cyccommute, that's interesting what you say. I'm going to see if the lux ratings are supposed to be done from a standardized distance. I certainly hope so, but you've raised doubts. And because of the inverse square law, the closer they measure, the bigger the potential for mismeasurement and fraud.

I did not read this whole thread so I'm not sure if it has been mentioned. They do have the Ansi F1 standard for flashlight.

http://flashlightwiki.com/ANSI-NEMA_FL-1

Many of the top name flashlight manufacturer uses this standard as a rating of their flashlight under using this standard. It also worth mentioning that reviewer of flashlight over at CPF also test the flashlight they reviewed using this standard.

I noticed bicycle light manufactor has yet to catch on. Don't get me wrong, I know there will be differemce when comparing a bike light with cutoff vs one without cutoff when using the Ansi standard, but it does comes in handy when comparing light with similar design.

Here is another interesting site, they look only at lumens (measured using an integrating sphere).

http://reviews.mtbr.com/2014-mtbr-bike-lights-shootout

I think there is such a thing as too much....
... but what that is keeps changing over time.

http://www.youtube.com/watch?v=dL9_Tldmrhs
http://www.youtube.com/watch?v=gBuiPZm6hK4

For the Lumotec lamps, I think they are measuring them at 5m which is about 1 car length. At 10m (about 2 car lengths), the lux would be around 30 for a 500 lumen and 40 for a 600 lumen light. My old halogens would be rocking a lux of 97 at 10m;) I may have to dust those off again.

Really? Why would that be? What lumens would that be at 10m? MagicShines are rated at 1000 lumens and most testers downrate them to around 500 lumens. It takes four 3.7V 18650 lithium cells to feed the LED's thirst for amp/hours. Do tell the wattage of halogen bulb(s) you were rocking in that obsolete light, and the other pertinent details of battery capacity and run time or your post becomes nothing more than suspect.

H

1. Lumens are a measure of the luminous flux of visible light from the source and aren't distance dependent.

2. Magic Shines and other single emitter lights claim 1000 lumens. Their actual output is dependent on the emitter used. A Cree XM-L T6 emitter can put out around 700 lumens under the best laboratory conditions. The actual output is probably lower. I've seen integrating sphere data that puts Magic Shines in the 600 to 650 lumen range,

3. The number of 18650 cells required to run an LED is 2 to get to the required voltage. You could run a Magic Shine on two 18650 cells for about 1.5 hours while 4 cell 2S2P packs tend to run for 2 to 3 hours in my experience. The charge capacity of 18650's depends on a number of factors but most of the ones I've seen for LED runs around 4.4 Ah.

Finally, you can find details on the old halogen lights I ran here. I still have several sets but I have to redo my battery packs to run the packs in series instead of parallel or get 14.4 V packs. I used to run 3.3 Ah to 5.2 Ah packs and got from 1.5 to 2.5 hours.

I suppose this subject has been flogged.

But here is an interesting article:
http://en.wikipedia.org/wiki/Luminous_efficacy


The halogen bulbs are incandescent, so black body radiators, and when you "over amp" them, they get brighter and their color shifts towards the blue.
That means more energy emitted nearer to yellow light where human eyes are more sensitive.
Because of the color shift at higher filament temperature, their efficacy increases. And these bulbs can be overdriven with only some loss of lifetime.

LEDs cannot be easily overdriven because their efficiency drops as temperature goes up, and there is also the danger of thermal runaway leading to possible destruction. LED's are usually driven by constant current to get constant intensity, incandescents can be driven with a voltage or current since they are resistive.

Based on that data, for a given light duration, the halogens should require a greater battery capacity compared to LEDs at the same light intensity,
because they would use more power. Also, halogens emit much more energy than LEDs out of the visible region, for example, as heat.

A long time ago, I knew someone who had a 12V Diehard battery (on a rear rack) running a ~50W halogen headlight, yes it was very bright and very heavy.

My take on this thread is that although many of us think our lights are more than bright enough already, others want more.

Although volts, resistance and amperage are related, we used to run halogens at a 20% higher voltage when we overvolted halogens. The light output is proportional to the voltage cubed and the luminous efficacy is is proportional to the voltage to the 1.3 power. However the life of the bulb is proportional to voltage to the -17. The loss of lifetime is on the order of 90% when running at 20% of nominal voltage. Since most halogens have about a 5000 hour life time, you still get 500 hours of useful light. And halogen lights are cheap.

