BICYCLE LIGHTS LAW REQUIRMENTS IN Tennessee
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.
Tenn. Code Ann. § 55-8-177
55-8-177. Bicycle lamps and brakes — Penalties.
(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 feet (500′) to the front, and either a red reflector or a lamp emitting a red light, which shall be visible from a distance of at least five hundred feet (500′) to the rear, when directly in front of lawful upper beams of head lamps on a motor vehicle.