Monday, January 08, 2007

A brief intro to bicycle lighting...

“What can go wrong, will go wrong, usually at the most inopportune moment.” Like when it’s dark and raining, for instance. Murphy was a wild-eyed optimist.

Posted by Hurricane Hattie to CycleDog at 4:32 PM

Hurricane Hattie has left a new comment on your post "Road1...continued":

From your Sep. 10, 2006 blog:
"Finally, I heard from several students who've read CycleDog. In fact, one said she was persuaded to try bicycle commuting by some of these posts. I have mixed feelings about influencing people. "

I suspect you mean me. I've been meaning to respond ever since I read this. I read your blog regularly and compose lots of rants, rebuttals and raves as I go down the road. They just never seem to make it to (virtual) paper.

Rants, raves, and rebuttals always seem to come easily when I'm in the saddle, too. The hard part is remembering the best parts to write down later. This is especially true when I've hit on something that strikes me as hilarious, yet when I arrive at home, I can't remember what it was! Maybe that's another manifestation of middle age.

You may rest easy on my account. For one thing I was close to commuting on my bicycle before I ran across your blog and would have done it anyway. You can be sure I did it more safely for having read your blog. Another reason you needn't be concerned is that unless it's extremely cold if I'm not riding my bicycle I'm riding my motorcycle - a Kawasaki ZZR 600. I've been riding a motorcycle as my primary transportation since I was about 15 and I'm several times that now.

One point I've tried to make recently is that a good cyclist, or a good motorcyclist, for that matter, needs to know everything that a motorist would know: rules of the road and best, safe practices, among them. But we need an additional set of skills in order to ride safely in motor traffic. That's the whole purpose of motorcycle skills clinics, and it's the stated purpose of BikeEd.

Back in the days when dinosaurs roamed the Earth - the 1970's - I rode a Yamaha RD250. It's very possible that I now weigh more than that motorcycle! I'd love to have another one, but then I'd probably avoid riding my bicycle. And I need the exercise far more than I need a motor bike.

After reading your blog I realized I've ridden a bicycle most of my life and knew nothing about it. I learned enough from your blog to keep me reasonably safe when I started commuting. However, the Road1 class was a godsend! It was such a wonderful class and I learned so much! It was just what I needed. I have since run into a couple of people (literally in one case) on bicycles that would benefit from a Road1 class and volunteered to pay for it if they would go. I hope they take me up on it.


I have found a solution for dealing with people who honk at me. I wave and pretend they know me and were just saying "Hi." I used to let my temper get the best of me and make rude jesters but realized one day I really might know them. Although recently when a lady made a left turn in front of me I chased her down in the Wal-Mart parking lot and had a little talk with her. She seemed to really think bicycles were always supposed to yield to cars. But we got that straightened out.

I'm finally writing because I need help. I will be riding in the dark soon, one of my shifts starts earlier, and I need lights. I've looked around online and there is a vast array of cycle lights available, some of which could be very painful to the wallet. I managed to assemble my winter riding clothes very inexpensively thanks to your blog on winter clothing. Could you write something on lighting? I would appreciate it tremendously.


There's nothing I love more than a plaintive cry for help! But before you read through my take on bicycle lighting systems, just be aware that I've included several links to more authoritative sources, Sheldon Brown, Steven Scharff, and Peter White, at the end of this post. They cover this subject in more detail, and they're better informed than I am.

First, a caveat. I've tried several different light systems, including small, handle-bar mounted units powered by AA or C batteries, cheap bottle-shaped generators, and one expensive (though now obsolete) dual beam unit. All have advantages and drawbacks. The dual beam headlight was the only one I'd trust if I were bombing down a steep hill at 30 or 40 miles an hour. It threw enought light that motorists sometimes thought there was a slow-moving motorcycle on the road!

The battery powered units don't throw as much light, but they're adequate for modestly paced night rides. Currently, I'm commuting behind a Cateye HL-EL300 and a Cateye HL-EL140. The HL-EL300 provides most of the light, while the HL-EL140 operates as a back-up. I'm a firm believer in system redundancy! I don't claim these are the best lights on the market. They were available at Tom's when I needed them. But they do have some nice touches for commuter lights. Both are easily removed at the end of a ride, and the HL-EL140 doubles as a helmet light. It has a versatile mounting bracket and it has a flashing mode.

Generator lights are divided into two groups: very good, very expensive ones, and cheap junk. Shimano and SON make high-end generator hubs that I find very appealing. But just like the HID units, cost puts me off. Cheap bottle generators are little more than kid's toys. Avoid them. The expensive units include some sort of voltage regulator. The cheap ones do not. I had a cheap unit on a commuter bike once upon a time. I was bombing down a hill, going faster and faster as the light got brighter and brighter, until - poof! - it was gone and I was going very fast in the dark.

Before discussing various lighting components, let's cover some basic physics. No math! I promise - sorta.

