all good advice.....I had back pain big time and, and as I have recommended before...get the "yoga for back care' book and try some of the stretch and stegnthening poses......don't need to go all yogi, just try it...start slow...and see if it makes a difference..Homer Simpson said:I had a similar problem until I switched to a Fisher with a longer top tube.
You should do some hamstring stretches and abdominal work. That will help a lot. Most people don't know how much the abdominal muscles help support the lower back. And the hamstrings are much larger than the lower back muscles, which means in a pulling contest, the hamstrings will cause fatigue in the lower back muscles. Stretching the hamstrings helps alleviate this problem. Sit-ups, crunches, etc. and stretch and you should be fine. You can even stop occasionally during a ride to stretch the hamstrings.