[FredBGG]

There are several products out there with deceleration activated lights that will come on when engine braking.

Not a bad idea.

I have my rear brake lever setup so that even just a little bit of pressure trips the switch on the peddle even if there is no actual rear disk braking kicking in yet. I will feather my rear brake pedal when down shifting significantly to slow down.

I also have a long steep downhill in my commute. For parts of it it's enough to just down shift on a bike when cars would also be braking. That is another time I will feather my rear bake lever to send a signal to someone behind me.

 

[FredBGG]

I bought a vololight but I haven't installed it yet.

My problem is that I usually ride solo so I'll have to enlist my girlfriend to drive behind me in order to tell if it's working correctly.

IF you have a rear brake light enhancment it's a good idea to wire an indicator to your dash so you can see what it is doing and know it's working.

 

[FredBGG]

Strobe wise makes a system that uses deceleration to trigger a rear led strobe.

Here is a video of one being installed on a Vstrom

http://youtu.be/SjYgV8xTqPU

 

[FredBGG]

You could make a quite elaborate even wearable accelerometer brake light system using an Intel Arduino and a Flora accelerometer.

Would be quite possible to program some custom signalling too.

Even tap into the turn signal of your bike with a wireless module for the arduino.

The Arduino is a mini wearable computer.