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Is latex magical because it's latex or because it is supposed to be light?

I've got new Michelin Air Comp latex tubes and they're 90 grams each and I've got Performance Forte Lunar Light butyl tubes at 50 grams.

Which should have the lower rolling resistance?

What happened to light latex tubes? I thought they were supposed to beat out butyl?
 

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Kestreljr said:
Why would rolling resistance matter on a tube? :confused:
It's supposed to be because they're stretchier and therefore flex easier and therefore interfere less with the flexing of the tire, therefore decreasing rolling resistance. It may be a myth, never proven, maybe unproveable, but maybe it's true. Some people swear they give you a more "supple" ride. Years ago I tried a brand of "butylized" latex tubes (mostly latex, but with a thin layer of butyl rubber on the inside to slow air loss), and I thought they made a difference in the ride. It could well have all been in my head.
 
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Latex tubes have been shown to decrease rolling resistance compared to butyl tubes used in the same tire. Latex tubes may also be less prone to some types of flats than butyl tubes. They do need to be pumped up more often as they lose air faster.
 
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If you join the "wattage" group on google groups they have a link to the information, but I will see if I can find it posted somewhere else.
 

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Kestreljr said:
Why would rolling resistance matter on a tube? :confused:
A very good tire and tube have a Crr of ~.004-.005 on the road. This is the equivalent of climbing a .4-.5% grade. The difference between a latex tube and a butyl tube is around .0005 Crr or around 10% of the total. Latex is a very bouncy material, while butyl is very dead. Flexing the butyl tube dissipates energy while latex dissipates much less.

Here are some results from a Tour test that shows a whopping 20% Crr difference between a 80g latex tube and a 75g butyl tube. Latex is such a "magic" that thickness and weight hardly matter, but thin butyl tubes are better than thick ones.

- latex (80 g) 23.9 W
- polyurethane (60 g) 25.1 W
- butyl (50 g) 25.9 W, (75 g) 28.8 W, (104 g) 32.1 W


For racing latex is the way to go...
 

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Thanks for the info. I was starting to wonder if I had bad valves or something
because mine were losing air faster. They are also damned expensive and I am
wondering what the scoffers\nay-sayers think?
 

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Or not

kytyree said:
Latex tubes have been shown to decrease rolling resistance compared to butyl tubes used in the same tire. Latex tubes may also be less prone to some types of flats than butyl tubes. They do need to be pumped up more often as they lose air faster.
Actually, on road tests by more than one organization have shown no difference or a disadvantage to latex tubes. To me, this suggests that any effect is just about lost in the noise. YMMV.
 
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