The problem is that LEDs have the capability to put out 150 lumens/watt but they are running more in the 60 lumen/watt range. Overvolting a halogen gets you more lumens/watt. A 20 W MR16 run at 12V puts out 42 lumens/watt. Bumping up the voltage to 13.2V, gives you 50 lumens/watt. Bumping up the voltage to 14.4V, gives you 62 lumens/watt. This is a better efficacy than HID and on a parr with current LEDs. LEDs will get better but it's going to take a while.

An 20W MR16 run at 14.4V will put out just about as much light as a 50W bulb run at nominal voltage. And, from my experience, you don't need a car battery to run one. Lead batteries really aren't that good as a power source.

I agree with all that you said.

And I agree that measuring lux at 10m would be a good standard method for bike lights.
That would mean, 10m on axis, with very little reflection from other surfaces

BTW, this link shows how MTBR measures lux in a 10' x 10' room
http://reviews.mtbr.com/httpreviews-...ights-shootout


They get a direct conversion from lumens to lux shown here:
http://reviews.mtbr.com/2013-bike-li...-lux-vs-lumens

I've been reading (and have posted) in this thread from day 1, and IMHO, I believe that you are missing the point on bicycle lighting. To explain this, I prefer to give a real world example with a couple of different light I already own and use on my nightly commutes.

I recently bought a MagicShine clone supposedly rated at 1800 lumens which had a very bright spot beam which only a very small portion was utilized for viewing the road (city streets). After a fellow forum member suggested, I went ahead and purchased a diffuser lens which replaced the original clear lens and threw a much wider beam across my path, with a big hit on the distance ahead, but overall a major improvement.

And for the comparison; I have a B&M CyoT (properly aimed via the instructions) driven by a dynamohub on my other bike which is rated at 60 lux, with my guesstimate of around 200-300 lumens (compared to other quality lights I've seen).

Even though the MS has a more powerful light source, the CyoT is a far better light for commuting since the optics on it almost 100% utilize the light with almost no side spill and total vertical cutoff. I have never been told of having the light shine onto cars or pedestrians, or fellow cyclists, which is not the case with the diffused MS.

At least in the urban environment, more is NOT better if you have the majority of the light shining on everything except where it should be focused on.

That's my 0,01 cents and I hope I didn't come out condescending.

Good point. At one time lights were usually mounted on the fork crown or even further down the fork. Now most people have them up on the handlebars, which is higher than the position of all but the largest trucks and 4-wheel drive vehicles. So that's going to make even my 350 lumen light seem more dazzling than it really is.
Hard to say where the happy medium is.

+1

people don't have an understanding if they haven't used an excellent dynamo powered light built to the standard provided within the Straßenverkehrszulassungsordnung (StVZO).

http://www.gesetze-im-internet.de/st...067910012.html

I don't total disagree but for different reasons. However, a couple of issues to address first. It is helpful if you use the "Reply With Quote" button when you reply to posts. Using lets everyone know to whom you are addressing your comments.

It took me a long time to understand why the "1800 lumen" claim on lights was wrong. I'm not an electronics guy but I can learn. The Cree emitter that is used on these lights has a maximum output of around 700 lumens. The claims of 1800 lumens is highly inflated and I wish that the manufacturers wouldn't do that but they do. We just have to live with the claims and understand that the output is more realistically in the 600 to 700 lumen range. That, by the way, is about what a car provides per lamp on low beam. Now on to the lights.

I think you are misunderstanding what you are seeing for the clone. Magic Shine and their clone lights use a reflector that is about a 35 degree flood light. That means that the light intensity across the beam is greatly reduced. It will have a central hot spot but all lights have that. The rest of the light will be spread out over a large circle on the ground. When you add a diffuser, you are increasing the diffusion of the beam to something similar to a 50 degree flood light. If the light were evenly spread over the beam, a 35 degree 600 lumen light has a lux of 77. Diffuse the light over a wider area with a wider angle and the lux drops to 35. Going to a diffuser or even a wide angle flood light shots more of your light off into directions that you don't want it to go.

Going to a tighter beam puts more light in a smaller space, which is what the CyoT does as well as other tighter beam spot lights do. All you've done is purchase a narrower spot light and noticed that you have a better beam. I use a spot light...not a Magic Shine clone but another type of LED...which has a reflector angle of about 20 degrees. Back in my halogen days, I use a beam that was 12 degrees and a 7 degree spot. Because of the very tight angle, you don't get much spillage outside of the beam's hot spot and glare is reduced. In fact the 7 degree beam was too tight. You need a little spillage outside of the beam or you end up with tunnel vision.

I agree that more isn't better if you diffuse the light all over everywhere. But I don't do that. I want...and get...a bright coherent beam that lights up what I need to be lighted while still providing enough illumination to be seen against a sea of lights in an urban environment.

