Hub Rolling Resistance - DA vs Ultegra vs 105?

Is there any meaningful difference in the rolling resistance between
the 3 primary lines of hubs in the Shimano line?

My cheap-skate dirt-bag opinion has always been that above the worst
of the hubs, you mostly pay for a) better polish and bling and b)
lower weight but that rolling resistance was largely the same.

If you think there is less rolling resistance in the top end hubs, can
you explain why and how this achieved?

Is it because in the inner surface of the bearing cup is so much
better?

Is it because the cones are so much better? Is there such a thing as
a DuraAce cone that differs in any way from, say, a 105 cone?

Is it because the bearings themselves are so much better? Again, is
there such a thing as a DuraAce ball bearing?

Many thanks,

-Dave


-- Dave
==============================================
"It is impossible, or not easy, to do noble acts
without the proper equipment."
Aristotle, Politics, 1323a-b, trans Jowett
==============================================

There is probably a difference due to better bearings, races, and
alignment... but even a 100% difference would not amount to much. Hub
bearing rolling resistance is ~ 100 times less than tire resistance...
which isn't even very much at high speeds.

pinnah wrote:
Is there any meaningful difference in the rolling resistance between
the 3 primary lines of hubs in the Shimano line?

not so as you'd notice while riding.


My cheap-skate dirt-bag opinion has always been that above the worst
of the hubs, you mostly pay for a) better polish and bling and b)
lower weight but that rolling resistance was largely the same.

If you think there is less rolling resistance in the top end hubs, can
you explain why and how this achieved?

there's very little measurable in r.r. - the difference is longevity
improved by improved precision and materials.


Is it because in the inner surface of the bearing cup is so much
better?

adjusted correctly, you won't notice much difference in r.r., just
smoothness.


Is it because the cones are so much better? Is there such a thing as
a DuraAce cone that differs in any way from, say, a 105 cone?

sure, they're smoother because the precision is better.


Is it because the bearings themselves are so much better? Again, is
there such a thing as a DuraAce ball bearing?

there's different grade ball and different grade races. as above, if
you're noticing a difference in actual rolling resistance [not
smoothness] the bearings need to be adjusted correctly.


Many thanks,

-Dave


-- Dave
==============================================
"It is impossible, or not easy, to do noble acts
without the proper equipment."
Aristotle, Politics, 1323a-b, trans Jowett
==============================================

On Fri, 14 Jul 2006 15:57:41 -0400, pinnah
wrote:

Is there any meaningful difference in the rolling resistance between
the 3 primary lines of hubs in the Shimano line?

My cheap-skate dirt-bag opinion has always been that above the worst
of the hubs, you mostly pay for a) better polish and bling and b)
lower weight but that rolling resistance was largely the same.

If you think there is less rolling resistance in the top end hubs, can
you explain why and how this achieved?

Is it because in the inner surface of the bearing cup is so much
better?

Is it because the cones are so much better? Is there such a thing as
a DuraAce cone that differs in any way from, say, a 105 cone?

Is it because the bearings themselves are so much better? Again, is
there such a thing as a DuraAce ball bearing?

Many thanks,

-Dave


-- Dave
==============================================
"It is impossible, or not easy, to do noble acts
without the proper equipment."
Aristotle, Politics, 1323a-b, trans Jowett
==============================================

Dear Dave,

You may be thinking of stuff like this:

2006 FSA Ceramic Hub Bearing Set for Mavic & Zipp Wheelsets $339.99
Item: FSA152

Ceramic bearings reduce drag in your hubs, and they do it in a big,
big way in comparison to the machine-quality cartridge bearings that
come stock in most wheelsets (even high end models) on the market
today. Ceramic bearings are immeasurably-and-thoroughly-devilishly
round, and it's this roundness that gives them their rolling
slickness. The reduction in mechanical drag you get by upgrading to
ceramic bearings is no different than magically shedding pounds off
your bike on a climb. For a given wattage, your speed increases.
Period. According to FSA, the use of their ceramic bearings (including
the specially formulated lubricant they roll in) gives you an added
20m-40m per 1km ridden. And keep in mind that mechanical drag is
utterly unlike aerodynamics -- it becomes more and more critical the
lower your speed is. According to FSA testing, the use of ceramic
bearings decreases friction 22-fold. It's not personal, it's just
physics.

http://www.competitivecyclist.com/za...Y.ID=830&MODE=
or http://tinyurl.com/rl66t

(Note the weird claim that "mechanical drag becomes more and more
critical the lower your speed is." Mechanical drag rises with load and
speed. It does become a larger part of the total drag as speed drops,
since wind drag is not linear--below about 15 mph, transmission and
rolling resistance are about as big as wind drag. But the notion that
mechanical drag becomes critical at low speeds implies that your
grandmother needs $340 bearings to idle down the block to visit a
friend.)

Below is part of the article "FSA Ceramic Revolution" mentioned in the
ad, from this site:

http://www.fullspeedahead.com/fly.as...t=news&cid=199

(Page down in the inset to get to the "Testing Data" reproduced
below.)

I hope to see entertaining comments about the claims.

Cheers,

Carl Fogel

TESTING DATA

Tests by the Danish magazine Cykel-Motion (Mar 2005) and subsequently
supported by calculation, show how using ceramic bearings can reduce
rolling resistance by 50%, saving 22m in just 55 seconds at 32kph. In
short, astounding speed improvement of 4%.

Further tests by SKF, and confirmed by the Danish cycle magazine Cykel
Magasinet (Sep 2005), describe dramatic reductions in friction
compared to conventional cycle bearings. For example:

With a pair of race wheels (total of six bearings), friction with
ceramic bearings is reduced 22 fold

While Dura Ace pulleys consume 0.78W @ 500rpm, ceramic pulleys use
less than 0.06W

A Record BB @ 100rpm and 400W consumes 0.6W, the same BB with ceramic
bearings consumes 0.02W

Such improvement is unheard of, even in this day of advanced bicycle
technology. So, it comes as no surprise to learn that top professional
riders are already using these amazing bearings to win major races.

Full Speed Ahead has been testing ceramic bearings with our teams for
the past two years. The results are great, teams and riders are
convinced.

The friction reduction of ceramic bearings aids a wide variety of
riders. Unlike aerodynamic features, which only the fastest riders
enjoy, the advantage of ceramic units is greater at lower speeds. This
is a crucial difference between aerodynamic resistance, which
increases exponentially with speed; and mechanical friction, which
increases in direct proportion to speed. From a technical point of
view, riders sheltered inside the peleton or riding off road have more
to gain with ceramic bearings.

Ceramic bearings last longer, perhaps 5-10 times more. From a strictly
economic perspective, they’re less expensive to run even without
considering the labor savings.

Now it’s time to share this exclusive technology with our customers.

On Fri, 14 Jul 2006 15:57:41 -0400, pinnah
wrote:
Is it because the bearings themselves are so much better? Again, is
there such a thing as a DuraAce ball bearing?

wrote:
You may be thinking of stuff like this:

2006 FSA Ceramic Hub Bearing Set for Mavic & Zipp Wheelsets $339.99
Item: FSA152

That's very interesting (and expensive).

But the FSA bearings are cartridge style and only available for Campy
type hubs, correct?

Can loose ceramic balls be used with traditional cup/cone hubs?
Are they available?


-- Dave
==============================================
"It is impossible, or not easy, to do noble acts
without the proper equipment."
Aristotle, Politics, 1323a-b, trans Jowett
==============================================

On Fri, 14 Jul 2006 22:00:24 -0400, pinnah
wrote:

On Fri, 14 Jul 2006 15:57:41 -0400, pinnah
wrote:
Is it because the bearings themselves are so much better? Again, is
there such a thing as a DuraAce ball bearing?

wrote:
You may be thinking of stuff like this:

2006 FSA Ceramic Hub Bearing Set for Mavic & Zipp Wheelsets $339.99
Item: FSA152

That's very interesting (and expensive).

But the FSA bearings are cartridge style and only available for Campy
type hubs, correct?

Can loose ceramic balls be used with traditional cup/cone hubs?
Are they available?


-- Dave
==============================================
"It is impossible, or not easy, to do noble acts
without the proper equipment."
Aristotle, Politics, 1323a-b, trans Jowett
==============================================

Dear Dave,

Interesting, expensive, and rather questionable.

Note the claim for a 4% speed increase:

http://www.fullspeedahead.com/fly.as...t=news&cid=199

This calculator . . .

http://www.kreuzotter.de/english/espeed.htm

predicts with defaults, hands-on-drops, and the 400 watts mentioned in
that FSA bearing link . . .

27.7 mph.

A 4% speed increase would mean 28.8 mph, which the calculator predicts
requires . . .

Er, 446 watts, suggesting that the bearing drag eliminated would be 46
watts. I think that most people would be hard pressed to find 46 watts
of bearing resistance in their hubs, pulleys, pedals, and bottom
bracket at 28 mph. That's about 7 watts per bearing.

