The goal of Reardar is to provide cyclists with a sixth sense of cars. Cyclists-especially those in cities-are constantly assessing and re-assessing their surroundings, maintaining a dynamic, mental map of their environment. This assessment relies heavily on sight and sound, exacting a tax on these senses. Reardar provides an additional sense of nearby cars to the cyclist through haptic feedback. This gives the cyclist an increased-or more accurate-awareness and confirmation of nearby vehicles. It also allows the cyclist to offload some of this awareness budget from vision. If the cyclist has an adequately low-fidelity sense of the car(s) behind her, she can dedicate more of her eyesight budget to the primary focus of what is more immediately in front of her. The prototypes were built with an inexpensive 24ghz radar and tested over a period of one month. More info here