ceramic bearings
IdealSP
bottom brackets and wheels.
Also has anybody used such bearing in there bikes, any information would be
useful
thanks for any replys
marcus
Alex Rodriguez
The question is why bother? Steel ones are easy to get and cheap.
-----------------
Alex __O
_-\<,_
(_)/ (_)
bob...@mediaone.net
Are you kidding? Ceramic ball bearings result in a major weight
savings!
Bob Q
Tony Raven
"IdealSP" <ide...@lineone.net> wrote in message
news:ohCF6.26583$vk1.60268@NewsReader...
> Does anybody know of a uk supplier of ceramic bearing, suitable to fit
> bottom brackets and wheels.
>
> Also has anybody used such bearing in there bikes, any information would
be
> useful
>
They are available but expensive, hard to get hold of, break more easily and
not worth the effort or weight saving. Go to a good bearing supplier and
spend your money on some quality steel bearings
Tony
Qui si parla Campagnolo
would be
useful >>
I've used them on a few hubs, they are really very smooth but for the $(about
$2 per bearing) don't think they are worth it-
Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl ST.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
Frank Day
wrote on 4/25/01 8:42 AM:
A company called Negative Mass has incorporated ceramic bearings into their
crank design with major weight savings. Last I heard (they were at last
years Ironman Hawaii expo) they were trying to sell their idea to a major
player.
--
Frank Day
PowerCranks
fd...@powercranks.com
www.powercranks.com
Walnut Creek CA USA
Jobst Brandt
> I've used them on a few hubs, they are really very smooth but for
> the $(about $2 per bearing) don't think they are worth it.
How smooth? How smooth are conventional steel bearing balls and which
has the smoother surface finish, the ceramic or steel ball?
How can you write this stuff without biting your tongue? Is there
nothing that embarrasses you?
Jobst Brandt <jbr...@hpl.hp.com>
Alex Rodriguez
>A company called Negative Mass has incorporated ceramic bearings into their
>crank design with major weight savings. Last I heard (they were at last
>years Ironman Hawaii expo) they were trying to sell their idea to a major
>player.
Bearings don't weigh enough that you can get major weight savings. If you
completely removed all bearings, you would only get minimal weight savings.
Frank Day
ad...@columbia.edu wrote on 4/26/01 9:53 AM:
They completely eliminate the metal of the spindle. The spindle is
incorporated in the crank arms as is the bearing surface and everything is
carbon fiber except for the ceramic bearings and bearing surfaces. The
entire assembly, including both crank arms, the spindle and bearings is
amazingly light.
George S. Hugh
But couldn't they could do this with steel bearings?
"Frank Day" <fd...@powercranks.com> wrote in message
news:B70DAA72.167C2%fd...@powercranks.com...
Jay Hill
> Peter Chisholm (aka can you say ridiculous) writes:
>
> > I've used them on a few hubs, they are really very smooth but for
> > the $(about $2 per bearing) don't think they are worth it.
>
> How smooth?
Very smooth, like he wrote.
> How smooth are conventional steel bearing balls and which
> has the smoother surface finish, the ceramic or steel ball?
There isn't a connection between what he wrote and what you've written.
You're wrong again, Jobst. Another of your ad hominem-based
non-sequitors. His statement did not say that ceramic bearings were more
or less smooth than steel bearings, which is what you're erroneously
implying he said, and the predication from which you've launched another
of your arrogant, nasty comments. He simply said ceramic bearings were
very smooth. There's no need for him to give a quantitative comparative
analysis.
> How can you write this stuff without biting your tongue? Is there
> nothing that embarrasses you?
You don't know when you should be embarrassed.
> Jobst Brandt <jbr...@hpl.hp.com>
Frank Day
wrote on 4/26/01 11:46 AM:
> Frank,
>
> But couldn't they could do this with steel bearings?
>
I guess they could but they were going for maximum overall weight savings in
an extremely stiff crank, not simply something that would work.
Killer
a show in about 1995 was that are very smooth, and can run in zero grease
conditions just as well as steel in fresh grease and last forever. Weight I
never thought of an issue. the total weight of all bearings on a bike must
add up to about 10grams.
Steve
"Frank Day" <fd...@powercranks.com> wrote in message
news:B70DBF90.167EA%fd...@powercranks.com...
PowerCranks Admin
killer...@ntlworld.com wrote on 4/26/01 12:43 PM:
> The point of ceramic bearings if I remember rightly when I heard about it at
> a show in about 1995 was that are very smooth, and can run in zero grease
> conditions just as well as steel in fresh grease and last forever. Weight I
> never thought of an issue. the total weight of all bearings on a bike must
> add up to about 10grams.
