Night riding and lights



randochap said:
As far as light output, etc. let's just note that not all lumens are created equal so this measurement can be misleading Lumen quotes do not tell us much about the "kind" of light that gets put down the road. All I can say is that the light output from an Edelux light for instance is truly stunning. I can't imagine that that I could benefit from any more light. I can comfortably descend at 50+kph on unlit, narrow winding roads. Motorists will dim their headlights a kilometre away.

Actually, there is nothing at all misleading about "lumens." A lumen is a watt weighted to the photopic response of the human eye. Therefore, a lumen is a measure of power output. Power out is power out. It's cut and dry. There are other factors, though. A big one is the sensitivity of the human eye to the spectral range of the light being used. The human eye's spectral range is centered at a green/yellow wavelength. That's no surprise. Our sun's visible spectrum is basically centered there. What this means is the eye is most sensitive to light that is yellow/green, like the Sun's output. What this means for LED users is that blue white light--that some LED's use--isn't ideal for human's to see by at night. Not only will blue-white at a given frequency seem less intense than yellow-green, it will also yield poorer contrast. Good contrast is essential for night time riding.

As important as power output is, illuminance is even more important. Illuminance is power per unit area. A simple to think about this is to think about a laser. Laser beams are narrow--on the order of 1-2 mm in diameter--so they pack a lot of power into a very small spot on an illuminated surface. A bare lightbulb, however, essentially spreads it's power everywhere, so less power is concentrated, everything else being equal, in a given area.

So, you have to consider power output (lumens), illuminance (lumens/sq. meter, a result of beam pattern), and light center wavelength (color). FWIW, at the center wavelength of the eye's response (555 nm), there are 683 lumens per watt. Be careful using that figure, though, because that conversion factor varies with wavelength in the spectrum.

If a manufacturer gives a power in watts, I tend to shy away, as either they don't firmly grasp how the eye responds to light or they're trying to do a little misdirection by using units that others don't use.
 
As I said, I'm no iLUMENati. But I know from actual experience that simple lumen ratings do not tell the whole story. I could quote Wiki articles, etc. without "illuminating" readers.

I know enough to understand that lumens per watt is the important measurement, but what is also important to me is what the lamp does with that. Beam pattern is an integral, not to mention practical, part of the equation.

Regarding spectrum. Indeed the blue spectrum of some LEDs limits their usefulness, especially in wet conditions. Therefore, some randonneurs still prefer the yellow light of halogen (twin Schmidt E-6s are still a good choice). The Edelux however is much more neutral than most LEDs.
 
randochap said:
As I said, I'm no iLUMENati. But I know from actual experience that simple lumen ratings do not tell the whole story. I could quote Wiki articles, etc. without "illuminating" readers.

I know enough to understand that lumens per watt is the important measurement, but what is also important to me is what the lamp does with that. Beam pattern is an integral, not to mention practical, part of the equation.

Regarding spectrum. Indeed the blue spectrum of some LEDs limits their usefulness, especially in wet conditions. Therefore, some randonneurs still prefer the yellow light of halogen (twin Schmidt E-6s are still a good choice). The Edelux however is much more neutral than most LEDs.

Uhm, I wasn't quoting Wiki. Optics is my field, and I was just trying to explain things. By lumens per watt I assume you mean lumens/per watt energy produced by the generator. Otherwise, in optics lumens and watts are two units that are the same in that they're both measures of luminous flux.......er....light power. Lumens/watt of energy produced really doesn't tell you anything except what the efficiency of the light system is in terms of output. Lumens per watt is just a conversion factor.

Otherwise, what I said explained what you felt: that lumens weren't the entire story.

The reason that blue-white light is limited in its usefulness is, again, 'cuz the typical human eye isn't as sensitive to that end of the spectrum as it is to the yellow/green part of the spectrum. That's all.
 
alienator said:
Uhm, I wasn't quoting Wiki. Optics is my field. By lumens per watt I assume you mean lumens/per watt energy produced by the generator. Otherwise, in optics lumens and watts are two units that are the same in that they're both measures of luminous flux.......er....light power. Lumens/watt of energy produced really doesn't tell you anything except what the efficiency of the light system is in terms of output. Lumens per watt is just a conversion factor.

Otherwise, what I said explained what you felt: that lumens weren't the entire story.

The reason that blue-white light is limited in its usefulness is, again, 'cuz the typical human eye isn't as sensitive to that end of the spectrum as it is to the yellow/green part of the spectrum. That's all.

Wasn't suggesting you were quoting Wki -- I'd have to to get into a technical treatise.

What I was originally suggesting, again, is I know ratings on a box are not created equal and lights with same rating do not necessarily light the road similarly. My experience is out on the road and from testing and selling the products.
 
randochap said:
What I was originally suggesting, again, is I know ratings on a box are not created equal and lights with same rating do not necessarily light the road similarly. My experience is out on the road and from testing and selling the products.

I agree. Rarely does on parameter describe the performance of anything. Luckily, now, riders have access to web pages that show light patterns and stuff like that. It's an extra data point that tells a lot more than a spec or two on a box.
 
catlike said:
+ for generator lights. But SON hubs are too expensive to me, i woul'd go with new Shimano dynamo hub (72 or 80) and B&M Cyo headlight.

The Shimano is indeed a decent hub. But for those that can afford it, the SON is without peer.
 
CygoLite seem to be making some decent stuff. I just ordered a Trion 600 for $280 shipped after Bing discount. Magic Shine also seem to be creating a buzz right now with about the same output as the Trion for $90. I went with the Trion as I prefer the integrated unit as opposed to separate battery and light units.

