Don't know if anyone has mentioned this but there is a very cheap adapter available that might solve the problem
http://cgi.ebay.com/PRESTA-VALVE-TO-SCHRADER-ADAPTOR-BIKE-TUBE-FRENCH_W0QQitemZ370112191030QQcmdZViewItemQQptZCycling_Parts_Accessories?hash=item370112191030&_trksid=p3286.c0.m14&_trkparms=72%3A1205|66%3A4|65%3A12|39%3A1|240%3A1318



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One of the things I have learned is that once I have the proper pressure in the tire, (I put the valve at knee level to pump) I use both my thumbs and "pop" the pump off the tire. I found that if I just used one hand to pull the pump off that I was more prone to bending the valve stem. I also was more prone to pulling the valve stem out of the tube, resulting in an instant flat. 
