2/ 1/2 weeks is how long it took me in a Giant Escape 3... on a Defy 4, you will probably be able to do it faster, though it will really depend on how hilly the route is and how well you pace yourself. I am 37, and had been sitting on my butt for 20 years, and was a heavy smoker until a year ago. Just yesterday I did 50 miles for the first time, 9 weeks after riding for the first time.