Bike lights are one of the most important safety features you can add to your bicycle to prevent injury or even death. They are useful during the day, but are essential equipment if you ever ride your bicycle at night or near dawn or dusk or on cloudy or rainy weather days. Bike lights improve not only your visibility so you can avoid debris on the road, but also so other people can see you.
How do you pick the right type of lights for your ride and circumstances? Most bike lights are rather standard white lights that hook up to the bike frame with a series of clamps and or Velcro straps. These bike lights either run off of battery packs or are powered by the pedaling effort you do while riding. The type you select depends on your budget, personal tastes and which you find more reliable and therefore safe.
After all, if your lights go off when you stop pedaling, your visibility will drop like a rock if you pause for a rest or readjustment on the side of the road. Bike lights should shine all the time if you are riding in dark weather or at a dark time of day or night. Battery backup may be a great idea.
In general, bike lights should be installed on both the front and back of your bike frame for maximum visibility. If you only have front lights, make sure to have large, visible reflectors as well.