For a lightweight option, an Ultrafire C3, Trustfire R5-A3 or a Uniquefire G10 with an XP-G R5 emitter will give you decent throw and flood - runtimes are good on AA but not so good on 14500 li-ions (its easy to carry 2 or 3 spare batteries though - I do) - (I use two C3's on my helmet) - if you want more output and a floodier beam again, go for a Fandyfire 2160 or a 501b with an XM-L T6 emitter, or for ultralightweight, something like a Xeno E03 XM-L T6.
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You can get the magicshine bike lights with a headband - I guess thats what you need.
http://www.alpkit.com/gamma
absolutely brilliant for the price. probably not bright enough for use on the bike though.