I ride a Trek FX 2. I had a rpm clock device installed on the bike for a while and when I cycled at a fast good clip for me for like an hour putting a lot of effort into it, it came up to about 15 mph I was able to maintain in an hour and I really am no where near in as good shape compared to many speed demons on the road. I rode my bike by one of those large speedometer looking things cops put in neighborhoods to show drivers what their speed is the other day when I was riding on the Dupage River Trail and it clocked me at 17 mph on a downhill in a subdivision.

At a more leisurely pace though I would say I average somewhere between 5 - 15 mph I average on say a 20 - 30 mile trip. It really depends on a lot of factors, very strong wind and hills is a huge factor as well as what surface your riding on. My bike rides fastest on asphalt and on streets. It really depends how fast or slow I want to ride that day. Sometimes I will just ride slow and enjoy my surroundings other days I want a good cardio workout and will ride a lot faster.

Sometimes a guy on road bike will pass me up when I am riding at a leisurely pace, "on your left". And I can tell if I would be able to keep up with him by seeing how fast he zooms by me. Sometimes I will decide to speed up and give myself a good cardio workout and tailgate him for a while or pass that guy up later in the trail "on your left!"

If I was to say a true speed based on total time including stopping/going, traffic lights, traffic on the bike trails... If I decide to ride straight through without taking a rest or water break it takes me about 1hour and 45 minutes to 2 hours to ride on a 23 mile bike trip I frequently take.