Carbon rims melting
DirtRoadie
In light of the nature of the material (specifically the resin) it
does not surprise me that it CAN happen, but until a friend described
it happening to him, I don't believe I have previously heard of it
happening.
Has anyone experienced this or know someone who has?
DR
almos...@yahoo.com
Yes, I have one.
Brakes can get hot, and can be often or never a problem; obviously
depending on terrain, rider weight, probably other factors.
Once the resin breaks down the rim surface can distort into odd
surface ripples (shape depends on layup I guess). I've seen other rims
do this too. Usually asian made; US-made rims seem to use better
resin...?
Another reason to stick with aluminum brake tracks IMHO.
Norman
I thought that all crabno fribe (at least as used in bicycles)
was a thermo-set resin. I know it isn't strictly applicable
but there are such things as graphite &/or carbon brake
rotors for certain racing and "end-of-flight" applications
which have to handle >600C*, which should be at least
one or two Kelvins more than a bicycle would see outside
of an atomic hydrogen torch. So, the upshot being that
if it did [melt] it seems like a crap bit to start with.
* to say nothing of the scores of Newtons or Dynes or
Ergs or SOMEThings
Michael Press
<c9a2dea1-5659-4deb...@c21g2000vba.googlegroups.com>,
DirtRoadie <DirtR...@aol.com> wrote:
Cross linked polymers do not melt.
--
Michael Press
David Scheidt
:In article
Really? Styroflex and Hytrel don't really exist? BASF and DuPont
have been feeding us all hallucengens to keep us buying their
non-existent products?
--
sig 85
Norman
> Michael Press <rub...@pacbell.net> wrote:
>
> :In article
>
> : DirtRoadie <DirtRoa...@aol.com> wrote:
>
> :> Anyone here ever actually melted a carbon rim from braking?
> :>
> :> In light of the nature of the material (specifically the resin) it
> :> does not surprise me that it CAN happen, but until a friend described
> :> it happening to him, I don't believe I have previously heard of it
> :> happening.
> :> Has anyone experienced this or know someone who has?
>
> :Cross linked polymers do not melt.
>
> Really? Styroflex and Hytrel don't really exist?
I don't know about cross-linked, but a quick search indicates
that those are both thermoplastics. I have no idea why they
would be used in a high temperature application, but you may
spec your bicycle as you wish.
David Scheidt
:On Oct 11, 7:16 pm, David Scheidt <dsche...@panix.com> wrote:
:> Michael Press <rub...@pacbell.net> wrote:
:>
:> :In article
:> :<c9a2dea1-5659-4deb-bc4b-a46475ee9...@c21g2000vba.googlegroups.com>,
:>
:> : DirtRoadie <DirtRoa...@aol.com> wrote:
:>
:> :> Anyone here ever actually melted a carbon rim from braking?
:> :>
:> :> In light of the nature of the material (specifically the resin) it
:> :> does not surprise me that it CAN happen, but until a friend described
:> :> it happening to him, I don't believe I have previously heard of it
:> :> happening.
:> :> Has anyone experienced this or know someone who has?
:>
:> :Cross linked polymers do not melt.
:>
:> Really? Styroflex and Hytrel don't really exist?
:I don't know about cross-linked, but a quick search indicates
:that those are both thermoplastics. I have no idea why they
They're thermoplastic elstamoers, which have the characteristic of
being cross-linked polymers that melt, which Mr Press doesn't think
exist.
:would be used in a high temperature application, but you may
:spec your bicycle as you wish.
Well, you wouldn't, but that wasn't the question. But I'm pretty sure
I've seen grips made of hytrel.
--
sig 4
DirtRoadie
> In article
> <c9a2dea1-5659-4deb-bc4b-a46475ee9...@c21g2000vba.googlegroups.com>,
>
> Cross linked polymers do not melt.
That is a VERY broad statement. Can you provide an example?
I believe there may be some examples of some heat resistant materials
that vaporize before melting. But how about a link to a data sheet for
some specific material? And will you concede that the statement is
inaccurate if we can come up with ONE counterexample? Doesn't cross-
linked polyethylene qualify?
I agree that carbon fiber itself is amazingly heat resistant.
DR
Michael Press
David Scheidt <dsch...@panix.com> wrote:
I do not understand the question. Let me make myself clear.
Cross linked polymers do not melt.
--
Michael Press
David Scheidt
:In article <i905s0$qap$1...@reader1.panix.com>,
: David Scheidt <dsch...@panix.com> wrote:
You deny the existence of Stryoflex and Hytrel?
--
sig 109
Mike Jacoubowsky
"DirtRoadie" <DirtR...@aol.com> wrote in message
news:c9a2dea1-5659-4deb...@c21g2000vba.googlegroups.com...
Are you certain the rim "melted" rather than delaminated? Using the
wrong brake pads for a given rim can cause them to heat up enough that
the surface layer meant for braking can separate from the rest of the
rim (the outer layer you see isn't usually carbon fiber but a "scrim"
material that's designed for braking). At that point the rim can
literally explode apart, a very bad thing. Using the recommended brake
pads we simply don't see this happen, ever.
For what it's worth I have a pair of Bontrager XXX-Lite carbon wheels
(with carbon rims, not aluminum rims glued to carbon). They're closing
in on 30,000 miles without incident. I haven't even touched a spoke,
although I'm sure that, if I checked the tension, they're probably a bit
low by now. But they ride great, they're straight, so why bother? They
even work well in rain, although if you've got $2500 wheels, you
probably should ride something else when it's that bad outside (at least
if your rides include 5 miles of descending, as mine do). Their
downside? Cost, for one. And you have to be careful about tire choice,
because some, like Michelins, just don't like carbon bead hooks.
--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com
DirtRoadie
wrote:
> "DirtRoadie" <DirtRoa...@aol.com> wrote in message
I do not know precisely what happened and have not yet seen the wheel.
But his description got me wondering and that was why I asked the
question.
He described the ride he was doing as having lots of steep up and
down. While descending he noticed a "thump, thump, thump" coming from
his back wheel. He described finishing the ride but that the rim was
"toast."
FWIW, I believe they were Reynolds wheels.
DR
Michael Press
<4034abbc-cc82-4c57...@g8g2000yqa.googlegroups.com>,
DirtRoadie <DirtR...@aol.com> wrote:
A cross linked polymer is one big molecule. When the
bonds are broken it becomes a different chemical
species; and cannot be put back together again.
When water or iron or table salt or glass melt
their respective chemical properties do not change.
--
Michael Press
Norman
> Michael Press <rub...@pacbell.net> wrote:
>
> : David Scheidt <dsche...@panix.com> wrote:
>
> :> Michael Press <rub...@pacbell.net> wrote:
> :> :In article
> :> : DirtRoadie <DirtRoa...@aol.com> wrote:
> :>
> :> :> Anyone here ever actually melted a carbon rim from braking?
> :> :>
> :> :> In light of the nature of the material (specifically the resin) it
> :> :> does not surprise me that it CAN happen, but until a friend described
> :> :> it happening to him, I don't believe I have previously heard of it
> :> :> happening.
> :> :> Has anyone experienced this or know someone who has?
> :>
> :> :Cross linked polymers do not melt.
> :>
> :> Really? Styroflex and Hytrel don't really exist? BASF and DuPont
> :> have been feeding us all hallucengens to keep us buying their
> :> non-existent products?
>
> :I do not understand the question. Let me make myself clear.
> :Cross linked polymers do not melt.
>
> You deny the existence of Stryoflex and Hytrel?
>
Water is a cross linked polymer?
DirtRoadie
OK so we are using semantic distinctions. So when I take a red-hot
poker and push it through the shell of a kayak made from cross linked
polyethylene, the resulting spooge is, by definition, not molten cross
linked polyethylene.
I was under the impression that materials like dyneema/spectra were
also a version of cross linked polyethylene. Is that incorrect? Those
materials also "melt" in any common sense of that word.
DR
David Scheidt
:On Oct 12, 4:34 pm, Michael Press <rub...@pacbell.net> wrote:
:> In article
:> <4034abbc-cc82-4c57-97aa-d5a8385d4...@g8g2000yqa.googlegroups.com>,
:>
:>
:>
:>
:>
:> DirtRoadie <DirtRoa...@aol.com> wrote:
:> > On Oct 11, 5:07 pm, Michael Press <rub...@pacbell.net> wrote:
:> > > In article
:> > > <c9a2dea1-5659-4deb-bc4b-a46475ee9...@c21g2000vba.googlegroups.com>,
:>
:> > > Cross linked polymers do not melt.
:>
:> > That is a VERY broad statement. Can you provide an example?
:> > I believe there may be some examples of some heat resistant materials
:> > that vaporize before melting. But how about a link to a data sheet for
:> > some specific material? And will you concede that the statement is
:> > inaccurate if we can come up with ONE counterexample? Doesn't cross-
:> > linked polyethylene qualify?
:>
:> > I agree that carbon fiber itself is amazingly heat resistant.
