Using a rear-facing radar sensor, BSD monitors the bike’s surroundings and alerts the rider to presence of a vehicle approaching in the rider’s blind spot. The rear-facing radar sensor scans behind in the lanes to the left and right of the rider. When an approaching vehicle is detected, an LED built into the rearview mirror will light up. (Note: BSD will not alert the rider to vehicles directly behind the bike, or vehicles that are moving away from the bike.) Should the rider indicate the intent to change lanes by switching on their turn signal while a vehicle is detected in a blind spot, the mirror LED will flash.