Tail light flashing modes, which is best?
 

I have a Cateye Rapid X2 tail light, which has a variety of flashing modes to choose from. I'm wondering why there are so many modes, and if there is a "best" in terms of visibility. This discussion doesn't have to be relegated to this light, just in general, if there is a preferred mode.

The Rapid X2 has a standard flashing mode (which is kind of on and off at a constant rate),
a "rapid" flash mode (rapid flashing of lower light and a single burst of very bright light),
a "pulse" mode which is basically like a wave of dimmer to brighter light (so there is not an "off" sequence),
and a "vibration" mode, which is another fast flashing mode, but with very bright light.

I generally use "rapid" since it gets twice the battery time of "vibration", though that would be my second choice. Pulse is ok, but the bright portion of the pulse is not as bright as the other flashing modes. Regular flash is my least favorite, as in my opinion, a constant flash is not as noticeable to drivers as a more random pattern of flashing.

Other opinions?

I use Cateye Reflex lights on all my bikes and they have the similar modes. I've read that there have been some studies in Germany that suggest that flashing lights actually attract some drivers because of their mesmerizing effect. That being said, I use the rapid mode that lights the internal lights at different times (with something always being on) most often along with my Reelights which are on steady.

I bet there's something to those studies even though it seems counterintuitive. It's hard to not look at the rapidly blinking light. I use slow blink on a PDW light, often consider using a second to be always on.

They basic idea is to be noticed/recognized from as far away as possible.

Bicycle lights are small and not very bright. Small solid lights tend to be lost in the background.

Lights that flash are noticed farther away than lights that are the same but solid. That's why lights on airplanes, buoys, and antennas flash. An irregular-like pattern might be more noticeable still and might counteract any possible "mesmerizing" effect. Rapid flashing seems overly irritating.

Nothing is perfect.

I'd use a flashing mode (that isn't high frequency).

I just looked at the modes on Youtube. For day I'd use the steady flashing mode where it's flashing at a constant rate. At night I'd use one of the flashing modes where the light never completely goes dark.

I've video recorded my lights at sunset facing into the glare of the setting sun, and at night while parked and riding up to 100 yards away, and observed them without a camera. Based on those observations, and reactions from cars, I use whatever the rapid flashing mode is for the light. It's the most noticeable and least likely to induce perspective or proximity error.

Steady lights are too difficult to quickly estimate distance. Particularly single lights. Placing lights around 6" or so apart - horizontally or vertically - may help lend some perspective for drivers if you prefer steady lights.

Regarding flashing interval/frequency, I'd guess that Bontrager, Blackburn and others have the right idea with irregular rapid flashing modes. In my videos I found it easier to spot and estimate distance when the Blackburn 2'Fer was used in rapid flashing mode, along with a couple other red LEDs that have only regular patterned slow and fast flashing modes. The combination of lights placed 6" or more apart, along with the varying flashing patterns, was very visible out to 100 yards in my test videos, at dusk and night.

In daylight I've been using the front facing white lights in flashing mode. Several times I've noticed drivers pause before leaping into traffic from parking lots or intersections, and so far I've experienced none of the close calls I used to have when riding without lights during the day. However at night I'm more inclined to use steady front facing white lights unless I'm in heavy traffic downtown at night. For one thing, it's less distracting to me - the bright white flashing lights reflect off signs up to 100 yards away. I prefer to use those signs as visual reference of cars approaching from behind at night - I can see the reflections of car headlights, which is helpful in addition to my mirror for keeping track of cars around me at night.

Depends on time of day.

IMO at night you should have some light steady. If you have a light that has a steady + pulse mode, that will work. However, I feel that you should also always be running two rear lights at night since you can have one fail and not know, and then you're in significantly elevated risk. So I run one in flash and one in steady.

Generally with regular lights I run a slow flash and a steady.

If I have the DS500 mounted, I run steady+triple pulse at night, high power triple pulse in daylight.

