If you ride only occasionally at night, and typically less than an hour, there are a lot of excellent battery light systems available. If your night riding is mostly dusk and twilight, a small "be seen" light may be enough. My topic here is "see the road" lights for darker conditions. That said, good "see the road" lights are getting affordable enough that they make a lot of sense for commuting in low light conditions as well. Unless your budget is very limited and you very seldom need to ride at dusk, a fully functional headlight is a good investment.
Needs
Some of what follows is applicable to short rides, but mostly I want to address the problem of extended rides (from a couple of hours to all night) at normal speeds and in full darkness. For this, important attributes of a light system include:- Adequate run-time. This eliminates a lot of the lights designed for commuters, many of which can run only an hour or two at high, a few hours on low, and require a blinking mode for run times in the range of 10 hours or so. Blinking mode is not suitable for riding at normal speed, and it can be dangerous because an oncoming driver, blinded by the blink, may actually steer toward you. Say no to blinking.
- Adequate output. This is trickier to judge than it should be, because of inconsistent and sometimes inappropriate ways of measuring light output. Fortunately, LED lights have improved so markedly over the last several years that it is not that hard to find lights with adequate output.
- Beam shape. Cheap headlights throw light in a cone. The best lights shape the beam so that light is used in the most effective way on the road, while also keeping it below eye level of oncoming vehicles and pedestrians. A well-shaped beam is more important than raw light output.
Front and Back
Of course you need a tail light as well as a head light, and I'll have more to say about that below. But the head light is most critical, for a few reasons. First, perfectly adequate battery tail lights, with run times of at least ten or twelve hours on a set of batteries, are easy to find at your local bike shop, while quality head lights are more difficult to find. It's quite common to use a decent, moderately priced battery tail light in combination with a much more expensive lighting system for the front. Second, while automobile-bicycle crashes from behind do happen, they are not as dominant as many imagine. A lot of crashes are from oncoming cars turning or from cars turning at an intersection without noticing a cyclist (because the driver is watching for cars, not cyclists), and a good headlight makes a very dramatic difference in making a bicycle visible from ahead. So, let's consider head lights first, and then consider tail light alternatives.
Batteries or dynamo?
The first decision you need to make is whether to power your headlight with a hub dynamo or with batteries. If you ride at night only occasionally, a battery powered light is economical, and adds weight to your bicycle only when it is attached; you can leave it at home when you know you won't be riding in the dark. But if you plan an all-night ride, or a ride that goes several hours into darkness, then finding battery powered lights with adequate run time can be a challenge. One simple solution is just to use more than one. I have seen randonneurs mount two or even four battery powered headlights to their handlebar, and simply turn on the second (or third, or fourth) when the first fades. You could also use a single headlight mount and have multiple headlights to attach to it. Again, this seems like a pretty reasonable approach if you ride only occasionally in the dark.
Dynamo wheels
I have a strong preference for lights powered by a hub dynamo, even for commuting. For one thing, I never have to worry about whether I remembered to charge the batteries before a ride. I never have to worry about run time, because the lights run as long as I ride, whether that's an hour or twelve hours. A multi-day and multi-night ride is not a problem. (Well, at least it's not a lighting problem.) And I can use the headlight also during the day to make myself more visible to drivers.
Several years ago, there were really only two choices for hub dynamos. The German company Schmidt made the Mercedes of dynamos, and the SON (Schmidt's Own Nabendynamo) was the overwhelming choice for riders who wanted low drag on timed events. Shimano made inexpensive, durable dynamo hubs with considerably more drag and weight, suitable for commuting. Sanyo also made a really terrible dynamo hub, suitable for approximately nothing.
But times have changed! Schmidt still makes really excellent dynamo hubs, and they are still the best you can get if your budget allows it, but you can do very well with less expensive hubs. Modern Shimano dynamo hubs are very good, and would be a reasonable budget choice even for an event bike (but be careful to get the 3 watt versions and not the 1.5 watt version). And there is a new player on the block: Shutter Precision is making high quality dynamo hubs at about half the cost of Schmidt dynohubs. The Shutter Precision hubs are too new for a judgment of long-term durability, but they appear to be the equal of Schmidt in efficiency, and increasingly I see them on event bikes. I use Schmidt on my event bike and Shimano on my commuter, and I'm very happy with both. I haven't used a Shutter Precision hub yet, but it might well be my choice if I were putting together a randonneuse on a budget.
