might be too late
but if you get some ultrafire WF-606A’s from dealextreme or kaidomain they’re more than 3W easily, and match my 150 lumen fenix with no trouble. a couple of those strapped to a crash helmet is plenty of light, with the added bonus that they take rechargeable AA’s, so if you’re stuck you can get some duracells from the nearest petrol station.
£30 or so, incl. batteries and charger and you’ll get a 2hour run time for about 300lumen. More batteries, and swap them over on the relay thing, and you’ve light for as long as you want it.