Towards a cycling-friendly city : An updated review of the associations between built environment and cycling behaviors (2007–2017)

Introduction: Cycling behavior has recently attracted great research attention as an important type of physical activity and sustainable mode of transportation. In addition, cycling provides other environmental benefits, such as reducing air pollution and traffic congestion. Various built environment factors have been demonstrated to be associated with the popularity of cycling behaviors. However, the most recent built environment cycling reviews were conducted nearly 10 years ago, and these reviews reached no clear consensus on which built environment factors are associated with which domain of cycling behaviors. To determine the crucial features of a cycling-friendly city, it is therefore necessary to conduct a review based on empirical studies from the last decade (2007–2017).
Methods: Thirty-nine empirical studies published in peer-reviewed journals between 2007 and 2017 were retrieved and reviewed. The results were summarized based on built environment factors and four domains of cycling behaviors (transport, commuting, recreation, and general). Weighted elasticity values for built environment factors were calculated to estimate effect sizes. 
Results: We found consistent associations with large effect sizes between street connectivity and cycling for commuting and transport. The presence of cycling paths and facilities was found to be positively associated with both commuting cycling and general cycling. However, the effects of land-use mix, availability of cycling paths to non-residential destinations, and terrain slope on cycling behaviors remained weak. The effects of urban density and other built environment factors are mixed. 
Conclusions: This review has demonstrated that street connectivity and the presence of cycling paths and facilities are the two most significant built environment factors that may promote cycling behaviors. With the emergence of advanced measurement methods for both the built environment and cycling behaviors, further studies may overcome current research limitations and provide robust evidence to support urban planning and public-health practice.