Is There A Limit To Bike Lights?

JAS

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Is a Streamlight Protac HL 5-X too much at 3500 lumens, either on high or strobe?
 

fulee9999

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depends..
high - is there oncoming traffic that might be blinded and crash because of you?
if yes -> too much
if no -> light up the valley, no issues

strobe - are you bored with the current integrity of your bones? or did you mean you would use the strobe at daytime?
 
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JAS

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depends..
high - is there oncoming traffic that might be blinded and crash because of you?
if yes -> too much
if no -> light up the valley, no issues

strobe - are you bored with the current integrity of your bones? or did you mean you would use the strobe at daytime?

This suggests strobe in the daytime and, at night, either a steady burn or a flashing light and steady burn combination.


Should I use my bike lights in flashing mode?

This is a popular question in the bicycling community, and the right answer depends on many factors. A study on snowplow safety found by Byron Ross on the Bicycles Stack Exchange site explains that flashing lights appear brighter to the human eye than a steady light at the same output level. Flashing lights grab attention faster, but it's also much harder to estimate the distance and speed of a flashing light than a steady one.

Although you will find many differing opinions, and we've yet to see a bicycling-specific study on this (although I'm told one is in the works at an undisclosed university in the midwestern US), these are our recommended best practices for when to flash:

  • Daytime riding: In broad daylight there is a lot of ambient light, so a steady burn light is unlikely to stand out. During daytime riding, it's a good idea to use your lights on the brightest, most attention-grabbing pattern they have, because it's easy for drivers to judge your position when your whole bike is visible, and you want to grab attention quickly.
  • Riding at night: High-intensity forward-facing lights should not be flashed alone at night, especially if they put out over 200 lumens. You run the risk of disorienting oncoming traffic (be it on 4 or 2 wheels), and make it difficult to estimate your position and speed. Having one flashing light and one steady light is a good compromise — you can grab drivers' attention but the steady light helps improve distance estimates. Avoid extreme strobe patterns though, and opt for a pulsing light (like on the Light and Motion Urban 700) or a subtler flash like Cygolite's Metro and Expilion series.
Rear lights tend to be less bright, and are therefore more appropriate for flashing at night; however, the same principle of distance and speed estimates applies. If riding with just a single light, using it in a medium-speed pulse mode (like those available on the Cygolite Hotshot and the PDW Danger Zone) is a good compromise. Using two taillights is strongly suggested though, using one in flashing mode and the second in steady burn. If you're upgrading to a new light, consider one with a rechargeable battery to use in steady mode, and use your old light in flashing mode.


How should I position my bike lights?

Generally speaking, lights should be positioned as far apart as possible. The further two points of light are away from each other, the further away the eye can distinguish them. Separating lights vertically also ensures that you will be seen by people in low and tall vehicles alike. For headlights a good setup is to have a primary handlebar mounted headlight, and a secondary light on the helmet. Good helmet lights should have a narrow beam and not be too bright - you want to be able to light up a specific area where you're looking without blinding everyone around you.

For taillights, a rack or seatpost mounted light in addition to a helmet light provides good coverage. More details on taillight placement are available on the recommended taillights page.


What do lumens, candlepower, and lux mean? How are they measured?

The three primary brightness units are Candela (luminous intensity), Lux (luminous flux per area, aka illuminance), and Lumens (luminous flux).

Candela measures absolute brightness at a point. In other words, it measures the amount of brightness going in only one specific direction. This unit is sometimes used to define maximum brightness of a light. The value for candelas is the same regardless of distance from the light, but will be different depending on the angle from the light.

Lumens measure total luminous flux, in other words the total output of a light source in all directions that it points. If you were to integrate the candelas measured in every direction around a light source, you would get lumens. Lumens are measured using an integrating sphere, a scientific instrument that uses a reflective sphere to normalize the light beam and measure its intensity.

