How many Rear Lights Do you Have?
 

A friend has four (in a row) of red blinking lights. Isn't that too much? How many do you have on your bike?

Just the one. But it also has radar in it, which is most excellent. I can't realistically see a need for more than two rear lights, and you would want them far apart-- say one on the seatpost and one on the helmet.

I used to have two when I was using tail lights with rechargeable batteries, so if the battery in one went flat I could use the other.

Now that I use a solar tail light, I only use one. The battery has never gone flat. I normally don't ride for long periods of time after dark.

If a tail light did fail, people from behind could see the headlight shining on things in front.

I normally don't ride in busy city traffic.

Two...helmet and bike. Although for the dark winter commutes home I wear LED shoes and a reflective vest and other stuff...a lot of other stuff...probably overkill...

Dyno lights on both my most-regular-riders, so I'm pretty certain I have a light while rolling.

In case a connection comes loose (has happened!), I've got a blinky on one bike and two on the other. On winter commutes they're (a) flashing and (b) backups. Two is redundant for the redundant -- if the dyno connection comes loose and the batteries on one blinky die on a winter commute, I've still got a light.

Context is suburban commute with some 4-lane 45 mph posted (designated bike route with sharrows) and 40 mph posted with 3 foot shoulder that pinches out in places.

At night, 2 Planet Bike Superflash on panniers and a Cygolite Hotshot on the seatpost, all on solid red plus a Serfas TL-something (very bright) on my helmet in blinking mode.

During daylight I have a minimum of one on solid. I turn on the helmet blinker when I take the lane or if I don’t like the situation forming up behind me.

One blinking red one, but I was also thinking about some blinking yellow ones like slow-moving vehicles have, which I definitely am on uphills relative to car speeds (and to turtle speeds). And a solid red one.

I have 3 all cygolite and rechargeable. I like redundancy and angle 2 of them on seat stays such that there is more side visibility.

four rechargeable lights in flashing mode regardless of time of day/night. one on each side of the handlebars (the knog "stick" ones that run about $20 apiece
that extend out approx two inches from the outside of the handlebars) in the middle of the hooks so i can climb in the hoods or drop down (rare for me) to the hooks.
two wraparound lights on the seat tube underneath the top tube since i normally use a saddle bag which would obscure most lights mounted to the seat post.

I run one on my helmet, but that’s because my route is almost entirely bike paths. I’ll add one to the bike if my commute is on the road.

When I commuted in the dark, I had 4. A rack mounted dyno powered light, 2 belt-mounted lights (port and starboard) on solid, and a helmet mounted solar light in blink mode. Distance between the lights aids others in gauging your distance and speed.

2, that way if one dies I still have one. I turn them both on all the time but they don't usually die at the same time.

I am working on getting the Garmin rear light with radar deal, looks pretty awesome.

Just one, a dynamo driven B+M Secula Plus. One of the more visible lights without being blinding and plenty of light for around here.

http://i.imgur.com/rf5r9k7.jpg

http://i.imgur.com/8Qkl3Xo.jpg
http://i.imgur.com/CN5fXkh.jpg
(Different bike, but same light. This is the standlight)

One cygolight hotshot, flanked by two old style reflectors.

One fewer than yesterday.

One hotshot that I use on two bikes. So is that 1/2?

Three: a Busch and Mueller dynamo tail light (toplight line brake plus) on rear rack, a 2nd gen Cycliq Fly6 series cam/light combo on seatpost, and a Light and Motion 360+ on the helmet. The latter is the older, better designed, more visible, built in reflector version, not the new one. Not sure what they were thinking when “improving” it, but I digress. My commute is 75% MUP and I turn off all but the dynamo light for those stretches. For traffic, day or night all three are in use. Overkill, perhaps.

So what happened to the other one?

There is some evidence to suggest that a flashing light is more visible to motorists, but a steady beam makes it easier for motorists to gauge distance. So, on my commuter bike, I run one of each - and I have them spread as far apart as possible, with one on the seatpost and one on the non-drive side seatstay.

Carry 2 taillights and headlights. Use 1 and have 1 as a backup. I use them day and evening.

​​i have two lights on the rear of my commuting bike. One a Cygoliite hotshot 150 and Orphos flare pro rear. The hotshot gives me a beam for far down the road but not much side visibility. The Orphos has great side visibility and shines 240° and when it is as bright as it can go it is 400 lumens. The cygolite has the shortest battery life but it has been great to have some duplication.
My rack also has a rear reflector. I bought a new winter helmet that has the spot for a light but I did not use one on it last season.

Occasionally, I see someone with more than two taillights. I notice it's a good attention getter. I don't think there is a number of too many lights, because bikes are so much narrower than other vehicles. It's too many when you can't manage the batteries or when the cost is prohibitive. I haven't reattached the dynamo lights on my bike, but I do plan to. When I run dynamo lights, I have a steady dynamo-powered taillight plus a flashing battery-powered one. I also have a spoke-mounted light in my rear wheel which has been observed (by others) to be good at grabbing attention.

I put it on my kid's bike at the beginning of a ride. It was not there at the half-way point. We searched 20 miles of road, but never found it.

I follow this same approach on each of my bikes. A bright (but not dangerously bright blinky/pulse light) with a bright solid light.

Two, I have a NiteRider Omega 300 on the saddle bag loop, and a NiteRider Sentry Aero 269 on my helmet at night on.

What Koyote said is what I've done for quite a few years and said that on various forums. Canadian studies have shown that a flashing light attracts attention better than a solid light; but European studies said that with blinking lights motorists had difficulty ascertaining their distance from the light, so they outlawed flashing lights. Knowing that when I ride at night I run my brightest light which is the Omega 300 on solid but the Aero 260 is on alternating flash; but during the day I run the Omega on strobe.