The problem with your logic is that few bike accidents happen from a 40 mph car overtaking a 15mph bike. Most car-bike collisions happen at intersections and n

The problem with your logic is that few bike accidents happen from a 40 mph car overtaking a 15mph bike. Most car-bike collisions happen at intersections and not only does riding on the sidewalk not reduce that problem, it makes it worse both because a bike on the sidewalk is not as easy for the car to see, but also it multiplies the number of intersections since suddenly every driveway becomes an intersection that a car might be pulling out of.