:>
:> A cross linked polymer is one big molecule. When the
:> bonds are broken it becomes a different chemical
:> species; and cannot be put back together again.
:>
:> When water or iron or table salt or glass melt
:> their respective chemical properties do not change.
:OK so we are using semantic distinctions. So when I take a red-hot
:poker and push it through the shell of a kayak made from cross linked
:polyethylene, the resulting spooge is, by definition, not molten cross
:linked polyethylene.
They can become softer, and suffer mechanical damage. That's not
melting. Most varieties of cross-linke PE have a glass transition
well below their deocomposition temperature, which is why you can poke
holes in them with a hot poker.
:I was under the impression that materials like dyneema/spectra were
:also a version of cross linked polyethylene. Is that incorrect? Those
:materials also "melt" in any common sense of that word.
No, they're ultra-high-molecular-weight polyethylene fibers, woven
into rope in more or less usual fashion. They indeed melt.
PEX, the stuff used for pipes, is cross-linked polyethylene. It
doesnt' melt.
Michael is being a pedantic ass (and a *wrong* pedantic ass, which is
worse) here, because what happens to fiber reinforced epoxy when it
come apart isn't really melting. Of course, since he feels the need
to be a pdeantic ass, he can't just say that, he's got to make (an
incorrect!) catagorical statement, as if he's some sort of oracle.
--
sig 13
AMuzi
Uh, Gene is already our Oracle.
--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971
thirty-six
> "DirtRoadie" <DirtRoa...@aol.com> wrote in message
>
> news:c9a2dea1-5659-4deb...@c21g2000vba.googlegroups.com...
>
> > Anyone here ever actually melted a carbon rim from braking?
>
> > In light of the nature of the material (specifically the resin) it
> > does not surprise me that it CAN happen, but until a friend described
> > it happening to him, I don't believe I have previously heard of it
> > happening.
> > Has anyone experienced this or know someone who has?
>
> > DR
>
> Are you certain the rim "melted" rather than delaminated? Using the
> wrong brake pads for a given rim can cause them to heat up enough that
> the surface layer meant for braking can separate from the rest of the
> rim (the outer layer you see isn't usually carbon fiber but a "scrim"
> material that's designed for braking). At that point the rim can
> literally explode apart, a very bad thing. Using the recommended brake
> pads we simply don't see this happen, ever.
>
> For what it's worth I have a pair of Bontrager XXX-Lite carbon wheels
> (with carbon rims, not aluminum rims glued to carbon). They're closing
> in on 30,000 miles without incident. I haven't even touched a spoke,
> although I'm sure that, if I checked the tension, they're probably a bit
> low by now. But they ride great, they're straight, so why bother?
That would be a stupid-ass thing to do.
The descrption I heard was "got ripped up" when I heard of a carbon
fibre rim being destroyed. This could suggest the incorrect brake
block, but could also have been more general application of the
terminology. I don't know what pads were being used but the rider
was/is a semi-professional downhill racer and was using his road bike
on the the downhill tracks.
> They
> even work well in rain, although if you've got $2500 wheels, you
> probably should ride something else when it's that bad outside (at least
> if your rides include 5 miles of descending, as mine do). Their
> downside? Cost, for one. And you have to be careful about tire choice,
> because some, like Michelins, just don't like carbon bead hooks.
I heard that some of the blocks get eaten up pretty quick, would this
require a rider to carry spares at any time?
DirtRoadie
> incorrect!) catagorical statement, as if he's some sort of oracle.
Understood. Under the "Pressian" concept, ice never melts either,
because when it is heated it becomes liquid "water, " and ice, by
definition, is a solid.
I used the "melt" in only the most general sense in my original post,
although I have learned a few things peripherally as a result.
But jumping back to the original question I am most happy to (1)
either have it understood that the word "melt" includes softening or
distorting, presumably as a result of heat, or, (2) if that offends
the sensibilities of the pedantic, I withdraw the word "melt" and
rephrase my question as follows:
Anyone here ever actually had a carbon rim suffer damage, distortion
and/or failure that appeared to be the result of heat (or any other
factor) caused by rim brakes?
DR
thirty-six
Wykes butter and rasberry conserve, MmmMMmm
thirty-six
Ah, now I can answer, NO, but I know a man who has. I was a bit
confused by the word melt because it had not been used by the rider of
the failed wheel. It disintergrated, he was forced to a stop.
>
> DR
Frank Krygowski
>
>
> Michael is being a pedantic ass (and a *wrong* pedantic ass, which is
> worse) here, because what happens to fiber reinforced epoxy when it
> come apart isn't really melting.
Let's see: The polymers used to bond the fibers in carbon fiber
wheels are cross linked polymers, right? Epoxy is probably the most
common, right?
Michael said those polymers don't melt, right?
And you're saying that _because_ what happens isn't really melting,
Michael is wrong and pedantic? Odd.
I don't know what happened to the rims in question. But any of us can
squeeze some two-part epoxy into the corner of a polyethylene sandwich
bag, knead it to mix it, let it harden (and feel the heat from the
exothermic cross linking reaction), then put a match to it. You'll
see the non-crosslinked polyethylene melt, but you won't see the epoxy
melt.
BTW, that corner-of-a-baggie kneading method is the best way of
blending two-part epoxies for gluing. It beats the heck out of the
usual mix-with-a-stick method. When the two parts are blended, just
snip a millimeter off the bag's corner. Then apply the epoxy by
squeezing it out as you do with a toothpaste tube. You'll never go
back to the old way of mixing.
- Frank Krygowski
Kerry Montgomery
Frank,
I like the sound of that - will give it a try the next time I'm doing epoxy
work.
Thanks,
Kerry
Tosspot
Good Lord! You may have contributed something useful to this thread!
David Scheidt
:On Oct 12, 8:03�pm, David Scheidt <dsche...@panix.com> wrote:
:>
:>
:> Michael is being a pedantic ass (and a *wrong* pedantic ass, which is
:> worse) here, because what happens to fiber reinforced epoxy when it
:> come apart isn't really melting. �
:Let's see: The polymers used to bond the fibers in carbon fiber
:wheels are cross linked polymers, right? Epoxy is probably the most
:common, right?
:Michael said those polymers don't melt, right?
No. He said "Cross linked polymers don't melt." That's a false
statement, if there is at least one cross linked polymer that does
melt. There are whole classes of melting cross-linked polymers. No,
they don't find their way into bicycle wheels. That doesn't matter,
because that's not what he claimed.
--
sig 8
DirtRoadie
> ... But any of us can
> squeeze some two-part epoxy into the corner of a polyethylene sandwich
> bag, knead it to mix it, let it harden (and feel the heat from the
> exothermic cross linking reaction), then put a match to it. You'll
> see the non-crosslinked polyethylene melt, but you won't see the epoxy
> melt.
OK, I hate to be pedantic, but if what I see is the polyethylene
"melting" then the epoxy is also "melting" in the general sense of
that word. In fact the epoxy "bubbles," giving the appearance of
having tuned into a viscous liquid, whereas the polyethylene (assuming
that's what it is) just shrinks from its original film structure into
blobs.
Nonetheless, as I previously stated I will happily forgo use of the
word "melt" if that will help the group focus on the issue I
originally raised.
DR
DirtRoadie
> A cross linked polymer is one big molecule.
I understand that is a nice way of conceptualizing but I doubt it
stands up to serious scrutiny.
>When the
> bonds are broken it becomes a different chemical
> species; and cannot be put back together again.
So back to the kayak of cross-linked polyethylene - If I poke a hole
in the bow, then the material comprising the stern ceases to be a
crosslinked polymer?
If I cut a section from the hull and take it to a lab for analysis, do
they say "Well, if it was a cross linked polymer it is NOT any more,"
since the "molecule" is no longer intact?
DR
Joy Beeson
<DirtR...@aol.com> wrote:
> Anyone here ever actually melted a carbon rim from braking?
Plastics are a constant source of amazement to this time-traveller.
It's been years since I saw my first disposable pepper mill, but
plastic grinding teeth still boggle me -- and you *don't* get little
specks of plastic in the pepper!
Last week I bought a bacon-wrapped hunk of beef -- and the toothpick
holding the bacon in place was a barbed plastic roofing nail! While
browning the bacon after frying the meat, I absent-mindedly rolled the
meat so that the head of the roofing nail was right against the
smoking-hot skillet -- and absodamlutely *nothing* happened to it!
Next thing you know, we're going to have plastic-lined frying pans.
I'm really, really grateful for lightweight plastic spectacles that
can be cleaned with anything I'd use on glass.
--
Joy Beeson
joy beeson at comcast dot net
DirtRoadie
> Next thing you know, we're going to have plastic-lined frying pans.
I believe I heard somewhere of frying pan lined with something called
polytetrafluoroethylene.
The next step is making the entire frying pan from plastic.
DR
Frank Krygowski
Now, who was calling whom "pedantic"? I forget.
