People riding free-floating bike share rentals in Seattle are wearing helmets infrequently, according to a new analysis conducted by University of Washington researchers. Only 20 percent of bike share riders wore helmets in the study, while more than 90 percent of cyclists wore helmets while riding their own bikes.

Different research on the free-floating bike share systems showed that bikes were usually available in all Seattle neighborhoods across economic, racial and ethnic lines. However, more bikes were located in more-advantaged neighborhoods

"There's nowhere that was systematically ignored during the first six months of the program," said Stephen J. Mooney, an epidemiologist at the Harborview Injury Prevention & Research Center and professor at the UW's School of Public Health.

Researchers counted the number of cyclists — noting helmet use -at four strategic locations around Seattle. Researchers found that only one in five people riding bike shares wore helmets. So far, researchers haven't seen an increase in head injuries among free-floating bike share riders, but they're watching.

It's important to observe rider behavior

The ways people ride free-floating bikes, and where they ride them, and how they fall from them when they crash may lead to a very different risk profile than that of private bike riders. Still, an overwhelming amount of research shows that wearing a helmet helps to prevent serious head injury in a bike crash.

"There's a lot of nuance in bike safety — we know that helmets protect heads, but we also know that places where more riders cluster usually have lower risk per rider. Obviously, we'd love to see more riders with helmets. But we recognize that not everyone wants to lug a helmet around just in case they decide to ride casually later in the day. So we're monitoring both ridership and injuries," he said.

Bike share improves health and reduces travel times

In a separate study, published recently in the Journal of Transport Geography, Mooney again looked at bike share programs. This time the research team wanted to see if the benefits of bike share — such as improved health and reduced travel times — were available to all neighborhoods regardless of economic status, race and ethnicity.

"Free-floating bikes went everywhere. Pretty much everyone has some access," Mooney said. Prior studies showed that docked bike share systems, which are geographically constrained by station locations, tended to favor advantaged neighborhoods. There were not stark differences in availability of the free-floating systems, the research found.

Researchers used the aggregate data collected from all the free-floating bike share operators in Seattle and combined that with neighborhood based census data."If you look a little bit deeper, there is some inequity in where the bikes go," Mooney said. "But bikes were usually available throughout the city."