Summary: One cyclist's approach to being seen at night.
I have used many devices over the years, since I commuted for about 20 years and still ride a lot at night. I started with white bicycles, then tried 3M's glass bead reflective paint. It looked great under headlights but was dull otherwise. I am now using neon orange bikes, and may go to neon lime green. I think all of those approaches are improvements over a standard dark frame, since seeing a frame identifies the vehicle immediately as a bicycle, at least from the side and some other angles.
The concept you have to keep in mind is that you want to establish your identity as you catch the driver's eye so they know what you are. Motorcycle research shows that if you want to be seen on a motorcycle there is one thing that beats daytime headlights, orange vests, flags, big windshields or any other device -- be a cop! It turns out that drivers usually see a police motorcycle. We have asked motorcycle cops and they agreed, although there are exceptions. So you are not just trying to catch an eye. You are really trying to register on a driver's brain that you are a vehicle moving on the road, and establish that you are a bicycle so that the driver has some idea of what your speed and position on the roadway are likely to be. Often you are doing that in the midst of incredible urban light clutter from other vehicles, traffic signs, streetlights, commercial signage, porch lights, windows and many other sources.
For headlights I used a car light for years. Nothing makes a driver respond quicker, even in the midst of urban light clutter, since they are conditioned from childhood to look for oncoming cars, and at night that means they are looking for oncoming car lights. The little bike lights may be bright, but they look like a pinpoint, and can just get lost among all the other light sources in the background. Car lights have a cutoff beam that does not blind others on a trail, and puts the light on the roadway where you need it.
In 2010 the battery powering my car light failed once again and I bought a new Magicshine system. It is LED powered and uses a Soul P7 SSC LED with four led's on one die. The heat sinking is adequate, and it lights up the road. Unfortunately, it lights up a lot of other territory as well, and can blind people coming the other way if not adjusted carefully. On trails I push it downward or cover it when people approach. I use two if I am using them. The original batteries were recalled, and I have the new replacement. If this light had a shaped beam with a sharp cutoff above the pavement it would be ideal. Magicshine disappeared for a while, but they exhibited at Interbike in 2016, so they are coming back.
Always looking for a light that would not blind oncoming cars or riders I found the Philips LED handlebar-mounted lights, running on 4 AA rechargeable cells. They have the same cutoff beam, and with two of them I had light on the road that approximated a car. My current headlights are by Barry Beams (Oculus). They also have the cutoff beam, but have newer LEDs and rechargeable lithium batteries. Using lenses to shape the beam, they don't blind oncoming riders on a trail or cars on the street, and with two I have more light on the road than a car. I can see the road surface at night when it is raining and most of your headlight lumens get reflected ahead rather than back. There are jillions of bright lights on the market now, but only a few with the cutoff beam that meets the German DIN standard. Unfortunately, the Oculus lights heat up too much for summer use. At 80 degrees fahrenheit they cut back the light output, so I am back to the Philips lights for warm summer nights.
Batteries used to be a problem. The nicads to run my car light were heavy and required charging every night, but they were cheap from surplus sources. For years I used D cells from power packs for an NEC 386 laptop. Then I converted to NiMH batteries, and tried using C cells due to the higher energy of NiMH cells, but went back to D cells eventually because the C's just did not seem to hold up and lost capacity. I used 11 (NiMH)or 12 (NiCad) cells rather than ten to provide extra voltage and keep the light bright. Again, the cheap NiMH D cells did not hold up that well in daily use, and I had to charge that battery almost continuously to have it work. In the fall of 2006 I started using a 5.5AH Powerizer Lithium Ion / Polymer battery that weighs 18 oz (500gr), puts out 14.7 volts for a very bright headlight and may melt down some day the way lithium cells sometimes do when cell protection circuits fail. The vendor says "for R&D use only and NOT for individual customers." I charged it in my bike parking area and use it while riding outdoors, so that's a concern but seems like a reasonable risk similar to those that laptop users are running. I am looking for one in the safer LiFePO4 chemistry that self-extinguishes if a protection circuit fails. Fortunately with LED lights the batteries are no longer critical.
