Bicycle Quarterly Rolling Resistance Tests: No Surprises

On Mar 27, 7:29 pm, "Jan Heine" wrote:
As you can see, the Michelin scored much better on the drum than on
real roads, or inversely, the Conti is better on real roads than the
drum tests indicate.

Jan... if "suspension losses" can explain why some tires perform
better on real roads, then shouldn't these tires have a smoother ride?
In the article you state that the Contis had a poor ride compared to
the Pro2. You also state that latex tubes have a smoother ride, yet
they are slower on the road... but they perform better on drum tests.
I can't think of any mechanism for this to occur... the concept of
suspension losses certainly doesn't do it.

6. We found a very distinct speed increase with tire pressure until
about 12% tire drop, then the speed increase flattened off almost
completely. This is very different from the curve shape found athttp://bike.terrymorse.com/imgs/rolres.gif

Is this curve published somewhere? I don't see it in the article.
There are only 2 data points for most of the tires you tested. There
are 4 for the Rolly Polly, but the drop-off looks about the same as
the IRC tests to me... plus, it is necessary to convert your run times
to Crr if you want to make a comparison. Converting to Crr will make
the differences more pronounced.

In article
. com,
wrote:

I can't get embroiled in an internet debate about this stuff, so I'm
afraid I won't be posting additional responses here. If you really
think we are off our rockers, write a letter to BQ, or better yet,
write an article critiquing ours. If you haven't at least read the
article(s) though, arguments that they are "nutty" simply show closed-
mindedness.

I appreciate that you do not wish to engage in an
extended discussion; and sympathize fully with your
position. Nobody would be served by such a discussion.
Therefore I am puzzled at your Parthian shot: a vague
accusation of nutty-ness and close-mindedness in this
forum. My email address is valid.
--
Michael Press

In article
,
Tim McNamara wrote:

In article ,
wrote:

On 27 Mar 2007 19:29:02 -0700, "Jan Heine"
wrote:

[snip]

Tire TOUR Crr BQ time
Deda Tre Giro d'Italia 0.0038 25.3 s
Vittoria Open Corsa CX 0.0039 25.8 s
Michelin Pro Race 0.0042 27.1 s
Conti Ultra Gator Skin 0.0058 27.1 s

As you can see, the Michelin scored much better on the drum than on
real roads, or inversely, the Conti is better on real roads than the
drum tests indicate.

[snip]

Dear Jan,

In hopes of preventing another outburst of format indignation, I've
taken the liberty of adjusting the spacing in your table:

Tire TOUR Crr BQ time
Deda Tre Giro d'Italia 0.0038 25.3 s
Vittoria Open Corsa CX 0.0039 25.8 s
Michelin Pro Race 0.0042 27.1 s
Conti Ultra Gator Skin 0.0058 27.1 s

There! Another senseless tragedy averted!

Oddly enough, Carl, in my newsreader Jan's table was more accurately
formatted than yours.

Luckily, this question can be settled. Here is a scale.

12345678901234567890123456789012345678901234567890 12345678901234567890
^ ^ ^ ^ ^ ^ ^
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWX YZ

Do the carats align with the zeroes?
Does the `z' align at 26 characters?
Does the `Z' align at 52 characters?
--
Michael Press

"Michael Press" wrote in message
...
In article
,
Tim McNamara wrote:

In article ,
wrote:

On 27 Mar 2007 19:29:02 -0700, "Jan Heine"
wrote:

[snip]

Tire TOUR Crr BQ time
Deda Tre Giro d'Italia 0.0038 25.3 s
Vittoria Open Corsa CX 0.0039 25.8 s
Michelin Pro Race 0.0042 27.1 s
Conti Ultra Gator Skin 0.0058 27.1 s

As you can see, the Michelin scored much better on the drum than on
real roads, or inversely, the Conti is better on real roads than the
drum tests indicate.

