Join Date: Jul 2005
Location: Dutchess County, NY
Bikes: Fuji S-12s, Trek Navigator 200, Dahon Vitesse D7, Raleigh Sprite Touring ('70's)
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
This may be way more than you want to know, but a lot seems to depend on what you want to spend, as well as how much you want to fuss. I have been looking at commercially available units, as well as toying with building my own.
Incandescent is still the cheapest way to go, with parts readily available. Self contained units with 'flashlight' style bulbs in separate reflectors may run up to 5 watts, and put out up to 75 lumens with a hot center spot, and a lot of scatter.
Prefocused halogens, like MR11 assemblies come in 5, 10 and 20 watt styles, with output up to 400 lumens in narrow spot (10 degree) or wide flood versions. That is an efficiency of up to 20 lumens per watt. Because of the increased juice required, the batteries are either in a water bottle, or a separate pouch, connected to the head by a wire. The very best halogens I have seen are good for maybe 25 L/w, but they were in wattages way higher than you will use on a bike.
HID lights better (maybe 25-30 L/w ?), but are very expensive (and maybe somewhat delicate).
LED is really the next generation in lighting. Obtaining comparative values is somewhat difficult as you need to carefully crawl thru spec sheets and work voltage, current and emission angle. New products have already broken the 50 L/w barrier, and prices are falling rapidly. The auto industry is on the threshold of going LED headlamps, and I think there are going to be some great new bike products on the market soon.