>
> Steve
Part of the "weight" of a bearing must include the surface upon which it
must interact and any other necessary supporting features as it will not
work without same. If one does not include the weight of the spindle in the
equation one is not looking at the problem in its entirety. The Negative
Mass "solution" to the weight problem was to incorporate the cranks,
spindle, and bearings into a "single" integrated unit and they happened to
use ceramic bearings integrated into a carbon fiber "spindle" in doing this.
While it is possible they could have done so using steel or some other metal
for the ball bearings to roll on, I doubt it would be anywhere near as
light. Ceramic bearings may have other positive features also but I believe
they were used in this application primarily to achieve the greatest
possible weight savings overall. I forget what the entire weight of the
system was but it was only a few hundred grams for the entire system, cranks
and spindle assembly.
My booth was quite close to his and I would provide him a pair of my cranks
(at about 3 pounds a copy without spindle) for him to use as comparison. My
cranks would be a useful personal defense tool. His would only work for that
purpose if you poked somebody in the eye with them.
Benjamin Weiner
> They completely eliminate the metal of the spindle. The spindle is
> incorporated in the crank arms as is the bearing surface and everything is
> carbon fiber except for the ceramic bearings and bearing surfaces. The
> entire assembly, including both crank arms, the spindle and bearings is
> amazingly light.
Cool, a carbon fiber Ashtabula crank.
Ben
still waiting for those trick
weight-saving magnesium brake pads
Chris Zacho The Wheelman
May you have the wind at your back.
And a really low gear for the hills!
Chris
Chris'Z Corner
"The Website for the Common Bicyclist":
http://www.geocities.com/czcorner
Chris Zacho The Wheelman
>the spindle. The spindle is incorporated
>in the crank arms as is the bearing
>surface and everything is carbon fiber
>except for the ceramic bearings and
>bearing surfaces. The entire assembly,
>including both crank arms, the spindle
>and bearings is amazingly light."
You mean thay re-invented the Astabula crank? Well I'll be damned, Huffy
was right all along!
George S. Hugh
Ah, marketing. Thanks.
"Frank Day" <fd...@powercranks.com> wrote in message
news:B70DBF90.167EA%fd...@powercranks.com...
Qui si parla Campagnolo
> the $(about $2 per bearing) don't think they are worth it. >>
Jobst blasts back from his desk at HP labs=instead of designing better
printers-
<< How smooth? How smooth are conventional steel bearing balls and which
has the smoother surface finish, the ceramic or steel ball? >>
Didn't say 'smoother' said smooth-felt smooth, like turning it and it felt
smooth-hello-
<< How can you write this stuff without biting your tongue? Is there
nothing that embarrasses you? >>
Easy, I sit down and type on my Mac G-3, with my lousy HP printer wating to
break, again-
I write about smoothness because, unlike you, as a bike wrench, I feel stuff
like bearing smoothness everyday-
Qui si parla Campagnolo
non-sequitors. >>
He didn't like my comment about lousy HP printers, something I assume he
actually sees and touches, unlike bike stuff-
Qui si parla Campagnolo
about it at
a show in about 1995 was that are very smooth, and can run in zero grease
conditions just as well as steel in fresh grease and last forever. >>
Yes, you use a tenacious oil that costs 10 times the cost of the bearings-
Alex Rodriguez
>
>Frank Day <fd...@powercranks.com> wrote:
>
>> They completely eliminate the metal of the spindle. The spindle is
>> incorporated in the crank arms as is the bearing surface and everything is
>> carbon fiber except for the ceramic bearings and bearing surfaces. The
>> entire assembly, including both crank arms, the spindle and bearings is
>> amazingly light.
>
>Cool, a carbon fiber Ashtabula crank.
Exactly what I was thinking.
Jay Beattie
Alex Rodriguez wrote in message
<9cc1jo$5at$2...@newsmaster.cc.columbia.edu>...
I put one on my son's bike along with a CF coaster
brake and a Ti bell that has a picture of the
Power Rangers on it. I am still looking for some
laminate streamers to hang out of his bar ends. I
was thinking of using some of those brightly
colored vectran spox. -- Jay Beattie.
Andrew Coggan
> My cranks would be a useful personal defense tool.
Ah, so you admit.......oh, never mind. It's too easy. ;-)
Andy Coggan
John Albergo
Qui si parla Campagnolo wrote:
> << How smooth? How smooth are conventional steel bearing balls and which
> has the smoother surface finish, the ceramic or steel ball? >>
>
> Didn't say 'smoother' said smooth-felt smooth, like turning it and it felt
> smooth-hello-
>
Gee, now my curiosity is piqued. I think the natural question for the reader
would be "smoother than steel"? I mean, bearings are *supposed* to be smooth.
