If your gonna ride a bike full time lights are going to be necessary, eventually. Finding a suitable light has been much more difficult than finding tires and other equipment. It’s complicated, initially, by differences in specific information about brightness. Watts versus lumens is at the center of the problem. Lumens describe the amount of visible light generated than does watts which relates more to power consumption. Lumens, therefore is more useful in determining which light will be more useful. Unfortunately, many manufacturers use watts in their information making comparisons difficult if not impossible. Certainly, more wattage suggests a brighter bulb, but not necessarily. The most useful reviews are the ones providing actual images of lighting capability, thereby making comparisons possible.
I looked at the light comparison in a 2009 edition of Bicycle Times magazine (http://www.bicycletimesmag.com/node/80249). It provided descriptions, technical information and images showing light patterns and intensity. Price was the deciding factor and I purchased an ungraded (better) light I chose a Princeton Tec EOS to replace an inadequate, vintage light.
At the time of the review in Bicycle Times light output was 50 lumens. When I purchased the EOS it had been raised to 70 lumens and that has been upped to 80 lumens in its current form. Other reviews identified it as a good “be seen” light and it has served well for the two years I have used it. As a helmet mounted light it works very well and adds no noticeable burden. Because I anticipated needing a good light if I toured I chose a light using batteries (three AAA) rather than a rechargeable light assuming recharging might pose a problem on the road. Among the nice things about the EOS is that it came with accessories to permit handlebar, helmet and head mounting. Costing about $40 (with shipping from BrightGuy) I have no complaints about its utilitarian qualities. The EOS is a satisfactory commuting light because most of my nighttime riding is on roads with which I have familiarity. Lighting is needed to show unexpected obstacles more than to actually light the way. At its brightest setting the EOS works very well for my short single track section where speed is greatly reduced. On unfamiliar roads it would be adequate but I would plan to ride at or below 10 mph. Because I commonly use the middle or lowest setting on well lighted urban streets and I do not do a lot of night riding batteries last a month of more.
I supplement the EOS with a tiny flashing light made by Nite Ize (http://www.niteize.com/product/BugLit.asp) called Buglite which is a micro LED flashlight. The flexible legs allow it to be fastened on handlebars, stays, bags or many other places. Its very bright light is hard to miss. Had I needed illumination while touring the EOS would have sufficed. One of the potential issues around here is the attitude of some police officers who have stopped riders because they were using only a flashing white light. The officers insist that the flashing light "distracts drivers." If distracting means a rider is noticed it's a good thing. Could "distract" mean something else?
I have had more reasons to ride at night since returning from my aborted tour and recognize reasons why more and better lighting is valuable. All of the things that Make Cars Dangerous exist after dark and inattention is compounded. Being seen and being able to see are good concepts! In my search for better information I found a test conducted by Road,CC, an English website; “The big road.cc lights test 2012”. Its method for depicting lighting quality is unlike any I have seen and the information they provide for a myriad of lights is complete. Some of the products are unavailable here in the Colonies, but most are. Pricing is in Pounds Sterling, but that’s fine for making relative comparisons prior to seeking local sources and costs. I won’t try to explain their images suggesting only that seeing it is worth the minimal effort required.
The result of recent lighting study has me leaning toward something from Nite Rider, specifically in their Mako series. Where the EOS is waterproof, the Nite Rider products are only water resistant. Since I do not intended to dive with my bikes this should not be a serious limitation My decision will be based on the usual combination of usefulness and cost and if anyone is interested my opinions and observations will appear here.