,
as some designs already do-- wouldn't that solve the theoretical
and/or real problems?

While you are at it, I think we would be better off if all fork
dropouts were angled at about 30? up/rearward.

Interesting, why? It seems then you might be close to risking wheel
ejections even with rim brakes.

Ooooh! They should slope up and to the rear means from bottom to top,
the bottom being the opening and the top being closed end of the slot.
The wording was chosen to not imply a 30° downward slop to the rear
whoch would make axle separation more likely.

I get it now, yes, sounds like a good idea. I did wonder what you were
on about...

On Feb 12, 2:27 pm, "G.T." wrote:
"Ed Pirrero" wrote in message

ups.com...

On Feb 11, 7:54 pm, Gary Young wrote:

This is a variant of the my-uncle-was-a-smoker-and-he-lived-until-95
argument.

Except for the small details that smoking will most definitely cause
some harm, and, so far, disk brakes have caused none due to the
ejection force being present.

None? You're sure about that?

Greg

The answer to both questions is in the part you trimmed.

E.P.

"Ed Pirrero" wrote in message
oups.com...
On Feb 12, 2:27 pm, "G.T." wrote:
"Ed Pirrero" wrote in message

ups.com...

On Feb 11, 7:54 pm, Gary Young wrote:

This is a variant of the my-uncle-was-a-smoker-and-he-lived-until-95
argument.

Except for the small details that smoking will most definitely cause
some harm, and, so far, disk brakes have caused none due to the
ejection force being present.

None? You're sure about that?

Greg

The answer to both questions is in the part you trimmed.


"(Qualifier: if some harm has occurred, it certainly hasn't been
distinguished from user error.)"

So now you're omniscient?

Greg

On Feb 12, 3:02 pm, "G.T." wrote:
"Ed Pirrero" wrote in message

oups.com...





On Feb 12, 2:27 pm, "G.T." wrote:
"Ed Pirrero" wrote in message

roups.com...

On Feb 11, 7:54 pm, Gary Young wrote:

This is a variant of the my-uncle-was-a-smoker-and-he-lived-until-95
argument.

Except for the small details that smoking will most definitely cause
some harm, and, so far, disk brakes have caused none due to the
ejection force being present.

None? You're sure about that?

Greg

The answer to both questions is in the part you trimmed.

"(Qualifier: if some harm has occurred, it certainly hasn't been
distinguished from user error.)"

So now you're omniscient?

Strawman.

If you've got any, and I mean ANY, credible data that any of the
incidents involving wheel ejection have been proven as disk-brake
caused, go ahead and cite it.

E.P.

In article ,
wrote:

On Mon, 12 Feb 2007 09:19:17 -0600, Tim McNamara
wrote:

[snip]

In 40 years of riding bikes I've never seen a broken pivot bolt on a
front brake. That of course doesn't mean it hasn't happened, just
that I've never seen it. I don't recall any reports of this in the
newsgroups, either, but that could be inaccurate as well. Carl
could probably use his prodigious Googling skills and find us some
photos of failed pivot bolts.

[snip]

Dear Tim,

No need to Google--the picture that you click on to see the bicycle
component failure museum shows a broken front brake pivot bolt:

http://materials.open.ac.uk/mem/mem_ccf2.htm

Thanks! I can't to the larger version of the photos for some reason.
In the small version it almost looks like it was sawed. Nice wear
pattern on the brake shoes, too.

Interestingly, it only broke because of poor maintenance:

"This front brake assembly broke off under braking and severely
injured the cyclist. Poor maintenance had allowed the brake bolt to
loosen and allow the assembly to 'chatter' when braking imposing
cyclic loads instead of steady stress on the fastening bolt."

In 40 years of riding, have you ever seen a disk brake eject a front
wheel?

Yes, I tested it on a couple of bikes with disk brakes to verify the
existence of the ejection force (which I didn't believe at the time. It
seemed like fearmongering and handwaving to me. Oops.). Of course, I
did leave the QR undone at the time...

In article ,
jim beam wrote:

wrote:
On Feb 11, 9:45 pm, jim beam wrote:
wrote:

Leading calipers on GasGas, Beta, and Sherco trials machines:
http://www.gasgasmotos.es/rcs/trial/...0/07txt300.jpg
http://www.betamotor.com/moto/trial/...rev4T_foto.jpg
http://www.sherco-moto.com/images/trials_2t_04_03.jpg
from what i can see, none of those are an identical fork with front/rear
options though - each are specific for their application.

That wasn't the point, jim. You were saying it was impossible to
design mounts for front mounted disks. Or, perhaps, it was impossible
to do it without some horrendous weight penalty. Whatever.

