If you are under 18, California law requires you to wear a helmet. Adults should wear a helmet that fits properly to reduce the impact of head injuries in an accident. Also, know your local ordinances: some counties and cities require riders of all ages to wear helmets. California law does require cyclists to have a white light that illuminates the road in front of the bicyclist and is visible from a distance of 300 feet from the bicycle. Cyclists must also have a red reflector or flashing light on the rear of their bike that is visible for 500 feet, white/yellow reflectors on shoes or pedals, and a white/yellow reflector on the sides of the bike. Bicycles equipped with reflectorized tires on the front and the rear do not need side reflectors.