Pepox369 says:
Yeah, well that's what I had quite seriously suspected!
SPECELIZEDRIDER says:
I figured that you'd have to have somewhat evenly displaced hills, each with ascents, almost the same distance as the descents (you go up the same distance as you come down). Also, there shouldn't have been many hills where each hill was much more highly elevated than the next. Otherwise, that would indicate that most of your trip was primarily "uphill" one way, but "downhill" the other way. In that case, it shouldn't have taken the same amount of time, each way.
Since, it did take over 2 hours to travel a distance of 15 miles, each way. You would have to assume that there were times when breaks were taken. Either multiple short breaks, or a limited number of longer breaks.
I don't know for certain, perhaps I'm in error, but it was fun just thinking about your trip, the hills, the time it took you, and how you might have gone about it!
At any rate...
I applaud you for successfully completing your first bicycle commute!
