MrAtom, a huge thing to remember is the speed that you can comfortably hold for part of your ride when you look down at your speedometer is usually NOT your average speed. If you're comparing average speeds, use a GPS or bike speedo, or at minimum a stopwatch and Google Maps. I think you'll be shocked how quickly that average speed drops with only one or two small changes in speed.
The other thing to remember is that a time is a huge influence on speed. Jim's reports and Rojo's ride data both confirm ballpark 20 mph averages for road bikes, but Jim says he rides 1 hour efforts (on what I assume is very flat topography) and Rojo is keeping that same speed for 6-10 hours at a time while climbing mountain passes.
Frankly, average speed is a terrible way to compare anything between riders. Just get out and enjoy riding your bicycle. If you want real comparisons, you need power data and then compare watts/kg vs time plotted out for each rider in question. But that's not really necessary for recreational riders.
Jim, do you track these rides on any medium that can be shared? Strava? Garmin Connect? MapMyRide? etc.?
EDIT: ninja'd by rojo. He didn't beat around the bush like I did. Typical
