Check your rim tapes. I just went through a similar issue. The rim tape was an old plastic one and it had some slices over the spoke holes that were holing the tubes.

What I did about 4 years ago was to go to tubulars. I ride Tufos (tubeless tubulars) and put in some sealant - either Tufo's or Stans. I never get flats anymore but when I look at my maintenance records, I'm getting 1/8th the flats I was getting before. The last several tires I've worn them out and they've never flatted. I've since switched all our bikes over to tubulars.


J.