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

Trek thinks it's time cyclists started using bike lights even in bright conditions. Do you agree?
This article was originally published in August 2015

Should we ride with a rear light on during the daytime? Or perhaps we should go further and ride with both front and rear lights on even when the sun is shining?

We had a forum topic about this issue on road.cc a couple of years ago and what you might call a heated debate when Bontrager announced its Flare R rear light, designed specifically for daytime visibility, earlier in the year.

The reason we’re thinking about it again is that we went to visit Trek last week and the brand is really keen to promote the use of rear lights during the day. It even had the members of Trek Factory Racing ride the prologue of this year’s Tour de France on time trial bikes fitted with the Flare R “to promote awareness of the most important cycling accessory available today”.

Daytime light.jpg

Of course, your cynical side thinks that Trek wants to encourage the use of lights in the daytime because Bontrager, it’s sub-brand, produces that Flare R rear light. It’s simply a way of boosting sales.

Trek acknowledges that, of course, it has an interest in selling lights, but says that the key motivation for launching the Flare R was to keep cyclists safe.

“About two years ago, I was in San Diego, and I’m driving along during the day, and I see a biker, a road cyclist, and he’s got a blinking light on the back of his bike, and I thought, ‘That is a great idea,’” says Trek President John Burke. “The only problem is you could barely see his light.

“When I got back to Trek, I put together a team of engineers, and I said, ‘Listen, what I’d really like to see is a light on the back of a bike that can be seen during the day.’ If we could do that, I think it would significantly enhance the safety of cyclists everywhere.”

The result is the Flare R. Here’s John Burke’s short video presentation on the light.

Trek argues that using a light during the day makes sense because that’s when about 80% of cycling accidents occur.

Well, yeah, says your cynical side, but what percentage of cycling takes place during the day? Maybe that figure simply reflects the number of people on bikes during the daytime compared to the number who ride at night.

Trek also argues that, “Studies on accidents resulting in the fatality of a cyclist show that in 40% of all bicycle vs. car accidents, the victim was struck from behind.”

That statistic is from the US. Put a light on the back of your bike, the argument goes, and you’re less likely to be one of them.

Bontrager Flare R City Tail Light.jpg

“We think products like the Flare R allow a rider to have more control over their safety, putting us in both offensive and defensive positions on the road,” said Trek’s Chris Garrison. “We want to get people talking about increasing their visibility not just at night, but also during the day.”

Chris cites a recent AA-Populous poll as evidence that more cyclist visibility is required. In that poll 91% of drivers said that it’s sometimes hard to see cyclists while driving

John Sullivan, an RAF pilot and keen cyclist, advised in his paper A Fighter Pilot’s Guide to Surviving on the Roads, “Aviation research shows that contrast is the single most important factor in determining the likelihood of acquiring an object visually – this is why military aircraft camouflage is designed to tone down their contrast.

"On the ground, dark coloured vehicles or clothing will result in reduced contrast against most usual backgrounds, and this is why high visibility clothing (for pedestrians, cyclists and motorcyclists) and/or bright lights are so important, in the daytime as well as at night.”

Back at Trek, John Burke says, “People should be able to see you all the time. And when they do, you’re going to have a better riding experience. Get a new Flare R, or buy something else. What I care about is making sure you have a really safe cycling season.”

Exposure Trace TraceR set

Of course, Trek didn’t invent riding with a rear light on during daylight. Some people have always done it and USE, for example, has been advocating it for years. The British lights brand says that its Exposure Flash front light and Flare rear light (yes, the same name as the Bontrager light) are designed specifically for both daytime and nighttime use (you could argue that USE, like Trek, has a vested interest in promoting more bike light use).

Our man Dave says, “I’ve used the Flare R rear light a lot and I’d say it makes a noticeable difference to the passes you get. Drivers tend to give you more space.”

Of course, that’s anecdotal evidence. If anyone knows of any scientific research that has been carried out, we’d be interested in hearing about it.

So, why do so few of us use lights during the daytime? We guess that most people don’t think it’s necessary, although some oppose the idea in principle.

“When a vehicle has lights on it makes any in front or behind without harder to see,” said Simon E in that road.cc thread mentioned earlier. “Every vehicle that runs with sidelights/LEDs/DRLs [daytime running lights] in the daytime is furthering the idea that you have to have lights on to be seen, so all the sheeple do the same. Baaaa! This means drivers to look only for lights, not other vehicles or people.

“Lights are NOT needed in daylight, whether on bikes, motorbikes or cars.”

