Disk brakes?

jim beam said:

[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.

So Frank's right and you don't think we should be riding welded frames?

Even if your ridiculous claims about casting were true, is there any
reason one couldn't use a forged part that encircles the lowers? For
example, something looking like this:

http://aebike.com/page.cfm?PageID=30&action=details&sku=BR1504

Gary Young said:

jim beam said:

frames crack at welds. idiot.

So Frank's right and you don't think we should be riding welded frames?

Even if your ridiculous claims about casting were true, is there any
reason one couldn't use a forged part that encircles the lowers?

Because, seemingly, there really are no wheel ejections? [1]

E.P.

[1] There have beren some claims that a few ejections have actually
taken place. Rigorous and non-biased looks at the available data do
not prove these claims one way or another.

jim beam said:

frames crack at welds. idiot.

If the weld cracks it was a bad weld. If the tube _under_ the weld cracks
it was a bad weld. If the tube _near_ the weld cracks (the most common
case IME), the finished frame was not properly heat treated or the
material was inappropriate, or was inadequately sized. With modern
machinery welding is fast but heat treatment is still slow, so it's the
heat treatment that gets missed out.

See that "6061-T6" decal? It was good material, and still is in the
middle of each tube. Close to the welds it's plain old "6061" unless it's
been heat treated after welding. Maybe the extra thickness of the butting
compensates, maybe it doesn't.

Mike

Gary Young said:

jim beam said:

[email hidden] wrote:
<snip idiocy>

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.

So Frank's right and you don't think we should be riding welded frames?

no dude, krygowski is trying to gloss over the fact that calipers are
rear mounted for materials reasons. straying off subject, yes, some
components are cast, and work well in tensile loading, steel bb shells
for example. but it depends on application, quality, price, material
and weight requirement. getting back on subject, since the tensile
fatigue strength of many aluminum and magnesium castings is typically
30% or less of its compressive, it's a pretty damned retarded not to
rear mount. krygowski's blanket assertion that all cranks, brakes, etc
are cast is pure ignorance.

Quoted message said:

Even if your ridiculous claims about casting were true,

eh? do you tell your dentist how to do their job as well?

Quoted message said:

is there any
reason one couldn't use a forged part that encircles the lowers? For
example, something looking like this:

http://aebike.com/page.cfm?PageID=30&action=details&sku=BR1504

yes - those are die cast, not forged. you could use clamp-ons, but why
when you can cast the right parts in? you could also put a roll cage on
the bike and a safety harness system if want to get really orbital - it
would make more sense than tensile castings.

Ed Pirrero said:

[1] There have beren some claims that a few ejections have actually
taken place. Rigorous and non-biased looks at the available data do
not prove these claims one way or another.

In a thread some time ago Frank pointed out something very relevant:

`Perhaps we're seeing the difference between a scientist and an
engineer. Scientists, particularly those with a theoretical
bent, are happy to spend a near-infinite amount of time learning
every last detail about a phenomenon. "Scientists seek merely
to know."

Engineers don't have that luxury. They must work in the real
world and produce practical designs based on imperfect
knowledge. "Engineers aim to DO."

If told to solve the reported problem of slipping front axles
with disk brakes, an engineer generally will NOT spend a few
thousand dollars on lab tests, if a simple force diagram shows
an ejection force in the direction of an open slot. He also
won't waste time claiming all the reports must be wrong. He'll
move the slot, or otherwise fix the problem.'

To that I would add that in our imperfect world we also have to deal
with lawyers and marketing people. This design is rather like the 70's
Ford Pinto. The engineers know it's wrong, but to change it would
invite such trouble that the corporate lawyers won't hear of it. Unless
of course the marketing types can dream up some reason why it's new new
and better better without implying in any way that the old version was
bad.

Full disclosure: I do know one honest and technically competent
marketing guy, and three, no four, honest and competent lawyers.
Non work in any transport-related field.

