Latex and lightweight tubes -- lower RR?

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.

Thanks,

Matt O.

"Matt O'Toole" wrote:
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 wrote:
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"
wrote:

"Matt O'Toole" wrote:

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.

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"
wrote:

Matt O'Toole wrote:

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.

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

Matt O.

Matt O'Toole writes:

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

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.

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.

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 writes:

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.

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

wrote:

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.

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.

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" wrote in message
...

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.

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