As a rule I get very few flats. Never any pinch flats, despite the fact that I'm no lightweight. Two flats in the same week, one just before a century ride, have got me thinking about the flats I have gotten, and most of them seem to arise from defect in the tubes, not from road hazards.
More recently, the valve core came out when I took disconnected the pump head from the tire. Rear tire, with a group start on a century less than an hour away. The other day I got what seemed to be a "normal" flat, but when I took it to the lbs they found nothing in the tire, and just replaced what was apprently a faulty tube in the front tire.
What can I do to minimize this? To anticipate some questions, I've used a variety of brand tubes--Sepcialized, Performance, Nashbar--, and the flats seem evenly distributed between front and rear tires. I do use the screw on doohickeys that hold the stem in place in the rim, and valve caps.
Since there's no replacement for Presta tubes anytime soon, how can I maximize their lifespan, and might it be my fault and not the tubes or valves?