General Discussion Triathlon Talk » Latex tubes and CO2 Rss Feed  
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2010-05-05 12:27 PM

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Subject: Latex tubes and CO2
I bought a set of tires to race with (clinchers) and I bought some latex tubes to go with them. This is the first time I try latex.

As part of rehearsal I decided to change them as if I had to change a flat in a race. In doing so, I used a CO2 cartridge on each wheel to inflate them. All was good, an hour later all was still looking good.

This morning both are almost flat( within 12 hours). So I pump them up and 6 hours later they are fine. I will check again in a few hours.

I found a couple of links that claim that Latex tubes and CO2 don't mix well, that Latex leaks more pump air and that CO2 leaks 10x more than pump air. They claim a race spare should be butyl because of this.

Is this true ? Any experience ?

Of course I thought I had a slow leak, but on both tires ? And why is it holding up now....very bizarre.

Edited by marcag 2010-05-05 12:28 PM


2010-05-05 12:30 PM
in reply to: #2838841

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Not a Coach
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Subject: RE: Latex tubes and CO2
Yes, I believe this is true.  Latex will lose air faster than butyl regardless, but the rate of loss is much greater with CO2.  It would probably hold up for a race, but I do carry a butyl spare for this reason--just in case.
2010-05-05 12:45 PM
in reply to: #2838857

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Subject: RE: Latex tubes and CO2
JohnnyKay - 2010-05-05 2:30 PM

Yes, I believe this is true.  Latex will lose air faster than butyl regardless, but the rate of loss is much greater with CO2.  It would probably hold up for a race, but I do carry a butyl spare for this reason--just in case.


x2

Shane
2010-05-05 2:56 PM
in reply to: #2838841


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Subject: RE: Latex tubes and CO2

Is the risk of such a low tolerence tube worth the weight savings? A wight savings most likely not noticable on a tri bike.

2010-05-05 3:11 PM
in reply to: #2838841

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over a barrier
Subject: RE: Latex tubes and CO2
Overnight you'll lose 20lbs of pressure or so.....A few days and they'll be completely flat. I air up every ride anyway.

You can certainly use a latex tube as a spare tube during a race, but you need to be careful installing them - during the race you don't want to spend the time babying your tubes so butyl is generally the way to go.

Weight savings isn't why we use Latex, less rolling resistance, 2-3 watts per wheel/tube.

Edited by running2far 2010-05-05 3:16 PM
2010-05-05 5:05 PM
in reply to: #2839441

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Subject: RE: Latex tubes and CO2
running2far - 2010-05-05 3:11 PM Overnight you'll lose 20lbs of pressure or so.....A few days and they'll be completely flat. I air up every ride anyway. You can certainly use a latex tube as a spare tube during a race, but you need to be careful installing them - during the race you don't want to spend the time babying your tubes so butyl is generally the way to go. Weight savings isn't why we use Latex, less rolling resistance, 2-3 watts per wheel/tube.


Why is there so much less rolling resistance?


2010-05-05 5:14 PM
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2010-05-05 5:25 PM
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Subject: RE: Latex tubes and CO2
crazyquick23 - 2010-05-05 7:05 PM

Why is there so much less rolling resistance?


The latex reduces the hysteresis of the system and therefore lowers rolling resistance.

Shane
2010-05-05 5:25 PM
in reply to: #2838841

over a barrier
Subject: RE: Latex tubes and CO2
Way above my head, I just listen to the smart folks:

LATEX INNER TUBES
A more specialized tube material that's typically used in “high performance” tubular tire models and is available for use in clincher tires is a form of natural rubber known as latex. This highly elastic rubber material is the same type of material as is used in common party balloons and some types of surgical gloves. The main advantageous feature of this material is it's elasticity, or it's ability to be stretched, or deflected by large amounts and then return to it's unloaded state with very little hysteresis, or energy losses, due to the deflection. Because of this property, the use of latex tubes in a bicycle tire tends to give the combination of tire and tube a lower overall rolling resistance as compared to the same tire with a butyl tube. Depending on the tire, the rolling resistance can be lowered by as much as 10-15%. This can result in a power savings of ~5W for a typical rider, which is not an insignificant amount. For example, over an Ironman distance bike leg (180 km) this would result in a time savings of ~1-1/2 minutes.

http://www.slowtwitch.com/Tech/What_s_in_a_tube__1034.html
2010-05-05 7:48 PM
in reply to: #2838841

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Subject: RE: Latex tubes and CO2
Hmmm interesting. Isn't that about the same gain as you get with an aero wheel set? Maybe not quite as much but in the neighborhood?


Edited by crazyquick23 2010-05-05 7:49 PM
2010-05-05 9:11 PM
in reply to: #2840015

over a barrier
Subject: RE: Latex tubes and CO2
zipp 808 is 30'ish watts savings over a box rim 32 spokes.

When you consider using fast tubes and tires and can save 10 watts for under 100 bucks and that money is going to be spend anyway...its a no brainer imo. Under Roller data lists all the tires/tubes combos for your calculating pleasure.

http://www.biketechreview.com/


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