When we look at lighting systems, there's a bewildering variety of power measurements: watts, candlepower, lumens, candelas, and possibly more. In most cases, comparisons are difficult because while watts indicate input power, the rest are indications of output power. The input power to a device is easy to calculate. Power is equal to current in amps multiplied by voltage. It certainly seems simple. The problem comes in when we consider the efficiencies of different light producing devices. Incandescent lamps are very inefficient, converting input energy into both light and heat. Heat (or infrared radiation, if you prefer) is wasted energy since we can't see it. Light emitting diodes are far more efficient at converting input energy to light, and in fact, heat is a big disadvantage with these solid state devices. If they get hot, they die.

Obviously, an efficient device can either run longer on a given power pack, or it can provide more light over the same amount of time as a less efficient one. For cyclists, this means we can carry smaller,lighter battery packs.

Most bicycle headlights are either halogen lamps or light emitting diodes (LEDs). Halogens may have an edge when it comes to sheer power. They put out more light than a similar LED unit, but they do so at the expense of shorter run times. Remember, halogen lights waste a lot of energy as heat. Halogen lamps are usually replaceable, where LEDs are not. (I'm ignoring HID light units, partly because I know very little about them, and partly because they're stop-your-heart expensive, which is why I know little about them.)

Reflector design can have a great impact on relative brightness - what's apparent to the human eye. The now-defunct Bicycle Guide magazine did a piece on this many years ago. They set up various light systems in a parking garage and photographed the light patterns each unit produced. Some were very tightly focused beams best used for road cycling, while others were broad, diffuse patterns that mountain bikers would like. Producing a well-lit broad light requires a lot of power, but the narrow beams do not. It's all in the reflector assembly. (This is very apparent when looking at beam patterns for auxiliary lights for automobiles, driving lights, fog lights, and some other supplemental lights, for example.) To make it even more confusing, some have broad patterns in close to the headlight, but also produce a narrow beam that illuminates farther out. So a comparison of relative power outputs is meaningless without a comparison of the beam coverage.

Some LED units offer both flashing and steady modes, but the flashing modes may not meet legal requirements everywhere. In Oklahoma, for instance, flashing lights are limited to use on emergency and maintenance vehicles. Still, many cyclists use tail lights in flashing mode and I've never heard of anyone being stopped for it. The basic bicycle lighting requirement here is that you have a white front light, a red rear light, and a red rear reflector. I would strongly advise that you have an amber rear reflector too, one that meets DOT specifications, because it's visible over a greater distance than any red reflector. (Come to think of it, that just reminded me that my amber reflector went missing. Gotta fix that!)

If you go with rechargeable batteries, the choices are usually lead-acid, nicad, or nickel-metal hydride (NIMH). The differences come down to weight vs power output. Lead-acid batteries are relatively cheap, but they're very heavy. Nicads and NIMH batteries can produce equivalent power while weighing considerably less, but they're expensive. Again, it's a trade-off. (I once sat through an engineer's lecture regarding the internal differences between lead-acid and nicad batteries, including the chemical processes. Honestly, while he went on for about 3 hours, I stayed awake for only the first 20 minutes. I could never drone on and on like that, boring an entire roomful of people. And don't listen to my daughter. She lies.)

The most critical aspect of rechargeable batteries is the charger. As a charge builds up, the battery develops internal heat. Without going into a long discussion, heat ruins batteries, so the less heat build up, the better. But preventing that requires longer charging times. The manufacturer's solution is the 'smart charger'. It puts a high current into the battery for a short period of time, then switches to a lower current as the battery nears capacity, and some units even monitor the battery temperature while charging.

For anyone interested in home-brew lighting equipment, the rule-of-thumb is to limit input current to not more than 10% of the amp-hour capacity of the battery. So a 2000 mAH battery would be charged to capacity in 10hours at 200 milliamps, or 20 hours at 100 milliamps, etc. Low charging currents limit the heat, and by keeping them very low, you prolong battery life.

Commuting info
http://sheldonbrown.com/commute/index.html

Lighting info
http://www.sheldonbrown.com/harris/lighting/index.html

Steven Scharff's pages:
http://www.nordicgroup.us/bikecoff/ Coffee - how could I resist?
http://www.nordicgroup.us/hosted/ Index to all pages
http://nordicgroup.us/s78/ Lighting
http://nordicgroup.us/s78/links.html Very useful links

Peter White
http://www.peterwhitecycles.com/lightingsystems.htm

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7 Comments:

Blogger Fritz said...

I have about a zillion LED blinkies.

I used a cheap Union bottle generator and light for years and years. I had a 20 mile commute and this was before the days of LED lights with batteries that last forever. I also had the old yellow "Belt Beacon" light.

My first blinkie was a xenon strobe with a red lens -- I was so excited when I found that! It was sold by VistaLite of Rantoul, IL (remember them?)

5:40 PM  
Blogger Coelecanth said...

I'm using a BLT Light Systems Ozone 9ine on the front. It's a one watt led running off of 3 aaa batteries. It's plenty bright for cnd$75 but I suspect only available in Canada.

One thing to keep in mind if you go with standard sized rechargables is that most chargers(meaning every one I've ever seen) will only recharge in pairs. This is very annoying when you have a light with 3 batteries because they'll charge better if the pair is around the same level of depletion. (This might not be true, it's something I've been told more than once, but never by an expert)

I got around this by using a 3 aaa rear light as well. I also swap the batteries from the front and rear light every couple of days so they deplete at more or less the same rate.