So, when a mechanic mentions "really very smooth"; I think to myself: "hey! they
must be *extraordinarily* smooth"! So no offense intended but were they
smoother than good conventional bearings in your experience?
Qui si parla Campagnolo
the reader
would be "smoother than steel"? I mean, bearings are *supposed* to be smooth.
>>
No, not smoother, AFAI can tell. but really smooth.
On par with a good race and cone with good quality steel BBs.
But at 100 times the price-so as I said earlier, not worth the $, IMO.
Jobst Brandt
How sensitive and cautiously you tip toe around Peter Chisholm's ego.
Don't be afraid of his bark, there are no teeth (or facts) behind
these claims and the response he gave me was the common one when hot
air on wreck.bike is tested. Steel ball bearings are the smoothest
metal surfaces we see in everyday life, being as smooth as the best
mirrors we look into. Those who claim they can feel that, you're
testing the reader's credibility (aka lying). Besides, ball bearing
roughness comes almost entirely from race finish, not from ball
smoothness.
Jobst Brandt <jbr...@hpl.hp.com>
Patrick Lamb
>
> Steel ball bearings are the smoothest
> metal surfaces we see in everyday life, being as smooth as the best
> mirrors we look into. Those who claim they can feel that, you're
> testing the reader's credibility (aka lying). Besides, ball bearing
> roughness comes almost entirely from race finish, not from ball
> smoothness.
>
> Jobst Brandt <jbr...@hpl.hp.com>
(It's been a few years [about 10] since I saw a technology assessment of
ceramic vs. steel bearings, so this may not be quite up to date.)
Anyhow, the analysis I remember had several points in favor of ceramic
bearings:
(1) Good ceramic bearings (and not all are good!) exhibit less strain
than steel. All bearings under load tend to deform slightly, in part
because the contact area is so small.
(2) Contact points in ball bearings, on a microscopic scale, are the
aspherites -- minute peaks in the surface, even of highly polished
bearings. The sources I remember said that the aspherites of ceramic
ball bearings were shorter than steel aspherites.
(3) Galling of the bearings and races were often caused by non-radial
tearout, usually caused (again at the microscopic level) by local
contact bonding between ball and race, and enhanced by stress
concentrations of the aspherites. Ceramic bearings, because of their
reduced strain, have smaller areas of non-radial contact. This, plus
the reduced height of the aspherites, reduces galling in ceramic
bearings when compared to normative steel bearings. In addition,
ceramics do not bond well with steel, which also reduces galling.
(4) Lubrication's role in bearings is to reduce the contact patch, and
interject a layer of lubricant between the bearing and the shaft/race.
The requirement for lubrication is reduced when using ceramics.
Of course, there is one big downside to ceramics. They are more
brittle, and can shatter when shocked. For the applications of which I
was aware, ceramic bearings were always used in conjunction with steel
races and shafts. This allowed the steel to absorb the shock and help
preserve the bearings.
So it is possible that ceramic bearings reduce galling. This may make
them feel smooth. (Noting only Jobst erected the strawman that they
feel smoother, which strawman he then proceeded to demolish.) It is
also quite possible that bearings made with ceramic balls, because the
balls are expensive, are made very well. I suspect a well made bearing
feels smoother than a poorly made bearing, and would be perceived by
feel as smoother.
Pat
Jobst Brandt
>> Steel ball bearings are the smoothest metal surfaces we see in
>> everyday life, being as smooth as the best mirrors we look into.
>> Those who claim they can feel that, you're testing the reader's
>> credibility (aka lying). Besides, ball bearing roughness comes
>> almost entirely from race finish, not from ball smoothness.
> (It's been a few years [about 10] since I saw a technology
> assessment of ceramic vs. steel bearings, so this may not be quite
> up to date.) Anyhow, the analysis I remember had several points in
> favor of ceramic bearings:
What is all this disclaimer ahead of a vague dissertation on bearing
wear when the discussion is on how smoothly ceramic balls roll. The
question is how smooth and in what magnitudes. Smoothness in bearing
balls is measured in nanometers, a dimension as absurd as one can get
when discussing how smoothly a bicycle rolls. Ball bearing smoothness
in this realm is important in applications that run for billions of
cycles and at speeds at least 100x than those in a bicycle. A hard
disk drive is such an application as is a refrigerator motor.
> (1) Good ceramic bearings (and not all are good!) exhibit less strain
> than steel. All bearings under load tend to deform slightly, in part
> because the contact area is so small.
