Latex and lightweight tubes -- lower RR?

Matt O'Toole said:

I wonder if a latex or lightweight tube
in a top-notch race clincher gives measurably lower RR than a normal
one.

Maybe measureable, but probably not much of a difference in actual riding.
And not worth having to pump up more frequently. I'm curious why you think
it might produce a higher RR.

Art Harris

Matt O'Toole said:

Has anyone ever seen a rolling resistance test of latex or lightweight
tubes? I'm not concerned with track tires or road tubulars with
latex tubes in them already. I wonder if a latex or lightweight tube
in a top-notch race clincher gives measurably lower RR than a normal
one. I can think of reasons why it might, or might actually be worse.

If you have a power meter and rollers (or know someone who does) then
you can test it for yourself. I'd be happy to help you with setting up
the test and interpreting the data.

On Sat, 10 Dec 2005 18:35:17 -0500, "Arthur Harris" <[email hidden]>

Quoted message said:

"Matt O'Toole" wrote:

Quoted message said:

Quoted message said:

I wonder if a latex or lightweight tube
in a top-notch race clincher gives measurably lower RR than a normal
one.

Quoted message said:

Maybe measureable, but probably not much of a difference in actual riding.
And not worth having to pump up more frequently. I'm curious why you think
it might produce a higher RR.

I would imagine the latex has lower hysteresis than butyl rubber, but
this may not be the case. Also, butyl rubber sticks to the tire and
becomes one with it, while latex may rub against it, causing some
friction.

I agree about having to pump more frequently, I'm just curious.

Matt O.

On 10 Dec 2005 17:23:26 -0800, "Ron Ruff" <[email hidden]>

Quoted message said:

Matt O'Toole wrote:

Quoted message said:

Quoted message said:

Has anyone ever seen a rolling resistance test of latex or lightweight
tubes? I'm not concerned with track tires or road tubulars with
latex tubes in them already. I wonder if a latex or lightweight tube
in a top-notch race clincher gives measurably lower RR than a normal
one. I can think of reasons why it might, or might actually be worse.

Quoted message said:

If you have a power meter and rollers (or know someone who does) then
you can test it for yourself. I'd be happy to help you with setting up
the test and interpreting the data.

I don't have one, but I may be able to find one.

Matt O.

Matt O'Toole said:

Quoted message said:

Quoted message said:

I wonder if a latex or lightweight tube in a top-notch race
clincher gives measurably lower RR than a normal one.

Quoted message said:

Quoted message said:

Maybe measurable, but probably not much of a difference in actual
riding. And not worth having to pump up more frequently. I'm
curious why you think it might produce a higher RR.

Quoted message said:

I would imagine the latex has lower hysteresis than butyl rubber,
but this may not be the case. Also, butyl rubber sticks to the tire
and becomes one with it, while latex may rub against it, causing
some friction.

It has lower RR for two reasons. First because it contains no carbon
and butyl rubber is lossier than latex anyway. And second, it is far
thinner, so there is less bending stress and rubber losses for the
same tire flex. A third advantage is that latex stretches many times
more before rupture and that helps prevent pinch flats.

Quoted message said:

I agree about having to pump more frequently, I'm just curious.

That is their great drawback. I recall the days when all we rode were
tubulars that required daily pumping almost as if the tires were flat
(down below 50psi). Only in freezing weather did they hold air for
the second day.

The difference is not worth the pumping work. If you look at RR
curves you'll see that the difference is about as much as having the
zipper up or down on your jersey.

Jobst Brandt

Matt O'Toole said:

Quoted message said:

Quoted message said:

Has anyone ever seen a rolling resistance test of latex or
lightweight tubes? I'm not concerned with track tires or road
tubulars with latex tubes in them already. I wonder if a latex or
lightweight tube in a top-notch race clincher gives measurably
lower RR than a normal one. I can think of reasons why it might,
or might actually be worse.

Quoted message said:

Quoted message said:

If you have a power meter and rollers (or know someone who does)
then you can test it for yourself. I'd be happy to help you with
setting up the test and interpreting the data.

Quoted message said:

I don't have one, but I may be able to find one.

Not to worry. You won't be able to see that because rider variation
is far greater than anything you'll see from the tubes. The way to do
it is to clock the coast down speed on rollers from 30 to 10 mph or
so. No feet on the pedals. However you still have to calibrate the
results to reduce that to power, but it is repeatably accurate if
you don't get the tire hot.

Jobst Brandt

Quoted message said:

Not to worry. You won't be able to see that because rider variation
is far greater than anything you'll see from the tubes.

