I'm trying to determine the relative suitability of LED, Xenon,
halogen and krypton bulbs for use in cycle headlights for use on unlit
roads. I hear people say that LEDs are the most efficient, but I also
hear people say that it's difficult to focus them into a long enough
beam for use on dark roads. I hear people say that Halogen lamps are
more suitable because they give longer beams, but are not as
efficient. I hear people say that krypton bulbs are better, and I hear
people say that xenon bulbs are better still. Anyone agree?

What I want, personally,  is a front light that is *inexpensive* and
will give a long and sufficiently wide, bright beam for 2-3 hours on 2
or 4 rechargeable NimH 'AA' batteries - and isn't likely to blow its
bulbs. Is that feasable? Which of the above bulb types is most likely
to be in such a lamp?

Thanks...

Jim D