A bicycle reflector is a simple, prism-based safety device developed in the 1960s in Finland. It is usually attached to the rear, front, pedal or wheel of a bike, and it aids with visibility in dark riding conditions. When light strikes the rear of a reflector, which is coated with prisms or beads, that light is redirected via two tiny right-angle mirrors back in the direction it came. The reflector is only visible, therefore, if the viewer is emitting light (e.g., the driver of a car with the headlights on). While bike reflectors can be highly visible under the right circumstances, they are generally insufficient visibility aids for night riding.
The drawbacks with reflectors are twofold. First, as previously mentioned, they only work if the viewer is providing a light source. That generally works for most motorists at night, who are (hopefully) using their headlights, but this fails to work for other bicyclists, pedestrians, skateboarders and animals. Second, variable conditions can render a reflector essentially useless. The entrance angle of the light source might be such that the reflected light is practically invisible. Also, the observer might be out of the relatively narrow reflected beam of light (called the “observation angle”) and might fail to see the bike reflector.
Backroads Pro Tip
Remember, adverse weather conditions, such as rain or fog, might absorb the light traveling to and from the reflector, rendering it useless. For this reason, never rely on a reflector as your sole light system.
It is important to note that bike reflectors can serve as great backup or auxiliary visibility aids. They never run out of batteries, only fail if severely cracked or broken, and can add to a bicyclist’s overall visibility. With their limitations and flaws, however, bicyclists should always ride with powered LED lights under any condition that might impede visibility, such as darkness, rain or fog.