This is not clear cut: see this review which concludes that this is not the case (helmets neither increase injuries nor risky behaviour). In general the idea of

This is not clear cut: see this review which concludes that this is not the case (helmets neither increase injuries nor risky behaviour). In general the idea of risk compensation is frequently brought up in these cases, and while it may seem intuitive, it usually does not appear in the data. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3989528/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3989528/