Are daytime bike lights a safety essential? Should you get daytime lights?

Something I noticed this morning, cycling along a cycle path and car coming towards me, then as drivers do it turns across in front of me ( I was a little way from junction so no issue) but it was only at the last minute that I noticed it actually had indicators! The DRLs so effectively masked the indicator! this isn't the first time I have noticed this.

More on topic, If you ride in sunny weather in and out of the cover of trees you can loose sight of things. I can see where a rear light may help, but this comes back to the old CTC argument. Why should bikes have lights, shouldn't the onus be on the driver to look where the f*** they are going? All those drivers complaining about not cyclists not having lights? If not having lights means you can't see them how do you know they are there, or is the issue that the drivers don't have hours to respond, that they aren't actually paying attention and are simply victim blaming to cover their own crap driving.

I have to admit when it gets gloomy and cars have their lights on I tend to put mine on too. It helps to be seen from a very long way off.
I see some riders do the same even when it's bright and sunny, which I think is of no use at all.

Realistically this is a sticking plaster solution to dangerous roads. It would be much better to fix our roads and make them safe for all, rather than just try to sell cyclist more stuff.

I ALWAYS have a flashing red on the go.
The human brain is hardwired to respond to changes in stimuli as a priority & de-prioritise stable state information. Whether consciously or sub-consciously, another road user will be more aware of you with a flashing tail light.
My commute used to be partly along leafy lanes and (even more so on a bright, sunny day) a car driver driving into shade under trees will suffer several seconds of visual acclimatisation; it's a physiological certainty. They WILL notice a flashing light in the shade of those trees where they might immediately see you otherwise. The earlier another road user notices you, the safer you should be.
Do whatever you can for yourself & stay safe.
I admit, I can be as self-righteous as anyone but I'd rather not do it from a hospital bed.

I’m sensing that most of the comments are from sports cyclists who are more likely to be mixing with fast moving traffic on busy roads. On a 70mph dual carriageway in poor visibility a rear light seems a sensible choice (although I would resist it becoming mandatory).

For your typical utility cyclist pootling about town or a leisure cyclist out on a quiet run in the country it’s not necessary. Yet another reason for people to be put off riding a bike.

Look at any video of Dutch people riding bikes during the daytime. Not a red light in sight. See for example: https://www.youtube.com/watch?v=Jpi01x_DgDY

I see the problem of cyclists not being seen on the road getting worse over the next 10 years.

A few years ago a euro law made daytime running lights on vehicles mandatory. Now drivers are used to seeing bright LED's when there is something in the road. Over time proportion of cars on the roads with daytime running lights is going to get higher and higher. This will make drivers eyes lazy, only looking for a bright light in the road lane.

I suspect it is only a matter of time for LED's front and rear to be built in to bike frames/ handlebars and powered from the electronic groupset or frame battery (for cable groupsets). The technology is already available, it just needs one leading brand to decide to do it.

Personally i don't use lights in the day, but make sure i have them for evening rides when there is a chance of being out at dusk.

Totally agree I ride with my See.Sense lights on all the time.
The problem I had with other lights in the past was they are just not bright enough to be seen during the day.

Anything under 70 Lumen will not be bright enough to be seen on a bright sunny day.
Also the way the light is dispersed is very important they need to have great side visibility.

I've always ridden in daylight hours with a rear light. Personal choice I know and (without waking the victim-blaming evangelists) having been cut across and hospitalised on my motorbike resulting in ruptured artery and lots of internal bleeding and a written off bike, I choose to use anything that might wake up a dozy or distracted driver to my presence.
My rear light of choice is the Niterider Cherry Bomb, which has a half mile visibility and was reasonably priced. The bracket is crap though and needed a little modding.
A few quid on batteries each year, why would you not?

This "only doing it to line their own pockets" argument has never made sense to me.

Tesco don't sell me food out of the goodness of their hearts. Doesn't mean I shouldn't eat.

Absolutely NOT!
Drivers need to learn to drive properly, more stringent tests.
Driving is a privilege and not a right (or money making scheme).

I agree. Think about those times you've been driving with the sun ahead, bouncing off your dashboard and making it difficult to see. You slow down a bit but the tall hedgerow to the left is no longer green, it's black and completely in the shade. Pedestrians and cyclists can easily be masked by that shade. Not all drivers will slow down, so I keep out of the shade but I also use my rear light (hope district) to reduce the chance of being hit.

In tree lined country lanes on sunny days visibility is a real problem- I nearly always have at least a rear light on. It is a bit like helmets- I don't see that it can do any harm, and it might help.

But, as with helmets, it must be the individual's choice/ responsibility.

I leave my lights on all the time. As they are dynamo lights it's just easier. My rear light also gets brighter when I brake, which is nice.

cant see it making a massive difference though. Just another way of victim blaming.

Ultimately I can't see that it can harm (except your wallet) to have a bright rear light during the day. I don't think it should be mandatory (ditto helmets, high-vis/YJA, reflective clothing), but I think it is more than somewhat cynical to believe Trek are only doing this to line their own pockets (after all they're hardly a monopoly, indeed Bontrager isn't the first brand I'd think of with respect to bike lights).

I find myself leaving my front light on flashing mode in more daylight hours these days mostly because of the 'sun dappled' country lanes. You can go from bright sunshine into, what for the eyes is, relative darkness, leaving your vision temporarily impaired. In an instance like that for a car coming the other way, having the front flasher on could make the difference between being seen or not.

As for the rear, I've got a Fly6 now which is always recording, so there's always a light on there anyway, but I guess the same thing applies.

run time: i mostly use it in night flash mode which, incidentally, isn't a mode i'd use at night because the flash is too bright. stated run time for that is 23hrs. day flash mode run time is stated at 5.75hrs, so not ideal for longer rides

I ride with lights 100% of the time, except today, as I forgot to grab them from charging

there's a full review of the Flare R coming, but for the record here are the things i like about it:

1) it has two sensible steady modes for night and group riding
2) it has two pretty brutal flashing modes that are genuinely visible in the daytime from a really long way away
3) it comes with a good mount and a neat clip for clothes or the back of a bag
4) it's nicely made

and does it make a difference in the daytime? well, anecdotally it seems to, yes. you still get crap, impatient passes from people that have seen you but just can't be bothered to give you decent space. but overall, there are fewer bad passes. i'm not claiming this as a scientific proof, it's simply my experience of using the light over a couple of months. your mileage may vary, etc and so on.

I keep my rear light fitted during the day, so its there if I need it - but should the lights be on as a rule during the day?

NO

The biggest issue is run -time. In order to be useful the lights will been to be very bright, which means that run times will be at a premium. How many will last an 8 hour ride?
Does not make sense to me to have the light on all day, only for it to run out of juice just as the evening gloom is starting to set in.

However it is sensible to switch on the lights an hour or two before sunset - when the sun is low it can make visibility difficult, and anything we can do to stand out in front of a glaring sun is worthwhile. Similarly worth having the light on during rain and mist etc

I have lights on all the time. One less excuse for other road users not to see me.

I wouldn't like this to become mandatory,

but I think its a good idea.

I personally notice other cyclists from farther away when they have lights on, even during the day.

I have no evidence to back up this opinion.

My commuter bike has hub dynamo lighting, and I leave it on all the time. The front light probably doesn't make much difference in daylight, but I like having the rear light set to always on; that way when it gets cloudy or you go under a bridge, you've got that extra 'notice me' element. I agree with Gazza that the main problem is drivers not looking, but having the option of daytime running lights is one that I appreciate.