On my main commuter the bike computer usually gives my average speed in the 14-15mph range. This is a road touring bike set up for commuting, with 700x32 tires and all the K-Rap I carry she probably weighs 35lbs or more. On a crappy day riding into a headwind I may drop below 13mph. On a great day with a tailwind or with skinnier tires I'll beat 16mph.

I need to put a computer on my roadie SS, I just feel faster on that bike.