I am returning to cycling after many years of not riding. I previously had some back problems which seemed to be excacerbated by riding my mountain bike, it had a long cockpit and a low, stretched out riding position. I would like to puchase an endurance road bike typified by the Specialized Roubaix series, but I need to keep the price down. I would like to have Shimano 105 level components and decent wheels, but would accept the next rung down of componentry if need be to keep the bike withing budget. I am trying to keep the price down to $1500 or less and realise that this is making things difficult. As a tall rider 6'3" I would need a large frame, probabaly 58-63 cm. I would happilly accept a secondhand or older model year bike to get better value and I am not stuck on the idea of any particular brand or frame material (although I want some shock absorbtion and endurance type geometry). Does anyone have any suggestions for what I should look at and test ride? Thanks.