I don't think you understand Hertzian contact between ball and race or
that steel is elastic and makes contact in a ratio known as stress,
load divided by contact area. What do you mean by "so small"?
Unloaded, contact is a point between two curved surface of different
radii, as ball and race are. Reasons for preload and contact area
have been discussed in this forum at length.
> (2) Contact points in ball bearings, on a microscopic scale, are the
> aspherites -- minute peaks in the surface, even of highly polished
> bearings. The sources I remember said that the aspherites of ceramic
> ball bearings were shorter than steel aspherites.
What are "aspherites"? I've worked with tribology for years and
haven't come across this term. Are you sure you know about what you
are talking? I don't see how an asphere enters into this.
> (3) Galling of the bearings and races were often caused by non-radial
> tearout, usually caused (again at the microscopic level) by local
> contact bonding between ball and race, and enhanced by stress
> concentrations of the aspherites. Ceramic bearings, because of their
> reduced strain, have smaller areas of non-radial contact. This, plus
> the reduced height of the aspherites, reduces galling in ceramic
> bearings when compared to normative steel bearings. In addition,
> ceramics do not bond well with steel, which also reduces galling.
The least you could do is copy this stuff verbatim instead of giving
it your non-technical interpretation. I see another great case of MAS
(Male Answer Syndrome).
> (4) Lubrication's role in bearings is to reduce the contact patch, and
> interject a layer of lubricant between the bearing and the shaft/race.
> The requirement for lubrication is reduced when using ceramics.
I think you should enroll in a basic course in tribology and maybe
read "Rolling Bearing Analysis" by Tedric Harris before lecturing on
the subject. Where do get the chutzpah to come up with this stuff?
It only gets worse from here on. Cut your losses.
Jobst Brandt <jbr...@hpl.hp.com>
A Muzi
will fall for anything!
Qui si parla Campagnolo wrote:
--
Yellow Jersey, Ltd
http://www.yellowjersey.org
Open every day since 1 April, 1971
A Muzi
Patrick Lamb wrote:
> Jobst Brandt wrote:
> >
> > Steel ball bearings are the smoothest
> > metal surfaces we see in everyday life, being as smooth as the best
> > mirrors we look into. Those who claim they can feel that, you're
> > testing the reader's credibility (aka lying). Besides, ball bearing
> > roughness comes almost entirely from race finish, not from ball
> > smoothness.
> >
> > Jobst Brandt <jbr...@hpl.hp.com>
>
> (It's been a few years [about 10] since I saw a technology assessment of
> ceramic vs. steel bearings, so this may not be quite up to date.)
> Anyhow, the analysis I remember had several points in favor of ceramic
> bearings:
>
> (1) Good ceramic bearings (and not all are good!) exhibit less strain
> than steel. All bearings under load tend to deform slightly, in part
> because the contact area is so small.
I am not an expert but deformation of a steel bearing has to be less than
that of the shaft and cups in bicycle applications. Think about it.
>
>
> (2) Contact points in ball bearings, on a microscopic scale, are the
> aspherites -- minute peaks in the surface, even of highly polished
> bearings. The sources I remember said that the aspherites of ceramic
> ball bearings were shorter than steel aspherites.
I really wouldn't know. Can this be significant given the components
involved?
>
>
> (3) Galling of the bearings and races were often caused by non-radial
> tearout, usually caused (again at the microscopic level) by local
> contact bonding between ball and race, and enhanced by stress
> concentrations of the aspherites. Ceramic bearings, because of their
> reduced strain, have smaller areas of non-radial contact. This, plus
> the reduced height of the aspherites, reduces galling in ceramic
> bearings when compared to normative steel bearings. In addition,
> ceramics do not bond well with steel, which also reduces galling.
maybe a good argument for trying them in a headset.
>
>
> (4) Lubrication's role in bearings is to reduce the contact patch, and
> interject a layer of lubricant between the bearing and the shaft/race.
> The requirement for lubrication is reduced when using ceramics.
Because the load is less? This doesn't seem right.
>
>
> Of course, there is one big downside to ceramics. They are more
> brittle, and can shatter when shocked. For the applications of which I
> was aware, ceramic bearings were always used in conjunction with steel
> races and shafts. This allowed the steel to absorb the shock and help
> preserve the bearings.
Huh? Shaft deformation preserves bearings?
>
>
> So it is possible that ceramic bearings reduce galling. This may make
> them feel smooth. (Noting only Jobst erected the strawman that they
> feel smoother, which strawman he then proceeded to demolish.) It is
> also quite possible that bearings made with ceramic balls, because the
> balls are expensive, are made very well. I suspect a well made bearing
> feels smoother than a poorly made bearing, and would be perceived by
> feel as smoother.
