Originally Posted by
steelbikeguy
the mis-match between the LED's radiation pattern and that of the incandescent is definitely an issue. You'd get better results by aiming the LED rearwards at the reflector than aiming it forward, where only a small percentage of the light will strike the reflector.
The Reflectalite uses a 'side emitting" optic, which aims most light to the sides. This does use some of the reflector, which forms the light into a beam. I used an early Luxeon 5 watt LED with the reflector from a Union headlight back when the Schmidt hub dynamo first came out. It was an improvement over the incandescent dynamo lights of the era! However, using a more modern LED with a good molded "TIR" optic produces much better results.
The other issue with installing a proper 3 watt LED is providing cooling for the LED. In a perfect world, you would provide some aluminum to conduct the heat from the LED to an external heatsink. Adding an external heatsink to a vintage or retro headlight is often not an option. A second option would be to conduct the heat from the LED to the steel housing of the light. It's not optimal, but might be good enough.
The Reflectalite avoids this issue by only using about 1 watt of power. With a 3 watt dynamo, that would be a waste. With a Dynohub that is also trying to power a taillight, it might be perfect.
Steve in Peoria
Cool, I'll look into it again. May also need to see about re-silvering the reflectors on both of my antique headlights.