Originally Posted by
JMANNIEUS972
I am surprised they don't sell red lens filters for use as a brake light. A flashing red strobe that you could see 1/4 mile away? Awesome.
LEDs don't work that way. Unlike filament bulbs, LEDs only emit light at specific wavelengths. Most of the LEDs you see on headlamps are what are considered cool white meaning most of the output is towards the blue end of the spectrum because those tend to have more light ouput. There is very little output at the red end. If you put a red cover over the light, then you will loose probably 90% of the output.
You'll need a red diode for red light out the back for best performance.