[gindely]

No, come on, provide something concrete. Searching for "cycling joint wear" just provides unreliable sources saying you don't use your joints up, but it doesn't provide unreliable (or reliable) sources saying the opposite.

It is easy to avoid incidental injuries, and everyone would much rather the trauma of an incidental cycling accident than the trauma of a highspeed car crash. Mentioning them in just scaremongering. Ride at a safe speed on a proper path and look where your going. If you can't look where you're going, you're going too fast; slow down. (You can't say "proper paths don't exist", because we're talking about the dreamland in which they do, therefore, by definition, they do.)

20 mi round trips are unlikely. You get long trips in cities developed for cars.

[kaybe]

And get a properly fitted bike. Japan, I'm looking at you.