How it works
The jacket uses an accelerometer to sense movement, changing the colour of LEDs on the back from green when accelerating, then to red when braking.
A tilt switch in the jacket also makes LEDs in the arm flash amber when the wearer lifts their arm to indicate a turn.
So it's fine if you pedal smoothly, but if you've got an action like a mad axe murderer.....
Not sure on the legal implications of green leds on rear either :?