I strongly disagree, as the surface of the shaft/cups is never as smooth or
round as the bearing set. You just can't feel bearing difference if
there's magnitudes more roughness in the races.
>
>
> Pat
Bearings (in anything we deal with) are not made smoother or rounder. They
are all made at the same time and more expensive bearings are sold by
alikeness not roundness. You are paying for inspection as the standard is
diameter variance within the lot and not surface finish of each ball.
Ted Bennett
> Reasons for preload and contact area
> have been discussed in this forum at length.
I have come into this discussion late. Because I understand the preloading
concept in wire-spoked wheels and in steel reinforced concrete I don't
dispute the benefits of preload in roller bearings. However I would
appreciate some explanation of that.
Ted Bennett
Qui si parla Campagnolo
>>
Didn't like the remark about HP printers, I guess-
<< Those who claim they can feel that, you're
testing the reader's credibility (aka lying). >>
That's nice-
I think you were lying about Campag brakes as well, since
you haven't actually used them or seen them or installed them-
Patrick Lamb
>
> Patrick Lamb writes:
>
> > (1) Good ceramic bearings (and not all are good!) exhibit less strain
> > than steel. All bearings under load tend to deform slightly, in part
> > because the contact area is so small.
>
> I don't think you understand Hertzian contact between ball and race or
> that steel is elastic and makes contact in a ratio known as stress,
> load divided by contact area. What do you mean by "so small"?
> Unloaded, contact is a point between two curved surface of different
> radii, as ball and race are. Reasons for preload and contact area
> have been discussed in this forum at length.
OK, you're the expert. How small is the Hertzian contact patch? If you
had read the paragraph above before spouting, you would have seen, and I
quote, "bearings under load tend to deform slightly." So who cares what
the unloaded bearing looks like?
> > (2) Contact points in ball bearings, on a microscopic scale, are the
> > aspherites -- minute peaks in the surface, even of highly polished
> > bearings. The sources I remember said that the aspherites of ceramic
> > ball bearings were shorter than steel aspherites.
>
> What are "aspherites"? I've worked with tribology for years and
> haven't come across this term. Are you sure you know about what you
> are talking? I don't see how an asphere enters into this.
Gee, I heard this term (aspherites) from tribologists both from MIT and
from Georgia Tech. Either they teach tribology poorly at both these
institutions (two of three that teach the subject in the US, as I was
told), or else, well, what other interpretation can you offer?
> The least you could do is copy this stuff verbatim instead of giving
> it your non-technical interpretation.
Sorry, I no longer have access to the briefing. It was prepared by
tribologists who worked on the space shuttle main engine cryogenic
pumps. So you have to take (or leave, if you prefer) my memory of the
information.
> I see another great case of MAS
> (Male Answer Syndrome).
Agreed. I tried to provide additional information at a level that could
be understood by many readers of this newsgroup. Since it didn't match
what your notions were, you had to answer me.
> Where do get the chutzpah to come up with this stuff?
Reread the first paragraph. If you disagree with me, or if my memory is
faulty, or my experts wrong, or if you have some more solid technical
information to offer (as opposed to your emotional flames), what is it?
> It only gets worse from here on. Cut your losses.
I wrote, "It is also quite possible that bearings made with ceramic
balls, because the balls are expensive, are made very well. I suspect a
well made bearing feels smoother than a poorly made bearing, and would
be perceived by
feel as smoother." Do you disagree that well made bearings feel
smoother than poorly made bearings, or do you maintain that bearings
made with $2 balls would not include good races?
Pat
Patrick Lamb
>
> Patrick Lamb wrote:
>
> > (4) Lubrication's role in bearings is to reduce the contact patch, and
> > interject a layer of lubricant between the bearing and the shaft/race.
> > The requirement for lubrication is reduced when using ceramics.
>
> Because the load is less? This doesn't seem right.
No, because the contact patch depends on the strain in the bearings and
in the race. Strain would be (very nearly) the same in the race, but
less in a ceramic bearing. Because the ceramic (plastically) deforms
less, there is a smaller contact patch.
> > Of course, there is one big downside to ceramics. They are more
> > brittle, and can shatter when shocked. For the applications of which I
> > was aware, ceramic bearings were always used in conjunction with steel
> > races and shafts. This allowed the steel to absorb the shock and help
> > preserve the bearings.
>
> Huh? Shaft deformation preserves bearings?
Ceramic ball bearings, yes. The shaft and race deform under a shock
load, reducing the instantaneous stress on the ceramic ball, which may
keep the stress on the ball below its yield.
