Another thread got me thinking about this again. I've been hatching this idea for years. Here it is:
Scooters and bikes should be equipped with a "deceleration light," which would be a flashing brake light, attenuated when the scooter slows down dramatically by means of compression.
Most scooters have very good compression deceleration, meaning that they slow down significantly just by letting the throttle drop. This can actually be very dangerous as the car behind you has no warning that you're getting closer, and because there is only one tail light, the tail lights down get further apart in a motorists field of vision as he approaches you, the way they do with a car. I feel scooters (if not all bikes) should be designed with a "decel" light which would be a flashing red whenever there is a sudden vaccum (rapid throttle release, or downshifting on a regual bike). Then the steady red when the brakes are applied. We certainly have the technology to recognize a dramatic throttle release as compared to a mild reduce in throttle. In a sudden downshift or deceleration, the light would flash until either the vacuum on the engine returns to "mild" levels, or until the brakes are applied. And with the advance in LED lights, the rapid flashing is not so injurious to bulb life as with traditional brake lights.
I'm sure the US DOT has no provisions for such a thing, but it would be such an accident reducer that, a little lobbying by the insurance companies would run this through congress in no time. It doesn't have to be required on all bikes, just available, like daytime "running" headlights on cars.
Yes! Tie it to the speedometer signal. Decelleration above a threshold triggers a flashing tailight, overidden by the brake light.
I do this manually. I took the MSF recommedation to flash my brake lights before fully applying the brakes a step further by also using my rear brake lever to flash the brake light when I let up on the throttle.