Lux is lumens per area. If you project a light onto a surface and add up the total amount of light hitting it and divide by the area of the surface, you get lux. The brightness in lux depends on the distance at which you measure it. Illuminance is inversely proportional to the square of the distance, so in order for lux to be a useful measurement you must know the distance at which it was measured.

Lumens are the most commonly reported value for bike light brightness. Many manufacturers use an "estimated" or "specified" brightness based on the LED's specifications at a certain power level, but the actual brightness will depend on the circuitry used, how efficient the light's optics are, the temperature the light operates at, and the quality of the LED. Many lights' claimed lumens are 10-40% higher than the actual brightness. The ANSI FL1 Standard specifies a specific, repeatable method for measuring the brightness of a flashlight or bike light. Lights certified by the manufacturer with the FL1 Standard are marked with an "FL1" logo on the Bike Light Database.


Why do some bike lights cost so much when I can get a 1200 lumen light on Amazon for $15?

As explained above, many manufacturers overstate their lumen claims - especially no-name overseas manufacturers selling exclusively through online stores. While these lights rarely live up to their claims, they are always more than bright enough for most users. The primary disadvantage is in the build quality: these lights are typically designed to be as cheap as possible, and are not built with cycling convenience in mind. Battery quality in particular is often overlooked, and the battery packs are rarely waterproof and often the capacity drops significantly after minimal use. On the generic "Cree T6 LED light" available on Amazon that we reviewed, the optics focused the beam into a small, over-bright circle of light. Even with an extra diffusing lens, the light still only illuminates a small area. That area is as bright as day, but it's too small to be useful. Additionally, the external battery pack is inconvenient, and the lights often don't have a quick-release in a useful position for removing the light when you leave your bike outside somewhere. Finally, with no warranty or even a real company to support the product, you're on your own if the light dies.

These types of no-name cheap bike lights are great for people looking to get a lot of light at a low cost, but they are not a replacement for the carefully designed optics, superior mounting hardware, and light-weight integrated systems offered from real bike light companies.


Bike Light Batteries

Most USB-rechargeable bike headlights these days use a single 18650 battery internally, which is recharged through a USB port on the light. In most lights the battery is not user accessible. A few lights have a removable battery but contain the 18650 cell in a proprietary casing. For example, the image above shows the proprietary battery packs for the Cateye Volt 700, Cygolite Expilion, and Serfas TSL, along with a standard 18650 protected cell. If you want extras of these proprietary packaged batteries, you have to pay $30-50 for a single battery pack which can't be charged in a standard charger or used in any other lights. With a few lights like the Fenix BC30, BC21R, and the Lezyne Super Drive XL), the batteries are directly accessible. This means you can get as many extra batteries as you want, swap them out any time, and charge them with any standard charger. For people doing really long rides, or who just don't want to worry about running out of charge on a ride, this setup is a great choice.

Bike taillights more commonly use lithium polymer battery packs (similar to those in cellphones) because they can be manufactured as smaller, flatter packs. Taillights usually don't draw as much power as headlights do, do these lower-capacity packs are possible. I have yet to see any bike taillight which takes a user-replaceable 18650 battery. If you see one, please let me know!

You always have to be careful when handling 18650 batteries. They have a very high energy density, so if they're overcharged, overdischarged, or shorted they can cause a fire. Some 18650 batteries are "bare cells". In certain lights they can give higher performance (although it shouldn't make a difference for the Fenix and Lezyne lights mentioned), but are more likely to become a hazard if not taken care of. Protected cells have a small circuit built into the top of the battery which prevents overdischarge, overcharging, and short circuits. The protection circuit adds a couple millimeters of length, so they won't fit in a few lights, but they do fit in every 18650 bike light I've tested. In general I would recommend protected cells – they cost a tiny bit more, but it's worth the extra peace of mind in my opinion.

