Of course you are quite right that this is of no importance when we go ride
our bikes, but when experimental data seems to contradict our understanding
of how something works I like to find at least a possible explanation.
Don't you?
I'm no engineer and my graduate degree has nothing to do wi
The way I wrapped my head around it is that 3 ( at least ) different
phenomena are involved; tire internal friction, tire contact patch (
external friction ), and vibration damping of the entire assembly ( Tires,
Bike, Human). At very low pressure tire internal friction is high and tire
contac
Just don't hold your breath.
On Tuesday, January 7, 2014 9:48:36 PM UTC-8, Christopher Chen wrote:
>
> I look forward to your results, Ted.
> On Jan 7, 2014 9:42 PM, "ted" > wrote:
>
>> I don't see how this relates to my question.
>> I think it is a possible (or even probable) explanation for res
I look forward to your results, Ted.
On Jan 7, 2014 9:42 PM, "ted" wrote:
> I don't see how this relates to my question.
> I think it is a possible (or even probable) explanation for resistance
> increasing as pressure increases from nominal to moderately high values.
> My question is what could
I don't see how this relates to my question.
I think it is a possible (or even probable) explanation for resistance
increasing as pressure increases from nominal to moderately high values.
My question is what could explain resistance then decreasing as pressure
continues to increase from moderate
What about rider/ bike weight?
On Saturday, January 4, 2014 7:46:07 AM UTC-5, Charlie wrote:
>
> http://www.schwalbetires.com/tech_info/rolling_resistance#why
>
> Another view on tire performance.
>
> Guess they do not use the same hill that Mr. Heine uses, or the same type
> of testing.
>
> Char
We just tested the tires and recorded the results – I only can offer
hypotheses why the tires behave that way. A likely explanation is that the
decrease in hysteretic losses becomes smaller once you exceed a certain
pressure, but the suspension losses still increase with higher pressures.
(You
Jan,
Agreed on the practical practice side, but I am still curious about the med
hi to hi pressure phenomena.
If I understand correctly, you say that from nominal to very high pressure,
losses in the tire itself decrease. But from nominal to moderately high
pressures, suspension losses increase
I pump up the Hetres, give em a squeeze and ride!
On Jan 5, 2014 9:50 PM, "Jan Heine" wrote:
>
>
> On Sunday, January 5, 2014 5:45:23 PM UTC-8, ted wrote:
>>
>> If I read that right, you are saying that your data shows a local maxima
>> at medium-high pressure with lower losses at tire pressures
On Sunday, January 5, 2014 5:45:23 PM UTC-8, ted wrote:
>
> If I read that right, you are saying that your data shows a local maxima
> at medium-high pressure with lower losses at tire pressures both above and
> below that point. Is that really what you mean to be saying?
>
Yes, that is what w
"just ride"
On Jan 5, 2014 8:45 PM, "ted" wrote:
> Jan,
>
> You wrote:
> "Low and very high pressures were marginally more efficient than
> medium-high pressures."
> If I read that right, you are saying that your data shows a local maxima
> at medium-high pressure with lower losses at tire pressu
Jan,
You wrote:
"Low and very high pressures were marginally more efficient than
medium-high pressures."
If I read that right, you are saying that your data shows a local maxima at
medium-high pressure with lower losses at tire pressures both above and
below that point. Is that really what you
On Sunday, January 5, 2014 8:32:54 AM UTC-8, Tim McNamara wrote:
>
> Interestingly that is pretty much in keeping with the traditional rolling
> resistance tests done in tire labs. The decrease in rolling resistance
> "flattens out" as inflation pressure increases. Even on a steel roller, an
Indeed, and given the relationships between load, width, and pressure, I
suspect how wide is wide enough depends on weight (of the rider that is). I
am much shorter and roughly 65lbs lighter than you (which is about 30%
less) and I run 32mm tires down around 55 or 65 psi. these days. Decades
ag
Interestingly that is pretty much in keeping with the traditional rolling
resistance tests done in tire labs. The decrease in rolling resistance
"flattens out" as inflation pressure increases. Even on a steel roller, an
increase from 100 to 140 psi doesn't reduce rolling resistance that much.
On Saturday, January 4, 2014 10:59:41 PM UTC-8, ted wrote:
>
> Are you equating the behavior of high performance 32mm clinchers and 25mm
> tubulars, or are both tires you mention clinchers?
>
I am just talking about test results. We tested the Grand Bois clinchers,
as well as the Vittorias as cl
I realized that my previous blog post may be misunderstood as saying that
width is all that matters for tire speed. In fact, it's a minor component -
it's just that when you are comparing tires of similar construction, wider
tires offer you more comfort and as much or more speed. To clarify, I
Thanks for the information Jan,
Some of your comments elicit some questions. You say:
"a Grand Bois 700C x 32 mm (or Vittoria CX Corsa 25 mm) tire is as fast at
60 psi as it is at 200 psi. At moderately high pressures (110 psi or so),
they actually were a little slower, but this is a minor effec
Obviously, if your tire is flat, rolling resistance is very high. So there
is a minimum pressure below which rolling resistance increases. In our
testing, we found that this pressure was about at the point where the tire
no longer cornered safely - pretty low!
There also must be a maximum press
Um yea Jan, hence the portion of the my original text between "resistance"
and the period:
"... (on smooth surface or neglecting suspension losses), but at very low
pressure this change is larger than at higher pressures, and as pressure
increases the effect becomes negligable."
That increasing
I would rather know how wide is wide enough (as opposed to how wide is too
wide).
It seems generally accepted that really low pressure results in more
rolling resistance than somewhat more pressure does. Somebody (sorry to say
I forget the proper citation to credit the appropriate party) did so
On Saturday, January 4, 2014 12:17:13 PM UTC-8, ted wrote:
>
> 3) For a given tire increasing pressure reduces rolling resistance.
>
It depends what you call rolling resistance. If you define it as only the
hysteretic losses within the tire, then it's true. However, if you are
looking at the OVE
On 01/04/2014 04:17 PM, Patrick Moore wrote:
Also, has he or anyone else determined that a 23 mm Pro Race 3 is
slower than a 25 mm on a very smooth road?
He has tested the Pro2Race in all 3 sizes and found that; and as I
recall, he quoted Michelin in the article as saying the same thing.
IIRC, Jan has asked aloud if there is a point where wider might begin to
make a tire slower. Has this been answered?
Also, has he or anyone else determined that a 23 mm Pro Race 3 is slower
than a 25 mm on a very smooth road? A 19mm? On glass? In brief, is there a
breadth below which an otherwise
As Jan Heine has often pointed out, his methodology is significantly
different than that of most tire manufacturers.
Despite that, what I get reading the article you linked to seems fairly
consistent with what I think Jan has written.
1) All other things being equal a tire with lighter more supp
Schwalbe's graph is nice, but unfortunately, it's an ancient graph that has
long been debunked. While it shows wider tires rolling faster, it also
suggests that very high pressures make tires roll faster. That simply isn't
true. We've used several different methods to confirm our initial results
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