> > So it is possible that ceramic bearings reduce galling. This may make
> > them feel smooth. (Noting only Jobst erected the strawman that they
> > feel smoother, which strawman he then proceeded to demolish.) It is
> > also quite possible that bearings made with ceramic balls, because the
> > balls are expensive, are made very well. I suspect a well made bearing
> > feels smoother than a poorly made bearing, and would be perceived by
> > feel as smoother.
>
> I strongly disagree, as the surface of the shaft/cups is never as smooth or
> round as the bearing set. You just can't feel bearing difference if
> there's magnitudes more roughness in the races.
Pardon me; I should have written the "bearing sets" made with ceramic
balls, not just "bearings."
Were I a manufacturer, I wouldn't put a $20 set of ceramic ball bearings
into a $25 bearing set (including races); I'd put $1 worth of steel
balls in that set. I'd put the $20 (about 10 x $2) balls into a bearing
set that cost $100 or more. And my customers would want that $100 set
to feel very smooth, so I'd make sure the races were finished better.
> Bearings (in anything we deal with) are not made smoother or rounder. They
> are all made at the same time and more expensive bearings are sold by
> alikeness not roundness. You are paying for inspection as the standard is
> diameter variance within the lot and not surface finish of each ball.
Keep in mind I'm talking about microscopic surface. "Smooth" and
"round" aren't the same on macroscopic and microscopic scales. Alloyed
iron micro-crystals aren't smooth on a microscopic scale; ceramics can
be smoother at this scale.
Pat
Jim Adney
>Does anyone here believe the bearings are smoother than the cups??? Geez, you guys
>will fall for anything!
For cup and cone bicycle bearings, I suspect that the balls are a
couple of orders of magnitude smoother than the cups. Makes the finish
on the balls pretty irrelevant.
-
-----------------------------------------------
Jim Adney jad...@vwtype3.org
Madison,Wisconsin USA
-----------------------------------------------
B. Sanders
sweet on a Merlin Newsboy.
Barry
"Benjamin Weiner" <b...@isis.ucolick.org> wrote in message
news:3ae8b311$1...@news.ucsc.edu...
Jay Hill
> John Albergo writes:
>
> >>> How smooth? How smooth are conventional steel bearing balls and
> >>> which has the smoother surface finish, the ceramic or steel ball?
>
> >> Didn't say 'smoother' said smooth-felt smooth, like turning it and
> >> it felt smooth-hello-
>
> > Gee, now my curiosity is piqued. I think the natural question for
> > the reader would be "smoother than steel"? I mean, bearings are
> > *supposed* to be smooth. So, when a mechanic mentions "really very
> > smooth"; I think to myself: "hey! they must be *extraordinarily*
> > smooth"! So no offense intended but were they smoother than good
> > conventional bearings in your experience?
>
> How sensitive and cautiously you tip toe around Peter Chisholm's ego.
Bullshit Jobst. He's simply being courteous. All Peter has said was
that they felt smooth.
> Don't be afraid of his bark, there are no teeth (or facts) behind
> these claims and the response he gave me was the common one when hot
> air on wreck.bike is tested.
Bullshit Jobst. Again, what you've done is attributed something to his
statement that was not there. You're wrong in your assertion. It's you
who is not substantiating your assertions with facts, again.
Tom Kunich
news:20010427090719...@ng-xc1.aol.com...
> jshill-<< Another of your ad hominem-based
> non-sequitors. >>
>
> He didn't like my comment about lousy HP printers, something I assume he
> actually sees and touches, unlike bike stuff-
The direct quote was:
> I've used them on a few hubs, they are really very smooth but for
> the $(about $2 per bearing) don't think they are worth it.
You said "very smooth" and in that context one has to come to the conclusion
that you were implying that they were smoother than steel bearings which
they are not.
We have hundreds of printers around this building and the most reliable are
the H-P printers. That isn't to say that H-P hasn't built some crappy
printers, but the worst H-P has always been better than the best Cannon I
used.
Tom Kunich
news:3AEC526B...@home.com...
> A Muzi wrote:
> >
> > Patrick Lamb wrote:
> >
> > > (4) Lubrication's role in bearings is to reduce the contact patch, and
> > > interject a layer of lubricant between the bearing and the shaft/race.
> > > The requirement for lubrication is reduced when using ceramics.
> >
> > Because the load is less? This doesn't seem right.
>
> No, because the contact patch depends on the strain in the bearings and
> in the race. Strain would be (very nearly) the same in the race, but
> less in a ceramic bearing. Because the ceramic (plastically) deforms
> less, there is a smaller contact patch.
Al correctly identified the fact that the race will deform more than the
ball. The differences in deformation from a steel to a ceramic ball are
inconsequential in magnitude in bicycle applications.
