Rim Width

Callistus Valerius wrote:
wider the rim the less rolling resistance, but higher the aerodynamic
resistance. that's why the pros, use skinny rims, they're less aero.




Your second sentence seems to contradict your first. And I do not
believe that aerodynamics play a part at all in racers' choice of rims.

Tom

Tom Reingold writes:

I recall a few years ago, Jobst Brandt did some extensive testing
and found that rolling resistance actually increases when tire
width goes below 28mm. I would guess that width doesn't have as
much an effect on rolling resistance as you'd think. I think the
tire material and construction and inflation pressure are more
important.

I got a mountain bike cheap at a local police auction. It had fat,
knobby tires. The tires were so loud, I thought a truck was behind
me when I went downhill. I replaced them with 1.4 inch (35mm)
slick tires and inflated them to 100 psi. The bike now rides like
a road racer. I'm a very happy rider now.

That's interesting and opposite of what I've read (I'm new to
this). My daughter was grumped because I roll better than she.
I'm on 23's while she's on 35's. OTOH, she has a LOT of tread
while I have almost slicks. So there is a factor we didn't put in
here.

I'll look for 28's with very smooth tread. My buddy who rides a
mtn bike with slicks says I'm faster than him because of my 23's.
I'd LIKE to think it's me and not the bike.

Is Brandt's work published on the Web somewhere?

It's not so much my work but rather a presentation of what IRC
measured for Avocet when Avocet introducing smooth tread tires at my
behest, tires that had been offered in the past but with no
explanation on their benefits or the lack of benefits of miniature
automotive tread imitations. Road motorcycles arrived upon that a few
years earlier and before that racing cars that inherited the concept
from drag racers. In this history the misunderstanding among
tribologists is revealed best. They had no idea where traction arose
and on what scale hydroplaning occurs.

Thanks to Terry Morse these curves are displayed on his website.

I'm sure weight, tire pressure, weight distribution, air drag, and
other factors are at play, too. But yes, tread is bad on a bike
tire. Jobst also found that tread on bike tires are purely cosmetic
unless you are in very slippery terrain. That's why he invented
slick tires. If your tires have very fine tread, it neither helps
nor hinders. Most people want a little tread, because they believe
it helps, but Jobst found it not to be true.

Let's say the motorized industry proved that one for me. I just
happened to be working in racing cars at the time these developments
came along and recognized their application in bicycling.

I don't know if it's on the web, but you can find old usenet articles at
http://groups.google.com

And he might be able to answer right here!

http://www.terrymorse.com/bike/rolres.html
http://yarchive.net/bike/rolling_resistance.html
http://www.cqq.ch/Moto/1Moto_images/.../GP-Vale_2.jpg

Jobst Brandt

wrote:


http://www.terrymorse.com/bike/rolres.html
http://yarchive.net/bike/rolling_resistance.html
http://www.cqq.ch/Moto/1Moto_images/.../GP-Vale_2.jpg

Thanks for the links and the discussion - you and the others who have
made this a very informative thread. -paul

wrote in message
...
Tom Reingold writes:

I recall a few years ago, Jobst Brandt did some extensive testing
and found that rolling resistance actually increases when tire
width goes below 28mm. I would guess that width doesn't have as
much an effect on rolling resistance as you'd think. I think the
tire material and construction and inflation pressure are more
important.

I got a mountain bike cheap at a local police auction. It had fat,
knobby tires. The tires were so loud, I thought a truck was behind
me when I went downhill. I replaced them with 1.4 inch (35mm)
slick tires and inflated them to 100 psi. The bike now rides like
a road racer. I'm a very happy rider now.

That's interesting and opposite of what I've read (I'm new to
this). My daughter was grumped because I roll better than she.
I'm on 23's while she's on 35's. OTOH, she has a LOT of tread
while I have almost slicks. So there is a factor we didn't put in
here.

I'll look for 28's with very smooth tread. My buddy who rides a
mtn bike with slicks says I'm faster than him because of my 23's.
I'd LIKE to think it's me and not the bike.

Is Brandt's work published on the Web somewhere?

It's not so much my work but rather a presentation of what IRC
measured for Avocet when Avocet introducing smooth tread tires at my
behest, tires that had been offered in the past but with no
explanation on their benefits or the lack of benefits of miniature
automotive tread imitations. Road motorcycles arrived upon that a few
years earlier and before that racing cars that inherited the concept
from drag racers. In this history the misunderstanding among
tribologists is revealed best. They had no idea where traction arose
and on what scale hydroplaning occurs.

Thanks to Terry Morse these curves are displayed on his website.

I'm sure weight, tire pressure, weight distribution, air drag, and
other factors are at play, too. But yes, tread is bad on a bike
tire. Jobst also found that tread on bike tires are purely cosmetic
unless you are in very slippery terrain. That's why he invented
slick tires. If your tires have very fine tread, it neither helps
nor hinders. Most people want a little tread, because they believe
it helps, but Jobst found it not to be true.

Let's say the motorized industry proved that one for me. I just
happened to be working in racing cars at the time these developments
came along and recognized their application in bicycling.

I don't know if it's on the web, but you can find old usenet articles at
http://groups.google.com

And he might be able to answer right here!

http://www.terrymorse.com/bike/rolres.html
http://yarchive.net/bike/rolling_resistance.html
http://www.cqq.ch/Moto/1Moto_images/.../GP-Vale_2.jpg

Jobst Brandt

Now that the compound has changed with the Avocet tires listed in the test,
has the results been the same, or updated?
-tom

Tom Nakashima wrote:

Now that the compound has changed with the Avocet tires listed in the test,
has the results been the same, or updated?
-tom




Are Avocet tires even available any more?


