# How to measure pressure of Presta valve tube??



## drew4392 (Nov 22, 2007)

I bought a floor pump with a gauge and when I attach it to the presta valve, and lock it on, there is no reading on the gauge. When I pump, the needle shoots up so quickly that I cannot get an accurate reading. I was hoping that once I put the pump hose on the valve it would give a steady, real-time reading of the current pressure. 

So then I bought a presta adapter at the bike shop and a car tire gauge (those silver pen things you always see). I attached the adapter to the valve, and went to go get the pressure with the tire gauge, and nothing. I guess the part within the gauge that needs to hit the top of the presta valve to release air couldnt reach. 

Any ideas??


Thanks!


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## grivooga (Mar 14, 2009)

Attach to floor pump and just push the handle down slowly so that the air from the pump pushes the valve diaphragm open without spiking the pressure. The reading on the pump gauge should be pretty close. 
A presta adapter won't work with a tire gauge. Bike shops sell pressure gauges that will work with a presta but all the ones I've seen are digital and expensive. I'm sure an inexpensive spring style gauge is available but I haven't seen one myself (haven't really been looking).


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## Zoke2 (Nov 16, 2007)

are you sure you are opening the lock nut on the top of the presta valve before trying to air it up ... and be sure to tighten it when you are done


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## drew4392 (Nov 22, 2007)

Zoke2 said:


> are you sure you are opening the lock nut on the top of the presta valve before trying to air it up ... and be sure to tighten it when you are done


Yes.


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## drew4392 (Nov 22, 2007)

grivooga said:


> Attach to floor pump and just push the handle down slowly so that the air from the pump pushes the valve diaphragm open without spiking the pressure. The reading on the pump gauge should be pretty close.
> A presta adapter won't work with a tire gauge. Bike shops sell pressure gauges that will work with a presta but all the ones I've seen are digital and expensive. I'm sure an inexpensive spring style gauge is available but I haven't seen one myself (haven't really been looking).


Ok, I'll try that. Thanks for the advice. Someone told me the tire gauge and presta adapter would work. Guess not. I'll search around for a presta pressure gauge.

Thanks!


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## Bikinfoolferlife (Feb 3, 2004)

Is your pump a shrader only pump? Or does it have a presta head? If it's convertible make sure it's in presta mode. The gauge on the pump should work if you're using the right type of attachment. One thing that might help is when you loosen the valve, to then tap it down with your finger and release the pressure on the valve before attaching the pump head...it sounds like in your first post when you were putting the pump head on the valve that you were getting a reading on just the pressure in the hose with no air getting into the valve which would explain the high reading...


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## FBinNY (Nov 7, 2008)

If you set up the pump correctly as explained above, it should smoothly open the valve during pumping and give you usable pressure readings, possibly with a bit of a spike first, but I've seen some sticky valves that won't open until the pressure difference is staggering, in which case you'll have to push the pumphead farther down to lock the valve into the open position. (the drawback being that you'll now lose some air on removal)

You can also buy a hand help Presta valve gauge for more accurate readings, or if you want to use your Schrader valve gauge and an adaptor, you'll need one with an O-ring at the bottom, and if your PV valve stem is too short to come to just short of the top of the adaptor, file the adaptor shorter until it does.


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## hado_pv (May 26, 2006)

Before attaching any Pump, I always flick the valve open releasing a little air from the tire. It avoids the sticky valve syndrome everyone is discussing. The gauge on the pump should read correctly as soon as it is correctly attached to the valve stem.


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