For being seen something like the Planet Bike 1/2W unit I was using should be fine but those don't light up the road nearly well enough to see where you are going in the darker stretches of my commute and I've hit potholes unexpectedly a few times, not to mention nearly ploughed through several piles of grass clippings.
 
I got tired of replacing batteries, both regular and the big expensive rechargeable packs, and went with a generator hub (Shimano). They put out more light than the claimed wattage would indicate (lots more). The B&M Lumotec is rated at 6 v 3 watt, and is overvolted to 9 volts and the Shimano is rated at 9v 5watt and is over volted to 12+ volts and throws light like some 10w beams. They never need recharged and my hub is over 5 with 10000 miles and still going strong.
And generator lights, unlike battery powered ones , do not start to lose intensity the moment you turn them on.
Did I mention I can ride over 3 hours without having to carry another heavy battery. I recently acquired a Son dynohub with Spanninga lights, it's fabulous to see with , but i can't speak of the reliability yet, as I've only had it about 6 months.

I ride an obscene amount at night, batteries just aint gonna work.
 
Just thought I'd bring this thread back to life to ask what people consider a 'baseline' number of lumens for unlit roads?
I have quite an electrical background and I'm looking at making my own front light. At the moment I believe I can produce 540 lumens for approx 5hrs for around £100 and 200g of mass. Is a focused beam of 540 enough for country roads at night when riding 20-25mph?
cheers
rob
 
Racer_Rob said:
Just thought I'd bring this thread back to life to ask what people consider a 'baseline' number of lumens for unlit roads?
I have quite an electrical background and I'm looking at making my own front light. At the moment I believe I can produce 540 lumens for approx 5hrs for around £100 and 200g of mass. Is a focused beam of 540 enough for country roads at night when riding 20-25mph?
cheers
rob

If the beam shape is right and you don't have any night vision issues with your eyes, it likely would be enough. Likely. If the beam isn't shaped correctly it could be cack.
 
Racer_Rob said:
Just thought I'd bring this thread back to life to ask what people consider a 'baseline' number of lumens for unlit roads?
I have quite an electrical background and I'm looking at making my own front light. At the moment I believe I can produce 540 lumens for approx 5hrs for around £100 and 200g of mass. Is a focused beam of 540 enough for country roads at night when riding 20-25mph?
cheers
rob

This is the data I took from one set of lights in a dark room from 5 metres.

I use two sets of lights. I have poor night vision. I average 30km/hr with max 60. These do an excellent job for me.

I guess one set (as in my attached data) would be just adequate for me. Like Alienator stated, spread is important.

Hope this helps.
 
That's interesting data. What did you use to measure the illuminance? Where in the illuminated area did you take the measurements? I'm assuming you did it in the center. It'd be interesting to measure the fall off at intervals toward the edges of the illuminated area.

Ayup makes great lights. From the plot, it looks like Ayup's battery life claims are pretty accurate.
 
Feltski said:
Expect any LED light thats worth buying to cost about a dollar/lumen. I know guys that night right quite frequently that have spent upwards of $250 on lights. I have also seen HID lights used (same lights used in bmw headlights). They will cost about the same as a $250 LED light, but you can get over 3000lm out of one light. The only downside to HID is that it requires a ballast that can get kinda bulky and youre probably limited to about 3 hrs battery charge. I think HID is the safest option though if youre doing serious night riding. The last thing you need is to get hit bc someone didnt see you
yes ,i also think some LED lights are very good.look at this one ,just for under $10.
21 LED bright lamp for bicycle.
 
alienator said:
That's interesting data. What did you use to measure the illuminance? Where in the illuminated area did you take the measurements? I'm assuming you did it in the center. It'd be interesting to measure the fall off at intervals toward the edges of the illuminated area.

Ayup makes great lights. From the plot, it looks like Ayup's battery life claims are pretty accurate.

I borrowed a light meter from work. It is a Tenma, model 72-6693.

Yes, I simply set the light up on a table and shone it to the corner of the room. Each reading was taken with the light meter from the same spot, in the centre of the beam.

I didn't really take the readings for the illumination itself. I wanted to check the battery life. Yes, you do get quite a linear drop over three hours but it does meet Ayup's claims. This test showed three distinct phases to the battery life.

I'm interested to do the same test in 12 months. This will test how the battery has stood up to the power/drain cycle. I recharge each three hour battery twice a week.

When I do the test next, I'll take different light readings as well, with a full charged battery. There is low and high beam, one and two sets of lights and as you say, to the periphery of the beam.
 
Originally Posted by Scott2468 I didn't really take the readings for the illumination itself. I wanted to check the battery life. Yes, you do get quite a linear drop over three hours but it does meet Ayup's claims. This test showed three distinct phases to the battery life.

I'm interested to do the same test in 12 months. This will test how the battery has stood up to the power/drain cycle. I recharge each three hour battery twice a week.

When I do the test next, I'll take different light readings as well, with a full charged battery. There is low and high beam, one and two sets of lights and as you say, to the periphery of the beam.
G'Day.

This morning I finally ordered two new half epic batteries.

I have been charging my old batteries twice a week now for 4-1/2 years. They no longer hold a charge properly. I havent redone the ilumination-battery life test again. Now, while commuting, one battery lasts about one hour on full power. The 2nd battery lasts about 1-1/2 hours.

Ayup gave a 30% loyalty discount on these. Would I buy these again? Without doubt. I love them just as much now as when new.