Hello i would like some advise and/or experiences with your own bike fit problems and solutions. The problems started when i purchased a new giant defy alu in small size . Seemed a good fit in the bike shop and quite close to my old bike witch I found v comfortable. The problem seem to occur when endurance riding I get really tight and cramped around the shoulders and middle and lower back area. Iam not entirely sure if the flexy carbon seatpost is doing my back any favours as I feel the jarring effect surly mustn't be benificial?? I come from mtb xc background and have never suffered so much on a bike.My first dropbar bike was a caadx cyclocross commuter and I took it out on the roads and found it very comfortable if a little slow.My giant defy matches tt length ,much lower stack and seatube. Can anyone give me advise or bikes to purchase ???