As a long-time sufferer of chronic low back pain due to a bilateral pars defect (fracture) that has resulted in one of my vertebra sliding forward off the vertebra below it (spondylolisthesis)...I can sympathize with anyone that deals with back pain, especially while cycling. I know it goes against what all the fitness "experts" out there preach, but I simply MUST stretch extensively BEFORE riding. I do a lot of knees-to-chest moves while still in bed, then I roll over on my tummy and do child pose for a minute or two. Then I do a few more stretches while sitting on the edge of the bed, before actually standing up. From there I'll do a runner's stretch on the floor beside the bed, and if time allows I may throw in a few prone planks. Once I'm done with my stretches, I move to my inversion table, where I invert to various degrees for about 6 minutes. Only then, am I ready to swing a leg over my bike. Even once I am on my bike, it takes me about a good 30 minutes before I actually feel limber enough. Back pain really sucks.
2012 Seven Axiom SL - Specialized Ruby SL 155