Mountain Biking - Would be nice to know my tire pressure

I must be doing something wrong because everyone talks about pressures they run & I cannot get an accurate read..

I use presta valves and have a pretty decent track pump with gauge, when I pump the tires the gauge doesn't hold the pressure of tire, it goes up when I pump air and then drops again..

what am I doing wrong ? do I need a more expensive pump ?

over time I have worked out what pressure I like and use the finger test, but would be nice to know what I am running and experiment a bit

Are you using a trail pump or a floor model? Trail pump gauges don't often work well. I use a Wrench Force floor pump and really like it. Once in a while, if I don't get the valve stem seated all the way, it will do what you're describing. I just remove it and reattach and that does the trick. I'd play with making sure the head is seated properly on the valve and if that fails, get a good floor pump.

I use a Zefal 2-headed tire guage.

mybee your pump is broken....my gauge never read anything...untill I got a nice new pump....it is very accurate

Got a park tool floor pump with gauge and a shox pump =P cant go wrong with that

All the floor pumps I've ever had never worked acurrately. My digital pressure gauge on the other hand...

I was about to suggest a car tire gauge. Cheap and accurate...but unfortunately you are using presta

I was about to suggest a car tire gauge. Cheap and accurate...but unfortunately you are using presta
riles
can't you just get one of these and then you can use any schrader gauge
http://www.loosescrews.com/Product_Images/KS-PO.jpg

ditto mx5099, thats what I use. buck and a half at most bike shops, less at Xmart