BICYCLE LIGHTS LAW REQUIRMENTS IN Wyoming
In US the bike lights die required by Law if you reading in low light conditions, The light can be attached to either the bike or to the cyclist but must be visible at least 500 feet to the front of the bicyde, so be careful how you position the light. Additional lighting must be consistent with the law specifying required lights and reflectors, so a rear light must be red.
2014 Wyoming Statutes
TITLE 31 - MOTOR VEHICLES
CHAPTER 5 - REGULATION OF TRAFFIC ON HIGHWAYS
ARTICLE 7 - BICYCLES
31-5-706. Lamps and other equipment.
(a) Every bicycle when in use at nighttime shall be
equipped with a lamp on the front which shall emit a white light visible from a distance of at least five hundred (500) feet to the front and with a red reflector on the rear of a type approved by the highway department which shall be visible from six hundred (600) feet to the rear when directly in front of lawful lower beams of head lamps on a motor vehicle. A lamp emitting a red light visible from a distance of five hundred (500) feet to the rear may be used in addition to the red reflector.