Chuck M 

Yet that won't stop someone from trying.

Polaris OBark

Oh, for those days of sex-segregated educational institutions, five cent Burma Shave, and hard-working white people.

FBinNY 

This is EXACTLY why I use a flashing AMBER in the rear. Red lights are used on moving vehicles, and drivers can easily make poor assumptions about my speed and underestimate thr closing speed.

Since flashing amber is used on stationary hazards, it's not b possible to underestimate closing speed.

Also, since flashing amber lights are used for hazards like trenches, they elicit a high level of concern for drivers which is always a good thing.

Paul Barnard

Flashing amber is used in the front turn signals of motor vehicles. Some models have amber on the rear as well.

FBinNY 

Flashing amber rear turn signals are a relatively new car feature in the USA.

When I started using flashing amber as a rear light on my bikes 50+ years ago, it was not legal in NYS. Now they've made it a legal option for rear bike lights.

Back then I was stopped twice over my lights. Both times I explained that drivers are more careful about stationary hazards then bikes, and I felt I should get equal respect. They agreed.

Bike Gremlin

My subjective experience. A lot of time and distance on the bike in traffic, as it is my main (and practically only) means of transport, in addition to weekend joyrides. But still just one man, so not statistically relevant (hear-say category, objectivelly).

During the night, lights are a no-brainer. It's not a topic (and I sure hope we can all agree on that), but worth mentioning for one point - as FBinNY mentioned: flashing rear light makes it easier for the drivers to notice you (there is a difference between being seen, and being consciously noticed by the drivers).

Cars coming from behind are usually going straight towards you, and you are riding away from them (though usually slower than them). This give the drivers enough time to notice the flashing light, and the fact it is flashing makes it more likely for them to notice you.

For the front light, during the night, the situation is the opposite. Drivers pulling in from a side road have very little time to notice you (many don't look left-right twice, and the wide beams on the modern automobile windscreens can block your profile).
Because of that, it is possible & probable for the driver to be looking at you just during the split-second that your blinking light is in the off-phase (if you don't have another full-on light).
Also, the speed difference is increased by your speed (you are going towards the cars coming from your front side, not away from them), which also reduces the reaction time.

For those reasons, I think that you should have a full-on front light (and add a blinking one if you think it's a good idea), while for the rear, it's probably good to have a blinking one (even without a full-on light, though there too it sure is safer to have both).

Now for the day.

I have noticed that a blinking front light lets drivers notice me more often (cut me off less often when pulling in from the side roads).
That also helps when there's rain, fog, or a low sun shining from behind me.
My dynamo-hub light starts blinking when I slow down below 10 km/h (the main beam, while the daytime "position" LED stays full-on). That flashing does seem to draw drivers attention when I slow down (before an intersection, or when I see driver who is likely to do something silly).
Again, that's my subjective impression - I didn't do any stats or counts, as they make little sense for this kind of phenomena when tracking fewer than a few thousands of riders.

For the rear light, I can't really tell if it helps during the day. I can presume, guess, but I can't figure out when the drivers first notice me.
My dynamo-hub rear light shines a bit brighter when I'm braking (like automobile brake lights), and starts blinking (with a full-on LED) when I slow down below 10 km/h (at about ~6-7 km/h probably).
Not sure if that helps, but I suppose it does no harm.

Now, what Leisesturm wrote about, well, basically common sense and caution - I very much agree.
I've been riding for decades without day-running lights, and managed to stay safe.
Lane positioning, looking in front and around you, making a "plan B" in case a driver does something silly - it all helps tremendeously, and without that, lights will not help.

Having said that, I do believe that daytime lights do make a tad of a difference. Say an extra few percent of chance for being noticed (on time).
So, for me, it boils down to whether it's a hassle to use.
With a dynamo hub and LEDs, it's no hassle whatsoever (at least for me).
I even mounted some dynamo lights on my "gravel" bike (the one I take into dust and mud on the weekends).

With batteries, I never bothered to use the lights during the day, unless it's raining, foggy, or the sun is very low.

Relja

TC1

No, it does not mean that at all. For an easily accessible counter example, try looking at the sun. I am routinely forced to look away from excessively-bright and poorly-aimed bicycle headlights during daylight rides -- especially on MUPs, where usage of such is particularly ignorant.

If they are that bright, they are probably blinding road users at closer range. And there's no actual reason to be visible from great distances on the road, when the penalty for such is blinded fellow road users who are much closer to you, and who present the critical danger -- this is precisely why every civilized society has rules about automotive high-beam headlight equipment and usage. One could, if ignorant, drive around all the time with their high-beams on, and be noticed "from a great distance", but this would not have a positive effect on their safety nor that of other road users.

TC1

Again, you were unable to understand the previously-posted data, so more is unlikely to help your situation.


Because none exists -- which was my point. Again, it would behoove you to understand the conversation before replying.

jon c. 

You gotta love it.

Rick

I haven't ever ridden on an MUP with flashing lights. I routinely see motorists with there hi beams on in my face while driving my car and on my bicycle. I occasionally have to drive my car in conditions were the sun is in my eyes. I know my quad red flasher is not as bright as the sun in your eyes from seated in a car. If I rode in a group It would not be on unless I was the last rider. If I were to ride on an MUP I would have it off. I personally have never been blinded from someone's tail flasher or headlight during the day. I have very lite colored eyes and when in heavy traffic after dark I wear my sunglasses.

Bleu

Yeah , can be hard to see anything when the highway patrol has lights blinding.... Of course during daylight my tail lights are all flashing and they'd be awful at night , there are 6. I still use a flasher at night, but its not quite as brite and the extra solid tail lights make it easier to see where I am. Interesting that it isn't uncommon for me to see the highway patrol at 5 miles, yet the cars slam on their brakes and move over at 200 feet, or sometimes less.

work4bike

Some flashing lights, but also one non-flashing light.

BATTLESTAR75

Great post, absolutely dead on about the over-lit emergency and police vehicles.