I use a Fenix LD20 as a helmet light; it cost about $60. It runs on rechargeable AA batteries and puts out 180 lumens on high, although I usually run it on the 105 lumens or less. I also have a Magicshine LED light on my handlebars, but they can be mounted on helmets as well. It is much brighter than the Fenix but also heavier and bulkier. It cost about $80.