Soon after I started planning for my Y2K bike trip to France I decided to get a bike light to help me through the unlit tunnels which one encounters on the mountain roads of Europe. As a rider who does everything I can to keep my bike light, my body lean and to keep both of them as free of extraneous accoutrements as possible getting a bike light just to get me through the occasional unlit tunnel was a hard decision but I decided to bite the bullet; I knew I just needed some help getting through those god damn things.
Now the hard part came - finding a light that was both bright enough to light the near pitch blackness and yet lightweight enough so that it didn't significantly increase the diesel truck factor. 1
The last time I went to Europe, my 1996 trip to the Italian Cycling Center, I'd gotten a self-contained CatEye light that mounted on the handlerbars. It wasn't too heavy and the batteries were small and inside the unit which dismounted easily. The problem was that it didn't do anything. Well that's being unkind. It simply wasn't bright enough to deal with the near total blackness inside one of these tunnels.
Unfortunately I was looking for characteristics that tend to preclude each other. Specifically a light that is both bright and lightweight. Generally, lightweight lights share the same disadvantages of the CatEye one I already had tried - their bulbs have low wattage which is all their feeble batteries can power. Bright light systems, on the other hand, feature powerful bulbs but also heavy batteries needed for sufficient burn times.
Enter the Digital Head Trip by NiteRider. This light is the closest thing to the perfect unlit tunnel light. It has a three way bulb with wattages (changeable on the fly) of 6, 10 and 15 watts. The light itself is mounted to the helmet which allows one to illuminate whatever one needs to regardless of the direction of the bike. Just turn your head and you can see where the tunnel wall is (or read that road sign).
These features are nice but they are also garden variety for high end bicycle lighting systems. The battery is the key to this product's success in the unlit tunnel application. The Nickel Metal Hyride battery is the size of a deck of cards and that makes the whole system weigh in at one pound - considerably less than the cubersome competition. The battery's small size also allows you to put it in your jersey pocket which I found nice. Some, however, might say this is a bug rather than a feature since on long bike rides over mountain passes you need to preserve pocket real estate for food, a jacket, maps, etc. but the battery has to go somewhere and I found this solution satisfactory.
The bulb that I used for my trip was a special wide angle bulb which I bought separately. I found that it lit up even the blackest of tunnels sufficiently for me to get through. The "spot" bulb that the light came with has the same three-way wattage (6, 10 and 15 watts) but I didn't try it except in a test in a dark room at home before I left just to see what difference I could perceive between the two bulbs. They seemed real close but I decided to go with the wide-angle although the spot bulb may have proven the equal of the wide-angle or even better in practical use. I had thought if I had the time I might try both - in a side-by-side taste test so to speak. Ride through a tunnel with one, change the bulb and ride through again. Never got around to it though.
I had a back and forth email dialog with a member of the tech support staff at NiteRider and found the fellow to be very friendly and well informed too. He was the one who recommended the wide angle bulb which he said he had in his own light. I suggested to him that NiteRider create a special light just for the unlit tunnel application. "Call it the P.L.T. (Pour Les Tunnels).", I suggested. :^). It would require significantly less burn time which I would think would allow an even smaller battery. A battery half the size would give more than enough burn time, even at maximum wattage, since one doesn't actually spend that much time in the tunnels and most of the time the light is dead weight. He was open to the idea but my impression was that he felt this would be too small a niche. Oh well.
The worst tunnel I encountered on my Y2K trip was one that rates a Hors Categorie in the world of unlit tunnels. It was on the D219 on the climb from Bourg d'Oisans to Villard-Notre-Dame. The light performed quite well there and I'm very happy with it. For more babbling about the light's performance click here.
1 Contributing to the slow transformation of a light racing machine into a diesel truck by the incremental addition of extraneous accoutrements and baggage. ;^)