I don't know if I agree with the German conclusion that flashing lights are dangerous or inadequate. To be safe, I try to run two tail lights, one steady, one flashing. If I only have one tail light, I set it on flash. I also put a red light in my spokes so others see the motion of my rear wheel. I've gotten compliments on it, so I suspect it helps.

Wow, great replies thanks! I agree with those who don't like a solid steady light, it doesn't seem very useful, especially in daytime. And at night, a solid red light may look like it's just a reflector on the side of the road on someone's mailbox, to a car. Definitely need the flash mode. Any flashing mode that has an "off" position is the least preferred to me, and if it's regular, it again seems like it would not be as effective. It seems like the randomness of the flashing, plus the brightness are key. I'm just starting to use this light in full darkness, so I'll do some experimenting, but the rapid mode (semi-random and intensity change) and vibration mode (very rapid flashing) seem like they'd be the best.

Also, for the front, I decided to use 2 lights. My Volt 700 for steady light, and another less bright light set to flash. At night, it's just too distracting to have my main light flashing at all, so the more dim one gets washed out in the intensity of the main light, and doesn't bother me. But (I hope) the smaller flasher should act as an attention grabber to cars.

Lastly, I have amber spoke lights on my front and rear wheels for a bit more side viewing. Combined with a retroreflective jersey, I was pretty impressed with how cautious cars were around me in almost total darkness. This is my first winter of trying to do dedicated rides after dark, and I'm actually looking forward to it.

To ItsJustMe and others who have Axiom pulse taillight: the light has a strobe mode and a flashing mode. Which one do you prefer? Or which mode is better for what situation? The strobe mode is something between flashing and constant, though it seems to be on lower brightness when on this mode.

That strobe mode is horrible. I don't think I'd ever use it. MAYBE in daylight only. I'd prefer it if they changed it to some better mode, like a low+PopPopPop mode, or a quad fast flash with 500 to 700 ms off spacings.

While I agree about daytime, it's still far more visibility than nothing at night. A steady light also makes it easy to track where you are on the bike from behind you.

Steady is useful when riding in a group - something flashing can be a problem negatively affecting the vision of the person riding behind you. A friends bike has 2 rear lights, one is fine on flashing, the other is so bright that if I'm riding behind him I ask him to put it on steady.

I agree, it's easy to lose a cyclist if they run only a flashing rear light at night. The flashing light draws the attention to you and the steady light allows them to keep track your location. I am not a fan of strobing lights in the darkness. I also think reflective gear is at least as important as lighting in the dark. I use a cheap coin-cell flashing light on my helmet at night time as a flasher and turn my Dinotte 300r on steady-low mode. Combined with the reflective gear there's no way a car overtaking me is going to miss me at night.

Right...

Your eye seems to perceive it as movement and it gets it's attention.

It's a debate in and of itself. I am a fan of moderately powered ones - they make you stand out as a bike. As a driver I more easily recognize a bike.

When they reach a level brighter with a pattern more obnoxious than that I become torn. On the one hand it's annoying. On the other hand, it can keep cars from passing right next to you, the annoyance causes them to want to go wide around you and not get to close. I'm on the fence about what I think about it.

I personally don't agree...I don't think anything beats a light. Reflective gear is a light that only works when someone else is pointing a light at you.

If one wanted to maximize their visibility, I've seen bikes with those strings of low power led's on them. This guy is as visible as possible:
http://rollinghcycles.com/wp-content...ike_lights.jpg

These bikes are pretty visible:
https://s-media-cache-ak0.pinimg.com...2213a49e08.jpg

Reflective gear is better than nothing, but I don't like how it only lights you up when someone else's light is on you.

See above pics if you really want max visibility. :D

@cthenn, I'm glad you also like spoke lights. I think they create a lot of value. They run on watch batteries and are not bright in an absolute sense, but they're mighty useful. I can't run one in the front wheel because it distracts me, but I think I'm OK having it just in the rear wheel.

The tracking issue is mostly irrelevant. Since a rear light is primarly seen from behind, there isn't much lateral movement going on.

