Most bicycle helmets provide good protection for the top and back of the head, but little or no protection for the temple regions on the sides of the head  A study of head injuries resulting from bicycle accidents showed that a large proportion were caused by blows to the temple area
Ttherefore, if bicycle helmets protected this area, the risk of serious head injury in bicycle accidents would be greatly reduced especially since
the bone in the temple area is relatively thin and impacts in that area are thus very likely to cause brain injury