An 11-year study of 24 California cities determined that cities with denser street networks were safer for cycling. The study also found that cities with high bicycling rates show a much lower risk of fatal crashes for all road users. Improving streets and street networks to better accommodate bicycles may enhance safety for all.
Marshall, Wesley E., and Norman W. Garrick. Evidence on why bike-friendly cities are safer for all road users. (2011) Environmental Practice, 13(01), 16-27.