# Is the Continental Race Light tube supposed to lose air fast?



## Ventruck (Mar 9, 2009)

(Much) Faster than the plain' ol' "Race" tube?

Asking because the damn thing is asking to be pumped every day. I took the tube out, inflated it, and felt/looked/listened for holes. Nothing. I've also taken it out on two, 1-2 hour rides with no sudden blowouts or change in pressure. wtf m8.

If it's meant to lose air in such a way, doesn't Continental have an even lighter-spec tube (Supersonic)? Does that deflate in like 2 hours?


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## cpark (Oct 13, 2004)

I used them.
I have to pump every 7 to 10 days.


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## jmlapoint (Sep 4, 2008)

Thin butyl tubes lose 1-2 psi ever day.
I top my tubes off every day before my workout.

john


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## GPB (Mar 27, 2006)

I run Michelin Aircomp Ultra Light's and they lose about 5 psi in 24 hours from 115 psi. I top them off before every ride. After a week or so, I've seen them fall to the 80 - 90 range. Normal.


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## Ventruck (Mar 9, 2009)

Dumb follow-up question: But does the rate of air loss increase at initially-lower pressures?

e.g: does a tire deflate faster from 80psi as opposed to 115?


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## EMB145 Driver (Aug 17, 2006)

Check the valve. I had to replace a Michelin tube today that had a fairly slow and quiet leaky valve.


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## frdfandc (Nov 27, 2007)

Pull the tube, inflate it and submerge it in your bathtub or sink looking for pin holes. 

I've had tubes leak through really small pinholes that could only be found using this method.


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## AM999 (Jan 22, 2007)

EMB145 Driver said:


> Check the valve. I had to replace a Michelin tube today that had a fairly slow and quiet leaky valve.


Ditto that. If the tube has a replacable valve core these can come loose with a consequential slow leak. After checking that and as another poster suggested, submerge the tube in water and look for bubbles. That's really the only way to find very slow leaks.


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## Kerry Irons (Feb 25, 2002)

*Driving force*



Ventruck said:


> Dumb follow-up question: But does the rate of air loss increase at initially-lower pressures?
> 
> e.g: does a tire deflate faster from 80psi as opposed to 115?


The driving force for diffusion of a gas through a membrane (air through an inner tube) is pressure. The higher the pressure, the more gas will diffuse through per unit time. If you plot tire pressure vs. time, you will get an exponential decay (the rate of pressure drop will be reduced as time goes forward).

So the answer to your question is no. In fact, it is just the opposite.


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## Ventruck (Mar 9, 2009)

Kerry Irons said:


> The driving force for diffusion of a gas through a membrane (air through an inner tube) is pressure. The higher the pressure, the more gas will diffuse through per unit time. If you plot tire pressure vs. time, you will get an exponential decay (the rate of pressure drop will be reduced as time goes forward).
> 
> So the answer to your question is no. In fact, it is just the opposite.


Enlightening, thanks.


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