A recent study of bikesharing safety that used data from Capital Bikeshare and other systems found that "bikesharing appears to have a lower nonfatal injury rate and fatality rate than personal cycling." Despite the lower injury rate, CaBi still appears to be more risky then motoring. In addition, the study determined that CaBi was not contributing much, if any, to a safety-in-numbers effect. The data comes from CaBi and the authors note that
Capital Bikeshare does record non-injury collisions when they are reported. Capital Bikeshare reports confirmed crashes, as long as the location is known, even if there is no police involvement or hospital visit. But like Nice Ride Minnesota, Capital Bike Share does not search police reports or emergency room data to find incidents. Those incidents must be reported back to the operator by police, emergency medical services, or a member. There do exist cases of “discovered damage,” in which incidents appear to have occurred but no report was made.
Over nearly 5 years, CaBi reported 150 collisions and 55 hospital injuries
Compared to personal cycling
The good news is that CaBi seems to be safer than personal cycling. CaBi users had a non-fatal injury rate that was only 65% of the national rate for all cyclists.
In addition, CaBi has had no fatalities (in fact there have been none in the United States). Though the sample size is likely too small for accurate comparison, if there had been 1 CaBi fatality by mid-2015, the fatality rate for CaBi users would be roughly half the national rate for cyclists (10.6 per 100M trips as opposed to 21).
Of course, comparing national data to data from a bike-friendly city brings in a little bit of an apples to oranges issue, but it still is encouraging.
For reasons unknown, DC's has a higher crash and injury rate than the San Francisco Bay Area does (Nice Ride doesn't record this data).
But it's safer on a per-mile basis
Comparing per-mile data for vehicle-collisions from British Columbia, CaBi's rate of 277 per 100M miles compares favorably to that rate of 425 per 100M miles.
The primary reason for bikesharing being safer seems to be the design of the bikes themselves, but experts note that their presence exclusively within urban environments - with slower speeds - could also be a factor.
Compared to motoring
Despite improved safety, CaBi's injury rate of 919 per 100M trips was still higher than the rate for passenger-vehicle occupants which is 803 per 100M trips.
Safety in Numbers
The study authors suggest that DC is not benefiting from the "Safety in Numbers" effect.
The high linear correlation between the rise in bicycle commuters and collisions provides an early suggestion that a rise in bicycle activity may have led to a proportional rise in collisions during this period in at least two of the three case study areas [Minneapolis being the exception].
They further looked at safety-in-numbers by comparing data based on zip code and again it doesn't appear to be much benefit.
The results, presented in Table 10 suggest that in Washington DC, there is little to no relationship between the relative change in collisions within a zip code and the number of bikesharing trips in that zip code. This result suggests that there is little evidence in the collision and activity data to support a safety-in-numbers effect resulting from Capital Bikeshare. At the same time, it also does not suggest that the presence of Capital Bikeshare is contributing to an increase in collisions within high-volume zip codes. The number of Capital Bikeshare trips within an area is not found to alter the localized change in bicycle collisions from the broader trend that is underway. That is, a growth in collisions occurred in the evaluated region (Washington DC), but as shown earlier in Figure 15, this growth was broadly correlated with a general increase in cycling activity.
They also created a set of crash heat maps and concluded that "some change in the concentration [of crashes] has occurred, but in general the spatial pattern of collisions was found to be rather stable over time."
Unrelated to safety, but interesting nonetheless is a comparison of ridership data for the systems in DC, Minnesota and the Bay Area. Minnesota shuts its system down from November until April, but comparing DC's to San Francisco's does show how the weather differs, and how that impacts usage.