Hi,
I had the surgery a couple of years ago. Biking was recommended as a great exercise. I did experience pain on my ill fitting 930, and also on most affordable hardtails. I ended up with the Specialized FSR XC for around $1000 usd. No back pain at all. Bumps that should hurt like h_ll, I don't even feel. Now I love biking again (okay, I never stopped loving biking).
I should mention that I tried a variety of recumbents and found them to be extremely painful.
good luck to you