> > > So it is possible that ceramic bearings reduce galling. This may make
> > > them feel smooth. (Noting only Jobst erected the strawman that they
> > > feel smoother, which strawman he then proceeded to demolish.) It is
> > > also quite possible that bearings made with ceramic balls, because the
> > > balls are expensive, are made very well. I suspect a well made
bearing
> > > feels smoother than a poorly made bearing, and would be perceived by
> > > feel as smoother.
> >
> > I strongly disagree, as the surface of the shaft/cups is never as smooth
or
> > round as the bearing set. You just can't feel bearing difference if
> > there's magnitudes more roughness in the races.
>
> Pardon me; I should have written the "bearing sets" made with ceramic
> balls, not just "bearings."
And the original message had something about replacing steel balls in wheels
with ceramic balls. While I agree with you that expensive balls are likely
to indicate expensive assemblies that doesn't apply in such a case.
> > Bearings (in anything we deal with) are not made smoother or rounder.
They
> > are all made at the same time and more expensive bearings are sold by
> > alikeness not roundness. You are paying for inspection as the standard
is
> > diameter variance within the lot and not surface finish of each ball.
>
> Keep in mind I'm talking about microscopic surface. "Smooth" and
> "round" aren't the same on macroscopic and microscopic scales. Alloyed
> iron micro-crystals aren't smooth on a microscopic scale; ceramics can
> be smoother at this scale.
Firstly, steel ball bearings are the roundest objects one can find in common
usage. Secondly, as several people have pointed out, the races are at least
two orders of magnitude rougher finished. Of what use is a smoother ball
regardless of the material?
I have heard people would put rouge into the bearings and devise some system
to rotate the wheel for days on end. At the end of this process they would
clean out the races, replace the balls and have perfectly smooth bearings.
So what? Does anyone believe that this difference made a fig's worth of
difference in the performance of the bicycle?
Campi's trick of using oil instead of grease in "record" attempts made a
much greater difference.
Jobst Brandt
> I have come into this discussion late. Because I understand the
> preloading concept in wire-spoked wheels and in steel reinforced
> concrete I don't dispute the benefits of preload in roller bearings.
> However I would appreciate some explanation of that.
A radially loaded ball bearing deforms elastically so that clearance
develops on the unloaded side, leaving the balls on that side loose.
If there is no preload or even some slight clearance, the elastic
eccentricity of the inner race will leave all balls except the one
directly under the load free and non load carrying. This causes
mainly two effects, 1. "ball drop" a wavy vertical position of the axle
as it climbs over successive balls, and 2. Stress concentration from
single ball loading. The second effect affects bicycles, ball drop
being imperceptible and unimportant.
Preload in a bearing distributes load over more balls and roll with
less loss although, unloaded, the bearing seems to have more drag to
the feel. What is less apparent is that this drag is small compared
to the loaded drag that is larger without than with preload.
Cartridge bearings in industrial applications are preloaded by axial
displacement of the inner race, either by a spring load or a rigid
fixed anchoring such as lock nuts or a dead weight applied during
Loctite fastening. For cup and cone on a bicycle, the method is self
evident.
In practice, most QR wheel bearings run with preload inadvertently,
their cones being adjusted to zero clearance/preload, they achieve
preload by closure of the quick release lever. The closure force
compresses the axle just enough to preload the bearing appropriately
if the QR is not excessively tight.
http://draco.acs.uci.edu/rbfaq/FAQ/122.html
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
> I think you were lying about Campag brakes as well, since
> you haven't actually used them or seen them or installed them-
What part of that item did you find inaccurate and unsupported?
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
> OK, you're the expert.
That's always a great defense, pulled out of the hat by guys caught
with their pants down. Nice try. Contact area is dependent on load
and is not a simple parameter as is described in the reference I gave:
"Rolling Bearing Analysis" Tedric Harris.
I'm sure your library has a copy.
>> What are "aspherites"? I've worked with tribology for years and
>> haven't come across this term. Are you sure you know about what you
>> are talking? I don't see how an asphere enters into this.
> Gee, I heard this term (aspherites) from tribologists both from MIT and
> from Georgia Tech. Either they teach tribology poorly at both these
> institutions (two of three that teach the subject in the US, as I was
> told), or else, well, what other interpretation can you offer?
I don't think you did and it is not in any dictionary. Are you sure
your're not GWB in disguise? You must have overheard a conversation
that you didn't understand. I'm sure they did not use that term if
they were in fact tribologists. So back to the question, what are
"aspherites"?
>> The least you could do is copy this stuff verbatim instead of
>> giving it your non-technical interpretation.
