Originally Posted by
Gresp15C
Just to see if I understand, are you trying to measure Presta tubes with a Schrader gauge and P to S adapter? If so, you might not get a meaningful reading at all.
I'm with the others, on getting a floor pump with built-in gauge.
Knowing that my tires are at the desired pressure, I make a mental note of how much they pooch out under my weight, in case I have to re-inflate them while on the road.
Amusing story: Back when I was in college, I had this ancient pump with a huge bore. I figured out how many PSI I'd get from my full weight on the pump handle, and it was roughly the correct amount. So I just pumped until the piston would support my weight.
Actually as of last night I now have one presta tube and one schrader. I had a flat tire and had to replace it with a Slime tube which turned out to be a presta valve, even though I'm pretty sure I had confirmed it was labeled as schrader when I bought it. (The box disintegrated quickly in my backpack so I can't confirm) I realize I can't take the pressure on the presta so I was just checking my front tire which is a schrader.