Disk brakes?

In article
<[email hidden]>,
dabac <[email hidden]>

Quoted message said:

Werehatrack said:

....Disc brake function places a stress on the front wheel which may...
cause the wheel to be ejected from the bike when the brake is applied.
...reduce the likelihood of wheel ejection...by the use of skewer
retention shoulders at the fork ends.

If the dropouts were symmetrically aligned with the axis of the fork
legs a really neat and simple solution would be to simply turn the fork
legs around. With the caliper on the front side of the fork as opposed
to the rear heavy braking would simpy force the wheel deeper into the
dropouts. It'd look a bit odd, but I can't see any drawbacks.

There is no drawback. The manufacturers have their
reasons not to acknowledge that the current
configuration exerts a force in the axle ejection
direction.

--
Michael Press

Michael Press said:

In article
<[email hidden]>,
dabac <[email hidden]>

Quoted message said:

Werehatrack said:

....Disc brake function places a stress on the front wheel which may...
cause the wheel to be ejected from the bike when the brake is applied.
...reduce the likelihood of wheel ejection...by the use of skewer
retention shoulders at the fork ends.

Quoted message said:

If the dropouts were symmetrically aligned with the axis of the fork
legs a really neat and simple solution would be to simply turn the fork
legs around. With the caliper on the front side of the fork as opposed
to the rear heavy braking would simpy force the wheel deeper into the
dropouts. It'd look a bit odd, but I can't see any drawbacks.

There is no drawback.

That you know of.

Quoted message said:

The manufacturers have their
reasons not to acknowledge that the current
configuration exerts a force in the axle ejection
direction.

What reasons would those be, and where is the hard proof that such
definable reasons actually exist?

The mere fact that a force is exerted does not imply that the force
creates a dangerous situation. While it is fun to argue the point,
FACTS don't bear out the hazard postulated by the armchair bicycle
engineers in r.b.t.

Have you noticed that the vast majority of the so-called "problems"
with the QR/disk brake system are reported from Great Britain? With
the obviously larger base of installed disk-braked bicycles in the
U.S., logic would suggest that the reporters of problems would more
likely be from the U.S. than anywhere else.

I've always found that to be a bit of a head-scratcher. Anyone want
to take a poke at an explanation for this odd circumstance?

E.P.

Ed Pirrero said:

Michael Press said:

In article
<[email hidden]>,
dabac <[email hidden]>

Quoted message said:

Quoted message said:

Werehatrack Wrote:
> ....Disc brake function places a stress on the front wheel which may...
> cause the wheel to be ejected from the bike when the brake is applied.
> ...reduce the likelihood of wheel ejection...by the use of skewer
> retention shoulders at the fork ends.

Quoted message said:

Quoted message said:

If the dropouts were symmetrically aligned with the axis of the fork
legs a really neat and simple solution would be to simply turn the fork
legs around. With the caliper on the front side of the fork as opposed
to the rear heavy braking would simpy force the wheel deeper into the
dropouts. It'd look a bit odd, but I can't see any drawbacks.

Quoted message said:

There is no drawback.

That you know of.

Quoted message said:

The manufacturers have their
reasons not to acknowledge that the current
configuration exerts a force in the axle ejection
direction.

What reasons would those be, and where is the hard proof that such
definable reasons actually exist?

The mere fact that a force is exerted does not imply that the force
creates a dangerous situation. While it is fun to argue the point,
FACTS don't bear out the hazard postulated by the armchair bicycle
engineers in r.b.t.

Have you noticed that the vast majority of the so-called "problems"
with the QR/disk brake system are reported from Great Britain? With
the obviously larger base of installed disk-braked bicycles in the
U.S., logic would suggest that the reporters of problems would more
likely be from the U.S. than anywhere else.

I've always found that to be a bit of a head-scratcher. Anyone want
to take a poke at an explanation for this odd circumstance?

E.P.- Hide quoted text -

- Show quoted text -

It's because they ride on the wrong side of the road.

Chris

Mark Hickey said:

Werehatrack <[email hidden]> wrote:

Pardon the top post, but... "excellent summary". That would sum up
anything I'd be likely to say as well (but now I don't have to). ;-)

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

I was thinking the same when I read it. Good FAQ material. I even
learned why I have 24mm through-axle front hubs --Bill Westphal

Quoted message said:

Quoted message said:

Opinions vary.

The weight issue remains. Most disc setups are heavier than common
V-brake setups. Whether this is important is rider-dependent. I
should note that old-style cantis are no longer common on current
models.

The wheel-strain issue was always a red herring. The wheels can take
it.