In a comment under our story announcing the launch of the Flare R, McVittees said, “Whilst it is perfectly reasonable to want to run as bright a rear light as possible either during the day to warn cars or at night when riding on unlit country roads, I hate being stuck behind someone who is running a high output rear light at night during my urban commute. I find it distracting and obscures my vision of the road (and thus traffic) ahead.”

andyp said, “[Bontrager are] pouring money into something which will make them more money, not into solving a problem.”

What do you reckon? Do Trek’s arguments convince you that you should use a rear light during the day? Let us know what you think.

Mat has been in cycling media since 1996, on titles including BikeRadar, Total Bike, Total Mountain Bike, What Mountain Bike and Mountain Biking UK, and he has been editor of 220 Triathlon and Cycling Plus. Mat has been road.cc technical editor for over a decade, testing bikes, fettling the latest kit, and trying out the most up-to-the-minute clothing. We send him off around the world to get all the news from launches and shows too. He has won his category in Ironman UK 70.3 and finished on the podium in both marathons he has run. Mat is a Cambridge graduate who did a post-grad in magazine journalism, and he is a winner of the Cycling Media Award for Specialist Online Writer. Now over 50, he's riding road and gravel bikes most days for fun and fitness rather than training for competitions.

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212 comments

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Tartle | 8 years ago
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Always use lights, even in daylight, because conditions exist on the road where they help.

Bright sunlight means deep shadows, cars in the light cannot see riders in the shadows ahead of them. Rear lights help this.

Front lights are even more effective for cars pulling out of side streets. Typically they only give a quick glance when they pull out, but my urban-550 flasher means they never miss me. The difference is very noticeable, and probably measurable.

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Bill H | 8 years ago
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Making lights compulsory in daytime will just be another layer of victim blaming to distract from serious safety concerns. While people argue the toss about helmets, hi-viz, vehicular cycling etc the real changes to our streets cape that are required are not discussed.

Once we have safe routes then individuals can campaign for their personal safety hobby horse (lucky heather compulsory on all new bikes) but until then try to stick on message and not get sidetracked.

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TrekBikesUK | 8 years ago
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Hi all, great comments on here, and it's good to see people having a conversation about daytime visibility because ultimately, we at least want to get people thinking about it.

A few points:
-We are in no way advocating the idea that there should be regulation that mandates the use of lights during the day.
-We have not created the Flare R for the purposes of solely placing the responsibility for our safety on us as riders. We completely agree that the solution is better driver training, better infrastructure, and a more Dutch/Danish style transport culture in general.
-Please read the link Mat has provided to John Sullivan's report. It's a great read in general, but also provides really useful information about how we interpret visual inputs, and the speed at which we can process them.
-We wish we could point you to some peer-reviewed study that demonstrates the effects of the Flare R, but we can't. As far as we know, it doesn't exist. However, we do know about optics and how the brain processes various visual stimuli, so there are some elements of science behind why we know, albeit anecdotally, that using the light does have an impact.
-As Dave mentioned, even with the Flare R, you will still get people making terribly bad decisions when driving near you. This is not the be all/end all solution. It just makes you have a bit more of a say, and hopefully eliminates SMIDSY excuses.

A couple of technical notes:
-Using a light typically designed for night use is potentially not bright enough. It depends on the beam pattern, and how wide a viewing angle it has.
-There are brighter lights available, but this light was designed to maximise the visual output of the 65 lumen it has during daylight. The optics are designed to create the most visible beam pattern possible, so even though you can find lights with higher lumen count, the Flare will appear much brighter due to the lens design.
-The beam pattern range is 270 degrees, so quite wide.
-While runtime in full daytime mode is sub-6 hours, for longer rides you can get away with running the other mode, which has one flash that is as bright as full day mode. It will dramatically increase battery life and at least provide the same level of brightness in one interval of the flash pattern.

It's unfortunate that there are those who think the Flare R was created either as a way for us to make more money, or to solve a problem that doesn't exist. We are in the business of developing new products, both bikes and accessories, so of course we have a vested interest in being profitable so that we can continue to be on the leading edge of technology in the bike industry. We reinvest back into the R&D phase of everything we do, because costs a huge amount of money to engage in multi-year research projects for something like the Flare R. Then there is the prototype phase, and, in some cases, hiring people who have specialist knowledge of a product. In this case, optics.

As far as how much of a problem visibility actually is, that's where we do have a wealth of evidence to choose from. Anyone familiar with Rachel Aldred's Near Miss Project will understand that there is indeed an issue with not just visibility, but the perception that drivers have about cyclists.

As John Burke says in the video, even if you don't get a Flare R, get SOMETHING that makes it harder for drivers to not see you.

