If you find yourself in a situation without the right pump for a presta valve you'll need to use an adapter. Using the adapter adds a couple of steps, mainly putting it on and taking it off. You start off by opening the presta valve as you would normally, tap it once to make sure it's not stuck, put the presta valve adapter on. Once it's on you can then use a pump that is only equipped for the schrader valve. So in this situation we're going to put the schrader valve end of the pump on, lock it, and pump it up. Once you have it to the desired pressure, take the chuck off, remove the valve adapter, close the valve, this is really important because if you don't close the valve the tire will slowly go flat. Normally I tell people to store these on a valve if they need to travel with them or do not own a pump. So, leaving it on the valve is usually the best place for them. It certainly beats lost of the road where you dropped it out of your saddlebag, or in the widget drawer at home.