Many low-quality super-cheap generic Chinese lights use 18650 batteries. Some are fine, but many of these batteries are extremely dangerous and most are low-quality. It's very common for the battery's actual capacity to be much less than its stated capacity. For example, 18650 batteries sold under the "UltraFire" brand often claim 4000+ mAh of capacity. In reality, the highest capacity 18650 available as of spring 2016 is 3600 mAh, and independent testing has found the UltraFire counterfeits to only be about 900 mAh cells in reality. These cheap cells are also less likely to have a protection circuit, and the construction quality is usually very poor. For safety reasons, most lighting enthusiasts strongly recommend only purchasing and using 18650 cells by reputable manufacturers and sold by authorized dealers.

The cheapest high-quality and high-capacity protected 18650 batteries available are the KeepPower 3400 mAh, sold by Illumn.com. At $11 each, they're about half the price of most other 3400 mAh protected cells, and use the same Panasonic NCR18650B cell inside as name brands like Nitecore and Olight. These are the top choice of many flashlight addicts, and it's hard to find a better bargain.




You could check out a light that has a beam cutoff so you dont blind anyone. Maybe youre offroad and dont care though in which disregard. Im happy with this one.

https://www.amazon.com/dp/B07WFDRPW8/?tag=cpf0b6-20

Or go big and get a Lupine.

The Lumintop looks interesting.

I also learned that there is a German standard for bike lights. I did not know that until today.
 

fulee9999

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to be honest, at daytime the best you can do is a hi-vis jacket and helmet if you really want to be seen, and in the night some reflective elements on your clothing ( reflective stripes really stand out at night in a cars headlight ) and/or bike and a red tail light, and a white ( strobing ) front light, even a single rechargeable led will do.
if you also need it to illuminate where you're going, you can mostly use any light, just don't blind people
 

turbodog

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to be honest, at daytime the best you can do is a hi-vis jacket and helmet if you really want to be seen, and in the night some reflective elements on your clothing ( reflective stripes really stand out at night in a cars headlight ) and/or bike and a red tail light, and a white ( strobing ) front light, even a single rechargeable led will do.
if you also need it to illuminate where you're going, you can mostly use any light, just don't blind people

Gonna have to disagree with that daytime statement. I've ridden my whole life. The day-glow jerseys... they are nice, but cars didn't start slowing down and moving over till I went to a high brightness rear flashing light.

Several studies show that drivers drive CLOSER to riders wearing 'bike gear and helmets' because they view the rider as a 'pro' as opposed to a casual rider.

Have upgraded as new models come out. We are current 350 lumens red flashing right now.

To answer the OP:

I run 350 on the rear and a 1000 lumen zebralight strobe flashlight up front. I'd say that daytime riding... I'm well in diminishing returns up front. Rear could probably double/triple. Adding some off-axis reflectors/prismatic lenses would be nice.

This is going from noticing car behavior around me and seeing other riders with this exact same setup at a distance.
 
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fulee9999

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Gonna have to disagree with that daytime statement. I've ridden my whole life. The day-glow jerseys... they are nice, but cars didn't start slowing down and moving over till I went to a high brightness rear flashing light.

Several studies show that drivers drive CLOSER to riders wearing 'bike gear and helmets' because they view the rider as a 'pro' as opposed to a casual rider.

Have upgraded as new models come out. We are current 350 lumens red flashing right now.

To answer the OP:

I run 350 on the rear and a 1000 lumen zebralight strobe flashlight up front. I'd say that daytime riding... I'm well in diminishing returns up front. Rear could probably double/triple. Adding some off-axis reflectors/prismatic lenses would be nice.

This is going from noticing car behavior around me and seeing other riders with this exact same setup at a distance.

