“Law and public education around lawmaking help change behavior and norms,” McDermott said. “And 30 years later, it’s important for us to re-evaluate the goals we had in mind when we adopted the helmet law and the unintended consequences of implementing it.”

Helmet use in the city reaches 91 percent among private cyclists, according to a study. Near Portland, Ore., repeal advocates note, use is the samedespite the fact that the city does not have a helmet law for all ages.

Access to helmets is a particular challenge for low-income people: according to a study from the National Highway Traffic Safety Administration, people in the lowest-income groups are about half as likely to wear a helmet for all trips as people in the highest-income groups. . .

But Mr McDermott said he doubted that the differences led to a disproportionate extent of enforcement. And he says the district could address the gap without the police: The district recently budgeted more than $200,000 to buy helmets and expand bicycle safety education.

Across the country, other types of cycling regulations were also found to be enforced in a discriminatory manner.

In Chicago, a study found that tickets were issued to cyclists eight times more often in a predominantly black part of the city. An investigation by the US Department of Justice found that 73 percent of bicycle stops in Tampa, Fla., between 2014 and 2015 involved black cyclists, despite the fact that black people make up 26 percent of the population.

“The data reveal that layoffs do not reduce crime or produce other positive outcomes,” such as reducing bicycle accidents or injuries, the report said.

“The best investment in keeping people safe while riding a bicycle is in creating safer roads, safer transportation systems,” said Bill Nesper, director of the League of American Bicyclists. “That’s the kind of investment that will make people walking and cycling the safest in our community, instead of investing in laws like these that can be a barrier to people riding bicycles and that can be enforced in a discriminatory and discriminatory way.”