I'm 56 and have a daily round trip commute of 10 miles that I generally turn into 25 - 30 miles. I've been an off and on bike commuter since I was in high school, and have been doing this daily year round (rain/shine/snow) for the past two years. I put in a total of 7800 of commuting and weekend miles for 2008 and 7300 so far this year.