There seems to be a lot of confusion between light output and watts here they are in no way the same thing. Watts control how fast your batteries run down and lumens control how much you can see, well roughly obviously I’m assuming the same battery size and a good reflector.

LED’s currently in use (luxeons) will produce about 25 Lumen/w
Small (10-20w) Hids will do 50 Lumen/w
Halogen will do 5-40 Lumen/w

Witch is where the confusion stars and why people have such differing opinion, incandesant lights (lights that make light with a bit of glowing wire) like halogen have several factors that effect the efficiency, fist the wattage the higher the wattage the more efficient doubling the watts will roughly increase efficiency by 20-40%, secondly the physical size of the bulb an mr16 halogen bulb will be twice as efficient as an mr11 halogen at the same wattage (mr 11 is a very common bulb in bike lights mr16 is bigger and is used in some bikes is also used in buildings at a high voltage)

So the important question is is a halogen better that an LED
Well a typical mr11 10w halogen will produce 190 lumen and 2 5w LED 240 lumen

So LED’s are just staring to compete of this front but there so much more expensive but as you get bigger halogens for off road work like a mr16 20w your LED is noticeably less efficient and much more expensive not to mention you would need 4 of the to reach a comparable wattage and 6 to reach the same light output so is just not worth having.

But again if we go smaller so for riding on a road a 6 w halogen will produce about 80 lumens and a 5w led 120 so the LED is staring to beet the halogen by almost 50% hear, and as you get down to 2w and 1w halogens you can produce the same amount of light with half or a quarter the wattage LED’s

So which is better really is decided by how much light you use. I got the figure I used of the web but I don’t think halogens are changing much though LED’s are I used the 25lm/w because that’s luxeon led/s achieve witch is what lights are using at the moment but if you go to specialist LED websites like this http://www.ultraleds.co.uk/product_i...533cdc1ec083af
You can get LEDs witch will produce 50lm/w ich is actually about the same as a HID but again these are only 1w at the moment so you would 3-4 to rival a 10w halogen.

If you made it to the end of this well done I hope people understand things better I know I don’t tell you what to buy but remember that LED’s are no more efficient than a 10w halogen and much more expensive but anything less than a 10w halogen and they start beating them hands down, but keep an eye on those LED’s give then a year or 2 and they will be rivalling HID’s as well as large halogens.