^^ For similar reasons, this is why I also think that average speed -- without other measures of cycling ability -- is pretty useless.

When I started out about 1 yr ago, I could average 18-20 per ride, pretty impressive ! But I was never going more than 10 or 15 miles at a time, a few days a week, on mostly flat terrain. Now I'm doing 20-30 per ride, 4-5 days/week, usually with several thousand feet of elevation gain per ride, and my averages have dropped down to 14/15. I am pretty sure I am much better off now