Hi folks, I am 69 and trying to get back into biking. Purchased a Giant Talon 27.5 medium bike and have been having trouble getting started. When I was a kid I rode a bike all the time, but as I grew into adulthood I kind of let myself go and now find myself at 245 lbs. at 5'9". Doc said I need to take about 80 lbs off and recommended I get into something I enjoy for exercise. I have tried walking on a treadmill and it is OK but gets pretty boring after awhile. What I am experiencing on the bike is that I have lost the flexibility and strength to keep myself balanced. Also, after a short ride on the grass doing figure eights my legs start burning. I told the bike dealer that I would like to have the seat a little lower because I was used to riding an old heavyweight single speed. He did cut the seat post down 2 inches for me and that helped some with the balance. He told me for the maximum benefit for my legs that I would want to raise the seat back up slowly to the 2 inches he had cut off. I can walk 30 to 45 minutes on the treadmill at 1 to 2 levels of elevation and at 3.2 to 3.5 mph. But I am wondering if I am using different muscle groups on the bicycling? Any suggestions from you folks as to how it would be best for me to proceed? I don't want to give up the cycling since I would love the rides out on all the new bike paths we have here in Des Moines.