I was fitted to my bike with the BG fit this year in July. The technician put shims under my right cleat since my right leg is 3/8-inches shorter than my left. Prior to the new fit, I was pain free for 2 years. After the fit, my average speed had increased so it did make a difference. I have been back to the LBS for minor fit adjustments. However, I developed debilitating back pain after long rides (>50 miles). It's not the lower back muscles but concentrated to the spine right about my tail bone. It feels like my hips can't support my weight and, ocassionally, I get siatica on both legs. The pain lasts for about 2-3 days and comes back after a long ride. The technician thinks I need a shorter stem but I don't think the stem is the cause. 1600mg ibuprofen is not doing anything to help. Any thoughts out here? Thanks in advance