Ceramic balls for bearings?

wrote:
According to the manufacturer, a full
accoutrement of ceramic bearings can save as much as a full second per
kilometer in a time trial.


According to my calculations, with a rider producing 400W and traveling
at 30mph, a 15W power savings is needed to drop 1 s/km. This is 3.75%
of the total power.

That is a lot of evergy to be sucked up by bearing friction... let
alone *saved* by using ceramics. I'd say the burden of proof is on
FSA...

But wait! For the same person producing only 10W and traveling at
6.5mph, a mere .065W savings would yield a 1 s/km improvement! Maybe
this is the realm they are thinking of?

Complete external bottom brackets will run about $249USD and complete
hub upgrades will cost consumers about $300-400 for six cartridge
bearings. Sure, it sounds like a lot, but what's that podium spot
worth to you?

Or... How much is marketing hype worth to you? Sure, if I was making a
million dollars a year to go fast on my bike...

wrote:
On Fri, 28 Oct 2005 18:10:26 GMT, Jasper Janssen
wrote:

In another bike group someone appears to want to buy ceramic bearing
balls. WTF? Why on earth?

Jasper

The word of the day at the FSA booth was ceramic. FSA has been working
closely with the Danish firm, CeramicSpeed, to offer ceramic bearing
upgrades on a number of drivetrain components.

The ceramic bearings, made of silicon nitride, offer hugely reduced
friction, dramatically lighter weight, and reportedly, practically
infinite life spans as compared to even the best steel bearings.
Upgrade kits will be available for external bottom brackets (including
non-FSA branded ones), cartridge bearing hubsets, as well as
derailleur pulley wheels. According to the manufacturer, a full
accoutrement of ceramic bearings can save as much as a full second per
kilometer in a time trial.


Except the cones and cups are the things that wear\, not the ball
bearings. Unless they harder tha cones/cups, ceramic is an expensive
answer to a not asked question. Like a guy at shimano once told me when
I pointed to a shimano 'thing', asking, "what's that for?", "selling'
was his response.

Interestingly, the manufacturer is also quite sure that Tyler Hamilton
was the only rider to use ceramic bearings in the Olympic time trial.
How's he so sure? Well, there aren't exactly a bunch of people making
these things, and he still has the copy of the check from Tyler (yes,
he actually paid for these himself, and they're not cheap).

Skeptics of Tyler's innocence cite the whopping 19 second advantage he
held over second place in that race, but if these projected time
savings are accurate.... well, you do the math. I'm not taking sides
here, but it is rather interesting nonetheless, don't you think?
Complete external bottom brackets will run about $249USD and complete
hub upgrades will cost consumers about $300-400 for six cartridge
bearings. Sure, it sounds like a lot, but what's that podium spot
worth to you?

Too bad their bearing seals will still be sluggish, in spite of ceramiv
balls.

http://www.cyclingnews.com/tech/2005.../interbike0513

On 29 Oct 2005 07:23:23 -0700, "Qui si parla Campagnolo"
wrote:

Too bad their bearing seals will still be sluggish, in spite of ceramiv
balls.

Well, sluggish or ineffective. Ineffective can work for some people.

Jasper

Francesco Devittori wrote:
Jasper Janssen wrote:
In another bike group someone appears to want to buy ceramic bearing
balls. WTF? Why on earth?

Jasper

Zipp makes an uberexpensive version of some of their wheels with ceramic
ball bearings.
You can distinguish them on some pro bikes because they have white
stickers instead of red.
Over the 35k km a pro rides during a year, you can probably save a
couple of Joules :-)

Ouestion #1; A typical Cat 2 rider, say 150 lbs, on a recient $2000
bike, riding at 25 mph alone, what % of his power is used to over come
wind & what % friction?
Just ballpark figures. I seem to remember 10%, maybe even 5%.
Question #2; If a rider at any speed, is riding into a 60 mph head
wind, why isn't he going backwards?
On a windy day, I once saw the Goodyear blimp flying backwards relative
to the ground.

Just curious, John

Francesco Devittori wrote:
Jasper Janssen wrote:
In another bike group someone appears to want to buy ceramic bearing
balls. WTF? Why on earth?