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bigshape | 8 years ago
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as a rule i generally ride with a rear light on flash during the day.
the way i look at it, people are less likely to drive into the back of me with it on, it's probably more effective than wearing a high-viz (and doesn't look crap), and it doesn't slow me down.

I do 25 commuting miles a day, and even though people shouldn't be on their phones, reading the paper, etc. they still do it and they're always going to.

at least a bright flashing red light might give me a chance of getting noticed out of the corner of someone's eye whilst they're updating their facebook status.

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Ush | 8 years ago
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Quote:

I was in San Diego, and I’m driving along during the day,

Tells you most of what you need to know about this: a car driver that makes bike bits decided to make another bike bit.

No evidence presented as to the effectiveness of this at all.

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jasonlig | 8 years ago
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I kill two birds with one stone and ride with my Fly6 on all the time, as it's the original version I have to have the light on.

Sods law, with my main bike in the shop for the day, I got knocked off my other bike that didn't have the fly6 on. Wouldn't have helped as someone decided to pull a u-turn as i overtook a traffic que.

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WashoutWheeler | 8 years ago
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I can see no reason not to ride with lights!
They weigh next to nothing, no one is putting peoples arm up their back to use them and I have yet to see any sensible or compelling argument against their use.

The "Ah yes but" brigade will no doubt bore us sensless with any number of silly reasons why we should not ever have to ride with lights, (day or night probably) but as long as they are kept busy grinding their little choppers on this issue they are not annoying anyone on more serious matters.

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ChairRDRF | 8 years ago
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The advocate of this victim-blaming strategy argues that it "hopefully eliminates SMIDSY excuses"

No it doesn't . It backs up the whole SMIDSY philosophy.

For evidence on the conspicuity cone see Chapter 9 here http://rdrf.org.uk/death-on-the-streets-cars-and-the-mythology-of-road-s... For why it's victim-blaming and ineffective in both short (and certainly long) term see also http://rdrf.org.uk/2013/10/31/hi-viz-for-cyclists-and-pedestrians-sensib... and related posts.

After a while a red herring such as this is not only of negligible or zero effect, it feeds into a culture which allows the problem to become more entrenched, thus raising the prospect of NEGATIVE effect.

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ChairRDRF | 8 years ago
1 like

From Road CC in 2018:

"TREND SPOTTING: Should we be wearing body armour on-road as well as when doing downhill mountain biking?"

Manufacturer X thinks we should be wearing their body armour/knee/shin/elbow protectors with full-face lids, although other stuff may be relevant and they don't want it to be compulsory.

Loads of commenters write: " I wear Manufacturer X (or Y or Z) produced body armour/knee/shin/elbow protectors with full-face lids and they have saved my life/saved from serious injury dozens of times. So get the kit or it's your fault. And I'm not victim-blaming".

I bet you it will come. Maybe before 2018. And, above all, do not expect any rational argument to dissuade the advocates.

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Seavemeyer | 8 years ago
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My comment is this

Where I live and ride there is a lot of narrow tree covered roads
When the sun is out it casts very strong shadows of the trees across the road. The light and dark shadows are so strong it obscures pot holes and other road debris.

I find myself using a rear facing light during the day for safety reasons
If I can't see potholes, drivers can't see me or my bike.
A flasher immediately solves that problem.

Despite views from many who feel Bontrager is only looking for ways to cash in. I feel much safer because I use a light during the day

My 2 cents

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Yorkshie Whippet | 8 years ago
1 like

Can someone explain the followign to me?

As an mtber one of the first rules is never to look at something be it a rock or tree or whatever as you will hit it.
Yet on the road so many people are "shouting" "Look at me, look at me."

How come there are more rear enders as driver attention is attracted to the bright flashy light just like a moth to a flame?

To Trek and other light companies, How far ahead do you think a cyclist needs to make their presence known. Do I as a car driver really need to know that a bike is say a mile away or in heavy traffic 2 minutes away? At what point do you think it essential to let other know you are there or is it a case that people have all fallen into the brighter is better trap?

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Alankk | 8 years ago
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If Trek sold the lights at near cost price, then I'll believe without any salt.
Like when Volvo gave away their patent for three point seatbelts, now that, deserve to be praised.

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DaveE128 | 8 years ago
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While many may argue that one shouldn't need a light to be seen, as people should be looking harder, it is fairly plain to see that we as humans are pretty rubbish at consistently spotting everything we need to spot on the road. Anything that makes it less likely that someone will fail to notice you is likely to reduce the chances of an accident.

I also know from driving experience that it can be hard to quickly see cars (let alone bikes) when moving into dark shady areas from bright sunshine, and DRLs really conspicuity safety here.

I'd rather be safe than take a moral stand on hoping people will look harder.