- Frank Krygowski
Tom Ace
wrote:
> Are you certain the rim "melted" rather than delaminated? Using the
> wrong brake pads for a given rim can cause them to heat up enough that
> the surface layer meant for braking can separate from the rest of the
> rim (the outer layer you see isn't usually carbon fiber but a "scrim"
> material that's designed for braking). At that point the rim can
> literally explode apart, a very bad thing. Using the recommended brake
> pads we simply don't see this happen, ever.
What does the right pad do that the wrong pad doesn't?
I mean, braking makes heat no matter what.
Tom Ace
Jobst Brandt
>> Are you certain the rim "melted" rather than delaminated? Using the
>> wrong brake pads for a given rim can cause them to heat up enough
>> that the surface layer meant for braking can separate from the rest
>> of the rim (the outer layer you see isn't usually carbon fiber but
>> a "scrim" material that's designed for braking). At that point the
>> rim can literally explode apart, a very bad thing. Using the
>> recommended brake pads we simply don't see this happen, ever.
> What does the right pad do that the wrong pad doesn't? I mean,
> braking makes heat no matter what.
I have a feeling that heat conduction through a carbon fiber laminate
is poor enough to cause melting when kinetic energy is turned into
thermal energy (aka heat). I can imagine delamination when the binder
that holds fibers together overheats... something that doesn't occur
with aluminum as rim material.
On the other hand, having witnessed years of tire blow-offs, typically
with tandems on long grades, and having it occur on my single bicycle
descending alpine passes, I see a major misunderstanding of these
occurrences. Riders have crashed fatally on Metcalf Rd south of San
Jose and on Hicks Rd. south of Los Gatos from tire blow-offs.
Tires blow off rims not from over-pressure caused by brake heating.
For proof of that we often hear of riders with 140PSI for racing and
TT competition who don't have this problem. In contrast we are aware
that tires can readily be mounted with plastic "tire irons". The
reverse action of this is caused by tire beads, both wire and Kevlar
filled, becoming soft and deformable enough to creep over edge of a
rim, a rounded bead that does not cut tires. This action doesn't take
much effort, considering how easily tires are mounted over these rim
beads.
Jobst Brandt
Jobst Brandt
>> Are you certain the rim "melted" rather than delaminated? Using the
>> wrong brake pads for a given rim can cause them to heat up enough
>> that the surface layer meant for braking can separate from the rest
>> of the rim (the outer layer you see isn't usually carbon fiber but
>> a "scrim" material that's designed for braking). At that point the
>> rim can literally explode apart, a very bad thing. Using the
>> recommended brake pads we simply don't see this happen, ever.
> What does the right pad do that the wrong pad doesn't? I mean,
> braking makes heat no matter what.
I have a feeling that heat conduction through a carbon fiber laminate
is poor enough to cause melting when kinetic energy is turned into
thermal energy (aka heat). I can imagine delamination when the binder
that holds fibers together overheats... something that doesn't occur
with aluminum as rim material.
On the other hand, having witnessed years of tire blow-offs, typically
with tandems on long grades, and having it occur on my single bicycle
descending alpine passes, I see a major misunderstanding of these
occurrences. Riders have crashed fatally on Metcalf Rd south of San
Jose and on Hicks Rd. south of Los Gatos from tire blow-offs.
Tires blow off rims not from over-pressure caused by brake heating.
For proof of that we often hear of riders with 140PSI for racing and
TT competition who don't have this problem. In contrast we are aware
that tires can readily be mounted with plastic "tire irons". The
reverse action of this is caused by tire beads, both wire and Kevlar
filled, becoming soft and deformable enough to creep over edge of a
rim, a rounded bead that does not cut tires. This action doesn't take
much effort, considering how easily tires are mounted over these rim
beads.
I suspect this will not ride well with bicycling religion where all
sorts of common knowledge seems tho have found a safe home, but I have
instruments a wheel and made tests to support this contention.
Jobst Brandt
Jobst Brandt
>> Are you certain the rim "melted" rather than delaminated? Using the
>> wrong brake pads for a given rim can cause them to heat up enough
>> that the surface layer meant for braking can separate from the rest
>> of the rim (the outer layer you see isn't usually carbon fiber but
>> a "scrim" material that's designed for braking). At that point the
>> rim can literally explode apart, a very bad thing. Using the
>> recommended brake pads we simply don't see this happen, ever.
> What does the right pad do that the wrong pad doesn't? I mean,
> braking makes heat no matter what.
I have a feeling that heat conduction through a carbon fiber laminate
is poor enough to cause melting when kinetic energy is turned into
thermal energy (aka heat). I can imagine delamination when the binder
that holds fibers together overheats... something that doesn't occur
with aluminum as rim material.
On the other hand, having witnessed years of tire blow-offs, typically
with tandems on long grades, and having it occur on my single bicycle
descending alpine passes, I see a major misunderstanding of these
occurrences. Riders have crashed fatally on Metcalf Rd south of San
Jose and on Hicks Rd. south of Los Gatos from tire blow-offs.
Tires blow off rims not from over-pressure caused by brake heating.
For proof of that we often hear of riders with 140PSI for racing and
TT competition who don't have this problem. In contrast we are aware
that tires can readily be mounted with plastic "tire irons". The
reverse action of this is caused by tire beads, both wire and Kevlar
filled, becoming soft and deformable enough to creep over edge of a
rim, a rounded bead that does not cut tires. This action doesn't take
much effort, considering how easily tires are mounted over these rim
beads.
I suspect this will not ride well with bicycling religion where all
sorts of common knowledge seems tho have found a safe home, but I have
instrumented a wheel and made tests to support this contention.
Jobst Brandt
Tom Ace
> Tom Ace wrote:
> > What does the right pad do that the wrong pad doesn't? I mean,
> > braking makes heat no matter what.
>
> I have a feeling that heat conduction through a carbon fiber laminate
> is poor enough to cause melting when kinetic energy is turned into
> thermal energy (aka heat). I can imagine delamination when the binder
> that holds fibers together overheats... something that doesn't occur
> with aluminum as rim material.
My question wasn't whether carbon fiber rims have heat-related
problems that aluminum rims don't, but rather what advantage
one pad could have over another when used with CF rims.
You've often pointed out that pads don't have what it takes
to dissipate much heat.
Tom Ace
Jobst Brandt
Brake pad material has poor thermal conductivity, therefore cooling
fins on the back of brake pads is a hoax. I believe your first
contention, that any differences one might see are heat related as
well as coefficient of friction related. In any event, the energy has
got to be converted to heat and that is through the rim.
Jobst Brandt
Tim McNamara
AMuzi <a...@yellowjersey.org> wrote:
> David Scheidt wrote:
>
> > Michael is being a pedantic ass (and a *wrong* pedantic ass, which
> > is worse) here, because what happens to fiber reinforced epoxy when
> > it come apart isn't really melting. Of course, since he feels the
> > need to be a pdeantic ass, he can't just say that, he's got to make
> > (an incorrect!) catagorical statement, as if he's some sort of
> > oracle.
>
> Uh, Gene is already our Oracle.
Accept no substitutes.
--
That'll put marzipan in your pie plate, Bingo.
Tim McNamara
David Scheidt <dsch...@panix.com> wrote:
Some of this discussion has been very interesting.
What is an example of a meltable cross-linked polymer for us
non-chemists? By this I mean one that changes from a solid to a liquid
with the application of heat, that being what I think of as melting.
There appear to be other options for defining "melting" which I had not
previously considered:
http://en.wikipedia.org/wiki/Polymer#Melting_point
"The term melting point, when applied to polymers, suggests not a
solid-liquid phase transition but a transition from a crystalline or
semi-crystalline phase to a solid amorphous phase. Though abbreviated as
simply Tm, the property in question is more properly called the
crystalline melting temperature. Among synthetic polymers, crystalline
melting is only discussed with regards to thermoplastics, as
thermosetting polymers will decompose at high temperatures rather than
melt."
Michael Press
<ee4b398b-87d2-4304...@g17g2000yqo.googlegroups.com>,
DirtRoadie <DirtR...@aol.com> wrote:
The cross links in a cross-linked polymer are covalent bonds.
Breaking them is a chemical change. If you heat a CLP and
get a puddle, it is not melting, it is a chemical change.
When it cools and solidifies it is a different chemical species.
--
Michael Press
Michael Press
<4d0c455a-b65b-4067...@j25g2000yqa.googlegroups.com>,
DirtRoadie <DirtR...@aol.com> wrote:
I said otherwise above.
--
Michael Press
Michael Press
<c77ae59e-4572-46c7...@n26g2000yqh.googlegroups.com>,
Frank Krygowski <frkr...@gmail.com> wrote:
Nor will I. Many thanks for mentioning it.
When squeezing a part out of the tube
use a toothpick to cut the stuff off
at the nozzle, wait a bit and clean
the ooze again before putting on the cap.
(Use a different toothpick for each part)
--
Michael Press
Joy Beeson
<DirtR...@aol.com> wrote:
> The next step is making the entire frying pan from plastic.
