On Sunday, August 20, 2017 at 6:36:14 AM UTC-4, somebody wrote:
A recent thread mentioned the Cree XPL-HI white LED.

What's the current hot red LED? Either in terms of lumens/watt or
totoal output. My taillight is several years old and there must be
something better by now.

"Better" isn't necessary. You don't need the brightest LED, especially since
bright LEDs now blind other cyclists. You need a lighting system that makes you
visible from maybe half a block away for city use, or maybe 1/4 mile for other
use. Add some reflectors and you're in fine shape.

Years ago, I got spontaneous compliments from two different motorists about my
generator taillight (with an incandescent bulb), my 1990-something LED blinky
and some reflecting stuff.

- Frank Krygowski