Turns out it's been done. Just like I said. How about that?

you are spectacular krygowski. as i said at the beginning, as as i
shall repeat for you now since you can't get it into your skull, YES,
YOU CAN HAVE A FRONT MOUNTED CALIPER, BUT WHY THE **** WOULD YOU?

So that there is no reaction force trying to eject the front wheel from
the dropout. Duh.

In article ,
jim beam wrote:

Tim McNamara wrote:
In article ,
jim beam wrote:

Tim McNamara wrote:
In article ,
jim beam wrote:

Tim McNamara wrote:
In article ,
jim beam wrote:

Tim McNamara wrote:
In article ,
wrote:

On Sat, 10 Feb 2007 22:47:04 -0600, Tim McNamara
wrote:

In article
, jim beam
wrote:

tim, do you ride disk?
That's already been answered.
Dear Tim,

What was the answer?
Sigh. I do not own a disk brake bike. First, because I
regard it as needless weight and complexity. Rim brakes work
fine. Second, because there is a design flaw
are you an engineer? what qualifies you to make that
definitive statement?
The design flaw is evident, jim old pal. There's an ejection
force on the front wheel. It's a design flaw. Simple as that.
you have a fundamental problem with engineering concepts - we
come back to this sort of thing time and time again, regardless
of subject. [i find it hard to comprehend what would keep you
stuck in a place of ignorance like this.]
LOL. Disagreeing with you = place of ignorance?
no tim, inability to grasp basic concepts is a place of ignorance.

Yes, jim, it is. That's your problem in these and other threads.
You fail to grasp the basic concepts. Like designs that
unnecessarily endanger the safety of users under normal
circumstances are flawed designs.

so, did your engineering degree arrive in the mail?

LOL! The same day yours did.

Sorry, your long history of clutching the wrong end of the stick
doesn't inspire me to decide that you're right.

in any case, this is simply action and reaction. ultra basic.
Dat's what-a I been sayin'. It's a reaction in the wrong
direction.
still don't get it - if x is greater than y, y is not greater than
x. see point above.

Your inability to do simple math apparently prevents you from
understanding that y can be greater than x.

except that x is greater than y....

.... except for when it isn't.

Funny that you continue to ignore the fact that the industry
appears to have decided that Annan was right all along and has
changed the design of dropouts to reduce or eliminate the problem.

so why hasn't the industry redesigned brake cable clamping designs?
front mounted rim brake calipers, etc.?

You're just raving wildly now. I have front mounted rim brake calipers
on all 5 of my bikes and both of my wife's. They are not exactly a new
invention.

As for brake cable clam designs, what would you change it to? That's
hard to visualize. Whereas it's easy to visualize changing fork designs
to eliminate the unnecessary ejection force resulting from disk brakes.

no tim, it's marketing - something on which you seem to have a
strongly negative opinion no less. simply give the punters what they
think they want. it costs no more, so why not? if the punters
wanted flotation devices and started bleating about them, guess what
would come attached to every new bike?

Eh, marketing is a constant. It just has to be sifted to find something
approximating the truth. My negative opinion about marketing comes
about from marketers taking over bike design. But whaddya gonna do?
That's been the case since bikes became consumer goods.

Why would I be opposed to companies providing an actual better product
without a cost increase? I think that's a good development.

In article ,
Ben C wrote:

On 2007-02-12, jim beam wrote: [...]
Funny that you continue to ignore the fact that the industry
appears to have decided that Annan was right all along and has
changed the design of dropouts to reduce or eliminate the problem.

so why hasn't the industry redesigned brake cable clamping designs?
front mounted rim brake calipers, etc.?

I think front mounted calipers is overkill, and has the drawback of
putting the mountings in tensile fatigue as you've explained.

And yet it is done successfully on other vehicles, so that is a
surmountable problem and a straw man raised by jim.

But moving the dropout angle forwards and the caliper upwards a bit,
as some designs already do-- wouldn't that solve the theoretical
and/or real problems?

It could. Look at motorcycle disk brakes, which often place the caliper
up tight against the fork leg. The caliper ends up nearly at the top of
the disk. The vector of the reaction force from braking would be in a
much more benign direction. Placing the caliper in from of the fork
would result in the reaction force driving the axle into the dropout and
eliminating the ejection force altogether.

In article ,
wrote:

Ben C? writes:

But moving the dropout angle forwards and the caliper upwards a
bit, as some designs already do-- wouldn't that solve the
theoretical and/or real problems?

While you are at it, I think we would be better off if all fork
dropouts were angled at about 30° up/rearward.

I don't grok why that would be.