Danish manufacturer Reelight introduced a bicycle lights that are powered by a small magnets mounted on the bike’s spokes, so no batteries are required. The lights can be used day and night. Magnets are coin-sized and create very little rolling resistance. The waterproof lights have no switches or other controls – you just start riding, and the revolving magnets engage generators in the lights, causing them to start flashing. A built-in capacitors keep flashing for up to two minutes when the bike is stopped.
The lights are mounted on the left-side fork and seat stay using an included product-specific tool. Installation takes just a few minutes, and involves the tightening-down of nylon-coated stainless steel wires. The lights can be seen in use, in the crowdfunding promo video below.