I get what you're saying, however I think your dismissal of the "car analogy" is flawed. If you are talking about 4 (or even 2) lane state or interstate routes, that have dedicated bike paths and pedestrian sidewalks next to them, then yes, traffic of differing speeds and types is separated. Where I live, on the other hand, most of the roads are narrow, rural, 2 lane roads, with all sorts of turns and elevation changes. Just today, while driving up my road, I saw a number of walkers and runners, plus some cyclists, plus normal car traffic, plus some...