There are a growing number of city bike-share programs across the country, but it appears that renters are less likely to wear a helmet than people who ride their own bikes. For example, a study in Washington, D.C., measured helmet use at only 26 percent for bike-share riders, compared with 70 percent for riders on their own bicycles. Studies in other large cities showed similarly low helmet-use rates. One probable reason: It can be a pain to cart around a helmet.

Bearing that in mind, Seattle, which has a mandatory helmet law, took a straightforward approach. There’s a locked bin of helmets next to each bike-share station. Members can put in a code and access the helmets free; others who buy a one- or three-day pass can rent a helmet for $2. The modest loss rate of about 2 percent suggests that this could be a feasible long-term solution.

Another solution could be a truly portable helmet. We tested the Overade Plixi folding helmet, which is designed to fit into a shoulder bag. Our testers gave it mixed reviews. The helmet easily passed our impact tests with a Very Good rating, but its fit adjustments and ventilation were judged to be Poor. It is portable, though, so it might be a good option for people who use their city’s bike-share and don’t ride long distances.

This article also appeared in the August 2016 issue of Consumer Reports magazine.