I'm glad I found this thread as I have never really given this issue much thought! But now I'm thinking about it and I bet I'll be thinking about it the next time I'm out riding too!

I ride where it's very hilly. I'm not kidding...there isn't really anything flat here at all (this is a real bummer if you're looking for a recovery ride or if you just want to go out for an easy spin). I think I do what a lot of other people have posted here...I pedal if the hill isn't too steep and I still have gears left. But if it's steep and I'm going 30+ mph, then I coast. My legs appreciate the break. I just wish all the steep uphills around here had a nice fast downhill right beforehand so I could bank up some speed!