Bike commuters have more choices than ever when it comes to bike lighting. The possibilities include: headlights with multiple low-output LEDs that are powered by standard AAA or AA batteries (such as the Cateye EL-220); headlights with a single high-output LED that are either powered by rechargeable internal NiMH batteries or a separate NiMH or Li-Ion battery pack (such as the L&M Vega); headlights with multiple high output LEDs that are almost always powered by a high capacity Li-Ion battery pack (such as the NiteRider TriNewt); integrated generator systems; and high output LED flashlights and headlamps repurposed as bike lights. There are still a few halogen and HID headlights on the market, but with LEDs becoming more efficient and cheaper all the time, lights other than LEDs are on the way out.

I’ve recommended generator systems in the past and I still feel that a high-quality hub generator system is the ultimate for commuters that ride in the dark on a daily basis. You can’t beat a SON hub combined with a high-quality LED headlight such as the B&M IQ Fly or the Schmidt Edelux. The downside to such systems is that they are quite expensive (they can run upwards of $700) and for the most part they need to be dedicated to one bike because a wheel has to be hand-built around the generator hub. For some, the convenience is worth the expense, though others may balk at a $500-$700 lighting system, particularly if it’s to be used on an inexpensive commuter bike.

Battery-powered systems with multiple high-output LEDs are the brightest, but they’re arguably overkill for commuting. Most were designed specifically for endurance racing and, like generator systems, they can be quite expensive ($350-$1000). Again, many people will balk at a headlight that costs more than their bike, particularly because a compact LED system can so easily be stolen.

I’m guessing most people would agree that lights in the $25-$200 price range are more realistic for commuting. There are many lights on the market in this price range (far too many to cover here), and generally, the more you pay, the more you get in performance. Surprisingly, some of the best values are found in high-performance LED flashlights, not bike-specific headlights.

Fenix L2D
The Fenix L2D LED flashlight is commonly recommended for use as a bike light. I first heard about it over at the CandlePower Forums. (For the uninitiated, the CandlePower Forums are the equivalent of our BikeForums, but for flashlight fanatics.) After hearing so many people at the forum recommend the L2D as a bike light, I decided to pick one up for myself to see what all the fuss is about.

The L2D is available in a few different configurations; I ordered what is called the “L2D CE Premium Q5″ with a smooth reflector. The specifications are as follows:

• Price: $59.50
• Emitter: Lifetime Cree 7090 XR-E LED
• Max Output: 180 lumens @ 2.4 hours
• Batteries: 2/1.5V AA (alkaline, NiMH, or lithium)
• Body: Hard-anodized aluminum
• Waterproofing: IPX-8 standard
• Lens: Optical glass

The L2D has 6 output levels: 4 in standard mode (3 levels and 1 strobe) and 2 in turbo mode (1 steady and 1 strobe). Twisting the light head changes the light from standard to turbo mode. Within each mode, the different output levels are accessed by a button on the back of the light. The same button also serves as the on/off switch. I suspect most people will use the brighter turbo mode for commuting. The flashlight instructions warn against running in turbo mode for over 10 minutes at a time for fear of overheating, but from all reports this is not an issue, particularly on a bicycle where the airflow will keep the light sufficiently cool.

On the highest setting, the L2D’s output is 180 lumens with a runtime of 2.4 hours (over twice the output of the popular L&M Vega). On the next highest setting, the output is 107 lumens with a runtime of 4 hours. The fact that this little flashlight puts out 180 lumens for over two hours on only 2 AA batteries is nothing short of amazing.

B&M Ixon, L&M Vega, Fenix L2D

The L2D’s beam pattern is circular with a marked bright spot in the center that fades out quickly toward the edges. This is typical of most LED flashlights and bike lights manufactured for the U.S. market. I prefer a more controlled Euro-style beam (see above left), but there’s currently nothing coming out of Europe that comes close to the L2D at this price.

The light body is nicely machined and is plenty waterproof for cycling. Officially it’s consider “water-resistant” or “dunkable” which is more than enough for bike commuting in the rain.

Mounting the L2D requires an accessory mount of some sort. The Twofish Lockblock is a simple, effective, and inexpensive mount that can be clamped onto a handlebar or any other tube that would normally be used for mounting a headlight. For a mounting position other than the handlebar, a Lockblock used in conjunction with a Terracycle Accessory Mount should make it possible to mount an L2D almost anywhere on a bike.

Since most people will want to run the L2D in turbo mode, I highly recommend rechargeable NiMH batteries over disposable alkalines. I have a couple dozen rechargeable NiMH batteries that I use for my LED headlights and tail lights, cameras, wireless keyboards, wireless mice, and whatever else requires a AA battery in the household, and I was able to drop the L2D into the charging rotation without purchasing more batteries.

Conclusion
The Fenix L2D is widely regarded as the best high-performance LED flashlight in its price range. It uses a high-end Cree emitter that produces an output of 180 lumens for 2.4 hours on 2 AA batteries, all housed in a lightweight, but tough, water-resistant body. At under $60 it is probably the best value on the market in a bike light. The fact that it’s marketed as a “flashlight” should not discourage anyone from considering it for use as a serious headlight for bike commuting.