Just finished my second ride on a new-to-me Large 5 spot and have a couple of setup questions. After about 60mins into both rides the middle part of my back started to get sore . I took all the parts of my old frame and the bike I was coming off had a TT length of just over 23 inches while the Spot has a 24 inch TT. To partially compensate for this I slid the saddle forward about 1/2 inch leaving me a little more stretched out than before but not much. I thought being more stretched out took pressure off of your back but the opposite seems true for me. My stem is 100mm so maybe I need to get a shorter one? Any other setup suggestions? I am 6 feet tall if that helps.