[snip]

Dear Jan,

In hopes of preventing another outburst of format indignation, I've
taken the liberty of adjusting the spacing in your table:

Tire TOUR Crr BQ time
Deda Tre Giro d'Italia 0.0038 25.3 s
Vittoria Open Corsa CX 0.0039 25.8 s
Michelin Pro Race 0.0042 27.1 s
Conti Ultra Gator Skin 0.0058 27.1 s

There! Another senseless tragedy averted!

Oddly enough, Carl, in my newsreader Jan's table was more accurately
formatted than yours.

Luckily, this question can be settled. Here is a scale.

12345678901234567890123456789012345678901234567890 12345678901234567890
^ ^ ^ ^ ^ ^ ^
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWX YZ

Do the carats align with the zeroes?
Does the `z' align at 26 characters?
Does the `Z' align at 52 characters?
--
Michael Press

Using Outlook Express:
No
No
No
Kerry

In article ,
Michael Press wrote:

In article
,
Tim McNamara wrote:

In article ,
wrote:

On 27 Mar 2007 19:29:02 -0700, "Jan Heine"
wrote:

[snip]

Tire TOUR Crr BQ time
Deda Tre Giro d'Italia 0.0038 25.3 s
Vittoria Open Corsa CX 0.0039 25.8 s
Michelin Pro Race 0.0042 27.1 s
Conti Ultra Gator Skin 0.0058 27.1 s

As you can see, the Michelin scored much better on the drum than on
real roads, or inversely, the Conti is better on real roads than the
drum tests indicate.

[snip]

Dear Jan,

In hopes of preventing another outburst of format indignation, I've
taken the liberty of adjusting the spacing in your table:

Tire TOUR Crr BQ time
Deda Tre Giro d'Italia 0.0038 25.3 s
Vittoria Open Corsa CX 0.0039 25.8 s
Michelin Pro Race 0.0042 27.1 s
Conti Ultra Gator Skin 0.0058 27.1 s

There! Another senseless tragedy averted!

Oddly enough, Carl, in my newsreader Jan's table was more accurately
formatted than yours.

Luckily, this question can be settled. Here is a scale.

12345678901234567890123456789012345678901234567890 12345678901234567890
^ ^ ^ ^ ^ ^ ^
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWX YZ

Do the carats align with the zeroes?
Does the `z' align at 26 characters?
Does the `Z' align at 52 characters?

What does this have to do with tires? If you must yank threads off
topic like this, please at least fork it off into its own thread.

Michael Press wrote:
-snip tabulation query-

Luckily, this question can be settled. Here is a scale.
12345678901234567890123456789012345678901234567890 12345678901234567890
^ ^ ^ ^ ^ ^ ^
abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWX YZ
Do the carats align with the zeroes?
Does the `z' align at 26 characters?
Does the `Z' align at 52 characters?

aligns perfectly in Netscape News
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

Tim McNamara wrote:
In article . com,
"Ron Ruff" wrote:

On Mar 25, 3:48 pm, Tim McNamara wrote:

I don't know with certainty one way or the other,
but it may be that the differences in rolling resistance resulting
from h igher or lower inflation pressures may be of far smaller
magnitude than smooth drum tests would suggest.

That is one of the issues... the IRC, Tour, and BQ test actually
agree on the effect of pressure on rolling resistance. The BQ re sults
were misinterpreted however, as they report that the effect of
pressure was much smaller than that shown in roller tests. This is a
reprint from my earlier post:

"They say that roller test show that a drop in pressure from 10 5 to
85 psi resulted in a Crr increase of 15%, whereas their testing
showed a drop in speed of only 2%. Apples to oranges... Crr is not
speed. An increase in Crr of 15% *is* equivalent to a drop in speed
of ~2%... so they have verified the drum tests."

