Machined from solid aluminum, the Blink Steady is a rear-facing bike light with a built-in accelerometer. Start pedaling, and the two-setting light automatically turns on; stop, and it turns off. Two AAA batteries give it at least 80 hours of run time. [$95; blinksteady.com]
The Motion-Sensitive Bike Light
With a built-in accelerometer, this bike light intelligently turns on and off to illuminate your rides for countless nights.