how to pump up schrader valve bike? I'm quite new to bikes.
I have a Schrader valve bike with deflated wheels. When I try to pump it up. I take off the protective cap, then there is a valve secured down by a nut (there is another nut securing it to the actual wheel) I then put the pump onto the bit of valve poking up and lock it in. I can then pump it completely with about 5 pushes of the pump. Once it is complete I unlock the bike pump off of the valve, at that moment all the air rushes out immediately (10 seconds) even if I put the protective cap on. What does this mean??
From these three, which one you have?

Case ①:



Schrader valve

Check if the inner part (valve) is properly installed (tight enough). If is and still loose air — you need to change the valve or the inner tube, the problem is with one of them.

Case ②:



Presta valve

You need to unlock the valve before pumping, or you will pump air only into you pumps' hose. After pumping don't forget to lock the valve back.

Case ③:



Woods (Dunlop) valve

Very old system. Check inner parts (steel needle and rubber tube) for damages, rubber tube can degrade flexibility with years → air loss.