I'm in desparate need of advice/information on a back pain issue. In July 2012, I got fitted to my bike with the BG Fit system. My right leg is 3/8-inches shorter than my left so the technician added shims to my right shoe. The fit worked because my average speeds increased and took a minimum of 30 min off my ride times of rides >50 miles. However, after a 50+mile ride, my spine above the tail bone is so sore that it feels like my hips can't support my body weight. On ocassion, both my legs get siatica. This condition lasts for 2-3 days and comes back after another 50+mile ride. I been back for bike fit adjustments and now the technician thinks putting a shorter stem might be a solution. I'm not convinced. Any suggestions/advice out here? Thanks in advance.