To all those who felt bad because they have trouble pumping up their tires and need to lift their feet off the ground to apply enough weight on their floor pump, think about this:

(And keep in mind that I'm not very good at physics. But I hope this makes sense.)

Think about how a bike pump works. You need to compress the air that's in the pump to the point where you build more pressure in the shaft of the pump than there already is in the tube, so that the air in the pump needs to "escape" in the tire. Let's say you're pumping your tires to 100 psi (Pound per Square Inch) and let's imagine that the surface of the bottom of your pump is 1 square inch (in fact it's probably a bit bigger than that), you need to push increasingly close to 100 pounds down as you approach 100 psi on the gauge, in order to push the volume of air that's in the pump into the tire.

For us petite women with not a whole lot of upper-body strength and not a lot of weight, it's almost as much as we our own weight!