[snip, enforced by my newsreader]

Michael Press said:

...The manufacturers have their
reasons not to acknowledge that the current
configuration exerts a force in the axle ejection
direction.

Are they saying:
A)There is no force acting in the ejection direction present?

or are they saying:
B)There is no significant force acting in the ejection direction present?

The existence or not of a force acting in the ejection direction should be easy to determine. If it IS there then moving to a front caliper configuration would cancel this cause for concern completely.

But I have the feeling that by now the trenches are so deeply dug that the manufacturers would be very unwilling to consider such a change even if it there was sound reason for it.

Ed Pirrero said:

....Have you noticed that the vast majority of the so-called "problems" with the QR/disk brake system are reported from Great Britain? With the obviously larger base of installed disk-braked bicycles in the
U.S., logic would suggest that the reporters of problems would more
likely be from the U.S. than anywhere else.

I've always found that to be a bit of a head-scratcher. Anyone want
to take a poke at an explanation for this odd circumstance?

E.P.

Question is, does bikes sold equal bikes ridden(regularly, and roughly)?
I can think of several reasons for more UK than US bikes being bought and then actually getting used on a regular basis.

Now, if the quote between no. of incidents to no. of ridden miles is higher in the UK than in the US, then it would be really odd.

On Jan 31, 2:20 am, dabac <dabac.2l9...@no-

mx.forums.cyclingforums.com said:

The existence or not of a force acting in the ejection direction should
be easy to determine.

This has been hashed over repeatedly. DAGS on this subject.

Quoted message said:

If it IS there then moving to a front caliper
configuration would cancel this cause for concern completely.

Probably. It may raise other concerns, however. This has also been
discussed.

E.P.

In article
<[email hidden]>,
dabac <[email hidden]>

Quoted message said:

Michael Press said:

...The manufacturers have their
reasons not to acknowledge that the current
configuration exerts a force in the axle ejection
direction.

Are they saying:
A)There is *no* force acting in the ejection direction present?

or are they saying:
B)There is *no significant * force acting in the ejection direction
present?

The manufacturers say _nothing_ about the matter.

Quoted message said:

The existence or not of a force acting in the ejection direction should
be easy to determine. If it IS there then moving to a front caliper
configuration would cancel this cause for concern completely.

The static force diagram confirms the ejection force.
Yes, moving the caliper forward of the fork will
reverse the direction of the reaction force at the
axle-fork tip junction.

Quoted message said:

But I have the feeling that by now the trenches are so deeply dug that
the manufacturers would be very unwilling to consider such a change
even if it there was sound reason for it.

Yes, you can see where that will lead.

--
Michael Press

In article
<[email hidden]>
,

Ed Pirrero said:

On Jan 31, 2:20 am, dabac <dabac.2l9...@no-

mx.forums.cyclingforums.com said:

The existence or not of a force acting in the ejection direction should
be easy to determine.

This has been hashed over repeatedly. DAGS on this subject.

Quoted message said:

If it IS there then moving to a front caliper
configuration would cancel this cause for concern completely.

Probably. It may raise other concerns, however. This has also been
discussed.

No reason for you to take valuable time over it. Move
along, nothing to see here.

--
Michael Press

dabac said:

Michael Press said:

...The manufacturers have their
reasons not to acknowledge that the current
configuration exerts a force in the axle ejection
direction.

Are they saying:
A)There is *no* force acting in the ejection direction present?

or are they saying:
B)There is *no significant * force acting in the ejection direction
present?

there is "ejection" force, but it's exceeded by the retention force by a
considerable margin.

Quoted message said:

The existence or not of a force acting in the ejection direction should
be easy to determine. If it IS there then moving to a front caliper
configuration would cancel this cause for concern completely.

but that leads to a much more serious concern - cast aluminum/magnesium
fork sliders are not good in tensile fatigue. having the calipers on
the front means the worst possible situation for the caliper mounting tabs.

Quoted message said:

But I have the feeling that by now the trenches are so deeply dug that
the manufacturers would be very unwilling to consider such a change
even if it there was sound reason for it.

it's not entrenchment - it's sensibility.

jim beam said:

Chris Nelson said:

Except I use mechanical disks(BB7s) and still feel that they modulate
better than cantilever. I haven't converted to hydraulics because they
tend to be more problematic, especially in the cold weather conditions
in which I ride.

maybe ice in the caliper? it's not brake fluid - that freezes /way/
below zero [<-40C].

Some hydraulic disc brake systems use mineral oil rather than glycol.
It is less toxic and less harmful to paint and rubber.