However, I would strongly argue against making them compulsory.

I run a bright flashing light front and rear in all conditions on the road. Smart R1 rear and Moon Meteor 200 front. At night I angle the front light down towards the road and use it in constant mode so I can see where I'm going.

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jollygoodvelo | 8 years ago
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Just on the subject of car DRLs: in Europe they're now compulsory fitting on all new cars. http://ec.europa.eu/transport/road_safety/topics/vehicles/daytime_runnin...

I ride with a rear light on whenever it's dim/cloudy/rainy/etc.

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atgni | 8 years ago
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There must be some real data somewhere about rear end crashes for Barclays bikes. Although I guess you'd have to run them all without flashing lights for a period to make any valid comparisons.

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postmandick | 8 years ago
0 likes

I always ride with a blinker going  4 but i replace the batteries every 6 weeks .
I will replace it with a USB one as a believe the software inside it will always give 100% whilst a AAA version will slowly lose brightness .

cateye 1200 on front / blackburn 1 on back

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ChairRDRF | 8 years ago
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Whoops! A few posts back I refer to the "conspicuity cone". I meant "con", not "cone".

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don simon fbpe | 8 years ago
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Quote:

While many may argue that one shouldn't need a light to be seen, as people should be looking harder, it is fairly plain to see that we as humans are pretty rubbish at consistently spotting everything we need to spot on the road. Anything that makes it less likely that someone will fail to notice you is likely to reduce the chances of an accident.

Unfortunately there is plenty already in place to make the life of a cyclist more secure in the form of the Highway Code, I see no reason why the addition of a light is going to make drivers drive with any more care. I find this type of conversation counter productive as your average muppet driver will simply try and use it as another tool for victim blaming. I didn't see the bike as he wasn'tt wearing hi-viz or using a light.

Quote:

I also know from driving experience that it can be hard to quickly see cars (let alone bikes) when moving into dark shady areas from bright sunshine, and DRLs really conspicuity safety here.

Again I've never had an issue with this, I usually change my driving speed or am extra vigilant. The only lime a light would be useful is when the sun is in the eye line and the driver can't be arsed adjusting their driving style to suit the conditions, just like what it says in the Highway Code.

I was out for a walk yesterday and some of the roads are narrow and without pavement. The level of driving was truly atrocious, there appears to be an assumption that cars have some kind of divine right to be there and nothing was to impede their progress. I was brushed by one car, had two stop just before hitting me and numerous pass me dangerously close. Hi-viz or a light would not have benefitted me at all as I was easily seen, the drivers just weren't concentrating.
This country is a horrible place to be on the roads and I'm afraid comparing the UK to other countries won't wash either. The attitude here is different. For example, the scaffold wagon that tried to run me off the road had been sat behind me for two minutes at the traffic lights. If he hadn't seen me, how was it possible for his passenger to give me the bird as he was driving at me?
The people who punishment pass then justify it by telling me I should ride in the gutter?

All these victim blaming stickers telling cyclists not to pass them on the inside. Seriously?

And it's not just restricted to cars v cyclists. It's the pavement parker who blocks wheelchair access, it's the summer music being played loudly that annoys the neighbours, it's the queue jumper at the supermarket, it's the neighbours who block access for sporting/music events..... Etc...

It's a selfish country and until this is addressed there will always be a problem and a silly little light isn't going to resolve it.

....And breathe...

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ronin | 8 years ago
0 likes

I sometimes ride around the country lanes that are shaded by trees. You can go from a bright road to dark shade on a summers day.

I have a flashing light on whenever I ride; I usually ride routes that go past those kinda country lanes. And anyways, in the UK it always rains  4

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agingbrit | 8 years ago
0 likes

This is why I ride everywhere with my Fly6 rear light AND video camera running.

1) It's fun if riding with friends
2) It's way safer - drivers do see you better
3) Worse case when accidents happen - you have a legal record

Long term it also changes drivers behaviour - if they know potentially most bikes they encounter are running video - they will drive better around you.

Sad fact of the world we live in - but if it means safer roads - it is worth the investment. Just like body cameras.

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BigBadTrevsy | 8 years ago
0 likes

I've just got back from an 18 mile road ride with my young children. We all had front and rear flashing lights on. Here in the Chilterns, it's routine to go from very bright sunlight into dark beech tree shade. My own driving experience confirms that there's a small window of time when crossing from sunshine into shade, especially if wearing sunglasses, when it's really hard to see anything before your eyes adjust to the shade. That window is enough to hit a cyclist or pedestrian. I slow down, but plenty of drivers don't. A light reduces the risk. It keeps you visible even in the shade and it might save me from being run down. It's a cheap and easy way of reducing the many risks. What's not to like?