Oh yeah, I didn't mean day-glow jerseys, if you look like someone who just got lost from a tour de france, people will assume you're not bothered by trucks doing 50mph a foot away from you, I meant something that stands out, like so:

1654900218595.png


also the stripes on these are great at night for motorists to notice you
I do however disagree with the helmet part, get a nice helmet, if you ride around cars get a helmet in a vibrant color, hi-vis green, or pink or whatever, so your head would be visible above cars

1654900475129.png

this one protects the back of your head as well, for when you get rear-ended

oh, and yes, do agree with the nice tail light, something nice and visible, even a good one isn't that expensive
 

LEDphile

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Oh yeah, I didn't mean day-glow jerseys, if you look like someone who just got lost from a tour de france, people will assume you're not bothered by trucks doing 50mph a foot away from you, I meant something that stands out, like so:

View attachment 28782

also the stripes on these are great at night for motorists to notice you
Right, you want to look like someone that wandered away from a road maintenance crew, not someone that wandered away from the Tour de France. An ANSI Class 2, or even better, Class 3, high-visibility vest is going to make you more visible both during the day and at night.
 

raggie33

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my rear is crazy bright i had no idea how bright till i saw it from real far behind in the daylight
 

jtr1962

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Gonna have to disagree with that daytime statement. I've ridden my whole life. The day-glow jerseys... they are nice, but cars didn't start slowing down and moving over till I went to a high brightness rear flashing light.
Same observation here. Back when I had a rear flasher with a few 5mm LEDs, sure, I got noticed, but the difference was dramatic when I replaced those 5mm LEDs with a red power LED putting out north of 50 lumens. I noticed drivers were suddenly giving me a much wider berth. I hadn't thought of upgrading further to several hundred lumens, but it's not a bad idea.

And yes, I have the rear flasher on all the time, day or night. I seldom ride in the day anyway, but when I do it makes me more conspicuous.
Several studies show that drivers drive CLOSER to riders wearing 'bike gear and helmets' because they view the rider as a 'pro' as opposed to a casual rider.
Heard the same, and have seen it in action. Car goes by me (not wearing a helmet, street clothes), 5 foot berth or more. Car goes by a guy with all the gear half a block away, misses him by 6 inches. They see those without gear as actual human beings, those with gear more as some kind of mechanical thing riding a bike. The fact you look a lot more fragile and vulnerable without gear also has something to do with it.
 
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bykfixer

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I'll comment as a driver not a rider.
First off in daytime;
The type of bike and speed it's traveling makes a difference to how I interperate things. A narrow hybrid or road racer type with the rider going a nice steady rythm is seen as less prone to do something squirrly like suddenly swirve into my path. If the person is dressed like a pro, or some person wearing hi-viz gear does not matter. Nor does having lights or not. I give that rider at least 3 feet just in case they are unaware of me passing them. Sometimes I'll lightly tap my horn 25 yards or sp before passing if they have a mirror. Thought there is they may know I'm there and won't turn their head to look back at me.

Now the single speed beach bike type with a person peddling real slow gets a wider berth simply because they tend to wobble back and forth. Again, clothes or lights does not matter. I see them long before I need to decide how to pass by.

At night:
Flashing lights on the rear are ok but moving reflectors like reflective leg bands helps me decide their distance better. Reflective shoes, peddles, that sort of thing. Driving a car or truck, I can see those fine. Additional reflectors make it so I can see them from a farther distance. Red reflectors on the rear also helps with judging direction of travel of the cyclist. Most safety vests do not have red reflectors on the rear but using a sharpie to add some red spots on the rear is what we do on our night gear for roadwork. Red on the rear of our helmet, red on our vests.

If the rider is obeying rules of the road in my state they are on the opposite side of the road when approaching me unless on a sidewalk called "shared use path" but even then they are at a safe distance. But again reflective clothing probably makes the most difference. Reflectors across the chest and sleeves, along with helmet helps identify the object as a cyclist from farther away.

Again, as I driver:
I cringe when I see a cyclist at sun rise or sun set knowing at some point regardless of how safe they think they are the sun in the driver's eyes can make it so the only thing the driver sees is that dam bright light in their face.

