Where does the time go?
Two years ago, I bought a Light and Motion ARC Light, an HID bar-mounted headlight. I paid about $370, I think. I posted a review here:
http://www.bikeforums.net/showthread.php?t=16381
I thought it might be useful to say a few things about the light now, Popular-Mechanics style, after two years of use.
Just to save labor, I won't repeat much of the baseline performance specs on the light. That information is in great detail in the original thread. Some things I'll have to say, though, to make the time comparisons clearer.
I've had the light for almost exactly two years. Conservatively, I must have used it over two hundred and fifty different nights, though I haven't kept count. I probably average an hour or so per use of the light. I take some longer rides, but when I first got the light I would use it for short trips in town, too. (I don't bother with that now, and use a smaller light for trips on lit streets in town.) I still use the original bulb and housing, and the original battery.
The battery, new, promised 3.5 hours of run time at lower power, and 3 hours at high power.
As of a month or two ago, the battery on high power lasted about 2:45. I've not tested the battery for endurance on lower power, but extrapolating from the high power endurance seems reasonable.
The light's brightness is still intense. I should have taken photographs when I bought it, to compare to now. I suspect the light is not quite as bright as it was when I bought it, but I can't tell for sure.
The light still mostly starts right up, with no problems. If anything, it's more reliable now than when I got it. When the battery is low, and it's cold out, I sometimes have to try to start it more than once.
Like all HID lights, the light doesn't come to full brightness for a while, about a half minute. That delay hasn't increased noticeably since I've owned the light.
These endurance statistics are probably the most important things to report. I recall that two years ago there were some concerns about whether HID lights would last long enough to justify their expense. So far, so good.
There is ample light to travel at daytime speeds on completely dark roads. Pebbles, twigs, road kill, and even oil slicks don't surprise me.
I have to remember it wasn't always this way. I was out riding tonight, and I wondered to myself how I ever traveled on these dark, lonely roads with my old 20w halogen system. I'd never go back.
As far as traffic is concerned, there has not been a single incident in two years during which a car coming head on has behaved as if the driver hasn't seen me. If anything, there has been a lot more drama, as the intensity of the light and its odd height puzzle drivers and often cause them to slow to pass in the opposite direction on otherwise empty roads. I highly recommend the light for busy roads in darkness, though you may want to point the light a bit lower than you would do on a deserted road.
The charging is now slower than when I bought the light. Two hours of use requires significantly more than two hours of charging time, probably around three hours. That's still quick, especially compared to the lights I used to have. Nevertheless, when new the ratio of use to charge was about one to one. I've never fried the battery on the charger, and I've never let the battery sit for weeks and go completely dead, either.
If I were looking for a new headlight today, I would certainly buy another HID light. Whether I would buy a Light and Motion, I don't know.
Light and Motion is a good company. When I lost a screw, they just sent me one, no charge. I haven't bought any replacement parts, but their prices are reasonable. They still back support lights from 2002 now, with replacement batteries. The few times I contacted them with questions, they got back to me.
But now, two years later, there are more lights available, so I'd do some more research.
The light I bought has a compact water bottle battery, since displaced at Light and Motion's high end by a very small Ion battery that attaches to the top tube. This is a sensible improvement. I usually use a Camelback when I ride, but it would be nice to have the water bottle cage free. So, if I did get another ARC light, I would get the Ion version of the battery, to be sure.
All of the moving parts still work well, and haven't required any adjustment after some initial tinkering around. The light turns easily left and right, but remains in place over bumps and dips in the road. The bar mount moves easily up and down, too, and comes readily off of one bike to be used on another. There is now a helmet mount for this light, but as I don't always wear a helmet, I haven't bought the helmet mount. I like the shadows from the bar light, anyway.
The small size, light weight, and convenience of the ARC light compared to equally bright halogen systems are great advantages, in my view. I've become even more convinced of this over time.
One thing I would recommend to any user of this or a similar light is to keep a smaller light around. This would be for taking short rides on lit streets. The new LED lights are a good set for this purpose. You don't really need the HID power on well lit streets with light traffic. (On dark streets, or on streets with heavy traffic on which you might get lost in the glare, HID are a good idea.)