Check The Schrader Valve & Deflate The Tyre
Find the schrader valve and remove any dust-cap.
If the valve hasn’t been opened for a while release a short hiss of air to check it’s not stuck. The same process, holding the valve open longer, deflates the tyre.
Schrader Valve or Auto Valve
Release air by pressing down on the valve stem. A match stick or some other small blunt tool may be helpful.
Connect The Pump
The hose or pump connection may screw on or press on. Some push fit connections lock with a cam lever. To check the correct operation of the connection look at the rubber washer and move the lever back and forth. The the ‘locked’ position squeezes the washer, the ‘on-off’ position lets the washer relax. The rubber washer in a pump connector wears out with use. It needs to be replaced when it stops gripping valves to give an air-tight sea. It's considerable easier to inflate a tyre when you're pump has a good seal.
Floor or Track Pumps
Place both feet on the rests to stabilise the pump. Open the pump fully at the start of each stroke. As you get to the bottom of the stroke you can use your body weight – rather than your arms – to force the last bit of air out of the chamber by softening your knees. Using the full stroke is a more efficient way to inflate a tyre.
Many modern pumps can be converted between Presta and Schrader fitting, by dismantling the connection and reversing the direction of parts.