The paths are patrolled and nothing slows down your commute like being stopped and explaining to the police why you are on a closed path. Checking your ID, checking you background and writing a summons can take an hour or more. I'd rather get home.
Just giving a lux number for a light tells you nothing about the light without the distance to the target. To put it in chemical terms, I have a reaction with compound A and compound B going to compound C. If compound A has a concentration of 4 moles per liter and compound B has a concentration of 2 moles per liter while compound C has a concentration of 6 moles per liter, how long has the reaction been going on and what was the starting concentration of A and B? You can't tell me because you don't have enough information. If I told you a rate constant, you could figure out the problem but without it you can't.
Same holds for a lux measurement. Without knowledge of the distance to the target, the measurement is meaningless. If I have the lumens, I can calculate a lux at any point from the source to infinity. I can't determine if the light is bright or not based on just the lux measurement. A 29 lux light could be a 1 lumen light measured millimeters from the source or a million lumen light measured 10 km from the source. I can't tell and neither can you.
My wife runs this on her commuter, at 40 lux it is the equivalent of a 3 watt LED and runs off a generator hub.
The output is more than adequate to see and be seen, the daytime lights are excellent, and it has a high beam cutoff and standlight... the matching rear also has a standlight and voltage sensor that brightens the rear light at stops like a car or motorcycle.
European lights now come in versions that have twice the output and one thing that sets them apart is their high quality lenses and high beam cutoff that keeps you from blinding other road users.
I would like to take all these tactical flashlights and shove them where the sun doesn't shine and North American Cyclists shoulds be pushing for better regulations on bicycle headlights as it might get us a little more credibility and respect.
I'll second Sixty Fiver... have been running the following on my tourer with 60 lux and daytime running lights and am very satisfied with the spread of the beam and it's intensity. Whenever I use my tourer in the city with this light, I have people telling me that I've left my front lights on (the four bottom leds + 20% of the main led), which means that I can and am seen.
I had to change my rear dyno light because of a capacitor fail, and opted NOT to get the brake-light function since I believe would confuse the already dazed and confused drivers where I commute. I ended up getting the following which cost next to nothing (around $18) and has a very bright light, seen for 320 degrees. It of course has a 4 minute stand-light function, but unfortunately no off switch, which I believe is needed when you reach your destination and don't want the rear light on when you've walked away from the bike.
Telly, I plan on getting a Cyo for my Moulton which rolls out a little faster than my wife's commuter... it is another great light.
Therefore, I know that the light company has done the necessary measurements so that I know it works in a particular manner, hence I know that it's over a threshold performance.
As far as lumens goes, it's just a crapshot measurement that doesn't state when the light actually goes. In addition, it's grossly exaggerated by most makers, because the US doesn't have a mandatory testing service that must be undertaken before a light enters the market. So, when I see lumens, I know that 99% of the time there's no quality minimum that has been surpassed.
Yes, you're blocked as I find your comments distracting and really you want I'm totally bored.
cyccommute, some of us are happy with our lights, even though they are different from yours. It might pay for you to acknowledge that and also the fact that our reasons are not due to our ignorance or stupidity.
Sorry. I must have misunderstood you. When some of us say why we like our lights, you point out a problem you have with them. I took that to mean that you feel we're overlooking something important.
OK calm down.
Lux or lumens... the real problem is these metrics do not tell you how it will work for you under your riding conditions.
Lumens usually means the total luminous flux emitted (in all directions), and Lux is lumens per sq meter (so where do you position that square meter).
And light falls off with distance. What is not quantified is the shape of the emitted beam.
If you want to ride at say 20 mph in total darkness, you need a very bright light to see both what's coming up and the obstacles.
But a person on the trail/road coming toward you will be blinded by that much light.
We need lights with more abrupt cutoffs so you can see the trail surface without blinding oncoming people.
A helmet mounted light can be good because you can steer it away from oncomers.
And, I use my helmet visor to block the bright lights coming toward me.
I've been commuting 20 years, and the lights are MUCH brighter than they used to be.
If you are in bright city lights in every direction, then you simply need very bright lights, or many lights, or luck to stay safe.
Some of it doesn't translate so well into English, but this guy gives it a shot and does complain that it's not precise enough.
I detect some connection to the discussion.
Germany has regulations and specs on bike lighting, including specs on cutoff.
The vendors can meet these specs and therefore sell to the market.
But, it all breaks down if the user aims it incorrectly or ignores others.
If the person does not care about others, there is probably little to be done, other than giving them some feedback.
Another point is that if there were lights available that were both bright, and had a good cutoff, some of us would buy them and aim them correctly.
I made my own collumator from a plastic lid, to help reduce light intensity where it's not needed, but it's not ideal.
For those riders with very bright lights coming towards me in pitch darkness, I have my visor, ....