But that's my point, that the CyoT isn't a spotlight, and it definitely isn't as wide as a MS with diffuser (clone or not). There's a specific pattern emerging because of the optics which covers the needs of a commuter (at least mine).

Here's a beam pattern taken directly from the manufacturers site which shows the pattern (not conical as a spotlight would be) which resembles a car's headlight without the center line cutout which exists on cars so they don't blind the drivers coming in the other direction.

http://www.bumm.de/typo3temp/pics/0adbb1199c.jpg

honestly, i think that most won't understand it until they use one.

it only highlights what's necessary, which is very nice when commuting in darkness, rather than everything, which i find completely useless as one's eyes don't adjust to the dark as well.

more is not better when it comes to most things, including bike lights.

Look again. That's a spot light and a pretty tight one at that. It illuminates a "spot". Compare it to the Magicshine MJ 816E (a very floody light) or the Lupine Betty 12 (a tighter beam light) on Torchy the Battery Boy website

Your eyes don't "adjust to the dark" if you are using any kind of light other than a low intensity red light. Even the light above will completely saturate the rod cells in your eyes and render you night blind. You can see a little outside the main beam of the light because of the normal light spillage but if you were to turn off the lights and tried to walk around in complete darkness, it would be difficult. It would be impossible to ride a bike at any speed above walking speed. Don't believe me? Try it. Get away from any ambient light and see how long it takes before your rod cells relax enough for you to actually see enough detail to navigate.

The picture is also playing fast and loose with the photo set up. If they had pulled back and shined the light on the black part of the pavement, you'd see that less isn't necessarily better, either. Without that white surface to reflect the light, the black pavement would have swallowed the light and given us a better representation of what happens when you go to less light.

I think my Niterider 1800 is at 1800lums or very close to it. Its defintely not a 800 lum lamp.

The brain processes contrasts, which is exactly what the photo presents, so it is gaming the system slightly.

I don't know about you, but I don't ride anywhere without huge textural contrasts, usually in the form of water pooled on the side of the path/road, just like in the photo, or where the surface is painted, or where individual textures are interlocked.

I can't remember the last time I peddled anywhere that had a uniformly solid dark, darker or darkest background so I think your point is moot.

After all this discussion on lights, I finally took the time tonight and passed by a friend who has a auto-body shop and built the following base for the MS clone...

http://farm6.staticflickr.com/5524/1...5bd3a560_b.jpg

http://farm8.staticflickr.com/7409/1...84230f40_b.jpg

http://farm3.staticflickr.com/2867/1...27ccba3c_b.jpg


Tremendous difference from it's last position on the handlebars. Now I can clearly see even the most minute of road surface abnormality for a distance of at least 7 meters (around 20 ft). Because of the positioning closer to the road surface, I think I can get away with changing the diffuser lens back to the original clear lens.

Unfortunately I couldn't take any photos because it was raining, but I will take some photos asap with before and after pictures with both clear and diffuser lens.


BTW, the actual base was taken off some sort of electronics mount (ECU maybe) from a 5 or 7 series BMW, and when cleaned and polished should look like it was developed specifically for the MS lights.

Looks good. For version 2.0, I recommend a way to adjust the vertical angle. You'll want to point it up when traffic is light and down when it's heavy. I do that with my headlights.

Actually because of the diffuser (probably), it seems perfect, and it doesn't blind anyone on the streets since the beam reached a little below the rear truck lid on most sedans while I was stopped behind them.

Now any ideas on how the !@#$!$! wiring can be managed?

I liked the cutoff of the beam.
So the add on diffuser helped make this beam change? I think I've seen these advertised.

BTW, you might want a little more wire length going into the light head IMO.
Also, I usually use tie wraps near the ends of where wires spiral around brake/shifter cables (do not make them too tight).
Otherwise, the spiral section can slide around, and perhaps wear out the wire over time with vibration.

Not sight unseen .. can you solder ? do you have a place to buy heat-shrink tubing
to cover wire connections?

B&M has twin lead wires with the plugs on them , either on one end or both.

I just ordered a B&M double ended wire to cut and strip
for the short distance from the Brommy Fork crown mount to the Hub,
and use the other plug end to redo the taillight wire a bit longer ,

it already had the plugs on it for the taillight , but, it takes a more indirect path
to the rear light, than a regular diamond frame Bike ..

the plugs and the terminal pliers to make the connections are available
Peter White is in the US , but his website has how to suggestions.

in Greece , You would go through a German seller, I expect.