The Substitution Effect of E-bikes and Psychological Processes Influencing Its Use: Results from Two Randomised Controlled Trials in Sweden

The market share of e-bikes has increased extensively in Europe over the last decade. How this trend will affect the transport system depends to a large extent on the substitution effect which needs to be determined in detail to allow projections on the potential of e-cycling as a means to promote sustainable transport systems. Further, little is known about what psychological determinants influence e-bike use, an important topic for policy makers that wish to promote e-cycling. This study aggregates GPS data from two randomised controlled trials in Sweden to determine the effect of e-bike use on travel behaviour. Motives behind e-bike use are investigated within a pathanalytic structural model, based on an expanded theory of planned behaviour. The results reveal that, on average, total cycling increased by 4.5 kilometres per person and day during the trials and its modal share measured in distance increased by 19%. E-bike use was predicted by the intention to bike to work, which in turn mediated the effects of attitudes and self-efficacy on e-cycling. Attitude mediated the indirect effect of personal norm on intention and collective efficacy amplified the effect of self-efficacy on intention. The results show that e-cycling has a large potential to contribute to a sustainable transport system. Policy makers could increase the use of e-bikes by strengthening individuals' attitudes toward cycling and perceived self-efficacy to e-cycle, by making environmental personal norms more salient and by highlighting collective action in the effort to limit environmental degradation.