... may I ask which level(s) your back issue is at?

My PT has suggested that if I ever get back on a bike at all, I'll need to ditch the road bike. I've got issues at multiple levels, but the one that really gets nailed on the road bike is L3-4. I'm still skeptical that anything shy of a unicycle would let me ride in perfectly neutral spine regardless of terrain ... but I'd like to hear your experience.