Smartphones As Bicycle Lights: Still Not Catching On

The Monocle, a prototype in the workshop of Philadelphia's Studio KMD, is meant for people heading out in the evening who forget their bike lights (but quizzically remember to strap on a custom-made phone holster). The patent-pending design is simple: Turn on the Monocle app, then insert the phone into a fabric pocket looped through your belt. The photo flash blips through a red filter, giving the appearance of a tiny but intense rear safety light. Somehow, this process does not result in your phone being filled with thousands of blurry photos of the street.

How quickly will this invention kill your battery? Its makers say they've performed "a few preliminary studies" on this question, and that a rate of three flashes per second will drain about 7 percent of the power in 15 minutes. If you're worried about it, there's the option of setting an alarm when the juice is nearly gone.