Bicycle helmet use four years after the introduction of helmet legislation in Alberta, Canada

▶ We observed 9367 bicyclists before and after youth (<18) helmet legislation in 2002. ▶ Unadjusted helmet prevalence increased 23% for children and 110% for adolescents. ▶ Helmet prevalence changed from 52% to 55% among adults (18 years and older). ▶ Adjusted helmet prevalence ratios were similar to the unadjusted estimates. ▶ Increased bicycle helmet use followed helmet legislation in the target age groups.