The Velodrome

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3:59 AM

The light testing continues! I think the china light should be here today or tomorrow.

I also just set up the Niterider Solas, which is similar in many ways to the hotshot. Not sure yet which I prefer, but it definitely seems like a nice light.

4 hours later…

nhinkle

8:11 AM

China light arrived. It's pretty dang bright, although I doubt their claim of 1200 lumens.

For $36 it'd be hard to find anything this bright, but I'm not sure if that's a good thing, and I'm also not sure how long it would last.

It's so bright even on the minimum setting that I'd be hesitant to use it on roads.

9 hours later…

freiheit

4:55 PM

@nhinkle You need to measure some car headlights... Especially see if you can measure high-beam vs. low-beam on a modern car with halogen headlamps and a car with HID headlamps. Maybe both measure a single lamp and the combined output coming off the front of the vehicle at a reasonable distance. I think you'll find that even the "ridiculously overpowered" bicycle headlamps are dim when compared to that...

> The first U.S. halogen headlamp bulb, introduced in 1983, was the HB1/9004. It is a 12.8-volt, transverse dual-filament design that produces 700 lumens on low beam and 1200 lumens on high beam. The 9004 is rated for 65 watts (high beam) and 45 watts (low beam) at 12.8 volts.

> HID headlamp burners produce between 2,800 and 3,500 lumens from between 35 and 38 watts of electrical power, while halogen filament headlamp bulbs produce between 700 and 2,100 lumens from between 40 and 72 watts at 12.8 V

Headlamp

A headlamp is a lamp attached to the front of a vehicle to light the road ahead. Headlamp performance has steadily improved throughout the automobile age, spurred by the great disparity between daytime and nighttime traffic fatalities: the U.S. National Highway Traffic Safety Administration states that nearly half of all traffic-related fatalities occur in the dark, despite only 25% of traffic travelling during darkness. While it is common for the term headlight to be used interchangeably in informal discussion, headlamp is the term for the device itself, while headlight properly refer...

1 hour later…

nhinkle

6:29 PM

@freiheit agreed on the principle, but in practice it's different because of the optics. The total lumens put out by a car headlamp may be as high or higher, but car headlamps are specifically designed to put most of the light on the ground, in a diffuse pattern, without shining into oncoming drivers' eyes. With bike lights, they're typically a very focused beam (usually about 10° light spread), and the beam is typically circular, not spread out.

So, you end up with a really intense, narrow beam that's shining just as much at oncoming traffic as it is at the road, and that can be disorienting to oncoming traffic or riders. The total output is the same or less, but where the output's going is a problem.

Now, some lights are pretty good at dealing with that problem - for example, Light and Motion's lights have a nice wide beam that actually illuminates the whole road, instead of making a tiny intense spot. I'd argue that a 500 lumen L&M light can be much better (from the perspective of people around you, that is) than a 200 lumen light that's got a really narrow beam.

freiheit

@nhinkle I think car low beams do the "pattern mostly on ground", while high beams have a good amount going out level.

nhinkle

That china light has a very focused beam, but there is a wide-angle diffuser lense available that I intend to purchase (it's like $4), to see what that's like. I expect it'll be much more comparable to car lights with that on.

@freiheit agreed, although even with high beams it's typically a lot more diffuse than with a bike light. The light's facing more "up" in terms of how high, but it's still going wide. Also, we don't drive with high beams on when there's other traffic, so I think the point still stands.

freiheit

but, yes, still very different beam patterns. The kind of thing where it'd be worth testing what the watts per cm^2 at a standardized distance straight ahead actually are...

nhinkle

@freiheit absolutely. I'm still trying to figure out the best way to do measurements. I have a brightness meter that measures lux (that's lumens/m^2), which would be useful for a measurement like that.

I could set it up to point the light at a blank wall from some # of feet, measure at various points, and put it in a graph to show the brightness profile, as it were.

Anyhow I've got to go. Thanks for the ideas - there's a lot to consider!

Dan Hulme

@nhinkle If the brightest part of your headlamp is pointing at oncoming traffic instead of the ground, you're doing it wrong.

nhinkle

7:02 PM

@DanHulme agreed, but even if the brightest part is pointing at the ground, a lot will still be going up towards traffic

Dan Hulme

In the UK we have a British Standard for bike lights, which specifies how much light can be visible from different heights above the ground, to avoid this problem.

nhinkle

@DanHulme I didn't know the UK did that. I know Germany's pretty strict about it. I kind of wish US manufacturers thought more about that.

Dan Hulme

@nhinkle It's not enforced, though. There too many cyclists with no lights at all to start picking on people who do have them.

And because of EU harmonisation, lights are now allowed if they meet any EU member's national standard.

nhinkle

7:19 PM

At least there's some sort of standard :)

freiheit

7:52 PM

@nhinkle I think in the US, generator-powered lights are the ones you can find with some kind of beam pattern other than cone

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