dengi, I suspect that the cross section of posters here pretty much average out a good range of rider differences, and as we all know, its the uphills that bring down the avg speed so much, and so much more than on a road bike without the weight of all our stuff.

What I have always noticed personally is that while my speed will increase slightly over the course of a trip, or the course of the riding season, what is more apparent is just not being so bagged at the end of a long day.