So my bike’s wheels say something like 40PSI, and when I feel the wheel is kinda deflated or not fully inflated, I use the bike pump and pump until the gauge indicates 40PSI, but since the gauge starts at 0, and there was already some air left in the wheel, does that mean I went over 40PSI? Or does the bike pump compensates for the leftover air somehow? How should I properly pump the wheels to the recomended PSI?
In: 6
A bit has to do with the design of the valve. Usually, it only allows air to enter, not escape. So if you put on your pump, the valve doesn’t release air into the tube, it just doesn’t do anything. Once you start pumping, you’ll quickly bring the tube up to the same pressure as the valve. So it goes from 0 to say, 20psi very fast on the gauge. If the pressure in the tube is higher than the pressure in the tire, the valve lets air in, but only as long as the pressure in the tube is higher than the one in the tire.
So you are measuring the pressure in the tube, which is almost exactly, but oh so slightly lower, the pressure in your tire.
A bit has to do with the design of the valve. Usually, it only allows air to enter, not escape. So if you put on your pump, the valve doesn’t release air into the tube, it just doesn’t do anything. Once you start pumping, you’ll quickly bring the tube up to the same pressure as the valve. So it goes from 0 to say, 20psi very fast on the gauge. If the pressure in the tube is higher than the pressure in the tire, the valve lets air in, but only as long as the pressure in the tube is higher than the one in the tire.
So you are measuring the pressure in the tube, which is almost exactly, but oh so slightly lower, the pressure in your tire.
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