I've been doing a little circuit of just under 11 miles most days. Since I got the Bryton 20 computer, I've been tracking average speed, except when I went out with my wife, on her hybrid, didn't bother then, but suffice to say, it took around one and a half hours instead of my usual 35 minutes, though we did stop at a pub for a quick glass of water!
But my average speed seems to be around 18, which I'm guessing is pretty good, it's not massively hilly, altitude gain according to Bryton is around 310 feet.
Took my son out with me on Friday, he's ten, I just bought him a small Triban 3, I was amazed at his speed, we averaged nearly 15.5, and he seemed fine downhill even at 30+ mph! A little scary though, I was holding him back, seemed a little full on for a first ride at that age! Anybody got any advice on riding with kids?