Ceramic Bearing Systems and Marketing BS Systems - Cycling Mob: Road Cycling, Mountain Biking and More

12-12-2003, 04:44 PM

I'm no engineer, but I just read Lennard Zinn's column in Velonews this
week, and my marketing BS detector is ringing. Engineers on the list are
welcome to chime in, if what's below if defensible.

Lennard himself says "I have no experience with (ceramic bearings), ...so I
will defer to someone who knows a lot about them." This turns out to be
Bill Vance, National Sales Manager, ZIPP Speed Weaponry. So here's Vance:

"How much benefit is possible from adopting this new technology? According
to reports from real world testing done by ZIPP sponsored Team CSC an
average reduction in wattage of three to four percent under our standard
bearing systems, already the tightest standard within the industry can be
expected.

"For an average trained cyclist developing 250 watts, that's a savings of
approximately 10 watts. At any level of competition, that is significant.
The key is every part of the bearing system has seen marked improvements in
precision resulting an a total benefit greater than the sum of its parts.

"Similar to current math theory, at some point numbers reach a point where
the rules just don't hold true any more."

Wow. I love the chutzpah of "at some point numbers reach a point where the
rules just don't hold true any more."

But, as I said, I'm no engineer. So, for all you engineers out there, can
there possibly be that big a difference in total system efficiency in
changing from high-quality steel bearing systems to anything else?

Full column is at:
[Only registered and activated users can see links. ]

--
Mike Kruger
I didn't believe in reincarnation last time, either.

12-12-2003, 06:07 PM

In article <[Only registered and activated users can see links. ] m>,
[Only registered and activated users can see links. ] says...
> "Similar to current math theory, at some point numbers reach a point where
> the rules just don't hold true any more."
>
> Wow. I love the chutzpah of "at some point numbers reach a point where the
> rules just don't hold true any more."
>
> But, as I said, I'm no engineer. So, for all you engineers out there, can
> there possibly be that big a difference in total system efficiency in
> changing from high-quality steel bearing systems to anything else?
>

I'm an engineer, but unfortunately I am a computer engineer, so I can't
speak to ceramic vs steel bearings.

However, number always follow "the rules." Sometimes we learn that the
rules we know about the physical world don't work at some level, like
quantum mechanics. But I suspect that ceramic bearnings don't have this
kind of significance.

Now, if I pretend to be an M.E., I would expect that the difference in
friction between cermic and stell is probably *measureable* with
instruments. But I don't expect the difference in the ride is
measureable. Is 10 watts really that significant, given all the other
factors?

12-12-2003, 08:42 PM

Bearing friction in a bike is almost insignificant. A number like 10 watts
sounds incredibly high. I think you are dealing with pure BS.

Ernie

Slartibartfast wrote:

> In article <[Only registered and activated users can see links. ] m>,
> [Only registered and activated users can see links. ] says...
> > "Similar to current math theory, at some point numbers reach a point where
> > the rules just don't hold true any more."
> >
> > Wow. I love the chutzpah of "at some point numbers reach a point where the
> > rules just don't hold true any more."
> >
> > But, as I said, I'm no engineer. So, for all you engineers out there, can
> > there possibly be that big a difference in total system efficiency in
> > changing from high-quality steel bearing systems to anything else?
> >
>
> I'm an engineer, but unfortunately I am a computer engineer, so I can't
> speak to ceramic vs steel bearings.
>
> However, number always follow "the rules." Sometimes we learn that the
> rules we know about the physical world don't work at some level, like
> quantum mechanics. But I suspect that ceramic bearnings don't have this
> kind of significance.
>
> Now, if I pretend to be an M.E., I would expect that the difference in
> friction between cermic and stell is probably *measureable* with
> instruments. But I don't expect the difference in the ride is
> measureable. Is 10 watts really that significant, given all the other
> factors?

12-12-2003, 09:18 PM

Mike Kruger writes:

> I'm no engineer, but I just read Lennard Zinn's column in VeloNews
> this week, and my marketing BS detector is ringing. Engineers on the
> list are welcome to chime in, if what's below if defensible.

> Lennard himself says "I have no experience with (ceramic bearings),
> ...so I will defer to someone who knows a lot about them." This
> turns out to be Bill Vance, National Sales Manager, ZIPP Speed
> Weaponry. So here's Vance:

> "How much benefit is possible from adopting this new technology?
> According to reports from real world testing done by ZIPP sponsored
> Team CSC an average reduction in wattage of three to four percent
> under our standard bearing systems, already the tightest standard
> within the industry can be expected.

> "For an average trained cyclist developing 250 watts, that's a
> savings of approximately 10 watts. At any level of competition, that
> is significant. The key is every part of the bearing system has
> seen marked improvements in precision resulting an a total benefit
> greater than the sum of its parts.

> "Similar to current math theory, at some point numbers reach a point
> where the rules just don't hold true any more."

> Wow. I love the chutzpah of "at some point numbers reach a point
> where the rules just don't hold true any more."