The first thing you want in a light is to be seen from as long a distance as possible.

Flashing increases the noticeability. That is, a flashing light is seem much sooner than a solid light.

If they are close enough where tracking is an issue, the car's headlights are likely what is being used for that.

Reflective stuff is useful but that's usually recognized later/closer than a flashing light is.

The main reason for the German conclusion is that a blinking light is harder to keep track of and I agree with that. The best is a wide, multi-led, bar that is always on but most people don't want a 5 inch bar on the back of their bike for aesthetic reasons.

A blinking light can certainly draw attention but if you want to use those, combine an attention-drawing flash with a steady light.

But perhaps you like the idea of the Lightskin seatpost light? ;)

I don't agree, it's still important when you're passing them a few feet away.

I don't agree, being seen from 100 yards or 300 yards makes little difference to me. It's the person who's car is next to me or 10 feet back that I'm the most concerned about.

Blinking certainly catches your attention a lot more.

It works if the car is behind you, but not when you're coming in at an angle (bike path crossing a road for example, or a road crossing a road). I prefer anything I use to be visible from all needed angles 100% of the time. No drawback to reflective, not trying to talk anyone out of it, I just think active lighting is better.

Agree.

The best non-blinking tail light in my opinion is the Toplight Line Plus, which puts about a straight bar across the back of your rack. I've seen them while in my car, nearly as eye catching as a blinking light, and stands out as a bike and not a car.

Not sure about the lightskin light - in my limited personal experience a horizontal bar is eye catching more than a vertical bar. Not sure why, or if it's just me.

Lightskin light you linked to:
http://www.lightskin.co.kr/images/mtb.jpg

Agreed. It does look a bit more aero though. For those who care about that. ;)
Hence my comment about a 5 inch bar. The horizontal bit is why you often see them on racks in Holland.
But most North-American cyclists ride without a rack and there a horizontal light would only be very sensitive to damage.

The B+M Toplight Line plus works really well as a rear light and especially their model with the brake light function is intriguing.

Though I would say the Philips saferide gives it a good run for the money and looks better as well:
https://c1.staticflickr.com/9/8045/8...77bf5c6597.jpg

Fact is that rear lights are especially important for when there are other people nearby and that are either to your side or coming onto you.

To be clear, I think reflective gear + a solid red light and one flashing red light is the ideal solution. I would hope everybody driving after dark has their headlights on. The lights allow them to locate you and the reflective gear (a belt + ankle bands) make it easy for them to identify you as a cyclist. I use a Specialized Flux Expert headlight so I look more like a motorcycle to oncoming traffic. This is just my opinion having driven around seeing these various solutions in action. As far as the wheel lights I've seen them on slow speed bikes but I'm not a fan for quicker bikes. I think drawing too much attention to yourself can actually be more dangerous.

:D

I am so disappointed Philips left the bike light business...sigh.

I wasn't that impressed when they came out, then I bought a Saferide (gen 2) this year, and wow. They really made some good stuff. It only could have improved with the next gen of LED's.

I've got an older Dinotte blinkie that I run on steady "on", and then it gives high intensity blinking.

Toplight Line has visual width so a following car can judge distance as it approaches you

Its related in how it works to a Fresnel Lens , Reflected light from a Point source is spread Out..

The B&M Vista Taillight puts 1 led at the top and 1 at the bottom and uses the same line tech to give those Visual Width..

If they are that close, they won't really be able to see the light very well at all. If you are at the right side, the light is not pointed at the driver and may be obscured by the car.

No driver next to you is seeing your rear light. If they first notice you at 10 feet, reacting to you is a risky, emergency maneuver.

A safe pass has to be established much earlier than 10 feet.

The farther the distance, the longer time is available to notice you, plan an action, and execute that action.

If being distracted occurs briefly, that longer time make it more likely you will be noticed and much less of a surprise.

Rear lights are really poor for any angle except for a fairly narrow angle centered on straight-back.