If car users knew how fast cyclists were moving, would they be more willing to share the road? That’s the question posed by Mykle Hansen in the intro to his Speed Vest project from MAKE Volume 19.

Bicyclists receive a lot of honk-based grief from car drivers who perceive them as slow and in the way, and when drivers misjudge a bicycle’s speed, it can cause “right hook” collisions that kill several bicyclists each year. This lightweight night-cycling vest displays your current speed in glowing, 7-inch-tall numbers easily visible to cars. On the back, an Arduino microcontroller reads input from an off-the-shelf bike speedometer sensor, and then switches power to sewn-in numerals made from electroluminescent (EL) wire.

Mykle’s entire project is now up on Make: Projects for you to check out, collaborate, and build your own vest. Safety first! Check out this video to see the vest in action: