I just calculated my morning commute speed. I ride 14km in around 35 minutes. I am an experieiced cyclist and have participated in races, endurance rides, and recreational rides for a couple of decades now. THere are dozens of others doing a similar commute and I among the faster ones.. I seldom get passed when I am on pace to do 35 or so minutes, and I pass a lot of people...
Anyhoo, (14 km/1.6 km/mi)/(35 min/60min/hr) = 15 mi/hr