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TrekBikesUK replied to Ush | 8 years ago
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Ush wrote:
Quote:

I was in San Diego, and I’m driving along during the day,

Tells you most of what you need to know about this: a car driver that makes bike bits decided to make another bike bit.

No evidence presented as to the effectiveness of this at all.

Read our comment two posts up.

Avatar
ibr17xvii replied to TrekBikesUK | 8 years ago
0 likes
TrekBikesUK wrote:

It's unfortunate that there are those who think the Flare R was created either as a way for us to make more money, or to solve a problem that doesn't exist.

I would have to admit that reading the article that was my 1st thought.

What it has done however is provoke debate & that can only be healthy. It's certainly made me think about whether I need something or not.

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fukawitribe replied to ChairRDRF | 8 years ago
0 likes
ChairRDRF wrote:

From Road CC in 2018:

"TREND SPOTTING: Should we be wearing body armour on-road as well as when doing downhill mountain biking?"

Manufacturer X thinks we should be wearing their body armour/knee/shin/elbow protectors with full-face lids, although other stuff may be relevant and they don't want it to be compulsory.

...

I bet you it will come. Maybe before 2018. And, above all, do not expect any rational argument to dissuade the advocates.

Bet you it won't. See you back here in a couple of years.

Avatar
Ush replied to Yorkshie Whippet | 8 years ago
0 likes
Yorkshie Whippet wrote:

Can someone explain the followign to me?

As an mtber one of the first rules is never to look at something be it a rock or tree or whatever as you will hit it.
Yet on the road so many people are "shouting" "Look at me, look at me."

How come there are more rear enders as driver attention is attracted to the bright flashy light just like a moth to a flame?

To Trek and other light companies, How far ahead do you think a cyclist needs to make their presence known. Do I as a car driver really need to know that a bike is say a mile away or in heavy traffic 2 minutes away? At what point do you think it essential to let other know you are there or is it a case that people have all fallen into the brighter is better trap?

Good questions. Jan Heine posted this last year https://janheine.wordpress.com/2014/04/12/when-more-visible-%E2%89%A0-sa...

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mduncombe replied to Tartle | 8 years ago
0 likes

This is also how I see it. I ride in rural Somerset and even on a bright sunny day in summer there are some narrow lanes near me with dense tree cover extending right over the road, going from bright sunshine into near dark. I am very aware of how difficult it might be for a driver to see me when on such a lane and for this reason I started using daytime flashing LED lights.

As its not practical to switch the lights on and off all the time on a ride (you end up forgetting) I have now got into the habit of switching them on at the start of a ride and off at the end. I favour AAA lights over USB as I can always have a set of eneloupe rechargeables ready to replace flat ones.

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fukawitribe replied to ChairRDRF | 8 years ago
0 likes
ChairRDRF wrote:

For why it's victim-blaming and ineffective in both short (and certainly long) term see also http://rdrf.org.uk/2013/10/31/hi-viz-for-cyclists-and-pedestrians-sensib...

Just a quick point - the stopping distance figure in that article should probably be corrected viz

At town driving speeds, drivers can stop within 10 metres

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TrekBikesUK replied to Alankk | 8 years ago
0 likes
Alankk wrote:

If Trek sold the lights at near cost price, then I'll believe without any salt.
Like when Volvo gave away their patent for three point seatbelts, now that, deserve to be praised.

We aren't using proprietary technology in the Flare, so really anyone is already free to develop similar products.

Avatar
surly_by_name replied to Bill H | 8 years ago
0 likes
Bill H wrote:

Making lights compulsory in daytime will just be another layer of victim blaming to distract from serious safety concerns. While people argue the toss about helmets, hi-viz, vehicular cycling etc the real changes to our streets cape that are required are not discussed.

Once we have safe routes then individuals can campaign for their personal safety hobby horse (lucky heather compulsory on all new bikes) but until then try to stick on message and not get sidetracked.

When it comes to cycling, I tend to agree with Edna Moda that the approach should be (strictly) "no capes".

Avatar
wycombewheeler replied to jollygoodvelo | 8 years ago
0 likes
Gizmo_ wrote:

Just on the subject of car DRLs: in Europe they're now compulsory fitting on all new cars. http://ec.europa.eu/transport/road_safety/topics/vehicles/daytime_runnin...

I ride with a rear light on whenever it's dim/cloudy/rainy/etc.

A disaster for safety in my opinion. Research in Sweden found drl had no benefit to accident rates but actually increased accident rates for motorbikes (presumably because they no longer stood out) But if cars are going to be using them they will be more necessary for everyone else.

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