In 1993 (I was 23 at the time) I had Micro-laminectomy / Diskectomy was performed on my lower back due to a fragmented lumbar disk and spine pieces that caused debilitating back pain, removing disk fragments and smooth out the lumbar disk to function normal, and over the years I've had varying degrees of sciatic incidents, at one point in 2011 where my leg muscle mass and strength was deteriorate from my left leg. When I was finally able to an orthopedic doctor that specialized in sports medicine injuries, he was inclined to put me under the knife immediately. I strongly requested physical therapy, not to rebut the doctor's diagnosis, just for the fact the strength and muscle mass and function to that leg was considerably better and improving from when I had made the appointment. My doctor listened and put me into physical therapy for 6 weeks with the warning if it didn't improve, I would be at the end of my rope where surgery may not be effective at that time, but I insisted. I must say though the therapy was very effective in stabilizing and strengthening my core where I didn't need surgery, but I do find that if I neglect the gym/core exercises for too long my back will let me know, and it will be this way for me for the rest of my life.
From my experience I would suggest physical therapy to strengthen your core, to provide instructional exercises to increase stability and on how to deal with sciatic flair ups. I felt like a million bucks and fully mobile after I completed my physical therapy.

And I do hit the mountain bike trails mostly in the fall winter too.