3

I'm not clear on why tire pressure decreases over time. I understand that air escapes through the tube. Possibly some leaks through the valve too? In any case, do tire / tube / valve combinations exist that will maintain a constant pressure over time?

Edit: From reading How long should a road tyre hold its pressure? I learn that air leaks through the tube material. I've changed the title in response - it originally applied to values only.

Improve this question
7
  • 1
    A good quality valve, in good condition, will leak hardly any air at all. Tires loose pressure mainly because air diffuses through the inner tube wall. Some fancy-dancy racing tubes are quite bad in this regard.
    – Daniel R Hicks
    Jul 4, 2014 at 22:17
  • Daniel R Hicks and Blam responded to my original question which referred to valves only.
    – Paul Carey
    Jul 4, 2014 at 22:20
  • 2
    As I indicated, there are some tubes (lightweight racing tubes) that are worse than normal with regard to holding air. But I've never seen a tube advertised as holding air longer. I'm sure it could be done, but no one's developed a market for such a tube.
    – Daniel R Hicks
    Jul 4, 2014 at 22:25
  • 2
    The problem is that diffusion rate is proportional to wall thickness, material and external conditions being the same. But thicker walls make for heavier tubes and cyclists don't like that. I suspect manufacturers optimise wall thickness quite enthusiastically.
    – Móż
    Jul 4, 2014 at 22:28
  • 2
    You could fill the tubes with a gas that diffuses more slowly - the "advantages of nitrogen" question is helpful there.
    – Móż
    Jul 4, 2014 at 22:30

1 Answer 1

Reset to default
2

You assume the whole leak is the valve. Rubber is not air tight. Most of the leak is through the rubber.

Clearly can create a near airtight valve. And with enough rubber a near air tight tube. But it would be heavy. Just pump your tires once a week. I see the link said pump daily. OK, at least once a week. On my road bike I pump before every ride.

Improve this answer

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.