I am sure they are using more powerful emitters, they do cast some light on the road up close. Basically an accelerometer to sense orientation, and light white on the way up and red on the way down, a microcontroller to figure that out, mosfets to switch the leds, add a li-poly battery and charging electronics. The more interesting problem is sealing it all up, making it light weight, and not too sensitive to the inevitable bashes and bangs of living on the rim.