First we've got to develop a conductive plastic. Plastics that
conduct electricity have been around for decades, but I think that
they put powdered aluminum in them -- you'd be better off with solid
aluminum.
I gather that the current crop of non-stick pans are better than those
I threw out in the seventies, but I've discovered that the invention
of paper towels has made cast iron usable -- if you can find antique
pans. (The reproductions are deliberately given a grater-like texture
to make them look old timey; the old ones were ground smooth on the
inside.)
--
Joy Beeson
joy beeson at comcast dot net
http://roughsewing.home.comcast.net/
The above message is a Usenet post.
I don't recall having given anyone permission to use it on a Web site.
J. D. Slocomb
For information on "HEAT DAMAGE IN GRAPHITE EPOXY COMPOSITES" you
might try: http://www.ndt.net/article/v04n03/ntiac/ntiac.htm for a
synopsis.
Cheers,
John D. Slocomb
(jdslocombatgmail)
J. D. Slocomb
wrote:
Try http://www.ndt.net/article/v04n03/ntiac/ntiac.htm, for information
regarding degradation of epoxy composites. And yes carbon-epoxy
composites do degrade with heat.
Peter Cole
Contains the bottom line for me:
"When exposed to temperatures sufficiently high enough to cause resin
degradation, these materials experience a drop in the glass transition
temperature that effectively lowers the upper service temperature and
significantly reduces the room-temperature mechanical strength
properties of the composite [1,2]. Below a certain exposure threshold,
these composites can appear visually and microscopically to be undamaged
but, in fact, have lost a significant percentage ((60%) of their
original strength [3]. In addition, embrittlement and cracking of the
surface causes a loss in the impact strength of the material. Therefore
graphite/epoxy composite structures exposed to overheat conditions can
suffer irreversible and catastrophic damage in a very short time. "
Tim McNamara
Phil W Lee <ph...@lee-family.me.uk> wrote:
> Tom Ace <tom...@gmail.com> considered Wed, 13 Oct 2010 13:48:26 -0700
> Some pad materials conduct heat away into the metal backing
> structures better than others.
Which ones? Previous discussions have indicated that all brake pad
materials used in bicycles are poor conductors of heat (a.k.a., good
insulators). The heat has to be dispersed in the rim, something
aluminum is very good at, steel is fairly good at, but at which carbon
fiber and wood are poor. The end result is usually melting brake pads,
sometimes with bits of hot material hitting the back of your legs.
Tim McNamara
Joy Beeson <jbe...@invalid.net.invalid> wrote:
> On Wed, 13 Oct 2010 09:29:25 -0700 (PDT), DirtRoadie
> <DirtR...@aol.com> wrote:
>
> > The next step is making the entire frying pan from plastic.
>
> First we've got to develop a conductive plastic. Plastics that
> conduct electricity have been around for decades, but I think that
> they put powdered aluminum in them -- you'd be better off with solid
> aluminum.
>
> I gather that the current crop of non-stick pans are better than
> those I threw out in the seventies, but I've discovered that the
> invention of paper towels has made cast iron usable -- if you can
> find antique pans. (The reproductions are deliberately given a
> grater-like texture to make them look old timey; the old ones were
> ground smooth on the inside.)
Old cast iron pans are excellent tools for cooking non-acidic foods.
Stainless steel is better for acidic foods. A well-seasoned cast iron
frying pan if very nearly as non-stick as the best polymer-coated frying
pans.
David Scheidt
:I gather that the current crop of non-stick pans are better than those
:I threw out in the seventies, but I've discovered that the invention
:of paper towels has made cast iron usable -- if you can find antique
:pans. (The reproductions are deliberately given a grater-like texture
:to make them look old timey; the old ones were ground smooth on the
:inside.)
Much current cast iron isn't finished on the interior because that
would cost money, and consumers want cheap crap, not quality. A flap
disk on an angle grinder will do wonders for the surface. So will
plain sand paper and lots of elbow grease.
--
sig 89
Tom Sherman °_°
when used as a projectile weapon by your significant other.
--
Tom Sherman - 42.435731,-83.985007
I am a vehicular cyclist.
Jobst Brandt
> Some pad materials conduct heat away into the metal backing structures
> better than others.
None do, or they aren't bicycle rim-brake material. Cooling on the
back side of rim brakes is an old saw that has been around for a long
time from marketing hype.
It ain't so. The heat must exit through the rim. Just consider the
effective surface area of rim to pad... about 90:1. Sounds like a
vast error in perception... and physics. But then that's common in
bicycle science, judging from what appears in wreck.bike.
Tar Baby is hard at work again.
Jobst Brandt
Michael Press
Tim McNamara <tim...@bitstream.net> wrote:
Should not clean cast iron pans with water.
Unsaturated fats such as vegetable oils do
not cure the pan. A bit of tallow, suet, or
lard heated to the only starting to smoke
temperature is best.
After cooking I scrape the chunks out and put
the pan on the lowest heat to drive off all
the water (30-60 minute) cool and store. Next
use I remove any residual layer with a nylon
scraper and brown paper.
--
Michael Press
Frank Krygowski
>
>
> Some pad materials conduct heat away into the metal backing structures
> better than others.
"Better than others" does not mean "enough to make a practical
difference."
- Frank Krygowski
Chalo
>
> I know it isn't strictly applicable
> but there are such things as graphite &/or carbon brake
> rotors for certain racing and "end-of-flight" applications
> which have to handle >600C*, which should be at least
> one or two Kelvins more than a bicycle would see outside
> of an atomic hydrogen torch. So, the upshot being that
> if it did [melt] it seems like a crap bit to start with.
Carbon-carbon brake rotors don't use a resin matrix, except inasmuch
as it may have started out as a resin before being converted to more
or less pure carbon. As used, they consist of carbon fibers embedded
in a graphite matrix. They can burn in air at something like 1500F,
but they can't melt.
Chalo
Joy Beeson
wrote:
> Should not clean cast iron pans with water.
> Unsaturated fats such as vegetable oils do
> not cure the pan. A bit of tallow, suet, or
> lard heated to the only starting to smoke
> temperature is best.
>
> After cooking I scrape the chunks out and put
> the pan on the lowest heat to drive off all
> the water (30-60 minute) cool and store. Next
> use I remove any residual layer with a nylon
> scraper and brown paper.
Vegetable fats turn into varnish as easily as any other fat -- as
anyone who has freed up a sticky derailleur with sun-tan oil is well
aware. (But it got the rider home, and she knew to clean it out
before it had had time to set.)
I wipe a used skillet with a paper towel. If stuff is stuck, I scrape
it off with a spatula and wipe again. If there is congealed fat that
sticks the towel to the skillet, I heat the skillet and wipe out the
softened fat. If heating it doesn't work, I pour in a little oil,
which always dissolves the goo and allows me to wipe the skillet
clean.
And if I can't scrape the skillet smooth, I put it into the sink and
run water on it while I scrub it with a harsh abrasive called a
"stainless steel sponge". (It's coils of wire that look like lathe
scrap. I never use it on anything less hard than cast iron.) Then I
wipe the skillet very thoroughly with paper towels and store it in a
pilot-lit oven. I may warm the skillet a bit if I'm not sure of my
toweling. (Ironware that isn't used very often gets moved into the
cupboard the next time I use the oven.)
If a cooking surface isn't black and shiny, I put a drop of oil on it
and wipe it around. A freshly-oiled skillet is plenty non-stick, and
a "season" that builds up naturally is much harder than that created
by smoke-producing troublesome tricks. I used to keep oil with
lecithin in it for seasoning skillets, but I've been using plain oil
for some time now and it seems to work fine.
Ah! I'm almost certainly not going to use my bake kettle any more
this season -- I've already baked a batch of rolls in the gas oven.
Time to clean the ash off the lid and legs, and oil both pot and lid
to keep them from rusting in the garage during the winter. (Gets
pretty damp out there when we park a car inside.) Next spring, I'll
rub olive oil on the inside and wipe it off before using the kettle
for the first time.
Peter Cole
All of which is why I retired my cast iron pans a long time ago.
These days virtually all I use is All-Clad -- aluminum core between
stainless skins, everything will go from stove to oven, will cook
anything.
> Ah! I'm almost certainly not going to use my bake kettle any more
> this season -- I've already baked a batch of rolls in the gas oven.
> Time to clean the ash off the lid and legs, and oil both pot and lid
> to keep them from rusting in the garage during the winter. (Gets
> pretty damp out there when we park a car inside.) Next spring, I'll
> rub olive oil on the inside and wipe it off before using the kettle
> for the first time.
Why a bake kettle? I lay off baking in the heat anyway, I can't imagine
an open fire. I don't even like to BBQ.
mike.a...@gmail.com
wrote:
> On Oct 10, 10:12 pm, DirtRoadie <DirtRoa...@aol.com> wrote:
>
> > Anyone here ever actually melted a carbon rim from braking?
>
> > In light of the nature of the material (specifically the resin) it
> > does not surprise me that it CAN happen, but until a friend described
> > it happening to him, I don't believe I have previously heard of it
> > happening.
