Bicycle sharing systems have been spreading like wildfire over the past few years, with new initiatives in New York and Chicago bringing the idea to America's biggest cities. But even the oldest such systems aren't very old, so we're still learning a lot about how they work. One striking finding of a major new report from the Mineta Institute at San Jose State University is that bike shares cater disproportionately to the rich.

At least they do in the four major established systems in the US and Canada that the report examined:

For each city, this table shows two different populations. In the left column, you get the share of the city's total population that belongs to each income bracket. In the right column, you get the share of the city's total bike share membership that belongs to each income bracket. In all four cities, you see that low income cohorts are a lower share of the bikeshare population than they are of the total population. In the high income cohorts it's the opposite. 17 percent of Salt Lake City bike share members earn over $150,000 a year, even though such well-to-do individuals are only 8 percent of the city's total population.

So what's going on? The report focuses mainly on two issues that have loomed large for the Capital Bikeshare system in DC as well: the placement of stations in low-income areas and barriers to access around the lack of bank accounts and credit cards for low-income households.

Bike commuting is more popular with the poor than the rich

The problems of the unbanked are certainly pressing (postal banking could be the answer). But the bike share data doesn't quite support that theory. Eric Jaffe purports to see a "tipping point of roughly $50,000 in household income," but I don't see it. It looks like bike share is more popular among the middle class than the poor, but it's even more popular among the rich. It seems unlikely that the gap in bike share usage between the $100,000 to $149,999 bracket and the $150,000 and over bracket can be explained in terms of a lack of credit cards. And Luz Lazo reports that when the Capital Bikeshare went out of its way to place additional stations in low-income sections of Montgomery County, MD, they reported "the lowest usage in the county."

So here's another theory. Maybe rich people love bikeshare because bikeshare is like vacation travel or theater tickets — a high-end recreational amenity that people spend money on when they have money to spare, but that less-fortunate families find it easy to go without.

Bike share advocates want it to be something else, part of an urban transit system. But note that bicycle commuting in general is more popular with the poor than the rich. That's presumably because bikes are cheaper than cars, and pedaling is cheaper than gasoline or even bus fare. If you're looking for a workhorse method of getting around town, buying a bicycle is already a very thrifty option. If it doesn't work for you, it's probably because either the route you need to travel isn't suited for bicycling or else because you're not physically up to the ride. Bike share isn't going to solve either of those problems.

Bike share also isn't an especially reliable means of transportation. On nice days, demand for bikes spikes and stations and docks become suddenly unavailable. You can't rely on it as your sole means of transportation to work (especially if you're a shift worker who really can't be late), so becoming a bike share member doesn't really relieve you of other commuting expenses.

What bike share is good for is occasional recreational riding for someone who's not really counting on it. I walk to work for my daily commute. For other transportation needs, I sometimes walk, sometimes Metro, indulge in a fair number of Uber rides, and recently bought a car. I'm also a Capital Bikeshare member, because sometimes on a nice day when I'm not with my cycling-averse wife it's fun to pedal. A bikeshare membership is less of a hassle that storing a bike I rarely use. And I'm lucky enough to be able to afford the membership fee pretty easily.

My guess is that I'm a pretty typical bike share member in that regard.

If I'm right about that, cities may want to take a hard look at exactly how many resources they want to pour into encouraging low-income households to sign up for bike share. Spending money on installing rarely-used bike stations in low-income neighborhoods might be better spent on giving money to the residents of those neighborhoods. Money can buy bicycles or bus fare or gasoline or food or children's clothing or help pay the rent. If access to a bike sharing system just happens to fall pretty far down the list in the hierarchy of human needs, then money spent on subsidized bike sharing is going to be a lot less useful than more straightforward alternatives.