I highly recommend the Light & Motion for a helmet mount.
http://www.artscyclery.com/descpage-LMURB800AS.html?gclid=CIrlqabX-cgCFcISHwodeMUM9w
I ran the Night Rider and it was fine but always felt top heavy. The L&M is 50+ grams lighter & sits lower on the helmet. Almost can't tell it's up there. Same price (if purchased online but I suggest supporting your local shop ) , same run times & slightly brighter. Super happy with it.
http://www.artscyclery.com/descpage-LMURB800AS.html?gclid=CIrlqabX-cgCFcISHwodeMUM9w
I ran the Night Rider and it was fine but always felt top heavy. The L&M is 50+ grams lighter & sits lower on the helmet. Almost can't tell it's up there. Same price (if purchased online but I suggest supporting your local shop ) , same run times & slightly brighter. Super happy with it.