The rear conspicuity of bicyclists riding with traffic at night is critical for preventing collisions with motor vehicles. Past research suggests that bicycle taillights can offer conspicuity benefits at night but the effects of the placement and operational mode of taillights has not been studied. This study investigates the conspicuity benefits of bicycle taillights at night. Specifically, the distances at which participants respond to bicyclists as they are driven along an open-road route at night were compared. The bicyclists used either a full-intensity taillight on their seat post (either flashing or steady) or a half-intensity taillight on each heel (while either pedaling or not). One bicyclist was stationed on a road segment with a long sight distance and another was stationed on a road segment with a sight distance that was limited by road curvature. For the cyclist positioned at the end of the long straight section of a roadway, conspicuity was maximal when the lights were placed on the heels while pedaling. The conspicuity of the cyclist positioned at the end of a 90 degree curve was maximized when the lights were placed on the heels while pedaling and when the lights were placed on the seat post of the bike (both flashing and static). However, conspicuity for both cyclists was minimized when the lights were placed on the cyclists\u27 heels while not pedaling. These results confirm that highlighting biomotion enhances bicyclists\u27 nighttime conspicuity
