My commuter bike needed new skins so Saturday I decided to make the swap. Pulled the front, swapped the tires, aired it up and put it back on. By the time I was ready to let it down off the stand, it was flat. NUTS. I couldn't tell you the last time I pinched one, so I figured I was due. Went to the shop and picked up a new tube and back to the house I go. 15 minumtes later I'm airing it up again...psssssss. You got to be kidding me...I pinched another one. The bike shop was closed by now so I just patched it. Did the rear with no problems and all is good. Not sure what the problem was, but I felt like a tool. I've probably done dozens since I last pinched one and then I pinch 2 in the same day.