Air loss in different butyl tubes
04-06-23, 06:46 PM
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Air loss in different butyl tubes
Hi all, I've noticed (anecdotally, of course) that my front tire with a regular weight butyl tube installed seems to hold pressure slightly better than my rear with a Schwalbe "extra light". Do you all have any experience with this, or am I more likely managing a slow leak back there?
04-06-23, 06:57 PM
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Sounds quite normal. I think I am pretty safe in saying that all rubbers leak some. Certainly all bike inner tube rubbers commonly used do. The thickest take a long time but if you come back a year later, it will be pretty soft. Latex leaks a lot more but it too varies quite a lot from the thin tubes to the thick.
04-06-23, 07:02 PM
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Sounds quite normal. I think I am pretty safe in saying that all rubbers leak some. Certainly all bike inner tube rubbers commonly used do. The thickest take a long time but if you come back a year later, it will be pretty soft. Latex leaks a lot more but it too varies quite a lot from the thin tubes to the thick.
04-06-23, 07:46 PM
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Rubber is a porous material and oxygen and nitrogen molecules are small enough (diameter of about 0.3 nm) to pass through the pores over time. Thinner tubes will allow molecules to escape more quickly. Totally natural and expected.
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04-06-23, 08:27 PM
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That makes a whole lot of sense! Thank you, Otto.
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04-09-23, 04:41 PM
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Another factor is the width and recommended inflation pressure. Narrow high pressure low volume tire/tube combinations lose pressure much faster than low pressure high volume tires and tubes
04-09-23, 07:39 PM
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I ride mostly on pavement with some gravel, in the mid-40s. That seems to give plenty of squish for my size/weight without bottoming out. If I ride rougher stuff, I'll drop the pressure closer to 40.
04-09-23, 09:49 PM
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Intuitively, thicker tubes should hold air better than the thinner ones. And they probably do. But I've been really impressed by those Schwalbe Extralight/XXLight tubes. As long as they don't have a pinhole (or worse), I can go a long time without pumping, with tires in the ballpark of 50 psi.
