Bike Safety is taken very seriously here on Nantucket. You should always wear a helmet whenever you are biking, especially children. The most important thing to do before riding your bike is to make sure your helmet is fitted properly, as well as worn the correct way.
Here are some helpful tips from the CDC to make sure you and your child's helmet are properly fitted in order to provide the highest level of safety:
the helmet should fit snugly and leave no room for large spaces between the child's head and the helmet
make sure they can see out of the helmet, both forward and to the sides, because compromised vision can be a safety hazard
hair styles can affect the fit of the helmet, so make sure you and your children are wearing the desired hairstyle while fitting your helmet
the chin strap should be centered under your chin, no more than one or two fingers should be able to fit between the strap and the chin. When opening your jaw the helmet should pull down on your head, and if this does not happen then the helmet is not secured enough. The helmet should also not move side to side when shaking or turning your head.
the side straps should make a v shape both under and in front of the ears
make sure to check your helmet regularly for damages and clean the inside occasionally with warm water and mild detergents
never bike with a damaged helmet
Check out this video made by the CDC for tips on how to make sure your helmet is properly fit and safe for use.