The vast majority of cyclists killed in my state were riding at night, wearing dark clothes and travelling unsafely. ie near a roadside ditch and suddenly swirved into the path of the driver that hit them. But since pedestrians and cyclists take precidence in my state the driver is all too often cited. Cool or cold mornings when people tend to drive with fog'd or frosted windshields can also be hazerdous to the cyclist. You may have seen people driving with a tiny hole of cleared windshield leaving their field of view very narrow.

As a rider:
No headphones……ever. I use my ears as extra eyes. I take note of normal sounds like swooshing of tires as cars go past. If I hear sand that collects on the edge of the road, move over if I can.
Add a rear view mirror. The bigger the better. Flat allows faster judgement than a dome. If you're a gram counter take it off on race day. That wee extra bit of wind resistance gone on race day might help you ride faster anyway.

I don't ride very often and always in daytime. If I wear a helmet it's a ProTec skateboarder helmet similar to rock climber that stays put upon side impact. The turtle shell for kids should be outlawed!! Most people have no clue how to properly wear them, which makes them only good for protecting the melon from falling objects like space junk and it creates a false sense of security. They make "good" turtle shell kind these days but the average newb won't pay $150+ for a helmet. Me neither, which is why I wear a $35 ProTec.
Inflate tires properly. Insta-flat (POW) can cause the rider to wobble suddenly. Yikes!
Unless a seasoned rider one should consider a bike rider class so they don't end up like a former gubner in my state who fell and broke his wrist crossing railroad tracks one day.

Driver perspective again:
I can honestly say I have never been blinded by an approaching cyclists front light. Yet the flashy kind can be an annoyance if it's real bright. Use low output for flashy's and steady outout for the guiding light.
 
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the.Mtn.Man

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My general rule: When riding your bicycle at night, you can never be too visible.
 

JAS

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Is the Fenix BC30 considered a flashing light or modulating light?


 

Chicken Drumstick

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Using strobe is a silly idea IMO. Why would you want to dazzle and disorient cars coming towards you. Let alone be off putting for the rider of the bike also.

Blinding oncoming vehicles is a bad idea too with mega high lumen outputs.

Bikes have been about for a long long long time. No need to try and reinvent the wheel with regards to lighting. Plenty of well established and legalised requirements for vehicle lighting in almost every civilised country the world over. Just to stick to those and common sense.

Ie if you want to illuminate yourself, have a bright light off the frame or under the saddle the points down. It won't shine at or blind anyone. But will light you up and the road around you massively increasing your visibility to other road users.
 

DRW

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Using strobe is a silly idea IMO. Why would you want to dazzle and disorient ...
It's flashing (blinking) mode for enhanced visibility during the day. It is a significant safety enhancement for cyclist.

It's not a strobe in any way.
 
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bykfixer

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FBB05B21-B70B-4C61-8B82-FE5A68861E22.jpeg

This is too bright.
A really bright strobing light on a police car was causing me to say "holy crap, turn that dam thing off" from a 1/4 mile away.... in the daytime....

In other words don't do that to your bicycle. It's annoying.
 

kj2

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As a Dutchman cycling many kilometers each year, I would say; get a light with (German) Stvzo approving and angle your light to spec.
Have a Lupine SL AF 4 on my bike. Uses a lens system just like many cars on the road. Beam is angled towards the road instead of straight forward. Can tell you.. every road user will see you clearly if they pay attention. Flashing lights is a no-no in so many countries. Yes, it may be (extra) visible but you also move when that light is Off. And with flashing you risk the chance of blinding others.
 

The Hawk

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I enjoy riding my bike, but only ride in our subdivision. It is a large subdivision with over 1,000 houses. The main road is double wide on each side. I always have my red, rearward flashing light on. I wear highly visible clothing and if I ride at night, I have a couple lights on my handlebars. It is not unusual to see bikers riding at night with no lights at all.
 
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