You misread me.

>Bikes don't belong on the road with cars and they dont belong on sidewalks with pedestrians and they don't belong in between.

The NYC bike lanes are inherently problematic. These are the "in between" that I'm talking about. They are not entirely separate paths in the way that I mean. They are a new lane within the existing path. What I mean by a separate path is something that is above, below, or in an entirely different location than the road/sidewalk.

Normally, if you’re turning right you’re in the rightmost lane, so nobody to your right is going straight. And likewise for left. A bike lane puts straight-through traffic to the right of turning cars so they come in from your blind spot. A "yield to bikes" rule doesn’t help much when you can’t see who you’re yielding to. And car traffic presents the same problem for bikes. They have to deal with this by merging all the way across traffic or cross and become a pedestrian. The fact that they may have to become a pedestrian is a major flag that they inherently dont fit.

Parking and buses have the same problem. The sidewalk and the road were designed to touch. When you put a bike lane between them, every trip from curb to car, bus, etc. has to cross it.

It’s essentially splitting 1 road into 2 with separate rules. It's inherently problematic. You can't introduce bikes without increasing the rule complexity and worsening the experience for everyone else.

There is plenty of basic intuition here.

- Pairs. Each pair of modes (car,bike,pedestrian) needs its own set of rules. Two modes is one pair. Three modes is three pairs, so adding one mode triples the relationships.

- Introducing a "middle": Every segment of one street crosses every segment of the other. Adding a middle lane on both sides takes an intersection from 9 overlap zones to 25, and from 4 where different modes meet to 16.

- Fixed width: The street doesn’t get wider. Any space dedicated to bikes costs car lanes, parking, or sidewalk.