Jasper

Zipp makes an uberexpensive version of some of their wheels with ceramic
ball bearings.
You can distinguish them on some pro bikes because they have white
stickers instead of red.
Over the 35k km a pro rides during a year, you can probably save a
couple of Joules :-)

Ouestion #1; A typical Cat 2 rider, say 150 lbs, on a recient $2000
bike, riding at 25 mph alone, what % of his power is used to over come
wind & what % friction?
Just ballpark figures. I seem to remember 10%, maybe even 5%.
Question #2; If a rider at any speed, is riding into a 60 mph head
wind, why isn't he going backwards?
On a windy day, I once saw the Goodyear blimp flying backwards relative
to the ground.

Just curious, John

john wrote:

Ouestion #1; A typical Cat 2 rider, say 150 lbs, on a recient $2000
bike, riding at 25 mph alone, what % of his power is used to over come
wind & what % friction?

On a smooth road and no wind, roughly 10% would be tire rolling
resistance and 90% would be aero resistance. Bearing friction is
generally so small that it isn't even considered.

Question #2; If a rider at any speed, is riding into a 60 mph head
wind, why isn't he going backwards?
On a windy day, I once saw the Goodyear blimp flying backwards relative
to the ground.

Are you riding in a hurricane? If you actually experienced a 60mph
headwind you'd have a tough time going forward... but at least we have
the ground to push off against... the blimp doesn't.

On 29 Oct 2005 18:56:52 -0700, "Ron Ruff"
wrote:

If you actually experienced a 60mph
headwind you'd have a tough time going forward... but at least we have
the ground to push off against... the blimp doesn't.

But it soon would...
--
Kenneth

If you email... Please remove the "SPAMLESS."

On Fri, 28 Oct 2005 18:10:26 GMT, Jasper Janssen
wrote:

In another bike group someone appears to want to buy ceramic bearing
balls. WTF? Why on earth?

Boutique mentality. It's exotic and different, therefore it *must* be
Better. I have largely given up trying to actively discourage such
foolishness; I'll explain the issues as I understand them, and then
encourage the listener to spend *his* money verifying the data if
there's any question in his mind. If nothing else, I view this as an
investment in future entertainment.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

On 29 Oct 2005 15:26:04 -0700, "john" wrote:

Question #2; If a rider at any speed, is riding into a 60 mph head
wind, why isn't he going backwards?

In the face of a 60mph headwind, if he's moving at all, he's doing
pretty well. It's not difficult to remain motionless in that
circumstance, but progress upwind would be very tiring and very slow,
involving the use of a very low gear. Bikes interact with the air and
the ground; even when the air is moving fast, the ground isn't. By
choosing a low enough gear ratio, forward progress is still possible.

On a windy day, I once saw the Goodyear blimp flying backwards relative
to the ground.

Yes. The blimp's interaction is solely with the air, not the ground.
If the air is moving at a speed greater than the blimp's highest
potential airspeed, then the blimp cannot make ground-relative headway
upwind.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

According to Werehatrack "It's not difficult to remain motionless in
that circumstance"

Just to pick a nit here, how would a bike be able to remain motionless?
Isn't forward motion necessary (ie wheels rotating) to raise the
necessary gyroscopic force to hold the bike upright?

EJ in NJ

Werehatrack wrote:
On 29 Oct 2005 15:26:04 -0700, "john" wrote:


Question #2; If a rider at any speed, is riding into a 60 mph head
wind, why isn't he going backwards?


In the face of a 60mph headwind, if he's moving at all, he's doing
pretty well. It's not difficult to remain motionless in that
circumstance, but progress upwind would be very tiring and very slow,
involving the use of a very low gear. Bikes interact with the air and
the ground; even when the air is moving fast, the ground isn't. By
choosing a low enough gear ratio, forward progress is still possible.


On a windy day, I once saw the Goodyear blimp flying backwards relative
to the ground.


Yes. The blimp's interaction is solely with the air, not the ground.
If the air is moving at a speed greater than the blimp's highest
potential airspeed, then the blimp cannot make ground-relative headway
upwind.