For much of the population, a bicycle route is only as good as its weakest link. An average commuter can bliss out for 90 percent of their ride along an off-street path; but if the remaining 10 percent involve a particularly unsafe intersection or a troubling bridge crossing, it could be a show stopper. I call these choke points; they are often thought of as the weakest link in the chain of bicycle facilities for a city.
They represent an often glossed over, but important tenet of bicycle planning; ironically, they are also one of the most difficult to stay on top of. They come in two varieties. We can refer to them as (1) facility disruptions and (2) naturals.
Facility disruption: It’s simple for a city with no facilities to have no chokepoints; the whole city is a choke point. There are no real facilities that end prematurely. The more facilities a city brings on-line, the more likely choke points result. Every new lane or path needs a starting and ending point and unless they are seamlessly woven into the existing fabric, there is likely some discontinuity that will result.
Naturals: Some cities are naturals for choke points. Seattle, comprised of labyrinth of water barriers which serve to funnel cyclists to select routes, is littered with them. In most communities the ordinary constriction of roadway space owing to bridges over railroads or rivers provides good fodder for where chokepoints fester. And, oftentimes the worst choke points are temporary, resulting from detours owing to construction, which is probably best labeled a natural occurance.
The best thing a city can do about choke points is threefold: identify, address, and minimize them.
One of the more systematic efforts to address these comes from Minneapolis, Minnesota. As of 2010, they had 54 gaps in their system–one for each square mile of the entire city. What other cities are taking formal and detailed inventory of the discontinuities and reporting on them?
 Starting and ending point: Krizek, K. J. and R. W. Roland (2005). “What is at the end of the road? Understanding discontinuities of on-street bicycle lanes in urban settings.” Transportation Research Part D: Transport and Environment 10(1): 55-68.
 Choke points owing to construction: Krizek, K. J. (2002). Even Here, A Failure to Respect Cyclists’ Needs. Minneapolis Star Tribune,. Minneapolis: A2 (commentary).
 Gaps in the Minneapolis system: see chapter 7 in Pflaum, D. (2011). Minneapolis Bicycle Master Plan. Minneapolis, Minneapolis Public Works.
 One gap per square mile in Minneapolis: The city’s area is 58.4 square miles; once you account for the fact that 6 percent of that area is water, it comes to 54 square miles.