How to Choose a Bicycle Helmet.
Wearing a helmet when cycling is vital for both young and old riders to prevent head injuries, but it is important that a helmet fits properly. The Cleveland Clinic suggests the following: the helmet’s padding should fit snuggly, it should sit level and not move in any direction, look for the Consumer Product Safety Commission sticker when buying a helmet, and a pre-owned helmet should only be worn if it has no cracks or breaks and was made after 1999.
The Cleveland Clinic, May 2015