For tail lights I started with two "French leg lights," showing red to the rear and white to the front. Those had the advantage of going up and down, attracting attention and identifying the bike. But they are visible only on one side, so for a while I used two of them. I added yellow blinkers, starting with a 7 inch barricade light. Those are ideal for bikes, since they attract attention by the blink, have a big reflective band around them, and are identified in a car driver's mind with stationary objects on construction sites, so they grab a driver's attention. As with any blinking light, the blink saves a lot of electrical power, since the light is mostly off. The fresnel lens is very efficient, and the bulbs are designed to resist tremendous vibration from passing trucks. I run my 6 volt ones from a 9v alkaline cell or from NiMH AA or C cells. Their only disadvantage is the size and weight, but if you are still hung up on that you just have not ridden enough at night. There are LED versions available now at contractors' supply stores, or on a barricade near you.
After the barricade light I added smaller yellow blinkers. The best was something called the Far Out Flasher, sold by Schwinn stores in the 80's and by the late Ed Kearny (Bicycle Lighting Systems). The Belt Beacon was another, and I used those on my helmet, mounted with Velcro, juiced up by adding chrome tape to make a reflector behind the bulb. Yellow is still the best color for a flasher, since the population is aging, and red eyesight gets dim as eyes age.
I have tried turn signals, but never felt that they were really recognized by the motorist. The rack-mounted ones are too close together to give much of a directional indication. I tried one back in the 1980's that attached to my wrist and blinked only when the arm was raised, but you would need two of those, and again I had no way to know if the motorist behind me knew what the blinker represented or not, since they had probably never seen one before. That idea was revived in 2008 and updated with LED's by Safe Turn in Australia. They seem to have disappeared, but others have new ones out. Now there are helmet coming out with turn signals built in, controlled by a unit on the handlebar. Again I worry that a car won't know that it's anything but a simple blinker.
Beginning about 1990 I added the now-standard red LED blinkers, since they had taken over as the light signature of a bicycle and that increases the probability of being identified early as a bike. I had one on my helmet, mounted with hook-and-loop. Their only problem is that they are too small, and to a driver small means far away, so the car may not realize how close you are. There are some improved LED lights out now, that I first saw at the September, 1999, Interbike show, including a Vista that has "wings" with 15 LED's in the center and five in each adjustable wing. Vista also has a standard size tail light with multiple LED's that is very bright, but costs $60 and is designed to plug into their rechargeable system. At the same show I bought a very large LED flasher being test-marketed at a Chinese exporter's booth designed for use by cars as an emergency road flasher, and packaged as a "Highway Safety Light." It is 4" x 6", and has 18 extremely bright LED's in three rows. It's called the Fast Field Model HW-18, and it cost me $10, probably the dealer price. The light runs on 4 AA cells, with a claimed life of "at least 25 hours" which is about what I get from it. It looks like the biggest, brightest led flasher you have ever seen. But it had no bike mount, so I had to make one from aluminum bar stock. I have one now on all the bikes we ride at night. It is heavy for an led light, at 9 oz. with the batteries. It was hard to find at first, since they are imported in car parts channels, but our local Target had them for while, and now there are at several sources on the web. Not all of them are equal, and some are disappointingly dim. One decent one is probably the Real Light by Necessary Options. It even comes with brackets for mounting on a bicycle.
In December of 2001 I got an email from an importer who claims that his product is not only the bright version but has bike mounts. It is sold only through bike stores, so you have to go to your local LBS and hope they have them. I don't know how to tell you how to distinguish the high output ones from the low output ones, so you are on your own.
I replaced the incandescent blinking Far Out Flasher on my helmet with an Innova 24/7 led blinker. This is an octagonal light about 2" by 3" (50mm by 75mm) that velcros on well. It runs on a CR123 lithium primary cell. It is not approved for lithium rechargeables, but could run on two NiMH 1/5 AA cells. The CR123's are expensive in stores but cheap on the web, and one lasts me for many night rides. The light has a rectangular LED area with a rotating switch that selects different blink patterns and colors of LEDs. I use the one that flashes rapid red then white then yellow and looks vaguely like a police car flasher. But then I saw the Serfas Orion and fell in love. It's elongated to provide more than a single point of light, and it has screaming modes that are probably as bright as I will ever use. It's USB rechargeable. And not cheap.
