The Safety of Public Bicycle Share Programs in North America

In a recent article, Graves et al. analyze trauma center data in 10 major cities to show that head injuries accounted for an increasing proportion of total bicycle injuries in the year following implementation of a bicycle share program.¹ They conclude that helmets should be a requisite component of bicycle share programs.

Graves et al. misinterpreted the injury data. Although the proportion of injuries that were head injuries increased (Figure 1a), the authors fail to mention that the total number of head injuries declined by 14.4% in bicycle share cities, compared with a decline of only 3.9% in control cities (Figure 1b). The total number of nonhead injuries declined even more sharply—by 37.8% in bike share cities, compared with a 6.2% increase in control cities. Head injuries declined, but not as quickly as other injuries, explaining the increasing proportion of head injuries.

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FIGURE 1—

Comparison of cities with a public bicycle share programs (PBSP) vs those without (control) before and after program implementation by (a) percentage of bicycle-related injuries and (b) number of bicycle-related injuries per year.

Source. Table 2 from Graves et al.¹

It is striking that even as bike sharing programs encouraged an increase in bicycling, the total number of injuries declined by 28% after bicycle share implementation, compared with a 2.3% increase in injuries in control cities. While Graves described to National Public Radio that they found “an increase in head injuries,”² the data suggest that bicycle share programs were in fact associated with reductions in bicycle injuries, even though none of the programs provided helmets.

It follows that delaying the implementation of a bicycle share program may represent a lost opportunity to reduce bicycle-related injuries. The requirement for a helmet distribution and sanitization system has delayed the implementation of a bicycle share program in Vancouver, British Columbia, since 2012,³ although success in Vancouver, if attained, could expedite helmet roll-out in other cities.⁴ By contrast, Dallas, Texas, removed its mandatory adult helmet laws in 2014 in advance of implementing a bicycle share program.⁵

We encourage Graves et al. and other researchers to investigate the reasons for the potentially protective effect of bicycle share programs. For example, it would be worth investigating the proportion of injuries in which a helmet was used and the proportion involving a bicycle share user.

The current ramp-up of urban bicycle share programs in North America presents a unique opportunity to resolve the bicycle share debate through scrutiny of injury, ridership, and helmet usage data. Unfortunately, this early attempt by Graves et al., and its interpretation by major media outlets such as the Washington Post,⁶ misrepresents a clearly hopeful outlook for the safety of bicycle share programs.

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