Had a similar diagnosis about 35 years ago - herniated disc at L4-L5. Had sciatic pain down my left leg which sometimes got so bad I could hardly get around. Bicycling actually seemed to cause me less problems than walking or driving. Eventually had a week of complete bed rest followed by an exercise program which helped considerably. My orthopedist had no issue with my cycling and even signed up on my fundraiser form for a century ride the week after the bed rest regime. Haven't had any serious recurring issues since then but do immediately take note of any back twinges and take it easy while resuming the exercises. Still have a bit of numbness on the outer edge of my left foot but it's not bothersome.