A photo simulation of Contrail in action. Image: Jessi Pervola and Studio Gelardi.

Ever wonder which paths cyclists naturally take through the city? Not satisfied with the location or extent of designated bike lanes? Feel like other street users are quick to dismiss the presence of cyclists?

"Contrail" is a design concept that enables cyclists to increase their visibility to cars, pedestrians, and each other. Conceived by Pepin Gelardi and Teresa Herrmann, this frame-mounted device would allow cyclists to make their mark on the street with faint lines of chalk. The rear wheel spins a smooth trail of color onto the pavement as the bike whizzes along.

Contrail leaves an impression based on the cumulative movements of many
cyclists over time (a more lasting variation on the BYO bike lane concept employed by the laser-projected LightLane). Its provocative visual language lies somewhere between sky
calligraphy, temporary street graffiti, and overlapping footprints in
the snow.

Gelardi and Herrmann proposed Contrail for the Power to the Pedal competition, and are currently developing a prototype. They envision "a new cycle of biking participation" in which the criss-crossing chalk ribbons would pique curiosity, identify more popular routes, and inspire more cyclists to hit the road.