There seems to be some difficulty in this thread in understanding how
what tests mean in terms of statistically significant measurements, and
in turn what that means for interpretation of results. IIRC, without
rereading t he article before going to work this morning, Heine wrote
that the effects of inflation pressure were smaller than the error of
measurement (unless the differences in inflation pressure were very
large that is).

Yes, the resolution of the BQ test method was not sufficient to hear
the signal due to inflation pressu it got smothered in the noise.
That is (one of the reasons) why one does roller tests, to reduce the
noise and find that otherwise drowned out signal which is nevertheless
still athletically very significant: 13 sec per hour, roughly. Both BQ
and IRC tests come to that same conclusion, just that in the BQ tests
the noise levels were about that much too, while in the IRC tests they
were much smaller.

An important point to emphasize- so I will do it again in reply to JH
and MM's posts- is that the BQ tests prove that, for paved roads such
as used in the BQ tests, suspension losses ARE NOT a factor. We know
this because, all other things being similar, air pressure is by far
the major determinant of suspension losses. Yet, changing the air
pressure within an important range did not change the times any more
than one would have expected due to their influence on rolling
resistance alone, based on the IRC tests. Just as Jobst has been
saying all these years.

On Mar 29, 6:56 am, "41" wrote:
An important point to emphasize- so I will do it again in reply to JH
and MM's posts- is that the BQ tests prove that, for paved roads such
as used in the BQ tests, suspension losses ARE NOT a factor. We know
this because, all other things being similar, air pressure is by far
the major determinant of suspension losses. Yet, changing the air
pressure within an important range did not change the times any more
than one would have expected due to their influence on rolling
resistance alone, based on the IRC tests. Just as Jobst has been
saying all these years.

I think it would be more accurate to say the suspension losses were
small enough to be lost in the noise of the BQ test. I believe they
are there, but appear to be fairly small. Alan Morrison has been
testing tires on rollers with a powermeter, and his data is posted at
the Bike Tech Review site. He also tried testing on a "rough"
roller... one that had a series of wires attached to the surface. This
lessened the effect of tire pressure on Crr, but up to at least 140
psi there was no pressure where the resistance started to increase. I
had actually expected to see a clear "optimum" at a lower pressure.

Tim McNamara wrote:

Ja n's an intelligent guy and the team involved included a few PhDs who
are familiar with scientific method, as well as some attempts at peer
review which was perhaps not as strong as it might have been from an
academic standpoint. So I have confid ence that they did take as many
steps as they could think of to eliminate confounds- I am just not as
sure that they actually succeeded.

Since I am the one who started this thread, I should emphasize that I
find that they did succeed: within the limits of resolution of their
tests, they confirmed conventional tire theory as explained e.g. by
Continental or Schwalbe, with regard to tire width and thickness:
http://www.schwalbetires.com/wider_faster_page
http://www.schwalbetires.com/tech_info/rolling_resistance
http://www.cyclingnews.com/tech/?id=2005/features/conti_tech


Likewise they confirmed both the IRC tests, and the interpretation of
them that Jobst has been offering all these years:

-For paved roads, suspension losses acting in any way different from
ordinary rolling resistance losses ARE NOT a factor in how fast the
bike rolls. We know this because they found the effect of air pressure
within the relevant ranges to be no different from that found in the
pure rolling resistance tests as done by IRC.

-Tires are slower the more hysteretic their construction: thicker,
harder rubber; heavier, stiffer casing; tubular glue.


Equally important is what the tests DID NOT show (or test for):


We also, I think, have to contextualize the BQ viewpoint which is
randonneuring, and consider Jan's conclusions within that framework. In
a crit, TT or a (relatively, for randonneurs) short road race of 100
miles maximum efficiency is more important than comfort so tires are
inflated as hard as possible. If inflation pressure provides very small
practical effects on rolling resistance that's very useful for a
randonneur because running tires at 100 rather than 115 psi can be
noticeably more comfortable, and over 375 miles in a weekend that can
mean faster times due to reduced fatigue.


Since the BQ tests were over a short downhill test course, they did
not and COULD NOT test for the effect on event times as influenced by
comfort and fatigue. That trade off is individual anyway, since riding
styles and positions and body masses and bicycle wheelbases are
different. As I say, they DID prove, within the limits of their test
resolution, that the direct suspension effect (i.e. not via the
intermediary of how it fatigues the rider) as different from rolling
resistance per se IS NOT a factor on paved roads (at least, for
whatever particular surface they used). Just as Jobst has been
propounding all these years.

Another item they did NOT and could not test for: which is faster,
thin hard rubber or thick soft rubber, so as to give equal durability?
And: what to make of that question, since one simply doesn't find soft
rubber treaded tires, of any reasonable thickness, with the durability
of thin hard rubber.

In article om,
"41" wrote:

Tim McNamara wrote:

Jan's an intelligent guy and the team involved included a few PhDs
who are familiar with scientific method, as well as some attempts
at peer review which was perhaps not as strong as it might have
been from an academic standpoint. So I have confid ence that they
did take as many steps as they could think of to eliminate
confounds- I am just not as sure that they actually succeeded.

Since I am the one who started this thread, I should emphasize that I
find that they did succeed: within the limits of resolution of their
tests, they confirmed conventional tire theory as explained e.g. by
Continental or Schwalbe, with regard to tire width and thickness:
http://www.schwalbetires.com/wider_faster_page
http://www.schwalbetires.com/tech_info/rolling_resistance
http://www.cyclingnews.com/tech/?id=2005/features/conti_tech


Likewise they confirmed both the IRC tests, and the interpretation of
them that Jobst has been offering all these years:

-For paved roads, suspension losses acting in any way different from
ordinary rolling resistance losses ARE NOT a factor in how fast the
bike rolls. We know this because they found the effect of air
pressure within the relevant ranges to be no different from that
found in the pure rolling resistance tests as done by IRC.

-Tires are slower the more hysteretic their construction: thicker,
harder rubber; heavier, stiffer casing; tubular glue.

The resolution of the BQ tests, IMHO, was not fine-grained enough to
claim that they confirmed or disconfirmed "conventional" tire theory.
And indeed, the authors of the test appear to disagree with your
conclusion on several points- including finding that suspension losses
were a significant factor. There were several points of difference
compared to the IRC tests and the Tour tests.

Tests always have to be interpreted in the context of what was being
examined. In the case of the BQ tests they were not examining rolling
resistance but overall tire performance. Rolling resistance is one
factor in tire performance.

Equally important is what the tests DID NOT show (or test for):

We also, I think, have to contextualize the BQ viewpoint which is
randonneuring, and consider Jan's conclusions within that
framework. In a crit, TT or a (relatively, for randonneurs) short
road race of 100 miles maximum efficiency is more important than
comfort so tires are inflated as hard as possible. If inflation
pressure provides very small practical effects on rolling
resistance that's very useful for a randonneur because running
tires at 100 rather than 115 psi can be noticeably more
comfortable, and over 375 miles in a weekend that can mean faster
times due to reduced fatigue.

I wrote the above, not anyone from BQ, just to make sure that is clear.

Since the BQ tests were over a short downhill test course, they did
not and COULD NOT test for the effect on event times as influenced by
comfort and fatigue. That trade off is individual anyway, since
riding styles and positions and body masses and bicycle wheelbases
are different. As I say, they DID prove, within the limits of their
test resolution, that the direct suspension effect (i.e. not via the
intermediary of how it fatigues the rider) as different from rolling
resistance per se IS NOT a factor on paved roads (at least, for
whatever particular surface they used). Just as Jobst has been
propounding all these years.

Their conclusion about that is much the opposite of what you claim they
found. Again I ask: have you actually read the source article and the
follow up article? If not, you are really not in any position to say
what their findings were, let alone to rebutt them.