Since you are planning on spending up to 2k, why not buy a good $1200 road bike AND a nice Mountain bike. Unless you are going to race you do not need a $2000 bike. I have a $1300 road bike and love it!! I also started out like you...overweight with lousy joints and back. The bike is about the only thing that doesn't cause me pain. The weight is less of an issue on the bike than it was running. Running hurt and I was painfully slow. The road bike is like driving a Ferrari. There is no substitute.