|Authors:||Hanne Beate Sundfør, Aslak Fyhri, Ross Owen Phillips, Christian Weber|
It has been suggested that the safety benefits of bicycle helmets are limited by risk compensation. The current study contributes to explaining whether the potential safety effects of bicycle helmets are reduced by cyclists’ tendency to cycle faster in order to compensate for a reduction in perceived risk when wearing them. A previous study  showed that non-routine helmet users did not increase their speed immediately after being given a helmet to wear. The current study tests if having some time to get used to the helmet leads to any increase in speed, thus exploring whether risk compensation to bicycle helmets occurs after a short period of habituation. We did this by conducting a field experiment, in which we measured speed, GPS-coordinates (Strava) and self-reported risk perception. In order to test the effect of habituation, we used a two-phase design. We collected the data in June 2015. Approximately 40 non-routine helmet users were recruited in the field (along cycle routes in Oslo), and through a sample drawn from the Falck National register of bicycle owners. In the first phase of the study, all participants were asked to complete a test route (2.4 kilometres downhill) with and without a helmet. In the second phase of the experiment, conducted after 1.5 -2 hours, the same participants again completed the test route with and without a helmet. In the time between the first and second phases of the experiment, all participants were given helmets, and told to use them on a predefined bicycle route. Habituation to the helmet between the first and second phases of the experiment did not produce any increase in speed, on top of the habituation which occurred while cycling down the hill (the order effect). We argue that risk compensation is an unlikely effect of using a bicycle helmet, and probably cannot be used to help explain any adverse effects related to helmet legislation.