Is Bike Sharing Contagious? Modeling its Effects on System Membership and General Population Cycling

Bike share systems are relatively new, highly visible additions to urban transportation systems that provide new opportunities to cycle or combine cycling with other modes of transportation. This paper presents new evidence about the role of bike share systems in travel behavior based conceptually on diffusion of innovation theory. The authors hypothesize that bike share systems have spatial contagion or spillover effects on the (H1) propensity of individuals to adopt bike share and (H2) propensity to bicycle within the general population. They test the first hypothesis by modeling membership growth as a function of both system expansion and the existing, proximate membership base. They test the second hypothesis by using bike share activity levels near one’s home in a model of household- level bicycle participation and trip frequency. The study shows mixed results. Bike share membership growth appears to be driven in small part by a contagion effect of existing bike share members nearby, even after controlling for system growth. However, within the general population, the authors did not identify a significant relationship between proximity to bike share stations and cycling participation or frequency. These findings complement other recent studies of bike share systems that indicate systems still are evolving, and they have implications for marketing, infrastructure investments, and future research about bike share operations and innovation.