Mike

In article
<[email hidden]>
,

Ed Pirrero said:

Michael Press said:

In article
<[email hidden]>,

Ed Pirrero said:

On Jan 31, 4:19 pm, Michael Press <[email hidden]> wrote:
> In article
> <[email hidden]>
> ,
> "Ed Pirrero" <[email hidden]> wrote:

Quoted message said:

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

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.

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?

That's poser. What do you think?

--
Michael Press

On Feb 2, 12:03 pm, Mike Causer <[email hidden]>

Quoted message said:

Ed Pirrero said:

[1] There have been some claims that a few ejections have actually
taken place. Rigorous and non-biased looks at the available data do
not prove these claims one way or another.

In a thread some time ago Frank pointed out something very relevant:

`Perhaps we're seeing the difference between a scientist and an
engineer. Scientists, particularly those with a theoretical
bent, are happy to spend a near-infinite amount of time learning
every last detail about a phenomenon. "Scientists seek merely
to know."

Engineers don't have that luxury. They must work in the real
world and produce practical designs based on imperfect
knowledge. "Engineers aim to DO."

If told to solve the reported problem of slipping front axles
with disk brakes, an engineer generally will NOT spend a few
thousand dollars on lab tests, if a simple force diagram shows
an ejection force in the direction of an open slot. He also
won't waste time claiming all the reports must be wrong. He'll
move the slot, or otherwise fix the problem.'

To that I would add that in our imperfect world we also have to deal
with lawyers and marketing people.

Indeed. Frank's comments really have very little bearing on the
subject if, in fact, the current design has an exceedingly low failure
rate - so low as to be able to count the purported disk-brake-wheel
ejections on one hand, with fingers left over.

A few thousand dollars on lab tests, as opposed to what sort of figure
for a total recall of all the forks of the current design? Yeah,
practical vs. theoretical.

And there *are* lawyers to think about - bicycle parts makers, on the
thin edge of profitability, would probably not want to have to pony up
really big lawsuit dollars, and THEN do a recall. Even a non-
businessman like myself has a decent idea of where that would put the
companies' bottom lines. I think a lawyer's advice on the subject
would be fairly critical to a company wanting to remain solvent.

Quoted message said:

This design is rather like the 70's
Ford Pinto.

Except in this case, there have been no verified injuries or deaths
due to the design, the incidence of even reported potential failure is
so low as to not even register, and as far as anyone knows, there are
no actual bicycle part maker engineers that say the parts must be
redesigned.

This subject generates a ton of heat, conspiracy theories and circular
logic, but very little real-world use data.

The conversation always boils down to this:

"The design is faulty."

"OK, where's the carnage that's resulted from the faulty design?"

"THE DESIGN IS FAULTY!"

A realist says "no carnage = adequate to the task for which it was
designed." Oh, FTR - adequate <> perfect.

E.P.

Michael Press said:

In article
<[email hidden]>
,

Ed Pirrero said:

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

That's poser. What do you think?

Jello squares.

E.P.

On Jan 31, 2:36 am, dabac <dabac.2l9...@no-

mx.forums.cyclingforums.com said:

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.

Quoted message said:

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?

Quoted message said:

E.P.

Question is, does bikes sold equal bikes ridden(regularly, and
roughly)?

Even if not, the sales figures differences would be interesting to see
as to the magnitude of the difference in sales.

Quoted message said:

I can think of several reasons for more UK than US bikes being bought
and then actually getting used on a regular basis.

Oh? Why not list them, then?

Quoted message said:

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.

The listings on the web of various MTBing groups notes a staggering
difference in total numbers. An order of magnitude, or greater.

And yet, most of the reported "problems" are in the U.K.

Hmmm.

E.P.

jim beam said:

Gary Young said:

jim beam said:

[email hidden] wrote:
<snip idiocy>
>> 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.

> 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.

