Ok, for all you folks who DON'T use 'average speed' on solo rides as metric to gauge your performance:
What do you use to gauge your bike performance?
I can think of
1. Powermeter (win if you have one, no contest there)
2. How fast you are relative to your buddies (in my opinion, a far poorer metric than average speed)
3. Your race results (pretty good but still depends on how strong the field is)
4. You don't care how fast you go (also legit but don't plan on racing any time soon.)