> But, as I said, I'm no engineer. So, for all you engineers out
> there, can there possibly be that big a difference in total system
> efficiency in changing from high-quality steel bearing systems to
> anything else?

> Full column is at:
> [Only registered and activated users can see links. ]

Well you see in what language this is presented: "How much benefit is
possible from adopting this new technology?" Not the use of
"possible" not actual or otherwise. What is more important is that
harder bearing balls do not mean the cones or inner races of bearings
will last longer. Friction losses in bicycle ball bearings is so
minute that this is not a reasonable way to spend more money. This
goes along with all the other aerospace materials bicyclists are
advised to buy. It falls into the titanium-carbon fiber-sintered
metals-low spoke count" trend of the day. It may be good bragging
fodder but it won't change performance of the bicycle or the
checkbook.

Jobst Brandt
[Only registered and activated users can see links. ]

12-12-2003, 09:28 PM

"Mike Kruger" <[Only registered and activated users can see links. ]> wrote in message
news:728923353e517dd89fd5c11377b39b55@news.teranew s.com...
> I'm no engineer, but I just read Lennard Zinn's column in Velonews
this
> week, and my marketing BS detector is ringing. Engineers on the
list are
> welcome to chime in, if what's below if defensible.
>
> Lennard himself says "I have no experience with (ceramic bearings),
....so I
> will defer to someone who knows a lot about them." This turns out
to be
> Bill Vance, National Sales Manager, ZIPP Speed Weaponry. So here's
Vance:
>
> "How much benefit is possible from adopting this new technology?
According
> to reports from real world testing done by ZIPP sponsored Team CSC
an
> average reduction in wattage of three to four percent under our
standard
> bearing systems, already the tightest standard within the industry
can be
> expected.
>
> "For an average trained cyclist developing 250 watts, that's a
savings of
> approximately 10 watts. At any level of competition, that is
significant.
> The key is every part of the bearing system has seen marked
improvements in
> precision resulting an a total benefit greater than the sum of its
parts.
>
> "Similar to current math theory, at some point numbers reach a
point where
> the rules just don't hold true any more."
>
> Wow. I love the chutzpah of "at some point numbers reach a point
where the
> rules just don't hold true any more."
>
> But, as I said, I'm no engineer. So, for all you engineers out
there, can
> there possibly be that big a difference in total system efficiency
in
> changing from high-quality steel bearing systems to anything else?
>
>

Some ceramic materials, like silicon nitride, are excellent bearing
materials. They are harder, lighter, more thermally stable and more
wear resistant than metalic bearings. For motor-driven bearings, wear
resistance is usually a critical factor. Reducing energy consumption
by 4% seems high, but ought to be easily verifiable by testing if
true. The part about "the rules just don't hold true" is pure
marketing hyperbole.

OTOH, the Formula 1 cars are starting to use ceramic bearings and
they are usually on the bleeding edge of technology where money is no
object..
Here is some info, granted from another vendor:
[Only registered and activated users can see links. ]

12-12-2003, 10:30 PM

In article <[Only registered and activated users can see links. ].com>,
Slartibartfast <[Only registered and activated users can see links. ]> wrote:

> In article <[Only registered and activated users can see links. ] m>,
> [Only registered and activated users can see links. ] says...
> > "Similar to current math theory, at some point numbers reach a point where
> > the rules just don't hold true any more."
> >
> > Wow. I love the chutzpah of "at some point numbers reach a point where the
> > rules just don't hold true any more."
> >
> > But, as I said, I'm no engineer. So, for all you engineers out there, can
> > there possibly be that big a difference in total system efficiency in
> > changing from high-quality steel bearing systems to anything else?
> >
>
> I'm an engineer, but unfortunately I am a computer engineer, so I can't
> speak to ceramic vs steel bearings.
>
> However, number always follow "the rules." Sometimes we learn that the
> rules we know about the physical world don't work at some level, like
> quantum mechanics. But I suspect that ceramic bearnings don't have this
> kind of significance.
>
> Now, if I pretend to be an M.E., I would expect that the difference in
> friction between cermic and stell is probably *measureable* with
> instruments. But I don't expect the difference in the ride is
> measureable. Is 10 watts really that significant, given all the other
> factors?

10 watts in 250 is the quoted number, so it's a claimed 4% efficiency
gain. That's noteworthy. For a seasoned pro, that would probably be far
more noticeable than any other equipment change they could make, short
of dramatic body-position aero gains or something.

The number is so high, frankly, that it seemed questionable on that
basis to me. But all credit to Zipp for actually putting up a (claimed)
number in a meaningful format, rather than just their "matched bearings
with epsilon runout" numbers.