Light doesn't just "fall off with distance". Light intensity decreases in proportion to the square of the distance. So if the light has an intensity at point A of 1, if you measure the light at point B which is 2 times the distance of point A, the light isn't half as bright but the intensity decreases by 4 times. That's the problem with stating that only the lux of a light should be used for comparison. If you don't know how far away from the source the measurement is made, you can't really determine how much area is being illuminated. With lumens, you can calculate a lux...which is a useful measurement...at any distance. That will tell you a lot about how bright the beam will be. Without the distance measurement, you can't back calculate the lux for varying distances.
On any beam, you can assume that the beam shape is going to be roughly round. Even with cutoffs, the beam will eventually assume a round shape since it is going to be spreading out in a cone from the source. It may take a little while to assume a conical shape but it will get there.
As for light brightness, I have to disagree here too. LED lights are currently about where high end halogens were around 2000. You can force about 700 lumens from an MR11 halogen by overvolting it. LED emitters are currently putting out about that amount of light. If you go to an MR16 halogen, you can overvolt it and get out 1500 lumens from a single source. You can gang up several LEDs and get that kind of output but the throw of a single source 1500 lumen lamp is much, much further than that LED. Back when I used halogens, I could throw a coherent beam across Crown Hill Park lake and illuminate the trees on the other side of the lake. That's a distance of almost 0.5 miles. Haven't been able to do that with any LED I've used so far.
I guess I should be happy that someone agrees with at least one thing I say....
I agree with you that lux and lumens are good to know and compare.
And agree that the distance from the source is required to give any meaning to the claimed light intensity.
Of course, there is marketing... we do not always get that info. Others may disagree.
I recall that the inverse square law applies to a point source of radiation.
I'm pretty sure light falls off less rapidly when well focussed... (extreme case of shining a laser spot on the moon)...
Any light source, at a sufficient distance, does behave as a point source (divergent beam)
Others may disagree.
Overall bike light brightness: I was refering to, then and now, the brightness with "off the shelf" bike lights.
I think they are (on average) brighter now, due to LEDs and batteries. Others may disagree.
It's probably true that a bike light cutoff would work best if all roads and trails were flat,
so at 50 feet, the light intensity created in the first 2 ft above the ground was bright, and much less bright above 2 ft.
Since the world is not flat, having a bike light cutoff is sometimes no help at all. Others may disagree.
I like the idea of having a cutoff, I'm not saying to make them mandatory, just a choice.
Others may disagree.
cyccommute, I agree that lux ratings don't mean anything without specifying distance. I'm going to bet that bike light makers are assuming some sort of standard distance such as ten meters, which means that the ratings might very well have meaning.
Lest anyone believe that there is nothing here but arguments from irreconcilable opinions, I eagerly await a 1200 Lumen Cree XML T6 bike headlight (Amazon) to replace my Ultrafire, although the flashlight is performing acceptably. It was on someone's recommendation on one of these threads, I think cyccomute.
I kind of believe the claimed 1200 lumens even, or close to at least, and even though it's vague for describing how well a light will illuminate the area of most interest, I'm pretty confident that illumination volumes are similar enough between headlights that a higher number (if it is realistic) will be relatively brighter in practice. So I am optimistic and all is not as dark as it may seem here.
Although no one used an MR16 in an off the shelf unit, there were plenty of home brew systems around that put out 800 lumens at 12V and a few tinkerers that made lights that put out the 1500 lumen lights. Halogens are power hogs, especially the MR11 but an overvolted MR16 has about the lumen per watt output as is currently available with LED. LED has the potential to go to a much higher lumen/watt output but they aren't there yet. I currently get about the same run time on the same amp-hour battery with LED as I did back in my days of halogen.
Lux is a measurement that could, potentially, be even more inflated than lumen measurement. As I showed above, I have a million lux light if I measure in the right place. Because the lux measurement is so distance dependent, even a little variation in the distance can throw the measurement off. For example, Telly says he has a 60 lux light. Assuming 10 m distance, that means that the light is pumping out 1300 lumens. I find that value a bit hard to believe. If the lux measurement is made at 5m, the lumen output of his light is 330 lumens...a value that is more believable.
I went over to Peter White and looked at some of the Lumotec lights. He has a chart on the Luxos lamps. The claimed lux is 70 or 90, depending on model. At 10m, that's a lumen output for a dynamo lamp of 1500 lumens and 1971 lumens, respectively. I kind of doubt that you can get that kind of output from a dynamo. At 5m, the lamps have a lumen output of 380 lumens and 500 lumens, respectively. Both of those lumen values are more in the range of what I've seen for dynamo outputs.
This just goes to show that assumptions can be tricky. They are often wrong.
I have 2540 lumens between my Niterider Pro 1800 and Cygolite Turbo 740. The NR is mounted on my helmet on flash mode, the power is amazing...it has the capability of freezing cars in time and space if I want to.
That said, i am looking for a brighter 3000+ light in flash for the helmet, so that the Niterider can join the Cygolite on the handlebars to luminate the runway for me.
Does the lupine betty have flash mode?