Cheers,

Carl Fogel

wrote:

You may be thinking of stuff like this:
... According to FSA, the use of their ceramic bearings (including
the specially formulated lubricant they roll in) gives you an added
20m-40m per 1km ridden. And keep in mind that mechanical drag is
utterly unlike aerodynamics -- it becomes more and more critical the
lower your speed is. According to FSA testing, the use of ceramic
bearings decreases friction 22-fold. It's not personal, it's just
physics. ...

I hope to see entertaining comments about the claims.

Geez, Carl, just post the entire advertising brochure,
why don't you.

The typical power dissipated in front+rear wheel bearings
for a typical rider, traveling at 10 m/s (22 mph) should be
about 0.35 watts, as analyzed he
http://groups.google.com/group/rec.bicycles.tech/msg/9306a25dadee264e

For comparison the total power at 10m/s is of order 210 watts,
of which about 180 W is due to aero drag (depending on the
rider's area, of course). So about 0.17% of power is going
into wheel bearings. Riding on magical frictionless bearings
would save 0.17% of power and increase speed by about 0.06%,
or 0.6 meter per km, not the 20-40 m FSA claims. Of course
ceramic bearings are not actually magical nor frictionless, so
the savings should be less.

TESTING DATA

Tests by the Danish magazine Cykel-Motion (Mar 2005) and subsequently
supported by calculation, show how using ceramic bearings can reduce
rolling resistance by 50%, saving 22m in just 55 seconds at 32kph. In
short, astounding speed improvement of 4%.

While Dura Ace pulleys consume 0.78W @ 500rpm, ceramic pulleys use
less than 0.06W

These are referring to derailleur jockey pulley bearings,
and this is very likely horse****, because the angular
velocity of a jockey pulley is high but the force loading
is very small.

A Record BB @ 100rpm and 400W consumes 0.6W, the same BB with ceramic
bearings consumes 0.02W

I require a reputable engineering reference for the coefficient
of friction of ceramic bearings (in typical conditions, not
perfect oilbath or something) before believing this.

IIRC, the Zipp promo material that Lennard Zinn quoted
(what I was responding to in the post linked above) said
that ceramic bearing had about 3-4% less friction than
steel bearings, that is their friction was 0.96-0.97 of
steel bearings.

Ben

On 14 Jul 2006 19:26:11 -0700, "
wrote:

wrote:

You may be thinking of stuff like this:
... According to FSA, the use of their ceramic bearings (including
the specially formulated lubricant they roll in) gives you an added
20m-40m per 1km ridden. And keep in mind that mechanical drag is
utterly unlike aerodynamics -- it becomes more and more critical the
lower your speed is. According to FSA testing, the use of ceramic
bearings decreases friction 22-fold. It's not personal, it's just
physics. ...

I hope to see entertaining comments about the claims.

Geez, Carl, just post the entire advertising brochure,
why don't you.

[reluctantly snip entertaining and appreciated comments]

Dear Ben,

Surely you don't consider that an advertising brochure disguised as
test results?

You know, the kind of stuff that could make people wonder if they
could increase their speed 4% with $340 bearings?

Remember, "it becomes more and more critical the lower your speed is!"



Thanks for the technical comments, even though I snipped them. I
thought that someone might have a few minor objections to that
twaddle.

Cheers,

Carl Fogel

"pinnah" wrote in message
...
Is there any meaningful difference in the rolling resistance between
the 3 primary lines of hubs in the Shimano line?

My cheap-skate dirt-bag opinion has always been that above the worst
of the hubs, you mostly pay for a) better polish and bling and b)
lower weight but that rolling resistance was largely the same.

I have taken apart and put back together dozens of types of hubs. Unsealed
old-school cup and cone bearing hubs (as made by Shimano and Campagnolo)
have slightly lower rolling resistance than their sealed modern equivalents
(such as the excellent current generation of LX and XT hubs). Cartridge
bearing hubs have about the same rolling resistance as sealed hubs.

Properly set up (and that is the key here), there is no real difference in
rolling resistance between road hubs such as Dura-Ace and 105. You cannot
tell the difference spinning the hub by hand. Dura-Ace and XTR feature
forged bearing cups and cones and stainless bearings - which provides a
greater longevity when dirt and water gets in. Nevertheless, properly set
up and maintained, a 105 or LX hub should pretty much last the life of the
rider. Typically the cheaper hubs are set up too tight, and with too little
grease. This causes roughness, and premature wear.

Finally, the small differences we are talking about here - between different
hubs, or even more of a stretch, different types of ball bearings are so
minor and inconsequential, that they are not even worth thinking about. Go
out and train an extra second per month. That is the magnitude of possible
improvement we are talking about here.

As others have eloquently told you, resistance is so small down there.
The quality, and the good shape, of a bearing is only told by the noise
it makes while rolling, for which so little power is needed.

Sergio
Pisa