The limit on growing a mega-region with bicycles is simply that bicycles' limited speed makes them impractical for travel of more than 10 miles for most people.

The limit on growing a mega-region with bicycles is simply that bicycles' limited speed makes them impractical for travel of more than 10 miles for most people. But Tokyo's 38M-citizen megaregion of train stations accessed by pedestrians and cyclists[0] is probably the best-scaled megaregion yet to exist. [0]See this random suburban station in Tokyo full of parked bicycles: https://www.google.com/maps/@35.7324121,139.4176845,3a,73.1y,133.33h,87.16t/data=!3m6!1e1!3m4!1sXaPvx6gSWUndh7kBMQT7fQ!2e0!7i13312!8i6656 https://www.google.com/maps/@35.7324121,139.4176845,3a,73.1y...