So Frank's right and you don't think we should be riding welded frames?

no dude, krygowski is trying to gloss over the fact that calipers are
rear mounted for materials reasons. straying off subject, yes, some
components are cast, and work well in tensile loading, steel bb shells
for example. but it depends on application, quality, price, material
and weight requirement. getting back on subject, since the tensile
fatigue strength of many aluminum and magnesium castings is typically
30% or less of its compressive, it's a pretty damned retarded not to
rear mount. krygowski's blanket assertion that all cranks, brakes, etc
are cast is pure ignorance.

Quoted message said:

Even if your ridiculous claims about casting were true,

eh? do you tell your dentist how to do their job as well?

Sorry, I didn't realize you were a dentist.

Generally I don't tell my dentist how to do his job, but I don't feel any
similar compunction about anonymous newsgroup posters given to
contrariness who claim to be dentists while making frequent
errors and claims that defy common sense.

But just to clarify -- what I think is ridiculous is not what you say
about the weakness of castings, but your insistence that no amount of
overbuilding would be adequate.

Quoted message said:

Quoted message said:

is there any
reason one couldn't use a forged part that encircles the lowers? For
example, something looking like this:

http://aebike.com/page.cfm?PageID=30&action=details&sku=BR1504

yes - those are die cast, not forged.

As I said, I posted the image to convey the general idea of the shape of
what I had in mind. I take it from your response that a forged part would
do just fine.

you could use clamp-ons, but why

Quoted message said:

when you can cast the right parts in?

Sure, why not?

you could also put a roll cage on

Quoted message said:

the bike and a safety harness system if want to get really orbital - it
would make more sense than tensile castings.

Who said anything about roll cages or safety harnesses? I'm talking about
a small part no different from many other small parts.

jim beam said:

krygowski is trying to gloss over the fact that calipers are
rear mounted for materials reasons.

Sorry, jb. I'm not "glossing over" that fact. I'm categorically
denying it. If cast parts could not be designed to adequately resist
fatigue, then the many, many counterexamples I gave would not exist.

Again: There are many cast bike parts that resist tensile fatigue.
Engineers can obviously successfully design such parts. That's _not_
why disk calipers are rear mounted, no matter what you think.

Quoted message said:

straying off subject, yes, some
components are cast, and work well in tensile loading, steel bb shells
for example. but it depends on application, quality, price, material
and weight requirement.

Correct! Furthermore, they can work well in tensile _fatigue_
loading. And that's not only cast steel parts. Note that these,
http://aebike.com/page.cfm?PageID=30&action=details&sku=BR1504
must do just that - and as you said, they are very likely die cast.

Quoted message said:

krygowski's blanket assertion that all cranks, brakes, etc
are cast is pure ignorance.

You know, your technical mistakes about mechanical design are
unfortunate. Your lack of knowledge about manufacturing techniques is
regrettable.

But your lies are downright slimy.

Anyone can review upthread and see that I _never_ claimed "all cranks,
brakes, etc. are cast."

Here are the relevant quotes:

j.b. "brakes are forged."

F.K. "Some are, some aren't. Here you go: http://tinyurl.com/yuuapg"

j.b. "cranks are forged."

F.K. "Some are, some aren't. "

We don't expect a retraction, of course. We know you well.

- Frank Krygowski

A Muzi said:

Quoted message said:

Gary Young said:

On Fri, 02 Feb 2007 08:56:46 -0800, jim beam wrote:
> [email hidden] wrote:
> <snip idiocy>
>>> 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.

jim beam said:

no dude, krygowski is trying to gloss over the fact that calipers are
rear mounted for materials reasons. straying off subject, yes, some
components are cast, and work well in tensile loading, steel bb shells
for example. but it depends on application, quality, price, material
and weight requirement. getting back on subject, since the tensile
fatigue strength of many aluminum and magnesium castings is typically
30% or less of its compressive, it's a pretty damned retarded not to
rear mount. krygowski's blanket assertion that all cranks, brakes,
etc are cast is pure ignorance.

