A brake light for my bike

Every vehicle over the asfalt have a brake light, but bikes. This increases the probability of been run over if you must brake in short distance.

The idea is to use the accelerometer and the RGB and/or colour screen from hexiwear to show a red light when the acceleration in Z axis raises some value.

A further idea is to detect side displacements and show a yellow arrow, that will be like a turn signal or, at least, a simple warning for other vehicles behind.