I just got a new Schwinn Volare clone, and on the first day got a flat from a misaligned rim strip (a sharp-edged spoke recess).  I wanted to ride the bike around, to finish adjusting the derailleurs, and used this patch kit.  I followed the instructions EXACTLY.  The patch failed when I inflated the tube to 60 psi (the bike has Kenda 700 x 28 tires, which have a max inflation of 85 psi).