I'm not sure about that. One person (Jens Heycke), claims to be able
to get excellent repeatability. With power around 300W, even a couple %
change in Crr should be noticable.

Quoted message said:

The way to do
it is to clock the coast down speed on rollers from 30 to 10 mph or
so. No feet on the pedals. However you still have to calibrate the
results to reduce that to power, but it is repeatably accurate if
you don't get the tire hot.

I think that would be difficult because it would happen in a couple of
seconds, since the inertia of the system (wheels and rollers) is so
small compared to the load... and then there is the speedometer lag,
too. If there was an easy way of increasing the inertia, it would help.

Have you ever measured the effects of temperature? I've seen allusions
to this from others, but not any data.

Quoted message said:

The difference is not worth the pumping work. If you look at RR
curves you'll see that the difference is about as much as having the
zipper up or down on your jersey.

"Pumping work?" Is it really that much of a chore, or that exhausting, to
inflate a tire? How much payback would there have to be to make it
worthwhile?

As for being the difference between having a zipper up or down, I dunno,
sounds like a pretty good deal to me, if I can offset whatever downside
there might be to having a zipper in a position where it allow me to remain
cooler.

--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
Redwood City & Los Altos, CA USA

"Matt O'Toole" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Has anyone ever seen a rolling resistance test of latex or lightweight
tubes? I'm not concerned with track tires or road tubulars with
latex tubes in them already. I wonder if a latex or lightweight tube
in a top-notch race clincher gives measurably lower RR than a normal
one. I can think of reasons why it might, or might actually be worse.

Quoted message said:

I've seen snippets from tests of tubeless vs. standard MTB tires, but
nothing for road tires.

A Cal. State University study quoted in 'High-Tech Cycling' (Burke)
gives the following figures for the coeff. of rolling resistance of a
Specialized Turbo S Kevlar 700x19c:

with latex tube: 0.23
with butylized latex tube: 0.25
with butyl tube: 0.28
with polyurethane tube: 0.29

I don't have the book to hand: I'm quoting my own rec.bicycles.tech posting
of five years ago.

HTH

James Thomson

Check out Johns Laffords rolling resistance tests of recumbent tires -
some tests of tires with latex and buytl

http://www.users.globalnet.co.uk/~hadland/rolrec10a.pdf

Mike Jacoubowsky said:

Quoted message said:

The difference is not worth the pumping work. If you look at RR
curves you'll see that the difference is about as much as having the
zipper up or down on your jersey.

"Pumping work?" Is it really that much of a chore, or that exhausting, to
inflate a tire? How much payback would there have to be to make it
worthwhile?

Having to pump tires is like driving a crappy old car that you have to
let warm up before you can go anywhere, even a few blocks. It's a
stupid inconvenience, and in this case, totally unnecessary. With
decent tubes like Michelin Airstop, I can go weeks without pumping.

Some people like these rituals though. The fussiness makes their gear
feel more high-tech and special. To each his own.

The RR issue is just interesting to me in an academic sense.

Matt O.

Quoted message said:

Not to worry. You won't be able to see that because rider variation
is far greater than anything you'll see from the tubes. The way to do
it is to clock the coast down speed on rollers from 30 to 10 mph or
so. No feet on the pedals. However you still have to calibrate the
results to reduce that to power, but it is repeatably accurate if
you don't get the tire hot.

Well, if we're goofing with trainers this winter I might give it a
try, just for fun.

Matt O.

James Thomson said:

with latex tube: 0.23
with butylized latex tube: 0.25
with butyl tube: 0.28
with polyurethane tube: 0.29

A .005 difference (or 20% in this case) between butyl and latex is
pretty large. If you are racing, this is well worth the pumping hassle.

James Thomson said:

Quoted message said:

Has anyone ever seen a rolling resistance test of latex or
lightweight tubes? I'm not concerned with track tires or road
tubulars with latex tubes in them already. I wonder if a latex or
lightweight tube in a top-notch race clincher gives measurably
lower RR than a normal one. I can think of reasons why it might,
or might actually be worse.

Quoted message said:

Quoted message said:

I've seen snippets from tests of tubeless vs. standard MTB tires,
but nothing for road tires.

Quoted message said:

A Cal. State University study quoted in 'High-Tech Cycling' (Burke)
gives the following figures for the coeff. of rolling resistance of
a Specialized Turbo S Kevlar 700x19c:

Quoted message said:

with latex tube: 0.23
with butylized latex tube: 0.25
with butyl tube: 0.28
with polyurethane tube: 0.29

Quoted message said:

I don't have the book to hand: I'm quoting my own rec.bicycles.tech
posting of five years ago.

