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The tires of my bicycle deflate within a couple of days. I have to pump every time before riding it. Is it true that if a bicycle is kept stationary(not used) for a day or so, then the chances of deflating are more than those when it is used regularly? I want a solution to the problem of pumping every time before using my cycle. How to get rid of deflation? I think the ambient temperature of the bicycle matters a lot in this case, but I don't know how. So, please give me a solution so that the tires don't deflate so frequently.

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Tires deflating within a couple of days have a leak. If you don't ride your bike for a couple of weeks you may see some deflation but quicker than that you need to look for a leak in your tires.

Remove the inner tube and spray it with soap water. Pump up the tube a little, not a lot since you don't want to burst it, and check for bubbles. Repair any holes found.

Edit: also check the tire for sharp things to cause a new hole. Visually check the inside and outside of the tire. Then rub your fingers along the inside of the tire, be careful and do this slowly so you don't hurt yourself.

As far as avoiding pumping your tires up after storing the bike or not riding for a long time, you can either just deal with it or take the bike for a short ride every couple of days.

As a side note, I've heard storing a bike on carpet causes the deflation faster than other materials.

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    Got a citation for the carpet line? Nearest I could find was "parking on carpet decreases flatspots on car tyres" which was debunked. – Criggie Jun 6 '16 at 8:40
  • I don't, but I've experienced it personally. It my have been something other than the carpet, but when I stored my bike inside on carpet I had to reinflate much more frequently. – Doug Watkins Jun 6 '16 at 14:28
  • I checked this with my LBS who store bikes inside on carpet and they looked at me funny. Carpet is not going to make any difference to how fast a tube loses air. Its got a tyre between tube and ground, remember? – Criggie Jun 6 '16 at 23:29
  • Could have been something else that was the same between occasions. Both tires deflated at the same rate, and much faster than when I stored it outside. I just figured it was the carpet. – Doug Watkins Jun 6 '16 at 23:32
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If you don’t use bicycle for a "couple of days", then you will have to refill it. Try hanging your bicycle and try nitrogen filling instead of air. Nitrogen is supposed to last longer than air (should be available in petrol pumps)

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    Tires shouldn't have this problem. Last month I grabbed a bike which has been idle for at least 3 years. They probably weren't as hard as they used to be, but still plenty hard to ride to not notice the difference while driving. It was stored in an old shed. Storing it outside with heavily varying temperatures might be a different story altogether. – Mast Jun 7 '15 at 21:44
  • Nitrogen does not last any longer than any other enclosed gas in a bladder. The benefit of using Nitrogen in tires is that it expands and contracts less than normal air containing Oxygen resulting in less change of tire pressure as temperature rises due to heat from road friction and atmospheric conditions. – Stan Jun 6 '16 at 17:21
  • @Stan Please go through this link – lal Jun 8 '16 at 7:56
  • @lal - I tried N2 in my tires. My colleagues had N2 in their tires. We discussed this at length. I work with engineers from all over. We did experiments. We compared notes. We argued. We researched and argued some more. (Atmospheric air does contain H2O vapour which is forced out of the gas under pressure as per your link. Desiccated air doesn't. Maybe that's the difference.) Otherwise, all gasses are supposed to obey the gas laws of Boyle and others. – Stan Jun 8 '16 at 17:14
  • @Stan Dear Stan, i don't know much about chemistry and it’s laws but the point I was trying to say is “Nitrogen molecules (N2) are larger than oxygen molecules (O2) so therefore, pure nitrogen will permeate the walls of your tires less than oxygen molecules.” Source And good luck with the research :) – lal Jun 10 '16 at 7:17
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The loss of air pressure is due to the ambient pressure being lower than the pressure in the tires, and a path for with air can pass from inside the tube to outside the tube (commonly called a leak). There really are only two solutions:

  1. Store the bicycle (or just the wheels) in a hyperbaric chamber. You could theoretically even inflate the tires this way, though they will look deflated while the chamber is pressurized.

  2. Block the passage of air molecules from / to the tube. Also called repairing the leak.

As Doug mentions, you can use soapy water on the inner tube (not the tire) to find the leak. Don't forget to check the valve stem as this is where I find most slow leaks come from. You could even check the valve stem while the wheels are still on the bike.

  • That's 'valve', of course... (instead of value) – Hobbes May 13 '15 at 10:55
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    @Hobbes: Fixed, thanks. Say hi to Calvin, I miss you guys. – dotancohen May 13 '15 at 11:05
  • We're still exploring, just checking in now and then :) You missed one (last sentence). Normally I'd change it myself but SE doesn't allow edits that change fewer than 6 characters... – Hobbes May 13 '15 at 11:41
  • The horrible thing is, the muscle-macro in my fingers tries to change value to val() every time... – dotancohen May 13 '15 at 12:48
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When a tire deflates, it is because the air is escaping. Since air pressure in the tire is much higher than atmospheric (2 - 8 bar vs 1 bar for atmospheric) it is unlikely that changes in the weather / barometric pressure play a role. Similarly, temperature can play a minor role, but it would be on the order of a few % at most (pressure being lower on a really cold day).

There are three main paths for air to escape:

  1. the valve. Depending on the type of valve you have, it may be possible that you can replace (parts of) it - but it's hardly ever worth it
  2. a small puncture. If you drove over a sharp object you might have a tiny hole in your tire - but realistically even very small holes would cause the tire to deflate in a matter of hours, not days
  3. the rubber of the tire. This is where I put my money. Rubber in general is slightly porous - that is, air can "sneak out". Different kinds of rubber have greater or lesser porosity - some butyl rubbers are particularly hermetic, some natural rubbers quite porous. As a tire ages, it can become more porous.

You could take the tube out, inflate it in a bucket of water with a few drops of soap. Wait a little while - see where bubbles appear. My bet is "all over the tube". That would point to case #3, in which case the only remedy I know is to buy new tubes.

  • @Mast - fair point. I have adjusted the language. – Floris Jun 7 '15 at 21:51
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Another option (admittedly not a life hack) is to add tyre/tire sealant to your tube. This is a white liquid latex-based goop which goes in after you remove the valve core, and then sits inside the tube. If you get a puncture while riding the sealant is supposed to bubble out the hole for a few seconds, then harden and seal the leak.

One of the well known brands is Stans, http://www.notubes.com/Stans-Tire-Sealant-Quart-P51.aspx and while its intended for tubeless tyres, does okay in tubes too. Note it only stays effective for months, then you need to add more. Also, this stuff is sometimes called "stans jizz" so just call it "sealant" if you don't want a ribbing from, your riding mates.

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Otherwise replace your tubes, they're only a couple bucks each, and the dead tubes/valves can be used for many other things.

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