I use a Princeton Tec "EOS-Bike" on my helmet. That is in addition to my primary handle-bar mounted lights. The helmet lamp serves several purposes. First, it can serve as a back up to my bar mounted light. Since it's not as bright, I would have to ride slower, but it is workable. I should know, I had to do it once. Additionally, I can look into turns, read cue sheets, look at road signs, and on the rare occasion I get them, fix a flat(or my bike) in the dark.