Table 2

General descriptions of the 12 included studies

Study ID	Cyclist population	Intervention (legislation)	Control	Outcome	Methods
Cote, 1992	All rider ages	Helmet law for children <16 years	Communities without legislation	Helmet use	Recording: concurrent roadside observations;
					Factors: age, gender, race, place;
					Follow up timing: <1 year after legislation.
Cameron, 1994	All rider ages	Statewide helmet law for all cyclists	Pre-legislation period	Helmet use	Recording: Pre-post roadside observations;
					Factors: age, gender, time, place;
					Follow up timing: <2 years after legislation.
Ni, 1997	All rider ages	Statewide helmet law for children <16	Pre-legislation period	Helmet use	Recording: Pre-post roadside observations;
					Factors: age, gender, place
					Follow up timing: 3 years after legislation
Foss, 2000	All rider ages	Helmet law for all cyclists	Pre-legislation period	Proper and improper helmet use	Recording: Pre-post roadside observations;
					Factors: age, gender, bicycle type, protective devices, backpack, time, place;
					Follow up timing: 3 years after legislation
Kanny, 2001	Elementary school	Statewide helmet law for children <16	Other community without legislation	Helmet use	Recording: concurrent roadside observations;
					Factors: gender, race;
					Follow up timing: 1 years after legislation
LeBlanc, 2002	All rider ages	Provincial helmet law for all cyclists	Pre-legislation period	Helmet use	Recording: Pre-post roadside observations;
					Factors: age, gender, accompaniment, type of road;
					Follow up timing: 2 years after legislation
Thomas, 2002	All riders ages	Statewide helmet law for children <15	Pre-legislation period	Proper and improper helmet use	Recording: Pre-post roadside observations;
					Factors: age, gender, bicycle type, backpack, gloves, time, place;
					Follow up timing: <1 years after legislation
Delamater, 2003	Elementary, middle school	Statewide helmet law for children <16	Pre-legislation period	Helmet use	Recording: Pre-post roadside observations;
					Factors: age, time, place;
					Follow up timing: 4 years after legislation
Liller, 2003	Children <16	Helmet law for children <16	Pre-legislation period	1. Helmet use	Recording: Pre-post roadside observations;
				2. Bicycle injuries	Factors: age, gender, race/ethnicity, helmet use of companions
				2. Bicycle injuries	Follow up timing: <2 years after legislation
Parkin, 2003	Children 5–14 years	Provincial helmet law for children <16	Pre-legislation period	Helmet use	Recording: Pre-post roadside observations;
					Factors: age, gender, time, place;
					Follow up timing: 1 year after legislation
Hagel, 2005	All rider ages	Provincial helmet law for children <18	Pre-legislation period	Helmet use	Recording: Pre-post roadside observations;
					Factors: age, gender, time, place;
					Follow up timing: 2 years after legislation
Povey 2005	All rider ages	Nationwide helmet law for all cyclists	Pre-legislation period	Helmet use (the survey)	Recording: Pre-post roadside observation
					Factors: age
					Follow up timing: up to 11 years after legislation