--
Ryan Cousineau, [Only registered and activated users can see links. ] [Only registered and activated users can see links. ]
President, Fabrizio Mazzoleni Fan Club

12-13-2003, 12:51 AM

Mike Kruger <[Only registered and activated users can see links. ]> wrote:

> [Zinn punted on the question and quoted Zipp: ]
> "For an average trained cyclist developing 250 watts, that's a savings of
> approximately 10 watts. At any level of competition, that is significant.
> The key is every part of the bearing system has seen marked improvements in
> precision resulting an a total benefit greater than the sum of its parts. ...

> But, as I said, I'm no engineer. So, for all you engineers out there, can
> there possibly be that big a difference in total system efficiency in
> changing from high-quality steel bearing systems to anything else?

No.

This question would be more appropriate for rec.bicycles.tech than
r.b.misc, so I'm crossposting it and setting followups there.

I calculated that the power dissipated in two standard steel
ball bearing hubs is about 0.33 watts for a 75 kg rider+bike
traveling at 10 m/s. It's hard to see how an improved bearing could
shave more than some percentage of that (10-20% ?), which verges on
negligible, I'm sure the aerodynamics of your shoe straps are more
important.

Since I already wrote up the calculation, here it is:

Typical coefficient of friction for a ball bearing is about mu=1.5e-3
(for example, [Only registered and activated users can see links. ])
Power dissipated in one bearing is

P1 = mu * (m/2) * g * V_bearing where m is mass of rider+bike
V_bearing is linear speed the
bearing rotates at.
P_bearingloss = 2*P1 total power lost in two wheels
V_bearing = V_bike * d/D d = bearing race diameter
D = wheel diameter
P_bearingloss = mu * mg * d/D * V_bike

P_bearingloss = C_bearingloss * mg * V_bike
where C_bearingloss = mu * d/D, can be compared to C_rolling resistance of tires

For a bearing race diameter of 20 mm and wheel diameter of 668 mm (700x23)
C_bearingloss = 4.5e-5
for comparison, C_rolling resistance is supposed to be 4e-3 for
smooth pavement (e.g. from [Only registered and activated users can see links. ], or 100x higher.

For a rider+bike of 75 kg traveling at 10 m/s, the power dissipated in
wheel bearings is 0.33 watts. A major technological breakthrough that
cut bearing friction in half would only gain 0.16 watts. It might be
significant in hour records or even the pursuit world record. At
normal levels of competition, I think the sleep gained in not worrying
about it has a greater performance benefit.

12-13-2003, 08:46 AM

In article <[Only registered and activated users can see links. ] m>,
[Only registered and activated users can see links. ] says...
> I'm no engineer, but I just read Lennard Zinn's column in Velonews this
> week, and my marketing BS detector is ringing. Engineers on the list are
> welcome to chime in, if what's below if defensible.
>
> Lennard himself says "I have no experience with (ceramic bearings), ...so I
> will defer to someone who knows a lot about them." This turns out to be
> Bill Vance, National Sales Manager, ZIPP Speed Weaponry. So here's Vance:
>
> "How much benefit is possible from adopting this new technology? According
> to reports from real world testing done by ZIPP sponsored Team CSC an
> average reduction in wattage of three to four percent under our standard
> bearing systems, already the tightest standard within the industry can be
> expected.
>
> "For an average trained cyclist developing 250 watts, that's a savings of
> approximately 10 watts. At any level of competition, that is significant.
> The key is every part of the bearing system has seen marked improvements in
> precision resulting an a total benefit greater than the sum of its parts.
>
> "Similar to current math theory, at some point numbers reach a point where
> the rules just don't hold true any more."
>
> Wow. I love the chutzpah of "at some point numbers reach a point where the
> rules just don't hold true any more."
>
> But, as I said, I'm no engineer. So, for all you engineers out there, can
> there possibly be that big a difference in total system efficiency in
> changing from high-quality steel bearing systems to anything else?

I'm an electrical engineer rather than a mechanical, so it's not my area
of expertise, but to me it sounds like what you say in the subject line.

--
Dave Kerber
Fight spam: remove the ns_ from the return address before replying!

REAL programmers write self-modifying code.

12-13-2003, 11:17 AM

On Sat, 13 Dec 2003 01:44:47 +0000, Mike Kruger wrote:

> "How much benefit is possible from adopting this new technology? According
> to reports from real world testing done by ZIPP sponsored Team CSC an
> average reduction in wattage of three to four percent under our standard
> bearing systems,

Very hard to believe.

> "Similar to current math theory, at some point numbers reach a point where
> the rules just don't hold true any more."

Right. Now, I've only been studying math for 30 years, so maybe there is
something I don't know. But, then again, maybe this is pure bull****.

--

David L. Johnson

__o | Accept risk. Accept responsibility. Put a lawyer out of
_`\(,_ | business.
(_)/ (_) |

12-13-2003, 12:54 PM

That posting had me going for a minute - my server is called
Slartibartfast and I was wondering how come it had added its name to a
posting. What is it about engineers and Douglas Adams?

Guy
===
May contain traces of irony. Contents liable to settle after posting.
[Only registered and activated users can see links. ]