Originally Posted by TrojanHorse

Well, I have a few reasons - I do have a magicshine light I use at night and some of those chinese flashlights, so I'll hook those up when I ride at night, if they're charged (which is occasionally a problem!). I don't know how long the extension cord is on that model you linked, but my magic shine isn't long enough for the battery pack to reach my jersey pockets, and now I have a wire flipping around and hitting me in the head. So there's that. It's cheap enough that I may just buy it anyway and try it out. It would make a splendid additional light for the handlebar even if it doesn't work for my noggin.

My intent is to augment my regular lights - I hate it when it's dark and my main light is blinking but since blinking is easier to see, I want my "to be seen" light blinking. I could absolutely see using one of these on my helmet in blinky mode (or solid with the one on the bars in blinky mode) and I'm a fan of having more than one light so I may just go get one of these anyway and see what's up. I've also convinced myself that the extra elevation from that dude's helmet lights contributed to making him easier to see - I certainly noticed him.