-snip much-
I have not followed this thread closely but I can tell you, having spent
a lot of time with SR-Sakae on the Prizm precision cast lug frame
system, and having visited Shimano's Shin-Osaka plant, that the bulk of
bike parts are 'melt-formed'.

In that process, (think Campagnolo Centaur arms for example), parts are
pressure-molded from molten aluminum in a 'tree'. They come out joined
like model car parts from a tree with quick-change heated molds. The
material flows in heated tubes under pressure to the tree. Pressures are
well below cold forging values as the material is already flowing from
the heat. The tooling crew can make a tree with three right cranks,
five stem blanks, six left cranks and two pedal bodies, then change the
molds easily to balance against orders.

that's right, but it's not "casting" in the traditional sense, it's more
"thixo-forming". basically, the material "cast" is a semi-solid slurry
[bit like a slurpee] which on final solidification is not subject the
segregations, voids, gross grain structure, cracking etc., of
traditional liquid casting.

Quoted message said:

After being popped out of the mold, parts go through a heat treatment
[also called 'rapid aging' for aluminum]. Before finish work [at
SR-Sakae - didn't see one at Shimano -?] 100% were inspected for voids
in a fluoroscope with a very small reject rate. The operators watched a
screen outside the room with the belt-driven fluoroscope, positions on
the belt were numbered.

Cold forged parts were made in the same facilities but at a minuscule
fraction of the volume of pressure-molded parts.

right. and they cost a lot more.

Quoted message said:

So, when we speak of "cast", please don't picture some 60 year old
French abortion of a sand-casting waiting to crack. The industry is way
beyond that - and my report is from the middle eighties. I'm sure, from
looking at things like Frank's brake arms, the process has advanced even
further, blurring the line between 'forged' and 'cast'. Most stuff we
ride is neither, in the classic sense.

great points, and it would have been great to go there earlier if we'd
been able get the conversational i.q. into double digits.

On Fri, 02 Feb 2007 20:54:56 -0600, A Muzi <[email hidden]>

Quoted message said:

Quoted message said:

Gary Young said:

On Fri, 02 Feb 2007 08:56:46 -0800, jim beam wrote:
> [email hidden] wrote:
> <snip idiocy>
>>> 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.

jim beam said:

no dude, krygowski is trying to gloss over the fact that calipers are
rear mounted for materials reasons. straying off subject, yes, some
components are cast, and work well in tensile loading, steel bb shells
for example. but it depends on application, quality, price, material
and weight requirement. getting back on subject, since the tensile
fatigue strength of many aluminum and magnesium castings is typically
30% or less of its compressive, it's a pretty damned retarded not to
rear mount. krygowski's blanket assertion that all cranks, brakes, etc
are cast is pure ignorance.

-snip much-
I have not followed this thread closely but I can tell you, having spent
a lot of time with SR-Sakae on the Prizm precision cast lug frame
system, and having visited Shimano's Shin-Osaka plant, that the bulk of
bike parts are 'melt-formed'.

In that process, (think Campagnolo Centaur arms for example), parts are
pressure-molded from molten aluminum in a 'tree'. They come out joined
like model car parts from a tree with quick-change heated molds. The
material flows in heated tubes under pressure to the tree. Pressures are
well below cold forging values as the material is already flowing from
the heat. The tooling crew can make a tree with three right cranks,
five stem blanks, six left cranks and two pedal bodies, then change the
molds easily to balance against orders.

After being popped out of the mold, parts go through a heat treatment
[also called 'rapid aging' for aluminum]. Before finish work [at
SR-Sakae - didn't see one at Shimano -?] 100% were inspected for voids
in a fluoroscope with a very small reject rate. The operators watched a
screen outside the room with the belt-driven fluoroscope, positions on
the belt were numbered.

Cold forged parts were made in the same facilities but at a minuscule
fraction of the volume of pressure-molded parts.