> Sorry, I no longer have access to the briefing. It was prepared by
> tribologists who worked on the space shuttle main engine cryogenic
> pumps. So you have to take (or leave, if you prefer) my memory of
> the information.
Aha, rocket science. I am impressed. Cryogenics to boot.
>> I see another great case of MAS (Male Answer Syndrome).
> Agreed. I tried to provide additional information at a level that
> could be understood by many readers of this newsgroup. Since it
> didn't match what your notions were, you had to answer me.
My notion is that we gain nothing by repeating hearsay, myth and lore.
Jobst Brandt <jbr...@hpl.hp.com>
Mark Hickey
>Campi's trick of using oil instead of grease in "record" attempts made a
>much greater difference.
Funny, I was just wondering if it's possible that the ceramic bearing
had oil instead of grease (or perhaps, no lube at all). Hmmmmm.
Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame
Qui si parla Campagnolo
conclusion
that you were implying that they were smoother than steel bearings which
they are not. >>
You may have come to that conclusion, but not what I meant. meant they 'felt
very smooth' to me.
<< We have hundreds of printers around this building and the most reliable are
the H-P printers >>
Groovey-I had a HP printer for about three weeks and it broke. Even at a HP
warrenty center, it took 4 weeks to get it back.
Constantly have paper jams(even using HP paper) and software glitches.
Qui si parla Campagnolo
which is why the ceramic bearings were so smooth, I admit it......
Qui si parla Campagnolo
You may try to find a pair, install them and use them, instead of reading some
marketing BS and looking at a picture.
Qui si parla Campagnolo
had oil instead of grease (or perhaps, no lube at all). Hmmmmm. >>
The ones I used had some sort of whiz-bang oil, at $150 a bottle, instead of
grease. The gent that gave them to me actually said he was working on a ball
that 'sweated' lube when rotated and heated, don't know if that's possible or
not-
Tom Kunich
news:3AED60D6...@jump.net...
Peter is no more immune to making errors than the rest of us. Only Jobst is
perfect. Wait a minute. Jobst ain't perfect. I've met him and he is most
definitely out of round.
Jobst Brandt
>> What part of that item did you find inaccurate and unsupported?
> You may try to find a pair, install them and use them, instead of
> reading some marketing BS and looking at a picture.
Could you be more specific? What part of what I wrote was "marketing
BS" and what did you find inaccurate in my description of the brake?
Jobst Brandt <jbr...@hpl.hp.com>
Tom Kunich
> << What part of that item did you find inaccurate and unsupported? >>
>
> You may try to find a pair, install them and use them, instead of reading
some
> marketing BS and looking at a picture.
Peter, do you really think that Campi's latest single pivot offering is in
any way more efficient or more effective than any other Campi single pivot
brake, many of which Jobst has used?
I don't have to use their rear brake to know that it is just so much
marketing hooey. I have used Deltas and presently have monoplaners on my
beater which sees most of my use at present and while the monoplaners are a
whole lot better brake they seem to stop no better than the Deltas did. Or
for that matter a properly set up pair of Mafac Racers.
BTW, moving into my house and looking at the stuff I have in storage I note
that I have a set of Mafacs and another of those DiaComp Racers that are
more or less identical. Think I'll pull a Sheldon Brown and put them on a
bike.
Norman Yarvin
>Jobst Brandt wrote:
>>
>> Patrick Lamb writes:
>>
>> > (2) Contact points in ball bearings, on a microscopic scale, are the
>> > aspherites -- minute peaks in the surface, even of highly polished
>> > bearings. The sources I remember said that the aspherites of ceramic
>> > ball bearings were shorter than steel aspherites.
>>
>> What are "aspherites"? I've worked with tribology for years and
>> haven't come across this term. Are you sure you know about what you
>> are talking? I don't see how an asphere enters into this.
>
>Gee, I heard this term (aspherites) from tribologists both from MIT and
>from Georgia Tech.
They would probably spell it "asperities".
--
Norman Yarvin norman...@snet.net
Qui si parla Campagnolo
offering is in
any way more efficient or more effective than any other Campi single pivot
brake, many of which Jobst has used? >>
No,but not the point, Jobst called me a liar when I said that the ceramic
bearings 'felt' smooth, I'm just saying that he oughta do some 'hands on'
evaluation of the things he slams, that's all-
<< I don't have to use their rear brake to know that it is just so much
marketing hooey. >>
Their reason for doin' it, I think, is to make a rear brake still work and be
lighter. Marketing no doubt. But as to whether or not it 'works' as a bike
brake, this, along with Deltas, were dismissed as something bordering on
dangerous.