I got a sample at Interbike of a single yellow led that screws onto a shraeder valve and goes around. It uses hearing aid batteries. Another one introduced in 2002 has flashier led blinkers, but they are smaller. Either model adds to rotating weight right at the rim and uses an expensive battery. Saw another good idea at Interbike--a string of LED's that you weave around the spoke nipples. They are doubled up, with one facing each side, and about 8 inches apart on the rim. When the wheel turns fast enough (over 15 mph) it creates a ring of fire. It runs on two AA cells in a holder zip-tied to the spokes near the hub. I installed mine on my night bike and it looked great! They were available from Mr. Happy's Galactic Tracers under the trade name RimLites, but I don't see their website any more. I had problems with the battery contacts, and the instructions say don't use it in the rain (!) Mine self-destructed when I got a stick in the spokes, and I am not using them any more. There are now several LED arrays that go in the spokes and produce patterns while you ride, but all of those are not very visible from the car behind you that is about to run you down.
In 2004 I sent for a Californeon helmet light. It's a neon-like band about a quarter inch (7mm) wide that goes around the helmet and sticks on with a 3M adhesive. The battery pack takes a 9 volt battery and clips on your belt. Looked ok in the basement shop, but the circuit board burned out in less than 10 minutes of use, and before I had a chance to see what it would look like outdoors.
In general, I believe in redundancy, with at least two of everything just like a car. Redundant filaments in my car headlight let me use the high beam with a handlebar trigger flasher as a warning or passing through short tunnels, and also would provide an emergency option if the low beam ever died. (Car lights have a very long filament life.) Now I have two Barry Beams lights for the same reason. Redundant tail lights are essential, since nobody has ever produced a completely reliable light for a bicycle. I also like to "layer" my tail lights, with one at the level of the wheel axle, one on the rack or below the saddle, and one on the helmet. The more I observe about urban light clutter the more I favor big, big lights and lights that have a signature. You will find this concept better developed on Ken Kifer's web page discussion of the Flashing Neon Light Display, although I would not favor his use of a diesel generator to power the array, and I can't find his site any more.
Those who ride off road at night have found helmet-mounted headlights useful. If you use one, be sure to mount it with hook-and-loop or the kind of breakaway mount developed by Jet Lites. And please don't flash your light in my eyes on a dark trail.
There is now a category of lights called LED flares. They are designed for traffic situations. They should be durable. I have not seen them in use yet.
Some things can help in addition to the active lights that you should primarily rely on. For reflectors I use the hottest 3M product I can lay my hands on to add reflectivity to pedals, shoes, cranks (flashes as the cranks go around), panniers, clothing, helmet, anywhere else. 3M markets a "snake" in Europe that weaves around the spoke nipples, and under headlights looks like a ring of white, identifying the bike immediately. The 3M demo video is very impressive. I am trying a similar product now from a company called Techflex. Their product is called Reflex, and was originally developed for electricians to make electrical cables in big buildings easy to find and trace. They sell it for brake cables, but other than adding a point of light I don't think that helps identify a bicycle very well. As a round circle in your wheel, however, it can be much more effective. I am using one on the front wheel of my night bike, but my panniers obstruct it in the rear.
You can find 3M Scotchlite in many local stores, but for their hotter stuff, you have to go to the web to places like Itendi-tape. Be prepared to spend more, but the results are pretty impressive. I use it on helmets and some other spots, even though it adds only points, not an identifying signature.
Unfortunately, all reflective products depend on being in the beam of a headlight to have any light to reflect, so for a lot of situations they are not much help. But I frequently find that flashing pedal reflectors are my first warning that a cyclist without a headlight is approaching on a dark trail.
Flags are great for daytime. I use two on my recumbent. One has a blinking white strobe light on the top of the shaft. The blink of a strobe disappears too fast for the eye to follow it well, but combined with the flag it's better, and it gives a 360 degree flash. I asked a more experienced recumbent rider if his flag slowed him down. He said he did not know, but maybe, and for sure he felt slower with the flag.
For a far more detailed page with amazing amounts of info, lots of great photos and some great advice on building lights don't miss Steve Scharf's page. He has other links as well.
Bicycle Helmet Safety Institute