If you dig up some of the old threads on the toppic you'll see there are too many variables, terrain, wind, solo/pack riding, length of ride, etcForum members l'm interested to know how many miles in one hour would you normally do, l will start the thread off and say on l normally do about 15 miles so for me 15mph is good going.
Anything between 10 and 18 depending on distance, mood, weather, wind, company.
Oh dear. My avarage speed??? at the huuuge risk of being banned from this forum and relocated to snailsRus.com my avarage speed is between 8 and 10 mph
BUT, if i may redeem myself slightly, that is hilly, muddy, off road MTB miles. If I were to ride a road bike id prob avarage at least 40