Chalo

Chalo said:

jim beam said:

Chris Nelson said:

Except I use mechanical disks(BB7s) and still feel that they modulate
better than cantilever. I haven't converted to hydraulics because they
tend to be more problematic, especially in the cold weather conditions
in which I ride.

maybe ice in the caliper? it's not brake fluid - that freezes /way/
below zero [<-40C].

Some hydraulic disc brake systems use mineral oil rather than glycol.
It is less toxic and less harmful to paint and rubber.

Chalo

glycol brake fluid is a very good rubber preservative - for the rubbers
it's supposed to work with at any rate. as for "toxicity", it tastes
truly disgusting, but it's probably not much more poisonous on ingestion
than soap.
http://www.thecloroxcompany.com/products/msds/armorallstp/stpheavydutybrakefluiddotmsds8-04.pdf

Michael Press said:

In article
<[email hidden]>
,

Ed Pirrero said:

On Jan 31, 2:20 am, dabac <dabac.2l9...@no-
mx.forums.cyclingforums.com> wrote:

Quoted message said:

Quoted message said:

If it IS there then moving to a front caliper
configuration would cancel this cause for concern completely.

Quoted message said:

Probably. It may raise other concerns, however. This has also been
discussed.

No reason for you to take valuable time over it.

Right you are. Since this has been discussed repeatedly, why spend
time typing it for a third or fourth time?

A little searching this this group would provide HOURS of pleasurable
reading on this subject.

Unless you have a good reason to type it in for the fifth time....

E.P.

jim beam said:

dabac said:

The existence or not of a force acting in the ejection direction should
be easy to determine. If it IS there then moving to a front caliper
configuration would cancel this cause for concern completely.

but that leads to a much more serious concern - cast aluminum/magnesium
fork sliders are not good in tensile fatigue. having the calipers on
the front means the worst possible situation for the caliper mounting tabs.

Hmm, cast aluminum fork sliders are not good in tensile fatigue.

Neither are cast aluminum cantilever brake arms. Nor their mounts.
Nor crank arms. Nor hub flanges. Nor handlebars. Nor stems....

But somehow, somehow, engineers manage to design those parts so they
produce excellent fatigue life!

Gee, you don't suppose they do that by making them _big_ enough, do
you? ;-)

- Frank Krygowski

Quoted message said:

jim beam said:

dabac said:

The existence or not of a force acting in the ejection direction should
be easy to determine. If it IS there then moving to a front caliper
configuration would cancel this cause for concern completely.

but that leads to a much more serious concern - cast aluminum/magnesium
fork sliders are not good in tensile fatigue. having the calipers on
the front means the worst possible situation for the caliper mounting tabs.

Hmm, cast aluminum fork sliders are not good in tensile fatigue.

Neither are cast aluminum cantilever brake arms. Nor their mounts.
Nor crank arms. Nor hub flanges. Nor handlebars. Nor stems....

But somehow, somehow, engineers manage to design those parts so they
produce excellent fatigue life!

Gee, you don't suppose they do that by making them _big_ enough, do
you? ;-)

- Frank Krygowski

er, you need to learn the difference between casting and forging.
brakes are forged. cranks are forged. hubs are forged or machined from
bar stock, not cast. handlebars are extruded. stems are forged or
welded from extrusions. the welding is a form of casting, but that's
one of the reasons welds break. but you already knew all this because
you're the engineering professor and you were trying to catch me out,
right? and btw, magnesium, stuff fork sliders are frequently made from,
is not the same as aluminum either.

jim beam said:

Quoted message said:

Hmm, cast aluminum fork sliders are not good in tensile fatigue.

Quoted message said:

Neither are cast aluminum cantilever brake arms. Nor their mounts.
Nor crank arms. Nor hub flanges. Nor handlebars. Nor stems....

Quoted message said:

But somehow, somehow, engineers manage to design those parts so they
produce excellent fatigue life!

Quoted message said:

Gee, you don't suppose they do that by making them _big_ enough, do
you? ;-)

Quoted message said:

- Frank Krygowski

er, you need to learn the difference between casting and forging.
brakes are forged.

Some are, some aren't. Here you go:

http://tinyurl.com/yuuapg

Quoted message said:

cranks are forged.

Some are, some aren't.

Quoted message said:

hubs are forged or machined from bar stock, not cast.

According to http://www.bikepro.com/products/metals/alum.html

"The ingots can be remelted to make cast aluminum products, using
various methods of casting including (in the bike industry), die
casting where molten aluminum is injected under high pressure into the
cavity of a metal die. Aluminum alloys have a reasonably low melting
point which makes a dense, fine-grain surface structure with excellent
wear and fatigue properties when die cast. Also permanent mold casting
may be used, which uses a metal mold repeatedly for producing many
castings of the same form. These casting techniques are the way many
crank arms, pedal bodies, hub shells, seatpost head pieces, stems, and
some headset parts are commercially made in volume."