So, when we speak of "cast", please don't picture some 60 year old
French abortion of a sand-casting waiting to crack. The industry is way
beyond that - and my report is from the middle eighties. I'm sure, from
looking at things like Frank's brake arms, the process has advanced even
further, blurring the line between 'forged' and 'cast'. Most stuff we
ride is neither, in the classic sense.

Dear Andrew,

Nice post.

So how did you end up so far from Wisconsin and what else did you see
being made and have you been back and what other bike factories have
you seen but not told us about and so forth?

Cheers,

Carl Fogel

Quoted message said:

Quoted message said:

Quoted message said:

Gary Young wrote:
> On Fri, 02 Feb 2007 08:56:46 -0800, jim beam wrote:
>> [email hidden] wrote:
>> <snip idiocy>
>>>> 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:

Quoted message said:

jim beam said:

no dude, krygowski is trying to gloss over the fact that calipers are
rear mounted for materials reasons. straying off subject, yes, some
components are cast, and work well in tensile loading, steel bb shells
for example. but it depends on application, quality, price, material
and weight requirement. getting back on subject, since the tensile
fatigue strength of many aluminum and magnesium castings is typically
30% or less of its compressive, it's a pretty damned retarded not to
rear mount. krygowski's blanket assertion that all cranks, brakes, etc
are cast is pure ignorance.

-snip much-

Quoted message said:

A Muzi said:

I have not followed this thread closely but I can tell you, having spent
a lot of time with SR-Sakae on the Prizm precision cast lug frame
system, and having visited Shimano's Shin-Osaka plant, that the bulk of
bike parts are 'melt-formed'.

-snip, blah blah blah-

Quoted message said:

Quoted message said:

I'm sure, from
looking at things like Frank's brake arms, the process has advanced even
further, blurring the line between 'forged' and 'cast'. Most stuff we
ride is neither, in the classic sense.

Quoted message said:

Nice post.
So how did you end up so far from Wisconsin and what else did you see
being made and have you been back and what other bike factories have
you seen but not told us about and so forth?

Thanks. I used to spend a lot of time in Japan.
Carl, we all have lives outside of rbt!
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

On Fri, 02 Feb 2007 23:15:23 -0600, A Muzi <[email hidden]>

Quoted message said:

Quoted message said:

Quoted message said:

> Gary Young wrote:
>> On Fri, 02 Feb 2007 08:56:46 -0800, jim beam wrote:
>>> [email hidden] wrote:
>>> <snip idiocy>
>>>>> 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:

Quoted message said:

jim beam wrote:
> no dude, krygowski is trying to gloss over the fact that calipers are
> rear mounted for materials reasons. straying off subject, yes, some
> components are cast, and work well in tensile loading, steel bb shells
> for example. but it depends on application, quality, price, material
> and weight requirement. getting back on subject, since the tensile
> fatigue strength of many aluminum and magnesium castings is typically
> 30% or less of its compressive, it's a pretty damned retarded not to
> rear mount. krygowski's blanket assertion that all cranks, brakes, etc
> are cast is pure ignorance.
-snip much-

Quoted message said:

A Muzi said:

I have not followed this thread closely but I can tell you, having spent
a lot of time with SR-Sakae on the Prizm precision cast lug frame
system, and having visited Shimano's Shin-Osaka plant, that the bulk of
bike parts are 'melt-formed'.

-snip, blah blah blah-

Quoted message said:

Quoted message said:

I'm sure, from
looking at things like Frank's brake arms, the process has advanced even
further, blurring the line between 'forged' and 'cast'. Most stuff we
ride is neither, in the classic sense.

Quoted message said:

Nice post.
So how did you end up so far from Wisconsin and what else did you see
being made and have you been back and what other bike factories have
you seen but not told us about and so forth?

Thanks. I used to spend a lot of time in Japan.
Carl, we all have lives outside of rbt!

Dear Andrew,

And RBT probably wants to hear more about yours, specifically anything
that caught your eye in Japanese bike factories or Japan.

Immediately would be fine, but I suppose we can wait a little, while
you reflect on the highlights of the Muzi shogunate.