> > Has anyone experienced this or know someone who has?
>
> > DR
>
> Yes, I have one.
>
> Brakes can get hot, and can be often or never a problem; obviously
> depending on terrain, rider weight, probably other factors.
>
> Once the resin breaks down the rim surface can distort into odd
> surface ripples (shape depends on layup I guess). I've seen other rims
> do this too. Usually asian made; US-made rims seem to use better
> resin...?
>
> Another reason to stick with aluminum brake tracks IMHO.
At least the carbon rim did not blow up the tire with high pressure
due to heating by the rim, like aluminum brakes do.
Peter Cole
Don't you listen to Jobst?
Michael Press
Joy Beeson <jbe...@invalid.net.invalid> wrote:
> On Thu, 14 Oct 2010 16:43:53 -0700, Michael Press <rub...@pacbell.net>
> wrote:
>
> > Should not clean cast iron pans with water.
> > Unsaturated fats such as vegetable oils do
> > not cure the pan. A bit of tallow, suet, or
> > lard heated to the only starting to smoke
> > temperature is best.
> >
> > After cooking I scrape the chunks out and put
> > the pan on the lowest heat to drive off all
> > the water (30-60 minute) cool and store. Next
> > use I remove any residual layer with a nylon
> > scraper and brown paper.
>
> Vegetable fats turn into varnish as easily as any other fat
Animal fats do not turn into sticky varnish.
That is why I recommend them.
Way more trouble than I take. An ancestor put her ironware
directly in the wood fire to clean them
--
Michael Press
Jobst Brandt
>>> Anyone here ever actually melted a carbon rim from braking?
>>> In light of the nature of the material (specifically the resin) it
>>> does not surprise me that it CAN happen, but until a friend
>>> described it happening to him, I don't believe I have previously
>>> heard of it happening.
>>> Has anyone experienced this or know someone who has?
>> Yes, I have one.
>> Brakes can get hot, and can be often or never a problem; obviously
>> depending on terrain, rider weight, probably other factors.
>> Once the resin breaks down the rim surface can distort into odd
>> surface ripples (shape depends on layup I guess). I've seen other
>> rims do this too. Usually Asian made; US-made rims seem to use
>> better resin...?
>> Another reason to stick with aluminum brake tracks IMHO.
> At least the carbon rim did not blow up the tire with high pressure
> due to heating by the rim, like aluminum brakes do.
I guess you missed the item on tire blow-off that does not occur from
heat induced pressure but rather from pliable softening of tire bead
that surrounds a steel or Kevlar bead strand. The tire comes off in
reverse of installing it with tire a lever. I have instrumented and
tested this effect and, in spite of high pressures, did not get a
blow-off because the time of heating was insufficient to induce tire
bead flow over a smoothly curved aluminum edge of the rim. That is
the cause of tire blow-off rather than pressure.
Jobst Brandt
thirty-six
Er no, you switched from using velox rim tape to torrelli because you
couldn't bear to use a pair of scissors to fit the velox tape,
obviously 'those ancients designed it wrong'. The overlap of fabric
rim tape is frequently the initiation point for tyres to creep off.
In the real world one can safely say that the overlap causes the
demounting of the tyre.
Jobst Brandt
>>>> Yes, I have one.
> Er no, you switched from using Velox rim tape to Torelli because you
> couldn't bear to use a pair of scissors to fit the Velox tape,
> obviously 'those ancients designed it wrong'. The overlap of fabric
> rim tape is frequently the initiation point for tyres to creep off.
> In the real world one can safely say that the overlap causes the
> demounting of the tyre.
How do you explain tires blowing off on Torelli, Ritchey, Rolf, Trek
and other seamless semi stretch rim tapes that have no "overlap" ends?
How did you determine that your assessment is accurate? Did you
perform any tests? I have been involved in analyzing enough such
events to discover that it does not occur as folklore has it.
Jobst Brandt
Joy Beeson
<peter...@verizon.net> wrote:
> Why a bake kettle? I lay off baking in the heat anyway, I can't imagine
> an open fire. I don't even like to BBQ.
*Because* I don't like baking in the heat. Baking my bread on the
hearth in front of the outdoor fireplace keeps the house cool.
(The fireplace is too narrow to admit the kettle comfortably, so I
built a hearth just a little wider than the kettle nearby, and shovel
coals from the fireplace to the hearth when it's time to heat the
kettle. Easier to regulate the heat when the main fire is elsewhere
anyway.)
--
Joy Beeson
joy beeson at comcast dot net
Peter Cole
> On Fri, 15 Oct 2010 13:18:36 -0400, Peter Cole
> <peter...@verizon.net> wrote:
>
>> Why a bake kettle? I lay off baking in the heat anyway, I can't imagine
>> an open fire. I don't even like to BBQ.
>
> *Because* I don't like baking in the heat. Baking my bread on the
> hearth in front of the outdoor fireplace keeps the house cool.
Hmmm... I just go to salads. I don't even like making pasta in the
humidity. I have toyed with the idea of an outside pizza oven though. My
neighborhood is dense enough that even BBQ can be a nuisance, though.
BTW, as for plastics and cooking, the fairly recent appearance of all
the silicone utensils and baking sheets is another example. I haven't
got any yet -- it just seems wrong to put plastic in the oven.
thirty-six
Gammy-handed installation, use of levers, bent wires. Failure to
clean the tyre and rim before fitting. You know, the dreaded mould-
release. It was not such a problem when three seperate rubbers were
used on the surface of a tyre, but with a single mould application
excessive waxing is used.
> How did you determine that your assessment is accurate? Did you
INspection of a blown tyre showed the overlap of rim tape. Cut rim
tape and re-installed tyre in exactly the same position with exactly
the same procedure, inflated tyre past previous pressure by some
decent amount and left overnight. The tyre never again came off,
neither did any subsequent tyres of different branding. I've done the
same procedure with friend's wheels and again no further problems.
> perform any tests? I have been involved in analyzing enough such
> events to discover that it does not occur as folklore has it.
You prefer it not to. Your obscenities, as in 'folklore' are tiring
thirty-six
> On 10/16/2010 1:03 AM, Joy Beeson wrote:
>
> > On Fri, 15 Oct 2010 13:18:36 -0400, Peter Cole
>
> >> Why a bake kettle? I lay off baking in the heat anyway, I can't imagine
> >> an open fire. I don't even like to BBQ.
>
> > *Because* I don't like baking in the heat. Baking my bread on the
> > hearth in front of the outdoor fireplace keeps the house cool.
>
> Hmmm... I just go to salads. I don't even like making pasta in the
> humidity. I have toyed with the idea of an outside pizza oven though. My
> neighborhood is dense enough that even BBQ can be a nuisance, though.
>
> BTW, as for plastics and cooking, the fairly recent appearance of all
> the silicone utensils and baking sheets is another example. I haven't
> got any yet -- it just seems wrong to put plastic in the oven.
Silicone spat's are ideal for saucepans, saving you having to shape a
spoon to fit the pan. They also make excellent pot stands, conserving
pot heat and protecting work surface. I'm not convinced silicone
rubber has any purpose in the oven in the offerings so far presented.
DirtRoadie
wrote:
> "DirtRoadie" <DirtRoa...@aol.com> wrote in message
>
> news:c9a2dea1-5659-4deb...@c21g2000vba.googlegroups.com...
>
> > Anyone here ever actually melted a carbon rim from braking?
>
>
> wrong brake pads for a given rim ...
I had a chance to see the rim in question- a clincher. Roughly a foot
of the sidewall/bead (just one side) was simply bowed out as if it
had experienced an excessive side force. Picture the normal "U shaped
channel where one side is angled out as if in a "V." No suggestion of
delamination. There is some possibilty of a crack right at the point
where the sidewall meets the seat.
There are other spots around the rim where the braking surface shows
VERY slight ripples/bumps.
The rim remained ridable (I'm not saying "safely ridable," just
ridable) once the brake pad was moved to contact the rim below the
bulge.
Related anecdote - This occurred on a supported ride on some very
hilly terrain and the word was that the support stations saw more
than one of these incidents.
DR
Pads in use were the yellow Swiss Stop variety - for carbon.
Joy Beeson
wrote:
> Animal fats do not turn into sticky varnish.
> That is why I recommend them.
Very thin layers of *any* fat turn into hard varnish, much more
durable than the thick layer of soft charcoal my outdoor-cooking
teacher bragged about filling her house with smoke to produce. She
actually refused to let us stir the venison stew, knowing that that
meant it would burn on the bottom, because stirring would mix the soft
charcoal she called "season" into the food!
I learned a lot -- specifically, how to bake bread outdoors when it's
too hot to heat up the gas stove -- but she didn't know *anything*
about ironware. When cleaning up, I saturated a paper towel while
drying an iron pot, turned around to get another one -- and she took
that opportunity to grab the half-dried pot and smear on oil to seal
the dampness in!
