Speeds and distances vary by who I'm riding with. In my mellow grip, we'll go like 8 or 9 miles, 7 or 8 mph. In my fast group, it's more like 15-40 miles...maybe low teens for the shorter rides, and 7 or so for the longer ones. You have to pace yourself when going all day carrying 20 pounds of water up steep hills.
Same for road bike. If I'm commuting to work (11 miles) or on a short ride I always aim to average about 20, not including stops at lights. I can even do a 20 moving average on a century, but it involves lots of drafting and breaks. Steady pace without taking many breaks would be more like 15 on my own, 20+ in a group.
It takes a while though. Once you're comfortable, the best way to get faster is to try to ride with people faster than you.
Last edited by carve; 11-13-2011 at 11:18 PM.