For the general population, cycling is a reasonable option only for trips of 5 km and under. Perhaps I'm severely overestimating the shape people are in, but I

For the general population, cycling is a reasonable option only for trips of 5 km and under. Perhaps I'm severely overestimating the shape people are in, but I had a job where I commuted 15km by bike. You can ride 15kph without breaking a sweat, so that's an hour at a relaxed pace and probably 30-40 minutes at an athletic pace. I'd guess that the median American can ride 10km (6.2 miles) with no issues. I could be wrong, though.