As part of your research, you could check the pages on my site as linked in the signature line of my post, and you can also look at this thread:
Dual Fenix L2D 100 Premium Headlight Setup (Photos)
And there are quite a few other threads in this forum about using flashlights as bike headlights, as
dekindy indicated. You won't have to search very hard to find a lot on the topic.