Introduction: Although risky cycling behaviour (RCB) has been systematically linked with trip-related factors, no previous research has simultaneously investigated the influence of cycling frequency, car use frequency and trait anger on it. Further, the idea that cycling anger experiences and expressions might mediate the relations between these constructs represents an interesting causal chain to explore. Objectives: The primary aim was to assess the relations between trait anger, cycling frequency and car use frequency as predictor variables, mediated by cycling anger experience and cycling anger expression on RCB among adult cyclists, while controlling for the effects of age and gender. A secondary aim was to evaluate the impact of the COVID-19 pandemic on cycling anger experience and cycling anger expression on RCB, by means of a descriptive comparison of two surveys gathered before and during the second COVID-19 lock-down. Methods: A total of 1,346 participants in 2019 (‘before COVID-19 pandemic’) and 1,241 participants in 2020 (‘during lock down’) filled in an online questionnaire. The questionnaire consisted of a Risky Cycling Behaviour (RCB) variable from the Cycling Behaviour Questionnaire (CBQ), the Cycling Anger Scale (CAS), the Cycling Anger Expression Inventory (CAX) and the Trait sub-scale of the State-Trait Anger Expression Inventory-2 (STAXI-2). Because different participant samples were included in the 2019 and 2020 survey (independent observations), a two-group mediation model with cycling anger experience and expression as mediators was fitted. Results: The results from the 2019 and the 2020 cohort are relatively similar with significant direct effects between trait anger and RCB. At both periods, an indirect effect between trait anger and RCB was present through CAX. As compared to men, women tend to report less anger expression (CAX) while cycling in traffic, but experience (CAS) more anger. A small negative association indicated that older participants tended to report less RCB than ...