> Way more trouble than I take. An ancestor put her ironware
> directly in the wood fire to clean them
My bake kettle comes out of a wood fire fairly dirty.
Cleaning is nearly always a quick swipe with a paper towel. Except
when I've been frying something greasy, and leave paper towels in for
five minutes each to soak it up.
My ironware is easier to take care of than my stainless-and-aluminum
cookware. Burn something on an iron griddle, fifteen seconds with a
stainless-steel sponge. Burn a stainless-steel pot, boil water in
it, fool around with mild abrasives, and maybe end up with stained
stainless.
--
Joy Beeson
joy beeson at comcast dot net
Tim McNamara
Joy Beeson <jbe...@invalid.net.invalid> wrote:
> On Fri, 15 Oct 2010 11:28:38 -0700, Michael Press
> <rub...@pacbell.net> wrote:
>
> > Animal fats do not turn into sticky varnish. That is why I
> > recommend them.
>
> Very thin layers of *any* fat turn into hard varnish, much more
> durable than the thick layer of soft charcoal my outdoor-cooking
> teacher bragged about filling her house with smoke to produce. She
> actually refused to let us stir the venison stew, knowing that that
> meant it would burn on the bottom, because stirring would mix the
> soft charcoal she called "season" into the food!
>
> I learned a lot -- specifically, how to bake bread outdoors when it's
> too hot to heat up the gas stove -- but she didn't know *anything*
> about ironware. When cleaning up, I saturated a paper towel while
> drying an iron pot, turned around to get another one -- and she took
> that opportunity to grab the half-dried pot and smear on oil to seal
> the dampness in!
>
> > Way more trouble than I take. An ancestor put her ironware directly
> > in the wood fire to clean them
>
> My bake kettle comes out of a wood fire fairly dirty.
Is that the same thing as a Dutch oven?
> Cleaning is nearly always a quick swipe with a paper towel. Except
> when I've been frying something greasy, and leave paper towels in for
> five minutes each to soak it up.
>
> My ironware is easier to take care of than my stainless-and-aluminum
> cookware. Burn something on an iron griddle, fifteen seconds with a
> stainless-steel sponge. Burn a stainless-steel pot, boil water in
> it, fool around with mild abrasives, and maybe end up with stained
> stainless.
Make a paste of cream of tartar and vinegar. Excellent cleaning agent,
non-toxic and works great on stovetops, pots and pans, etc.
http://www.ehow.com/way_5554267_cleaning-cream-tartar.html
http://www.ehow.com/how_2081866_find-more-uses-cream-tartar.html
Joy Beeson
<tim...@bitstream.net> wrote:
> > My bake kettle comes out of a wood fire fairly dirty.
>
> Is that the same thing as a Dutch oven?
Yes. I hang out on a re-enactor's mailing list, where "dutch oven" is
an ambiguous term, and got into the habit of using the unambiguous
"bake kettle".
For example, in the forties, a "dutch oven" was a big pot used for
making jam, cooking soup for a re-union, etc. "Dutch oven" can also
mean a reflector oven, or an oven which is Dutch.
I once made soup in my -- big iron three-leg kettle with dished lid
for holding coals -- but keeping a small fire going all day was very
tedious. It would be easier now that I also have a hearth; I could
have a larger fire farther from the kettle. But we are now in the
season when a pot of soup simmering on the gas stove is a good thing,
and I'll have forgotten about it by spring.
Tim McNamara
Joy Beeson <jbe...@invalid.net.invalid> wrote:
> big iron three-leg kettle with dished lid for holding coals
That's my notion of a Dutch oven, conditioned by years of Boy Scout
camping. I baked many a peach cobbler (using Bisquick) in one of those.
These days I have a similar cast iron pot without the legs and with a
domed lid which I use on the stovetop and in the oven.
My cast iron frying pan is probably my favorite piece of cookware, I've
had it for nearly 30 years (and got it for free from a friend who was
"upgrading").
Frank Krygowski
> On Sat, 16 Oct 2010 22:59:48 -0500, Tim McNamara
>
> <tim...@bitstream.net> wrote:
> > > My bake kettle comes out of a wood fire fairly dirty.
>
> > Is that the same thing as a Dutch oven?
>
> Yes. I hang out on a re-enactor's mailing list, where "dutch oven" is
> an ambiguous term, and got into the habit of using the unambiguous
> "bake kettle".
A few years ago, passing through Lewis & Clark Caverns state park in
Montana on a bike tour, we saw there was to be a program on Dutch oven
cooking. Sounded interesting!
The local guy doing the program said he was going to show you could
cook anything using a Dutch oven - and he proved it. His Dutch oven
was hanging from a tripod over a propane burner, filled with cooking
oil (or maybe lard?) bubbling away. And he cooked chicken, he cooked
beef, he cooked potatoes, he cooked convenience store dessert cakes -
heck, he'd have cooked a rattlesnake if we could have caught one.
He'd just toss anything into the boiling grease then pull it out a
minute later. "That's good eatin'."
And the French think our food is unsophisticated.
- Frank Krygowski
Norman
Mmm, pizza.
I do have to be honest: if you battered and deep-fried a fistful
of shirt buttons, I'd probably eat it.
thirty-six
Ah, your origins are Glasweigan?
Tom Sherman °_°
> On Sat, 16 Oct 2010 22:59:48 -0500, Tim McNamara
> <tim...@bitstream.net> wrote:
>
>>> My bake kettle comes out of a wood fire fairly dirty.
>>
>> Is that the same thing as a Dutch oven?
>
> Yes. I hang out on a re-enactor's mailing list, where "dutch oven" is
> an ambiguous term, and got into the habit of using the unambiguous
> "bake kettle".
>
> For example, in the forties, a "dutch oven" was a big pot used for
> making jam, cooking soup for a re-union, etc. "Dutch oven" can also
"Dutch oven" is also slang for pulling the blankets over your bed
co-occupant's head after you break wind. [1]
Had to Google it after a cow-orker (sic) asked if I knew what it meant.
Norman
A word of warning: women do not find this amusing in the least.
And some women can punch hard enough to make your urine
pink.
Tom Sherman °_°
If I was a woman in someone else's bed and they did that to me, I would
leave the bed permanently.
James
<twshermanREM...@THISsouthslope.net> wrote:
Better to find a woman who enjoys fart humor.
JS.
James
> On Oct 19, 12:30 am, Tom Sherman °_°
> > "Dutch oven" is also slang for pulling the blankets over your bed
> > co-occupant's head after you break wind. [1]
>
> > Had to Google it after a cow-orker (sic) asked if I knew what it meant.
>
> A word of warning: women do not find this amusing in the least.
> And some women can punch hard enough to make your urine
> pink.
Speaking from experience?
JS
Mike Jacoubowsky
news:3f7ce802-04cd-4eaf...@u10g2000yqk.googlegroups.com...
On Oct 11, 9:15 pm, "Mike Jacoubowsky" <Mi...@ChainReaction.com>
wrote:
> Are you certain the rim "melted" rather than delaminated? Using the
> wrong brake pads for a given rim can cause them to heat up enough that
> the surface layer meant for braking can separate from the rest of the
> rim (the outer layer you see isn't usually carbon fiber but a "scrim"
> material that's designed for braking). At that point the rim can
> literally explode apart, a very bad thing. Using the recommended brake
> pads we simply don't see this happen, ever.
======
What does the right pad do that the wrong pad doesn't?
I mean, braking makes heat no matter what.
Tom Ace
======
I don't understand the mechanism at work, but it's demonstrably the case
that the yellow Swisstop "carbon compatible" brake pads will destroy a
Bontrager carbon rim when used on a gnarly descent, while the Bontrager
cork-style pads do not. Is it a function of abrasiveness, heat
dissipation, or??? I don't know. It's not likely an issue for most,
since it requires a couple miles of hard braking (the sort of thing
you'd do on a 10%+ descent) for a few miles. You don't get that in
racing, and most won't see that in normal use.
--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com
DirtRoadie
wrote:
> "Tom Ace" <tom...@gmail.com> wrote in message
>
> news:3f7ce802-04cd-4eaf...@u10g2000yqk.googlegroups.com...
> On Oct 11, 9:15 pm, "Mike Jacoubowsky" <Mi...@ChainReaction.com>
> wrote:
>
> > Are you certain the rim "melted" rather than delaminated? Using the
> > wrong brake pads for a given rim can cause them to heat up enough that
> > the surface layer meant for braking can separate from the rest of the
> > rim (the outer layer you see isn't usually carbon fiber but a "scrim"
> > material that's designed for braking). At that point the rim can
> > literally explode apart, a very bad thing. Using the recommended brake
> > pads we simply don't see this happen, ever.
>
> ======
> What does the right pad do that the wrong pad doesn't?
> I mean, braking makes heat no matter what.
>
> Tom Ace
> ======
> ... it's demonstrably the case that the yellow Swisstop "carbon compatible" brake pads will destroy a
> Bontrager carbon rim when used on a gnarly descent, while the Bontrager > cork-style pads do not.
