As winter bike commuter, I'm always on the look out for something that will increase side visibility. I have strobe light for my arm, but that covers just one side and is uncomfortable. I've tried various gadgets that go on the wheels, but rotating weight is the worst kind of weight to lug around town. WWW.BikeGlow.com is very bright. In strobe mode there is no excuse for anyone missing you. It is a simple, light weight string that wraps around the frame. Cars entering intersections see you long before their headlights would pick up a reflector. I can not more highly recommend this product for those of us that commute before day light.
Light & Motion
I have used Light and Motion (L&M) http://www.bikelights.com/ products for years. All their batteries work with all their light heads. There are a couple of exceptions for older products but this is true of the current product line. What this meant was that once I bought into the system I was hooked. I have a variety of light heads and several batteries. I mostly have them because I often invite others to go night biking with me and they don't have lights so I have to provide them or pass on the company.
Most of the current products use Li-ion batteries. This is a good chemistry for winter biking use because it works well when cold. If you really cold soak the batteries by leaving them on the bike when it is sub-zero they will not deliver power for long but if you start out with them warm and keep the battery in your pocket they work well in even in sub-zero temperatures. DO NOT recharge a cold Li-ion battery! Allow them to fully warm up to room temperature before charging. Li-ion batteries require a smart charger and the one that L&M supplies is an excellent one. It will also charge their NiMH batteries if you have one.
In this review I will discuss the Stella 200L and the Seca 400. Although I have other light heads, these are the two that I own that are still in production.
The Stella 200L is a good commuter light. It has a fairly tight beam pattern that makes very good use of the 200lm (lumen) light output. L&M claims 5hrs of run time with the 3 cell Li-ion battery. I really don't know as I have never run the battery out. The Stella is small and light and makes a very good helmet mounted light. Helmet mounting helps to compensate for the tight beam pattern as it allows you to aim the light where needed. This was my favorite commuter light until I got the Seca 400.
As you might have guessed from the name, the Seca 400 light head produces 400lm of light output. The Seca has a wider beam pattern that makes it more suitable for bar mounting than the Stella and with the extra light power the wider beam is still very bright. It is larger than the Stella but still light weight and I also use this as helmet mounted light. I find that a bright helmet mounted light really grabs the attention of inattentive motorists. Just point it in their face and they know you are there. It not a nice thing to do but its better than getting hit. L&M claims 2.5hr on the high setting and that seems about right.
Both are excellent commuter lights but if money is a constraint the Stella would be your choice.
B&M IQ Cyo generator light
See the review on a separate page.