Another thing to keep in mind is what are you using your lights for?

There are two broad catagories:

1) What's that over there?
2) Hello, I'm over here!

If you're riding in rural areas on unlit bike paths you'll need lights that illuminate what's on the road ahead. The Dogman did a great job discussing these types.

If you're riding in an urban area with good street lighting then #2 is all you'll need. These lights are Fritz's aforementioned "blinkies". You can get white for the front and red for the back, they're dirt cheap and weigh next to nothing

I never ride without having a couple in my bag just in case my main lights fail. I can always ride slower when I can't see the road well, but that doesn't help the other traffic to see me. My fiance even carries a couple of extras in her panniers to give away to people.

Also there's the "to blink or not to blink" dilemma. There's a well known thing called The Moth Effect. Drunk drivers often end up driving into the one tree on an otherwise open plain or hit the one parked car in the middle of an empty lot. Some people claim that blinking lights make cyclists more likely to be a victim of this effect.

I'm not sure I buy it. No one has ever shown me a study of bike/car collisions that proves that blinking lights are more dangerous. I think that the blinking makes it more obvious that you're a slow moving cyclist and that makes you safer.

The small size of bicycle lights, as compared to car lights, makes it hard for drivers to judge how far away you are. If it's steady they might assume that the light is on distant motorcycle travelling at the same speed as they are. This is also why it's good to have more than one light. It disinquishes you from other types of traffic and give the driver's eye a visual clue as to how fast they're closing. Humans are really good at judging relative speeds by how fast things get larger in their view. With a single tiny led light this cue is lost.

I might be talking out my asterisk here on any and all of this, if anyone has better info (and by that I mean a real study that I could read) on any of this I'd love to hear it.

7:07 PM  
Blogger kstoerz said...

My cousin works for Spectrum Brands in Madison, WI. Spectrum owns Rayovac, Remington, etc.

He sent me a care package for xmas that included a 4-cell NIMH charger that charges batteries individually. Like Coelecanth, I have never been able to find a charger that doesn't require batteries to be charged in pairs. This prevented me from using NIMH rechargeables in a few things I own that use three AAA batteries.

If you would like, I can find the model number of the charger. All I know right now (at work) is that it is manufactured by Rayovac.

Here's some info about HID lights. I'm considering buying one to play around with and do some night trail riding with. I presently commute through rural areas with just a Cateye white blinkie (the lipstick-shaped model) for front illumination. It is enough to see major road hazards in perfect darkness, but even the light of a full moon pretty much drowns it out, not to mention the headlights of oncoming traffic.

Light & Motion seems to make some of the best reviewed HID lights available based on the information I have found thus far. Here's the quote:

"High Intensity Discharge (HID) lighting technology replaces the filament of the light bulb with a capsule of gas. The light is emitted from an electric arc instead of a heated filament. The result is a more efficient light with a color that better simulates daylight. A more detailed description is available here http://www.halcyon.net/lights/hid-faq.shtml

Bottom line, the advantages are:
- More light. Better efficiency allows a 10 Watt HID to produce same amount of light as a 30 watt halogen
- Whiter light. The white light of HID compared to the yellowish light of halogen looks more like daylight and allows greater visibility.
- Long run times. This is just a side effect of better efficiency. Running a 10 watt HID with a good battery results in run times in excess of 4 hours."
(from http://www.mtbr.com/spotlight/lightshootout/)

3:50 PM  
Blogger Ed W said...

I intend to post a few more links that may provide more in-depth lighting information. I'll do that within the next few days, but I can't do it tonight because it's all on my laptop at work. More dummie, me.

Also, and this is for Fossil Fish - I fully expect to see some baby photos when the time comes. For that matter, some happy pregnant Momma photos would be OK too. Remember what Al Bundy - a great American - said about pregnancy. "It's divided up in trimesters", he said, "The puke-mester, the fat-mester, and the horny-mester."

I have no idea why I remember that, and if Mary asks, I'll deny it all.

6:43 PM  
Blogger Coelecanth said...

Done and done Dogman. In fact, there's going to be pregnant bride photos come Bastille Day. I'm not sure how I'm going to play that yet, buy a toy shotgun for her father perhaps? Mind you, we're moving into the fat-mester and I suspect getting any kind of belly shot of her will be a life-and-limb risking matter for the next little while.

I will not be taking photos of the birth though. I mean, who am I going to show them to?

kstoerz: pretty please!

11:58 AM  
Blogger Fritz said...

My wife *wanted* (and got) a professional portrait of her in profile showing off her big pregnant belly. The photos of her like that are nice. A lot of women like to strut their stuff and show it off.

1:59 PM  
Blogger kstoerz said...

Coelecanth, the battery charger I mentioned that is capable of charging individual or odd-numbered sets of NIMH batteries is a Rayovac model PS23-B. Search Ebay for the make/model and you should see a few for sale there for about $24.

Happy trails!

7:35 AM  

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