They're usually found on cars, less expensive bikes and mountain bikes. To open a schrader valve, simply unscrew the rubber cap at the top.
[header] How to inflate bike tires [title] A schrader valve is also called an american valve, or a car valve. [step] The valve stem is surrounded by a threaded valve core; to press down on the stem, you need to use a tool like a pen cap or your thumbnail. Schrader valves are typically wider in diameter and shorter than presta or woods valves.