That smells like "product recall" or "class action suit."
Could you elaborate on what constitutes "it's demonstrably the
case...?"
Thanks
DR
James
A mate just got back from the world masters cycling championships. He
destroyed a carbon rim of another brand (not mentioning names) using
Zipp carbon pads over some wicked mountains. He's still using the
Zipp 404s that survived the same descents in previous years.
JS.
Tom Ace
wrote:
> I don't understand the mechanism at work, but it's demonstrably the case
> that the yellow Swisstop "carbon compatible" brake pads will destroy a
> Bontrager carbon rim when used on a gnarly descent, while the Bontrager
> cork-style pads do not. Is it a function of abrasiveness, heat
> dissipation, or??? I don't know. It's not likely an issue for most,
> since it requires a couple miles of hard braking (the sort of thing
> you'd do on a 10%+ descent) for a few miles. You don't get that in
> racing, and most won't see that in normal use.
I have no reason to doubt that you are accurately reporting
what you have seen. But I can't draw much of a conclusion
from this other than that the rims do sometimes fall apart
from heavy braking -- which is worth knowing.
Tom Ace
Jobst Brandt
>> Are you certain the rim "melted" rather than delaminated? Using
>> the wrong brake pads for a given rim can cause them to heat up
>> enough that the surface layer meant for braking can separate from
>> the rest of the rim (the outer layer you see isn't usually carbon
>> fiber but a "scrim" material that's designed for braking). At that
>> point the rim can literally explode apart, a very bad thing. Using
>> the recommended brake pads we simply don't see this happen, ever.
> What does the right pad do that the wrong pad doesn't?
> I mean, braking makes heat no matter what.
> I don't understand the mechanism at work, but it's demonstrably the
> case that the yellow Swisstop "carbon compatible" brake pads will
> destroy a Bontrager carbon rim when used on a gnarly descent, while
> the Bontrager cork-style pads do not. Is it a function of
> abrasiveness, heat dissipation, or??? I don't know. It's not likely
> an issue for most, since it requires a couple miles of hard braking
> (the sort of thing you'd do on a 10%+ descent) for a few miles. You
> don't get that in racing, and most won't see that in normal use.
Watching carbon fiber equipment perform miserably while the faithful
defend this inappropriate material for unexplained reasons, is getting
farther into the religious realm. It was not without merit that steel
spokes, aluminum rims, and metal pedals and cranks were developed with
good reliability. Is it the "space age" epithet that makes the CF
stuff so sacred (and expensive)? Bring back the SST.
Brakes want pads that survive friction and heat, rims want a material
that has a good sliding surface for wear and heat dissipation, beyond
supporting spoke loads with safe tire retention. I don't see that CF
does any of that from what is presented here. "Black is beautiful" is
getting old.
Jobst Brandt
DirtRoadie
Ah yes! Please help us define that bright line in time at which all
improvement in materials ceased. Apparently it was at some point
AFTER aluminum came into use for rims, yet is behind us now. Tell us
more about YOUR "fundamentalist" religious zealotry.
DR
James
What is the thermal conductivity of CF?
Al is 239 W/m.K
What is the melting temperature, or temperature at which the epoxy in
CF degrades?
Al is about 660 deg. C
I tend to agree with Jobst. CF is a nice material, but not
necessarily applied to the right task in bicycle rims.
JS.
DirtRoadie
And by your estimation because CF may have limitations/weaknesses
NOW, it should be abandoned? Might it be appropriate to investigate
using different matrix materials that would be better suited to
extreme braking, since that seems to be the primary issue with CF for
rims? In other words if there is room to improve the material why
ignore it?. Typically the matrix material makes up something like 35%
of the composite anyhow.
CF itself is strong and highly resistant to abrasion.
Perhaps heat conductive brake pads are another place to look for more
effective braking performance.
As I noted at the start of this thread the failure of carbon rims from
braking hardly seems to be universal, although it is known to happen.
Note MJ's comments about using carbon rims.
I don't use carbon rims and I won't ask you to, but I think under
Jobst's religion we would have stopped working toward any innovation
in the days of the penny farthing.
DR
David Scheidt
:On Oct 26, 3:22�am, DirtRoadie <DirtRoa...@aol.com> wrote:
:> On Oct 25, 3:06�am, Jobst Brandt <jbra...@sonic.net> wrote:
:> > Watching carbon fiber equipment perform miserably while the faithful
:> > defend this inappropriate material for unexplained reasons, is getting
:> > farther into the religious realm. �It was not without merit that steel
:> > spokes, aluminum rims, and metal pedals and cranks were developed with
:> > good reliability. �Is it the "space age" epithet that makes the CF
:> > stuff so sacred (and expensive)? �Bring back the SST.
:>
:> Ah yes! Please help us define that bright line in time at which all
:> improvement in materials ceased. �Apparently it was at some point
:> AFTER aluminum came into use for rims, yet is behind us now. Tell us
:> more about YOUR "fundamentalist" religious zealotry.
:>
:> DR
:What is the thermal conductivity of CF?
Depends greatly on the particular fibers, and the direction you're
moving the heat. It ranges from several times better than copper
(which is, itself, several times more conductive than aluminum) to
really stinking bad.
:Al is 239 W/m.K
:What is the melting temperature, or temperature at which the epoxy in
:CF degrades?
well, it doesn't ever melt, at least not in air. Temperature limits
depend on the epoxy in use. I expect there is a lot of variation from
wheel to wheel.
--
sig 40
James
> On Oct 25, 2:53 pm, James <james.e.stew...@gmail.com> wrote:
>
>
>
> > On Oct 26, 3:22 am, DirtRoadie <DirtRoa...@aol.com> wrote:
>
> > > On Oct 25, 3:06 am, Jobst Brandt <jbra...@sonic.net> wrote:
> > > > Watching carbon fiber equipment perform miserably while the faithful
> > > > defend this inappropriate material for unexplained reasons, is getting
> > > > farther into the religious realm. It was not without merit that steel
> > > > spokes, aluminum rims, and metal pedals and cranks were developed with
> > > > good reliability. Is it the "space age" epithet that makes the CF
> > > > stuff so sacred (and expensive)? Bring back the SST.
>
> > > Ah yes! Please help us define that bright line in time at which all
> > > improvement in materials ceased. Apparently it was at some point
> > > AFTER aluminum came into use for rims, yet is behind us now. Tell us
> > > more about YOUR "fundamentalist" religious zealotry.
>
> > > DR
>
> > What is the thermal conductivity of CF?
>
> > Al is 239 W/m.K
>
> > What is the melting temperature, or temperature at which the epoxy in
> > CF degrades?
>
> > Al is about 660 deg. C
>
> > I tend to agree with Jobst. CF is a nice material, but not
> > necessarily applied to the right task in bicycle rims.
>
> And by your estimation because CF may have limitations/weaknesses
> NOW, it should be abandoned?
Abandoned? No, but I think it needs improvement. Some carbon pads
destroy some carbon rims, while not others during heavy prolonged
braking. The less robust seem to recommend cork pads I think, that
are about as useless as polished steel rims in wet weather, and no
where near as good as Al.
I think the only advantage CF has at the moment is weight. I'd prefer
to be able to stop.
> Might it be appropriate to investigate
> using different matrix materials that would be better suited to
> extreme braking, since that seems to be the primary issue with CF for
> rims? In other words if there is room to improve the material why
> ignore it?.
By all means, and I never suggested ignoring CF.
> Typically the matrix material makes up something like 35%
> of the composite anyhow.
> CF itself is strong and highly resistant to abrasion.
> Perhaps heat conductive brake pads are another place to look for more
> effective braking performance.
Or bond an Al strip into the CF.
> As I noted at the start of this thread the failure of carbon rims from
> braking hardly seems to be universal, although it is known to happen.
True. It takes heavy braking possibly with incorrect pads.
I've also heard of several people de-laminating the CF when removing a
well glued single.
> Note MJ's comments about using carbon rims.
>
> I don't use carbon rims and I won't ask you to, but I think under
> Jobst's religion we would have stopped working toward any innovation
> in the days of the penny farthing.
Hardly.
JS.
James
> James <james.e.stew...@gmail.com> wrote:
> :What is the thermal conductivity of CF?
>
> Depends greatly on the particular fibers, and the direction you're
> moving the heat. It ranges from several times better than copper
> (which is, itself, several times more conductive than aluminum) to
> really stinking bad.
>
> :Al is 239 W/m.K
Cu is 385 W/m.K. These are both for the material in the annealed
state. There is not a several times difference between Al and Cu.
Thanks for the information on CF heat conduction.
> :What is the melting temperature, or temperature at which the epoxy in
> :CF degrades?
>
> well, it doesn't ever melt, at least not in air. Temperature limits
> depend on the epoxy in use. I expect there is a lot of variation from
> wheel to wheel.
So the rims that behave badly may have inappropriate fibre material,
or layup or epoxy or a combination of the three.
Boy, it's a mine field for the consumer.
