The Bixi bike share system chosen by NYCDOT is a proven platform that addresses a lot of concerns that New Yorkers might have about bike sharing. Thefts have been low in recent Bixi installations; 0.0002% of bikes checked out in London over the first year never returned. The footprint of the system is pretty well centralized, which will ensure that plenty of daily users are around to foot the bill.

My principal concern with launching bicycle sharing in NYC is that it will be very difficult to keep the bikes/spaces balanced, the biggest operational problem that’s emerged in urban bicycle sharing. Alta has acknowledged its challenge in DC and it’s been a leading complaint in London (watch the striking daily inflow/outflow here); so far, these are the two biggest CBDs that have bike sharing. The operational environment for rebalancing in all other bike-share cities is far simpler than in Manhattan.

Bike share works best in areas of medium-high density and very high mixed-use, since it requires that a large number of people circulate bikes around the system, around the clock. That way, the bikes naturally circulate themselves without much intervention. Many European and Asian cities are organized in a way that’s fairly conducive to bike sharing. Their density curves are not that steep, and many neighborhoods have 18- or 24-hour street life. Moving a lot of people to a single point — i.e., very high density, single-use concentrations, is a job most efficiently done with transit whether that’s shuttle buses for sports stadiums or rail feeding a CBD. The capacity numbers speak or themselves: at any given moment, ~1200 people can use Capital Bikeshare, while Washington Metrorail runs enough trains at peak to move 153,000 people at once.

Even in London, the City is overwhelmingly mid-rise, and high-rise, office-heavy Canary Wharf is outside the bike share footprint. North American bike sharing programs so far are either in comparatively small cities (Minneapolis, Denver, a fraction of Toronto) or in cities with an exceptionally “European-style” mid-rise and/or mixed-use core (Washington, Montreal, that fraction of Toronto).

A bike share system attempting to serve Manhattan’s highly centralized employment density will be quite difficult to manage. DC and London both struggle with office cores twice the size of Montreal’s; NYC has a CBD that is seven times as large. A vast number of docks will be demanded within the office cores, where street space is already at a steep premium. Rebalancing vehicles will not be able to easily cycle bikes amidst streets already clogged with delivery vehicles. Without an ability to rebalance bikes, it will be difficult to find bikes in Brooklyn, or open docks in Midtown, during the day. Paying customers who are thus kept out of the system will get very upset.

What might work? Unfortunately, we can’t know which sites will have a fairly balanced flow of coming and going throughout the day, but that could be inferred based on observation of adjacent land uses. A high-density or vertical racking solution like the (as yet theoretical — I’ve only seen a mock-up) Bike Dispenser might come in handy for swallowing, or ejecting, vast quantities of identical bike-share bikes at key locations like rail terminals.

A class that I’m in this semester will investigate bike share rebalancing worldwide; keep an eye on the class blog for updates and the final report.

I recently got to ride with Tom Bertulis on Boston’s “Hubway”; he pointed to Seattle’s helmet law (among the few for adult cyclists in North America) as a serious impediment to introducing bike sharing there. I have to admit that although I wear a helmet 99% of the time with my own bike — since I keep helmets near my bikes and typically plan such trips — I often neglect to when riding bike share. Tom Fucoloro from Seattle Bike Blog notes bike share’s exemplary safety record, and (as Tom B. also did) Mexico City’s repeal of its helmet law in favor of bike sharing, to argue for at least modifying Seattle’s law.