Tire pressure lost when removing pump and hearing "kiccchhhhh"

Any idea how much tire pressure is lost when removing a pump from a presta valve? You know, when you hear that noise.

Something weird just happened to me. After I pumped my tires up to around 115psi, I put the pump back on the valve, and it said 90psi. Could I have lost that much air just when I removed the pump from the valve? I doubt it. I think my pump is messed up.

I always deflate my tires entirely before pumping, so I have never noticed this discrepancy.

Very little air is lost, unless the valve in the stem sticks. Almost all of the air you hear escaping when removing the pump head from the valve is air from the pump hose.

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Why would you do this? Sounds like you're asking for pinch flats if you're running clinchers....

Maybe he thinks the tube will reseat itself properly without any kinks ? i dont understand either Me, I just let out air for 2 seconds- to unseat the valve, otherwise the pump dont work- because the valve has stuck in the rubber valve seat.

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maybe he means 'between rides'

As others have noted, you don't need to deflate your tires, entirely.

BTW. If you are really having problems with your pump's head, then you can cut it off & REPLACE it with a SILCA pump head -- the SILCA pump heads are pressed onto a Presta valve stem without a cam lock & simply pulled off.

The various Silca pump heads are available separately -- they are about $10 +/-.

You do NOT need a SILCA pump to use one of their pump heads.

Your LBS can order one for you OR you can certainly order one from a place like Colorado Cyclist, etc.

I don't really have a good answer, other than it's easier to get the pump going when there is no air in the tire.

But I'm starting to get concerned about how after I pump to say 115psi, then take the pump off, then put it back on within 30 seconds, it says around 100psi. Perhaps when I put the pump back on I lose some air??

I even went to the LBS and tested a Joe Blow Turbo, which is a high end pump. It is a very nice pump, but I had the same loss-of-pressure issue. I would pump it to around 110, take it off, put it on, and it would be down to around 100psi. And it's not like I was hearing air gushing out at any point.

I just want the peace of mind that when I pump my tires to 115psi, that I'm not riding on 90psi without knowing it.

When you remove the chuck and then reinstall it to check pressure, air from the tire has to refill the pump hose and the gauge bellows. Since the same mass of air is now occupying more volume, the pressure will be lower. So, just stop checking.....pump the tire up to your favorite pressure, remove and ride with confidence

Who cares what the gauge says if the tires ride smoothly and fast, and you aren't blowing tubes out.

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Precision Sports

This is excellent advice. I absolutely hate the cam lock pump heads - very fiddly and you end up losing a ton of air when you pull it off. The Silca heads are awesome and so easy.

Yep. Plus you can adjust the rubber's tension a bit by tightening or loosening the top. Then.....you can decide if ya want threaded valves or not

I always check pressure after inflating. I use another gauge; not the one on the pump....

In my xperience more air is lost when fitting the hose than when removing it. Get it on, pump to required pressure, then it sort of blows itself off when removing it. If there is a botched removal then repeat the process and remove nicely with minimal blow-off.

A pressure guage will use very little air compared to a pump for measuring the pressure.

This isn't scientific, but it can be helpful. Get into the habit of pinching your tires after you get them properly inflated. The more you do it you will eventually train your brain to instinctively, by feel, know when your tire is at the correct psi. of course, if you change the make/model of tires you'll have to retrain your brain. This might come in handy out on the road or anywhere you don't have a gauge.

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That doesn't work. A finger pinch will not tell you the difference between a tire with 100 psi and one with 110 psi. All it might tell you is that your tires are way underinflated (if considering most road tires, 23-25c.

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