In my college days I commuted something like 45 miles to school. This was one way. I actually lived about 5 miles from the school, but I would go around the back way and take a long country route on the way... Took me over 2 hours.

Then I would shower in the college gym locker rooms, go to class (basically spend the day at college); then go to work a few miles away and finally ride the last 4 miles or so home. So my entire round trip was about 50 miles.

Later after I graduated, I bike commuted about 24 miles each way... took about an hour and a half each way. I decided that was as far as I ever wanted to ride though the city on a regular basis.

All my most recent commutes have been under 12 miles each way.

At one point I heard of a guy that commuted 65 miles each way... most of it was country road. Never met him though... so perhaps an urban legend.