You might be able to find a pre-built wheel with a suitable hub dynamo. If you build your own wheels, you could order a hub and build with a dynamo hub just like any other hub. But for most of us, provisioning a dynamo hub means having a wheel built at your local bicycle shop. That's a good way of ensuring a quality wheel with an appropriate combination of hub, spokes, and rim in any case. I've had dynamo wheels built at three different shops in Eugene (as well as one by a custom bicycle builder) and in every case I've been happy with them. Quality wheels appropriate to your bicycle and style of riding is one more reason to cultivate a good relationship with your local bicycle shop.
Dynamo headlights
Shaping the beam
The best dynamo headlights use mirrors to shape the beam. A well-shaped beam spreads the light in a rectangle or keystone shape on the road ahead, applying more light toward the far end so that it appears uniformly bright. It throws a minimum of light upward, so that it is possible to pass an oncoming pedestrian on a bike path with a very strong beam and yet not blind the pedestrian. (Really, I see their chests lit up and their faces in darkness.) Because they focus the light on where it is most needed, they are effectively much brighter than a light with a higher wattage and/or lumens rating.At present, all the LED lights I know with really excellent mirror-shaped beams are built in Germany by Busch and Müller. Schmidt also makes an excellent light, the Edelux 2, but that's thanks to using Busch and Müller bulb and mirrors. In time we may see equally good lights from other makers, but for now, if you invest in dynamo lighting, you really should get a B&M headlight or the Edelux.
At the high end, the B&M Luxos U offers USB charging, a cache battery to ensure a long steady stand-light, a gorgeous and very wide beam for an exceptional view of the road even at speed, and the size and style of a black grapefruit. Really, it's big and ugly. But I love mine. Caveat if you are thinking of charging your Garmin directly from the Luxos' USB outlet: It may cut out occasionally when you are slow, as when climbing a steep hill with the headlight on, and the Garmin's firmware will shut off if you can't push the "no goddammit don't do that" button on the screen within 15 seconds. They call that a feature.
The Edelux 2 has a very similar beam to the Luxos U (remember, they're using B&M mirrors), is gorgeous in its machined metal case, and is much smaller. It's an excellent choice if you either don't need the USB charging or choose to provide it with a different current converter (of which several are now available). (Aside: All dynohubs provide alternating current (AC), and USB requires direct current (DC), hence the need for conversion.)
Bot the Luxos and Edelux are pricey, and although lighter than the Luxos, even the Edelux might be more weight than some people would want on their bikes. B&M makes several other headlights with different prices and features. Among them, the Eyc is very small and light, relatively inexpensive at about $75, and throws a very good beam (although not as good as the Luxos). Peter White Cycles in New Hampshire maintains a good comparison of B&M lights; if you buy from your local bike shop (which you should), it is likely that they will order from Peter or from Compass Cycles in Seattle.
One reason to obtain your light from a local bike shop is that mounting is often a bit tricky. Ideally a headlight should be mounted at the fork crown or on a front rack. Mounting on the handlebars, or lower on the fork, will compromise the beam shape and direction. If you're handy, and lucky, mounting may go very smoothly, but my experience so far has been that the mounting hardware provided with the light is often not quite what you need. Three of my personal bikes have dynamo lights, and each of them has a substitute or custom-fabricated mount, because the stock mount didn't work. You might be good at trouble-shooting problems like that and finding the right replacement piece from your vast collection of bicycle parts, but I'm not, and I'm glad to have had competent mechanics take care of it for me.
The Tail Light
Battery-powered tail lights are very good, and might be all you need. But if you run a dynamo-powered headlight, at least consider running a dynamo-powered tail light along with it. One advantage of running a dynamo-powered tail light is that, as with the headlight, you never have to think about whether your battery is low, because it's just not. Also, although battery powered tail lights are very good and can be as bright as you need, some dynamo tail lights are even better, and they are not nearly as costly as a good head light. I am currently using a Pixeo on my randonneuse, but if I were outfitting a bike with dynamo lighting today, I would choose the Secula Plus from B&M. It is small but very bright, and the combination of light and reflectors makes it very visible from a distance. It can be mounted on a fender or seat-stay.The main disadvantage of a wired tail light is the wire. It runs from the head-light to the tail light. It's not terrible, but it's one more wire/cable/thingy running along your frame. If some of your cables are internally routed, the electrical wire might be the one thing you can't route inside the frame. For a tail light mounted on the seat-stay (on the left, to be most visible to drivers), consider running the cable along the down tube and chain stay. For a tail light mounted on a rear rack, along the top tube and then the rack is pretty much the only reasonable approach. If you are having a custom bike built, you may want to run electrical cables internally even if your brake and derailleur cables are external.
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