Or start stuffing a few anecdotes into more posts.

What struck you as the biggest differences between bicycling in Japan
and in Madison?

What did Japanese riders think of the Tour de France? Were there as
many recreational riders as you see at Yellow Jersey?

Do keirin bike mechanics do (or not do) anything curious when they
build wheels?

What's the weirdest bicycling thing that you saw there?

Cheers,

Carl Fogel

A Muzi said:

Quoted message said:

Quoted message said:

On Fri, 02 Feb 2007 08:56:46 -0800, jim beam lied:
krygowski's blanket assertion that all cranks, brakes, etc
are cast is pure ignorance.

-snip much-
I have not followed this thread closely but I can tell you, having spent
a lot of time with SR-Sakae on the Prizm precision cast lug frame
system, and having visited Shimano's Shin-Osaka plant, that the bulk of
bike parts are 'melt-formed'.

In that process, (think Campagnolo Centaur arms for example), parts are
pressure-molded from molten aluminum in a 'tree'. They come out joined
like model car parts from a tree with quick-change heated molds. The
material flows in heated tubes under pressure to the tree. Pressures are
well below cold forging values as the material is already flowing from
the heat. The tooling crew can make a tree with three right cranks,
five stem blanks, six left cranks and two pedal bodies, then change the
molds easily to balance against orders.

After being popped out of the mold, parts go through a heat treatment
[also called 'rapid aging' for aluminum]. Before finish work [at
SR-Sakae - didn't see one at Shimano -?] 100% were inspected for voids
in a fluoroscope with a very small reject rate. The operators watched a
screen outside the room with the belt-driven fluoroscope, positions on
the belt were numbered.

Cold forged parts were made in the same facilities but at a minuscule
fraction of the volume of pressure-molded parts.

So, when we speak of "cast", please don't picture some 60 year old
French abortion of a sand-casting waiting to crack. The industry is way
beyond that - and my report is from the middle eighties. I'm sure, from
looking at things like Frank's brake arms, the process has advanced even
further, blurring the line between 'forged' and 'cast'. Most stuff we
ride is neither, in the classic sense.

What Andrew describes sounds absolutely accurate. But to expand on
the final paragraph, in case anyone is confused by it:

The word "cast" does not imply molten metal poured by hand into a sand
mold. All that it implies is that liquid metal flows into a mold
where it freezes solid. There are many, many types of casting
processes, and many are advanced and highly automated. At one
extreme, sand casting is generally most economical for low production
parts that are not needed to be as precise or as strong. At the other
extreme, die casting (with its high initial cost) is best for high
production parts that need more precision and strength. Like bike
parts.

The process Andrew described sounds exactly like classic die casting.
That's exactly how it's done - although for most common commercial
products, the flouroscope inspection would be skipped. The essence is
that the molds (or dies) are expensive, complex, precise tool steel
devices, liquid cooled for quick freezing of parts. They are held
closed by large hydraulic forces, and the molten metal is injected
very rapidly and under high pressure, not gravity poured. The result
is strong, accurate parts with excellent surface finishes, with
tolerances generally held to a few thousandths of an inch. And to
increase production, all but the largest die-cast parts are made on a
"tree" with several parts produced in one shot.

jim beam's assertion - "it's not 'casting' in the traditional sense,
it's more
'thixo-forming' "- sounds like another typical beamish evasion, to
avoid admitting to a proven mistake.

First, it's _certainly_ not a forging process - and if you read
upthread, jim beam was claiming that the bike parts that fight tensile
fatigue are forged, _not_ cast. Here's a quote: "cranks are forged.
hubs are forged or machined from bar stock, not cast." So even if it
is thixoforming, he was still off-base.

Secondly, there's nothing in Andrew's description that indicates those
parts were thixoformed. "Pressure-molded from molten aluminum in a
'tree' " is die casting. Had he said "pressure-molded from a slurry
of semi-liquid aluminum" then I would have assumed the parts were
thixoformed.

