Originally Posted by
noglider
This is nearly perfect. You could tape over the light sensor so it always thinks it is dark, so it would rely only on the motion sensor. The trouble is that it's a tail light, and OP (@bmeehan1966) is asking for a headlight. I'd love to know if this exists.
I had the same thought, and interestingly, it looks like they do:
TL-LD570-F | CATEYE
From the page:
The Reflex Auto will automatically turn on whenever both darkness and motion are detected by the motion and light optic sensors. No more stopping on the bike path to double check that you’ve turned your safety light on – it’s automatic!
They also list what looks like an older 560 model which does not list out having any sort of automatic on/off (570 mentions it, 560 does not).
Interesting...