BICYCLE LIGHTS LAW REQUIRMENTS IN New York
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.
Lamps and other equipment on bicycles
Vehicle & Traffic (VAT)
(a) Every bicycle when in use during the period from one-half hour after sunset to one-half hour before sunrise shall be equipped with a lamp on the front which shall emit a white light visible during hours of darkness from a distance of at least five hundred feet to the front and with a red or amber light visible to the rear for three hundred feet. Effective July first, nineteen hundred seventy-six, at least one of these lights shall be visible for two hundred feet from each side.
(b) No person shall operate a bicycle unless it is equipped with a bell or other device capable of giving a signal audible for a distance of at least one hundred feet, except that a bicycle shall not be equipped with nor shall any person use upon a bicycle any siren or whistle.
(c) Every bicycle shall be equipped with a brake which will enable the operator to make the braked wheels skid on dry, level, clean pavement.
(d) Every new bicycle shall be equipped with reflective tires or, alternately, a reflex reflector mounted on the spokes of each wheel, said tires and reflectors to be of types approved by the commissioner. The reflex reflector mounted on the front wheel shall be colorless or amber, and the reflex reflector mounted on the rear wheel shall be colorless or red.
(e) Every bicycle when in use during the period from one-half hour after sunset to one-half hour before sunrise shall be equipped with reflective devices or material meeting the standards established by rules and regulations promulgated by the commissioner; provided, however, that such standards shall not be inconsistent with or otherwise conflict with the requirements of subdivisions (a) and (d) of this section.