I have a hilly but, unfortunately not rolling hills, 22 mile commute and the best I was able to do was 18.8 avg. That took all I had, it was nice and cool in the morning and I arrived with a shirt that had to be wrung out. I was not recovered on the way home and was nowhere near that fast. You are doing well to hold 17 both ways and not go home and immidiately start fantasizing about hammocks.

Craig