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-   -   Having problem releasing the pump nozzle after pumping tire, please advice!!! (http://www.bikeforums.net/general-cycling-discussion/551632-having-problem-releasing-pump-nozzle-after-pumping-tire-please-advice.html)

khalid 06-14-09 03:00 AM

Having problem releasing the pump nozzle after pumping tire, please advice!!!
 
Hi,

I have a question about removing the tire pump nozzle after i pump the tire. Everytime I pump the tire to 120 psi, when i release the nozzle, I will hear a loud air leaking noise. When I attach the nozzle to the valve again, the gauge read about 100psi. What can I do so that I can keep my tire in the 115 to 120 psi? should I pump the tire up to 130 and then release the nozzle, or am I doing something wrong? Please help. Thanks for reading.

duffer1960 06-14-09 04:45 AM

I have one of 'these' pumps, difficult to attach or release from a Schrader valve. :crash: It's only the latest ***mart purchase that's turned out not worth the price. :( I've found that careful adjustment of the 'grabber tightening ring' on the end of the chuck -- tightening the ring just-so as/during cinching the lever, then loosening just as/after releasing -- helps some. And yanking hard if necessary; haven't torn out the inner tube yet. At 120 psi, may be a Presta? I'm having just as much trouble because this pump requires use of the little brass Presta-to-Schrader adapter. Good luck.

Mulling purchasing a pump from a bike shop for about 2x what I paid for this one.

When you put a pressure tester, or an entire pump, onto a tire, the air in the tire is shared between the tire & the device you attach. It'll always read a lower pressure than was in the tire. Even moreso because it's hard to attach and release without losing some air. Only an infinitesimal difference for something as large as an auto tire, but a big difference with a low-volume high-pressure bike tire. You're best off to develop a technique to get the pump off quickly, after putting a little more in if necessary, to end up with a tire that's as hard as you need it without further testing.

JanMM 06-14-09 05:20 AM

Quote:

Originally Posted by duffer1960 (Post 9098094)



When you put a pressure tester, or an entire pump, onto a tire, the air in the tire is shared between the tire & the device you attach. It'll always read a lower pressure than was in the tire.

A proper gauge shows the actual pressure in the tire.

xenologer 06-14-09 06:50 AM

Don't reattach the pump to doublecheck afterwards, that should save you from 10 of those psi lost.

Dunno, if I believe it or not, but might give you peace of mind...
At a local LBS one point mentioned in a maintenance class, is that you shouldn't worry about the loud hissing noise after pumping up a tube; most of the air you hear rushing out is from the pump and hose.

Hask12 06-15-09 05:21 AM

Pull the nozzle straight up and off. The hissing you hear is coming from the pump, not the tire.

rm -rf 06-15-09 06:09 AM

It's working correctly. The pump's hose has pressurized air in it, too. So when you pull it off the tube's valve, that's the air that escapes. None comes out of the tire.

When you put it back on to pump up the tire, the hose has to be pressurized again from the tire, so it shows about 10 lbs less on the gauge.

( You might want to try lower pressures than 120. I'm 170 lbs, and I use 95 psi front, 105 psi back. The ride is a lot smoother, and the tires still roll efficiently. Front tires should be about 10% lower pressure, since they carry less weight.)


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