Quoted message said:

handlebars are extruded.

Yes, almost all are. That's almost always the best way to make
aluminum shapes of constant cross section.

Quoted message said:

stems are forged or welded from extrusions.

Some are, some aren't.

I'm afraid you've been seduced by some tiny bit of book learning. The
fact that forged parts are stronger per unit weight, or more fatigue
resistant for a given size, does not mean that parts can't be
successfully designed to use other manufacturing processes. The
designer simply has to account for the lower strength and increase the
size a bit. It's done all the time.

And it could _certainly_ be done with brake bosses.

Here's the real tradeoff: The bigger brake bosses might add, oh,
fifteen grams or so to the mass of the bike. But the brake-forward
design would completely remove the force tending to eject the axle.
Unfortunately, the manufacturers would have to admit that they've done
it wrong up to this point

- Frank Krygowski

Quoted message said:

jim beam said:

Quoted message said:

Hmm, cast aluminum fork sliders are not good in tensile fatigue.
Neither are cast aluminum cantilever brake arms. Nor their mounts.
Nor crank arms. Nor hub flanges. Nor handlebars. Nor stems....
But somehow, somehow, engineers manage to design those parts so they
produce excellent fatigue life!
Gee, you don't suppose they do that by making them _big_ enough, do
you? ;-)
- Frank Krygowski

er, you need to learn the difference between casting and forging.
brakes are forged.

Some are, some aren't. Here you go:

http://tinyurl.com/yuuapg

do you have those on your machine? if it didn't come from a department
store, your bike does /not/ have cast brake levers.

Quoted message said:

Quoted message said:

cranks are forged.

Some are, some aren't.

most are forged. only mega-cheap garbage is not. of the forgings, cold
are best but hot is much more common.

Quoted message said:

Quoted message said:

hubs are forged or machined from bar stock, not cast.

According to http://www.bikepro.com/products/metals/alum.html

"The ingots can be remelted to make cast aluminum products, using
various methods of casting including (in the bike industry), die
casting where molten aluminum is injected under high pressure into the
cavity of a metal die. Aluminum alloys have a reasonably low melting
point which makes a dense, fine-grain surface structure with excellent
wear and fatigue properties when die cast. Also permanent mold casting
may be used, which uses a metal mold repeatedly for producing many
castings of the same form. These casting techniques are the way many
crank arms, pedal bodies, hub shells, seatpost head pieces, stems, and
some headset parts are commercially made in volume."

some of that is just plain wrong - low melting point producing fine
grain structure? what garbage!

besides, just because a component /can/ be cast, doesn't mean that it
is. if you knew what you were talking about, you wouldn't have made a
blanked assumption that all such things were. they're usually easy
enough to tell apart - if you know what you were looking at.

Quoted message said:

Quoted message said:

handlebars are extruded.

Yes, almost all are. That's almost always the best way to make
aluminum shapes of constant cross section.

Quoted message said:

stems are forged or welded from extrusions.

Some are, some aren't.

why did you snip my comment about welding being a form of casting that
has a propensity to fatigue? that's the problem with cast disk brake
tabs - the subject of discussion.

Quoted message said:

I'm afraid you've been seduced by some tiny bit of book learning. The
fact that forged parts are stronger per unit weight, or more fatigue
resistant for a given size, does not mean that parts can't be
successfully designed to use other manufacturing processes. The
designer simply has to account for the lower strength and increase the
size a bit. It's done all the time.

weak frank. very weak.

Quoted message said:

And it could _certainly_ be done with brake bosses.

Here's the real tradeoff: The bigger brake bosses might add, oh,
fifteen grams or so to the mass of the bike. But the brake-forward
design would completely remove the force tending to eject the axle.
Unfortunately, the manufacturers would have to admit that they've done
it wrong up to this point

that's just hobby-horse b.s. to try and not look like you got it wrong.
the only "bikes" that have cast vital componentry like brakes and
cranks are the landfill variety you buy for less than $100 at mega-low
mart. you could also make them out of recycled plastic bags, but i
don't think the punters would fall for that.

bottom line, professor, if you don't know, don't b.s. like you do.
thanks so much.

jim beam said:

Quoted message said:

jim beam said:

er, you need to learn the difference between casting and forging.
brakes are forged.