And anyway, thixoforming is generally considered a variation on die
casting, not an entirely separate process.

Again, it's _certainly_ not considered a forging process!

- Frank Krygowski

frkrygow said:

A Muzi said:

Quoted message said:

> On Fri, 02 Feb 2007 08:56:46 -0800, jim beam lied:
> krygowski's blanket assertion that all cranks, brakes, etc
> are cast is pure ignorance.

-snip much-
I have not followed this thread closely but I can tell you, having spent
a lot of time with SR-Sakae on the Prizm precision cast lug frame
system, and having visited Shimano's Shin-Osaka plant, that the bulk of
bike parts are 'melt-formed'.

In that process, (think Campagnolo Centaur arms for example), parts are
pressure-molded from molten aluminum in a 'tree'. They come out joined
like model car parts from a tree with quick-change heated molds. The
material flows in heated tubes under pressure to the tree. Pressures are
well below cold forging values as the material is already flowing from
the heat. The tooling crew can make a tree with three right cranks,
five stem blanks, six left cranks and two pedal bodies, then change the
molds easily to balance against orders.

After being popped out of the mold, parts go through a heat treatment
[also called 'rapid aging' for aluminum]. Before finish work [at
SR-Sakae - didn't see one at Shimano -?] 100% were inspected for voids
in a fluoroscope with a very small reject rate. The operators watched a
screen outside the room with the belt-driven fluoroscope, positions on
the belt were numbered.

Cold forged parts were made in the same facilities but at a minuscule
fraction of the volume of pressure-molded parts.

So, when we speak of "cast", please don't picture some 60 year old
French abortion of a sand-casting waiting to crack. The industry is way
beyond that - and my report is from the middle eighties. I'm sure, from
looking at things like Frank's brake arms, the process has advanced even
further, blurring the line between 'forged' and 'cast'. Most stuff we
ride is neither, in the classic sense.

What Andrew describes sounds absolutely accurate. But to expand on
the final paragraph, in case anyone is confused by it:

The word "cast" does not imply molten metal poured by hand into a sand
mold. All that it implies is that liquid metal flows into a mold
where it freezes solid. There are many, many types of casting
processes, and many are advanced and highly automated. At one
extreme, sand casting is generally most economical for low production
parts that are not needed to be as precise or as strong. At the other
extreme, die casting (with its high initial cost) is best for high
production parts that need more precision and strength. Like bike
parts.

The process Andrew described sounds exactly like classic die casting.
That's exactly how it's done - although for most common commercial
products, the flouroscope inspection would be skipped. The essence is
that the molds (or dies) are expensive, complex, precise tool steel
devices, liquid cooled for quick freezing of parts. They are held
closed by large hydraulic forces, and the molten metal is injected
very rapidly and under high pressure, not gravity poured. The result
is strong, accurate parts with excellent surface finishes, with
tolerances generally held to a few thousandths of an inch. And to
increase production, all but the largest die-cast parts are made on a
"tree" with several parts produced in one shot.

"Die casting" sounds like what I've always pictured "hot forging" to be.
Is "hot forging" a misnomer or is that an entirely different process?

Quoted message said:

jim beam's assertion - "it's not 'casting' in the traditional sense,
it's more
'thixo-forming' "- sounds like another typical beamish evasion, to
avoid admitting to a proven mistake.

First, it's _certainly_ not a forging process - and if you read
upthread, jim beam was claiming that the bike parts that fight tensile
fatigue are forged, _not_ cast. Here's a quote: "cranks are forged.
hubs are forged or machined from bar stock, not cast." So even if it
is thixoforming, he was still off-base.

Secondly, there's nothing in Andrew's description that indicates those
parts were thixoformed. "Pressure-molded from molten aluminum in a
'tree' " is die casting. Had he said "pressure-molded from a slurry
of semi-liquid aluminum" then I would have assumed the parts were
thixoformed.

And anyway, thixoforming is generally considered a variation on die
casting, not an entirely separate process.

