I ride 75 miles per day and average 28 mph..
Oh... wait... I thought I was in the road forum for a minute...
Actually, I'm 51 and commute 6 miles each way to work and wade through the winter slush at around 12 mph.
Summer riding is slightly faster. Weekend rides are longer (50 - 75) and I throw in the occasional century but I don't like to make a habit of it.