JS.
J. D. Slocomb
It appears that better terminology might be useful. Carbon Fiber brake
disks were introduced into F1 racing by Brabham in 1976 and continue
in use to the present. The major caveat in using this type of disk is
the elevated temperatures needed for effective braking forces to be
developed, so obviously "Carbon Fiber" is an insufficient description
for dissection of the problem
Epoxy, as another poster mentioned, varies in strength viv-a-vis
temperatures one of the major sellers of epoxy, West System, seems to
refer to 230 degrees F. as a "damaging temperature".
(if WEST SYSTEM epoxy is not exposed to damaging heat (exceeding 230F
for extended periods), it will return to full strength when cooled to
room temperature.)
Seemingly, carbon fiber bicycle manufacturer is not subject to any
standards (or perhaps I just cannot locate the applicable standard) so
it is possible that various bonding methods are used by various makers
to fabricate wheels and thus performance of different makes of wheels
may vary considerably.
Cheers,
John D. Slocomb
(jdslocombatgmail)
Frank Krygowski
> On Oct 25, 2:53 pm, James <james.e.stew...@gmail.com> wrote:
>
> > I tend to agree with Jobst. CF is a nice material, but not
> > necessarily applied to the right task in bicycle rims.
>
> And by your estimation because CF may have limitations/weaknesses
> NOW, it should be abandoned? Might it be appropriate to investigate
> using different matrix materials that would be better suited to
> extreme braking, since that seems to be the primary issue with CF for
> rims? In other words if there is room to improve the material why
> ignore it?.
Personally, I ignore it. Here's why:
There really is such a thing as diminishing returns. It's rare for
any improvement or benefit to come without some detriment, and I think
carbon fiber for wheels is way past the point where the detriments
outweigh the benefits for almost all riders.
Suppose you had CF wheels that - like most other wheels - were safe to
ride down most mountain downhills, even if you were a heavy rider.
There would certainly still be the cost detriment, right?
OK, but say you're one of those guys for whom money is no object.
You'll spend any amount to have the latest thing Buycycling magazine
touts. It's just worth it to you. And so is having to fuss with
special brake shoes, and worrying about undetectable damage, etc.
What, then, are you really getting?
Your wheels are a bit lighter. As a guess, that means you'll climb a
hill about 1/4 percent faster. And if you sprint against your buddy
toward the next telephone pole, you'll be maybe 1/4 percent faster.
That's not a lot of benefit. If you are (or are pretending to be) a
contender for a Tour de France stage, maybe it's worth it to you. But
anyone's got to admit, it's not a LOT of benefit.
And that's where we are - a point way deep into Diminishing Returns.
Each gram that gets taken off a bike is harder and harder to achieve.
It's more expensive, and it comes with more reliability problems and
more service quirks and more catastrophic failures. We're way past
seeing benefits like we got when we moved from steel cranks to
aluminum ones, or steel rims to aluminum ones.
And what would be the ultimate? It would be truly weightless wheels,
right?
Try calculating how much your climbs or sprints would improve if your
wheels were absolutely weightless. It's going to be less than most
people think. It's just way down the cost-benefit scale. It's way
into diminishing returns.
- Frank Krygowski
Joy Beeson
<DirtR...@aol.com> wrote:
> Ah yes! Please help us define that bright line in time at which all
> improvement in materials ceased. Apparently it was at some point
> AFTER aluminum came into use for rims, yet is behind us now. Tell us
> more about YOUR "fundamentalist" religious zealotry.
In other words, you have nothing to say in favor of carbon rims except
that they are the latest fashion.
DirtRoadie
> On Mon, 25 Oct 2010 09:22:53 -0700 (PDT), DirtRoadie
>
> > Ah yes! Please help us define that bright line in time at which all
> > improvement in materials ceased. Apparently it was at some point
> > AFTER aluminum came into use for rims, yet is behind us now. Tell us
> > more about YOUR "fundamentalist" religious zealotry.
>
> In other words, you have nothing to say in favor of carbon rims except
> that they are the latest fashion.
I don't believe that's what I said at all. Please read again unless
this is matter of religious conviction for you, too.
Carbon composites have benefits and drawbacks, and room to improve on
the drawbacks. Things evolve with time and not every step is forward.
But I remain open.
DR
DirtRoadie
> On Oct 25, 5:22 pm, DirtRoadie <DirtRoa...@aol.com> wrote:
>
> > On Oct 25, 2:53 pm, James <james.e.stew...@gmail.com> wrote:
>
> > > I tend to agree with Jobst. CF is a nice material, but not
> > > necessarily applied to the right task in bicycle rims.
>
> > And by your estimation because CF may have limitations/weaknesses
> > NOW, it should be abandoned? Might it be appropriate to investigate
> > using different matrix materials that would be better suited to
> > extreme braking, since that seems to be the primary issue with CF for
> > rims? In other words if there is room to improve the material why
> > ignore it?.
>
> Personally, I ignore it. Here's why:
[snip]
You could have easily just said YOUR mind is made up (based upon the
facts which you choose and/or make up) and left it at that.
I understand. There's no point in trying to improve ANYTHING because
it can NEVER amount to "benefits like we got when we moved from steel
cranks to aluminum ones." That was, what 20-30- 40% "improvement?"
DR
Mike Jacoubowsky
news:d924aaa9-ccb5-456e...@l14g2000yqb.googlegroups.com...
========
That smells like "product recall" or "class action suit."
Could you elaborate on what constitutes "it's demonstrably the
case...?"
Thanks
DR
========
A recall of the offending brake pads, or just label them with a warning
that you need to make sure your rims and pads are deemed compatible by
the manufacturer?
Mike Jacoubowsky
news:4cc548ac$0$1631$742e...@news.sonic.net...
Jobst: You know where and how I ride. I am not easy on wheels, yet these
are closing in on 30k miles (may actually be there already, there's
probably a 5% margin of error in my mileage estimate due to use of the
rain bike vs primary). They have literally never been touched by a spoke
wrench. Braking works great wet or dry, although I try not to use them
much in the wet, fearing that I might pick something up in the pads that
would be hostile to the rim... and the cost of replacing a carbon rim is
obviously far greater than with aluminum.
Where is this "miserable" performance you speak of? How am I deceiving
myself? Is some gnome stealing my bike in the middle of the night and
resurfacing them?
Yes, bikes were originally developed using steel spokes and metal pedals
and cranks. Obviously, back in the mid-1800s, the engineers were much
smarter than those around today, and that's why they chose to use steel
instead of carbon fiber.
DirtRoadie
wrote:
> "DirtRoadie" <DirtRoa...@aol.com> wrote in message
I was just suggesting the the issue of a pad manufacturer claiming
"compatible with carbon rims" when they really should be saying
"compatible with carbon rims, well SOME carbon rims."
One starts to wonder what sort of exorbitant fees rim makers would
start charging to "approve" pads and whether such agreements would run
afoul of Magnuson–Moss:
http://en.wikipedia.org/wiki/Magnuson–Moss_Warranty_Act#Requirements.
You described:
>the yellow Swisstop "carbon compatible" brake pads will destroy a Bontrager carbon rim ...
Can you elaborate a bit on this? Inquiring minds want to know.
DR
Mike Jacoubowsky
news:243cf110-cfe2-4bc0...@t20g2000yqa.googlegroups.com...On
> On Oct 25, 2:53 pm, James <james.e.stew...@gmail.com> wrote:
> And by your estimation because CF may have limitations/weaknesses
> NOW, it should be abandoned?
======
Abandoned? No, but I think it needs improvement. Some carbon pads
destroy some carbon rims, while not others during heavy prolonged
braking. The less robust seem to recommend cork pads I think, that
are about as useless as polished steel rims in wet weather, and no
where near as good as Al.
I think the only advantage CF has at the moment is weight. I'd prefer
to be able to stop.
======
I weigh 172 pounds, I still ride hard and nearly every ride I do
involves at least 5 miles of descending. I ride no-matter-what, rain or
shine. I have a "rain bike" with conventional aluminum rims and Koolstop
black or salmon pads (truthfully I can't tell much if any difference)
and my "regular" bike which has carbon Bontrager wheels and Bontrager
cork-type pads. My "regular" bike ends up getting more rain use than it
should, so it's easy to make comparisons.
Stopping power in wet conditions is better on the carbon/cork
combination than conventional aluminum/rubber. Actually, absolute
stopping power is probably similar, but the carbon/cork combo doesn't
seem to have to dry out before working. The aluminum/rubber combo also
appears to lose power over time; again, no variation from beginning to
end with the carbon/cork.
This is a sample size of just one, but as I am that one, for me, it's
relevant.
--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com
"James" <james.e...@gmail.com> wrote in message
news:243cf110-cfe2-4bc0...@t20g2000yqa.googlegroups.com...
kolldata
wrote:
> "Jobst Brandt" <jbra...@sonic.net> wrote in message
>
> - Show quoted text -
amazing. never wudda thought this possible given the continuing bad
stream of carbon info.