http://tinyurl.com/kpghls

This is a reverse of the standard adapter which converts a Schrader valve pump head to work with Presta valve tubes.

I prefer Presta valves for bike tires as you do not lose air when installing or removing the pump chuck from the valve. Not much air in many bike tires so it is easy to lose appreciable pressure. Also most dual use heads on pumps are a not too satisfactory or require disassembly to switch valve type compatibility.

This adapter has it's own one way valve internally and once installed on a Schrader valve tube it can be left in place like a Schrader valve cap. No air loss noticeable during pump head installation or removal in my initial use. Some air loss does occur during adapter installation and removal so I will just leave them on.