wow.. tall order.. without going into something really big on your handle bars, your options are limited.. and at 900 lumens any small light will die out quick, unless you wire it to a larger power source or maybe your peddling. tho i do have a 700 lumen recommendation, if youre interested, this 3 inch long flashlight can put out 700 lumens, and has a 100% output, 30% output, and 2% output mode. im currently ordering one, and waiting for it to ship
Tri-EDC
link
http://macscustoms.com/TriEDC.aspx
tho if youre seriously looking for a beast bike light, heres a 1400 lumen specially made to be a bike light
http://www.bikelights.com/seca1400.html
i will keep an eye on this thread tho, as im looking for something similar, and have yet to find anything suitable