mongoose,
I have had back problems going on 18 years. These problems include spinal stenosis, arthritis and multiple degenerative discs which have resulted in debilitating sciatic pain down my right leg. There was a period of an entire year that I had to walk with a cane for support. I've had MRI's, gone to a chiropractor (who would have chosen to have me continue three times a week forever,) physical therapy, and several spinal epidurals. All produced limited success. Since I began riding in an upright (flat bar) position, I have had essentially no pain. I walk and work without pain as well. Any “minor” pain has subsided after a brief rest period. I attribute my success to the muscle strengthening that goes with riding a bike in an upright position. Having been there, (and still there,) I wish you much relief and success.