When I started out, I used my weekend rides as training rides for my commute. My goal was to make my weekend rides the hardest so that my commutes seemed easy. Works for distance too.

As for actually extending my commute, I started by extending the ride home once or twice a week. When I got really brave, I extended my ride to work on Saturday mornings, stopping at the diner a couple of blocks from work for breakfast before continuing to work. This gave me a time cushion along with recovery and refueling before work.

These days it takes me 17 miles to cover the 4.5 miles to work, 13 miles to do it coming home. My ride to work starts by heading 6 miles in the opposite direction.