[greggyb]

Bike lane congestion is wholly unlike car congestion. It happens, and for busy routes, you do need affordances in the bike lanes and infrastructure.

That said, I've never missed a light cycle while bicycling, even in rush hour in major metro areas with many people on bikes. The busiest bike intersection in the world, in Copenhagen, devotes less space to bikes than most US streets devote to one lane of vehicle traffic.

Every single US city I have seen has ample space for bicycle infrastructure. Many have lots of roads with sufficient space for dedicated transit lanes, and bicycle lanes, and widened sidewalks while still maintaining space for personal vehicles.

Even if we take your hypothetical to the extreme, with only bicycles and no personal vehicles, every US city has enough space for the bike traffic on its existing streets.