Last year, health officials in Seattle decided to stop requiring bicyclists to wear helmets. Independent research found that nearly half of Seattle’s helmet tickets in recent years went to unhoused people, while Black and Native American cyclists in the city were four times and two times more likely, respectively, than white cyclists to be cited…

Most crash data come from traffic-safety monitoring systems that happen to catch motor-vehicle-related bike injuries and fatalities. Medical records from bike-crash victims focus on diagnosis, treatment, and outcome, while typically leaving out details of the circumstances of the crash itself; they also fail to capture people who cycle without ever needing medical attention. Insurance claims and police reports catalog some bicycle crashes, but miss plenty: One study by San Francisco’s public health department found that 39 percent of bicyclists who required ambulance transport were not documented in police records. The United States can’t even accurately tally overall bike helmet use.