Go Dogboy - I too have been commuting sporadically for the past couple of months and kicked it up to 4 days per week just before the holidays – on the 5th day I drive my clothing in. My commute is flat (Florida) and 15 miles each way. 5 miles marked bike lane, 5 miles residential cut through & 5 miles in traffic. I have not done any serious mileage in a long time but I am 45, heaviest I have ever been, borderline hypertension, and it’s time for a change.