I had my T12 collapse and had spinal fusion in September. I spent 2 months with a brace and my main exercise was walking. Brace removed late October at which time I was allowed on the trainer and spent a lot of time in the pool strecthing the muscles etc. Just got the OK at 3 months to get back on my road bike. I put on a cm shorter stem plus a little more rise. So far my longest distance has been 30 miles a little climbing (I love to climb). Lower back gets sore riding so I stop and strecth throughout the ride, seems to help. Keep on working on flexability and the riding will get better.