Well... as they say, there's lies, damned lies, and statistics, or in
this case floating numbers. What is the power difference in these
figures and what percentage is it of and average size rider's effort
at, let's say, 25mph? It seems like this is comparing the aero drag
of bar tape, the thick cork type tape having more than twice the drag
of cloth tape... and who cares?

Jobst Brandt

James Thomson said:

A Cal. State University study quoted in 'High-Tech Cycling' (Burke)
gives the following figures for the coeff. of rolling resistance of a
Specialized Turbo S Kevlar 700x19c:

with latex tube: 0.23
with butylized latex tube: 0.25
with butyl tube: 0.28
with polyurethane tube: 0.29

I don't have the book to hand: I'm quoting my own rec.bicycles.tech posting
of five years ago.

Those figures are quite high for coefficient of rolling resistance.

Joe

Ron Ruff said:

James Thomson said:

with latex tube: 0.23
with butylized latex tube: 0.25
with butyl tube: 0.28
with polyurethane tube: 0.29

A .005 difference (or 20% in this case) between butyl and latex is
pretty large. If you are racing, this is well worth the pumping hassle.

But since the coeff of rolling resistance is somewhere between
0.004 and 0.010 as usually defined (F_rollres = Crr * mass * g,
where mass = mass of rider+bike), it's not clear what these
numbers really are.

See the link posted elsewhere in this thread:
http://www.users.globalnet.co.uk/~hadland/rolrec10a.pdf

Quoted message said:

From this table I don't see any significant difference between

the same tire with latex and butyl. There are differences between
tires. To first order I'd expect these to be related to the amount of
rubber and the suppleness of the casing. Note that the table is for
20" tires, which should have higher Crr than 700c. The very last
three entries for 700c tires support this.

Quoted message said:

Well... as they say, there's lies, damned lies, and statistics, or in
this case floating numbers. What is the power difference in these
figures and what percentage is it of and average size rider's effort
at, let's say, 25mph?

I'll assume that's a rhetorical question, as I don't believe you care, and
neither do I.

Quoted message said:

It seems like this is comparing the aero drag of bar tape, the thick cork
type tape having more than twice the drag of cloth tape... and who cares?

I suggest you read the original post in this thread, to which mine was a
response.

James Thomson

Quoted message said:

But since the coeff of rolling resistance is somewhere between
0.004 and 0.010 as usually defined (F_rollres = Crr * mass * g,
where mass = mass of rider+bike), it's not clear what these
numbers really are.

I'd overlooked a footnote in the original, which I've now found.

The rolling resistance coefficient in percentage. To get the resistance
to motion, multiply the weight on the tire by the coefficient divided
by 100. The tests were performed from 1984 to 1988 at California
State University, Long Beach, for the U.S. cycling team, Specialized,
General Motors, and Tom Petrie of Velimpex Marketing, El Cerrito, CA.

Apologies for the omission, though the original poster was interested in
the relative performance of different tubes.

Quoted message said:

See the link posted elsewhere in this thread:
http://www.users.globalnet.co.uk/~hadland/rolrec10a.pdf

From this table I don't see any significant difference between
the same tire with latex and butyl. There are differences between
tires.

There only appear to be a few examples of tyres tested with latex tubes.
One is a Continental Grand Prix 28-406 which shows a significantly higher
rolling resistance at 120psi with a butyl tube (.0082) than at 100 or
125psi with a latex tube (.0077 and .0069 respectively), though I'd guess
that this is not the same tyre in each case. The 37-349 "Primo w. ground
off tread" shows an increase in Crr at lower pressures with a latex tube,
and a decrease at higher pressures, which I find hard to account for, but
then there are no hints as to the number of tests performed, and
repeatability.

Quoted message said:

Note that the table is for 20" tires, which should have higher Crr
than 700c.

The tyres tested range from 16" up.

James Thomson

In article <[email hidden]>, [email hidden]
says...

Quoted message said:

Has anyone ever seen a rolling resistance test of latex or lightweight
tubes? I'm not concerned with track tires or road tubulars with
latex tubes in them already. I wonder if a latex or lightweight tube
in a top-notch race clincher gives measurably lower RR than a normal
one. I can think of reasons why it might, or might actually be worse.

I've seen snippets from tests of tubeless vs. standard MTB tires, but
nothing for road tires.

Before y'all go screaming at me about whether I should care about such
a thing, it's just curiousity. I'm curious about a lot of things that
I don't live by.

Not enough to be noticeable. What is noticeable is that you need to pump
up the tubes pretty much every day if you want the pressure to stay at a
reasonable level. That is why I stopped riding them.
-----------
Alex