Quoted message said:

Some are, some aren't. Here you go:

Quoted message said:

http://tinyurl.com/yuuapg

do you have those on your machine? if it didn't come from a department
store, your bike does /not/ have cast brake levers.

:-) Your statement above didn't say "SOME brakes are forged. It said
"brakes are forged." Clearly, that's not entirely true.

When you're absolutely proven wrong, it's sometimes best to simply say
"Sorry." Or just slink away in silence.

Quoted message said:

Quoted message said:

Quoted message said:

cranks are forged.

Quoted message said:

Some are, some aren't.

most are forged. only mega-cheap garbage is not. of the forgings, cold
are best but hot is much more common.

See, you _can_ back pedal nicely! And obviously, cast parts can be
designed to give perfectly acceptable fatigue life.

Quoted message said:

Quoted message said:

Quoted message said:

hubs are forged or machined from bar stock, not cast.

Quoted message said:

According tohttp://www.bikepro.com/products/metals/alum.html

Quoted message said:

"The ingots can be remelted to make cast aluminum products, using
various methods of casting including (in the bike industry), die
casting where molten aluminum is injected under high pressure into the
cavity of a metal die. Aluminum alloys have a reasonably low melting
point which makes a dense, fine-grain surface structure with excellent
wear and fatigue properties when die cast. Also permanent mold casting
may be used, which uses a metal mold repeatedly for producing many
castings of the same form.

some of that is just plain wrong - low melting point producing fine
grain structure? what garbage!

Ah, I see. You'd like to distract us from the important point:
"These casting techniques are the way many crank arms, pedal bodies,
hub shells, seatpost head pieces, stems, and some headset parts are
commercially made in volume."

IOW, although you claim otherwise, many of these components are indeed
cast, and they give perfectly acceptable fatigue life. Likewise, the
lugs mounting a disk brake to a fork can also be designed to give
perfectly acceptable fatigue life.

Quoted message said:

why did you snip my comment about welding being a form of casting that
has a propensity to fatigue? that's the problem with cast disk brake
tabs - the subject of discussion.

Because it's a red herring. When a suspension fork "lower" is cast,
the lugs would not likely be welded in place; they'd likely be an
integral part of the casting. But as an aside, if weldments are as
fatigue prone as you'd have us believe, you've got work to do, man!
Welded bike frames are pretty darned common! You've got a whole
industry to reform!

Quoted message said:

the only "bikes" that have cast vital componentry like brakes and
cranks are the landfill variety you buy for less than $100 at mega-low
mart.

You know, the ancient Shimano cantilever brakes on my commuting bike
look like die castings to me. It's tough to be positive, of course,
but - they've been in service since about 1986, for thousands of trips
to work, including stopping at the bottom of a big hill every day.

No, they're not top of the line. But they work for me. I think
Shimano's engineers understand how to make parts slightly bigger in
order to compensate for a casting's slightly smaller strengh.

It's really not very difficult.

- Frank Krygowski

[email hidden] wrote:
<snip idiocy>

Quoted message said:

Quoted message said:

why did you snip my comment about welding being a form of casting that
has a propensity to fatigue? that's the problem with cast disk brake
tabs - the subject of discussion.

Because it's a red herring. When a suspension fork "lower" is cast,
the lugs would not likely be welded in place; they'd likely be an
integral part of the casting.

a casting is not a casting if it's a weld? you need to resign your
position krygowski - posing as an academic is the perpetration of fraud.

Quoted message said:

But as an aside, if weldments are as
fatigue prone as you'd have us believe, you've got work to do, man!
Welded bike frames are pretty darned common! You've got a whole
industry to reform!

frames crack at welds. idiot.

Michael Press said:

In article
<[email hidden]>,

Ed Pirrero said:

Michael Press said:

In article
<[email hidden]>
,
"Ed Pirrero" <[email hidden]> wrote:

Quoted message said:

Quoted message said:

> On Jan 31, 2:20 am, dabac <dabac.2l9...@no-
> mx.forums.cyclingforums.com> wrote:

Quoted message said:

Quoted message said:

> > If it IS there then moving to a front caliper
> > configuration would cancel this cause for concern completely.

Quoted message said:

Quoted message said:

> Probably. It may raise other concerns, however. This has also been
> discussed.

Quoted message said:

Quoted message said:

No reason for you to take valuable time over it.

Quoted message said:

Right you are. Since this has been discussed repeatedly, why spend
time typing it for a third or fourth time?

Quoted message said:

A little searching this this group would provide HOURS of pleasurable
reading on this subject.

Quoted message said:

Unless you have a good reason to type it in for the fifth time....

Still here?

Yes. Do you have a reason, or are just being a jackass?

E.P.