Again, it's _certainly_ not considered a forging process!

- Frank Krygowski

On Jan 31, 4:20 am, dabac <dabac.2l9...@no-

mx.forums.cyclingforums.com 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 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.

--
dabac

The only thing I have to say on this subject is that I want my bike to
look and work like a bike, not a motorcycle. Disk brakes are the only
instance I can think of where the bicycle industry has been influenced
from the automotive/motorcycle industry. Strange, most of the time
it's the other way around. On a philosophical level it seems a step
backward, no longer influancing but rather following along. However if
you like to carry too much gear, ride in the mud, need to get the heat
off the rim, and or drop off cliffs, then you need to ride a bike that
works more like a motorcycle.

Quoted message said:

Quoted message said:

Quoted message said:

>> On Fri, 02 Feb 2007 08:56:46 -0800, jim beam lied:
>> krygowski's blanket assertion that all cranks, brakes, etc
>> are cast is pure ignorance.

Quoted message said:

Quoted message said:

A Muzi said:

-snip much-
I have not followed this thread closely but I can tell you, having spent
a lot of time with SR-Sakae on the Prizm precision cast lug frame
system, and having visited Shimano's Shin-Osaka plant, that the bulk of
bike parts are 'melt-formed'.

-big snip-

Quoted message said:

Quoted message said:

Quoted message said:

Cold forged parts were made in the same facilities but at a minuscule
fraction of the volume of pressure-molded parts.

So, when we speak of "cast", please don't picture some 60 year old
French abortion of a sand-casting waiting to crack. The industry is way
beyond that - and my report is from the middle eighties. I'm sure, from
looking at things like Frank's brake arms, the process has advanced even
further, blurring the line between 'forged' and 'cast'. Most stuff we
ride is neither, in the classic sense.

Quoted message said:

frkrygow said:

What Andrew describes sounds absolutely accurate. But to expand on
the final paragraph, in case anyone is confused by it:
The word "cast" does not imply molten metal poured by hand into a sand
mold. All that it implies is that liquid metal flows into a mold
where it freezes solid. There are many, many types of casting
processes, and many are advanced and highly automated. At one
extreme, sand casting is generally most economical for low production
parts that are not needed to be as precise or as strong. At the other
extreme, die casting (with its high initial cost) is best for high
production parts that need more precision and strength. Like bike
parts.

The process Andrew described sounds exactly like classic die casting.

-big snip-

Quoted message said:

Quoted message said:

jim beam's assertion - "it's not 'casting' in the traditional sense,
it's more
'thixo-forming' "- sounds like another typical beamish evasion, to
avoid admitting to a proven mistake.

-snip-

Quoted message said:

Quoted message said:

And anyway, thixoforming is generally considered a variation on die
casting, not an entirely separate process.
Again, it's _certainly_ not considered a forging process!
- Frank Krygowski

Gary Young said:

"Die casting" sounds like what I've always pictured "hot forging" to be.
Is "hot forging" a misnomer or is that an entirely different process?

As I understand it, a part's not 'forged' if it starts in a plastic
state, which is why manufacturers are vague. SR-Sakae called their
products "melt-forged' or 'melt formed' for example.

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

email hidden said:

On Jan 31, 4:20 am, dabac <dabac.2l9...@no-

mx.forums.cyclingforums.com 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 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.

--
dabac

The only thing I have to say on this subject is that I want my bike to
look and work like a bike, not a motorcycle. Disk brakes are the only
instance I can think of where the bicycle industry has been influenced
from the automotive/motorcycle industry. Strange, most of the time
it's the other way around. On a philosophical level it seems a step
backward, no longer influancing but rather following along. However if
you like to carry too much gear, ride in the mud, need to get the heat
off the rim, and or drop off cliffs, then you need to ride a bike that
works more like a motorcycle.

Dear Othy,

Rumor has it that modern bicycle suspension developed from modern
motorcycle suspension.

Cheers,

Carl Fogel