I'm a 61-year old, 5-day a week bike commuter who does some longer rides on the weekends. My commute is 14 miles round-trip, which really just means two 7-mile rides a day. I've been biking for a year and have done a couple of charity rides. I did a 33-miler yesterday with lots of hills, and I'm registered for a 50-miler in early June and a 62-miler about 3 weeks later. During the winter, I concentrated mostly on getting out the door and on the bike in the cold and dark. Now I want to use the commute to help me get in better shape for my longer rides. Suggestions on how to use my two daily 7-mile rides to help improve my longer rides? By the way, work and home responsibilities make increasing the distance not very practical.