Bicycle helmets. Mountain biking is particularly dangerous.
Jeys
L
L
Cribb
G
G
Toms
A
A
Hay
S
S
D000328:Adult; D001642:Bicycling / Q000293:injuries*; D005260:Female; D006801:Humans; D008297:Male; D011481:Protective Clothing; D014947:Wounds and Injuries / Q000209:etiology*