--
Tom Reingold
Noo Joizy
This email address works, but only for a short time.

On Wed, 3 Aug 2005 06:37:48 -0700, "Tom Nakashima"
wrote:


wrote in message
...
Tom Reingold writes:

I recall a few years ago, Jobst Brandt did some extensive testing
and found that rolling resistance actually increases when tire
width goes below 28mm. I would guess that width doesn't have as
much an effect on rolling resistance as you'd think. I think the
tire material and construction and inflation pressure are more
important.

I got a mountain bike cheap at a local police auction. It had fat,
knobby tires. The tires were so loud, I thought a truck was behind
me when I went downhill. I replaced them with 1.4 inch (35mm)
slick tires and inflated them to 100 psi. The bike now rides like
a road racer. I'm a very happy rider now.

That's interesting and opposite of what I've read (I'm new to
this). My daughter was grumped because I roll better than she.
I'm on 23's while she's on 35's. OTOH, she has a LOT of tread
while I have almost slicks. So there is a factor we didn't put in
here.

I'll look for 28's with very smooth tread. My buddy who rides a
mtn bike with slicks says I'm faster than him because of my 23's.
I'd LIKE to think it's me and not the bike.

Is Brandt's work published on the Web somewhere?

It's not so much my work but rather a presentation of what IRC
measured for Avocet when Avocet introducing smooth tread tires at my
behest, tires that had been offered in the past but with no
explanation on their benefits or the lack of benefits of miniature
automotive tread imitations. Road motorcycles arrived upon that a few
years earlier and before that racing cars that inherited the concept
from drag racers. In this history the misunderstanding among
tribologists is revealed best. They had no idea where traction arose
and on what scale hydroplaning occurs.

Thanks to Terry Morse these curves are displayed on his website.

I'm sure weight, tire pressure, weight distribution, air drag, and
other factors are at play, too. But yes, tread is bad on a bike
tire. Jobst also found that tread on bike tires are purely cosmetic
unless you are in very slippery terrain. That's why he invented
slick tires. If your tires have very fine tread, it neither helps
nor hinders. Most people want a little tread, because they believe
it helps, but Jobst found it not to be true.

Let's say the motorized industry proved that one for me. I just
happened to be working in racing cars at the time these developments
came along and recognized their application in bicycling.

I don't know if it's on the web, but you can find old usenet articles at
http://groups.google.com

And he might be able to answer right here!

http://www.terrymorse.com/bike/rolres.html
http://yarchive.net/bike/rolling_resistance.html
http://www.cqq.ch/Moto/1Moto_images/.../GP-Vale_2.jpg

Jobst Brandt

Now that the compound has changed with the Avocet tires listed in the test,
has the results been the same, or updated?
-tom


Dear Tom,

Those rolling resistance tests are from 1986:

"Tires, AVOCET and SPECIALIZED, 18 Apr 86"

"The age of these tests and the picture is apparent from the
old toe clips and straps."

"What should be noted is that no one has made subsequent RR
tests that are anywhere as comprehensive and inclusive of
tires on the market. I suspect there is little interest in
the subject from what I see on the road. [2001]

http://www.terrymorse.com/bike/rrdiscuss.html

Carl Fogel

Tom Nakashima writes:

Now that the compound has changed with the Avocet tires listed in
the test, has the results been the same, or updated?

Avocet is not actively pursuing tire marketing at the moment and their
tires are not currently made by IRC that got out of the bicycle tire
business a while back to concentrate on motor vehicles. That may
change, however, I am not involved in any of that.

Jobst Brandt

Carl Fogel writes:

Those rolling resistance tests are from 1986:

"Tires, AVOCET and SPECIALIZED, 18 Apr 86"

"The age of these tests and the picture is apparent from the old toe
clips and straps."

What should not be overlooked is that nothing substantive has changed
in tire casings, rims, tire beads, or carbon black rubber since then.
Rolling resistance is still caused by elastomeric deflection in tread,
casing and tube of clincher tires along with rim glue for tubulars.

These tests were landmarks in that respect and remain as valid now as
then. I suspect that Clement knew about rim glue losses or there
would not have been track glue for events where fractions of seconds
made a difference.

"What should be noted is that no one has made subsequent RR tests
that are anywhere as comprehensive and inclusive of tires on the
market. I suspect there is little interest in the subject from what
I see on the road. [2001]

That is correct. Today the emphasis is fashion and color is in. No
one seems particularly interested in RR, wear rate, or wet traction.
As I mentioned, Clement made TT tubular tires with red treads in the
days of yore because they were known at that time to have lower RR
than carbon black rubber. I and my riding companions discovered the
lack of wet traction first hand. I believe the Clement archives could
reveal some interesting measurements if they haven't all been
trashed... which they probably were.

http://www.terrymorse.com/bike/rrdiscuss.html

Jobst Brandt

wrote:
Tom Nakashima writes:


Now that the compound has changed with the Avocet tires listed in
the test, has the results been the same, or updated?


Avocet is not actively pursuing tire marketing at the moment and their
tires are not currently made by IRC that got out of the bicycle tire
business a while back to concentrate on motor vehicles. That may
change, however, I am not involved in any of that.

Jobst Brandt


Sad. I remember when I was just getting into cycling in 1975 at the age
of 14. My bike had steel rims. About a year or two later, I bought some
IRC tires to replace the original clunker tires. Wow, what a difference!

Would you care to say what tires you like these days?


--
Tom Reingold
Noo Joizy
This email address works, but only for a short time.