I am curious if anyone is experiencing the type of back pain that began to deal me misery toward the end of last year. I can ride for 20-30 miles at tempo pain free. At about that point I begin to feel the lower back getting tighter. Riding fast paced for long duration especially with head winds or big climbs it evolves to more of a cramp than a pain, causing me to stop with good legs/bad back . I am a certified personal trainer, phys. ed major and have made training progressive on a lift/ride every other day basis. I have a good endurance base coming from running to duathlons to riding. I also have done much expermenting with bike position and think I have the bike set. Any suggestions for cause or cure. THANKS!!