I have a herniated disk and it got so bad 4 years ago that I could barely walk. Each step was excruciating with sharp pains radiating down my left leg to my foot. I quit riding for a couple of months because it hurt to move my leg. To this day, I still can't ride my mountain bike even on smooth paved streets.

Now I have a back pillow strapped to the seat of my recumbent and commute every day. Riding the bent doesn't help or hurt my back but at least I am able to ride any time I want. If you do not have a bent you should try a couple of them. If it hurts -- stop. If not, keep going.