BICYCLE LIGHTS LAW REQUIRMENTS IN South Dakota
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.
2018 South Dakota Codified Laws
Title 32 - MOTOR VEHICLES
Chapter 17 - Vehicle Lights And Flares
§ 32-17-25 Bicycle lamps--Visibility and color--Violation as petty offense.
32-17-25. Bicycle lamps--Visibility and color--Violation as petty offense. Every bicycle shall be equipped with a lighted lamp on the front thereof visible under normal atmospheric conditions from a distance of at least three hundred feet in front of such bicycle and shall also be equipped with a reflex mirror or lamp on the rear exhibiting a yellow or red light visible under like conditions from a distance of at least two hundred feet to the rear of such bicycle. A violation of this section is a petty offense.