ProxiCycle: Passively Mapping Cyclist Safety Using Smart Handlebars for Near-Miss Detection

Active transportation is a valuable tool to prevent some of the most common causes of mortality worldwide, but is severely underutilized. The primary factors preventing cyclist adoption are safety concerns, specifcally, the fear of collision from automobiles. One solution to address this concern is to direct cyclists to known safe routes to minimize risk and stress, thus making cycling more approachable. However, few localized safety priors are available, hindering safety based routing. Specifcally, road user behavior CHI '25, April 26-May 01, 2025, Yokohama, Japan Breda et al.

is unknown. To address this issue, we develop a novel handlebar attachment to passively monitor the proximity of passing cars as a an indicator of cycling safety along historically traveled routes. We deploy this sensor with 15 experienced cyclists in a 2 month longitudinal study to source a citywide map of car passing distance. We then compare this signal to both historic collisions and perceived safety reported by experienced and inexperienced cyclists.