This web site details how to construct a high performance bicycle lighting system

Also contains information on bells, horns, dynamo powered lights, and other safety devices

NEW! Location Makes a Difference

Table of Contents

"For commuters, the best front light is the very bright rechargeable lamp." Ken Kifer, Ken Kifer's Bike Pages Ken Kifer was killed, while riding his bicycle, by a drunk driver, on September 14, 2003. His wisdom about cycling lives on.

Introduction
Not everyone can afford to buy a commercially manufactured, very bright rechargeable lighting system, which Ken Kifer accurately describes as the best light for commuters. While prices have come down, a rechargeable lighting system is still over $100 when you add in a good tail light.

This site describes how to build a high performance, rechargeable. lighting system without spending a lot of money. You can spend as little as $40 to construct a system, complete with a sealed beam headlamp, xenon strobe tail light, rechargeable battery, and charger.

All components are available from retail or mail-order stores. I don't sell anything, this is purely an informational site. This site contains my informed opinions, as well as the views of other groups and individuals. There are many different solutions for bicycle lighting that meet the criteria of "seeing and being seen," and there are many solutions that do not meet these criteria. Choose wisely and use common sense.

You don't have to spend hundreds of dollars for an adequate lighting system. A lighting system is not rocket science, it's basically connecting a battery to some lamps, through some switches. The challenge is in sourcing the proper components and mounting them to the bicycle in a secure and reliable manner.

HID bicycle lights, which cost at least $400 for a commercial system, are now also available to cyclists wanting to build their own systems, with all-in-one (internal ballast) 13W HID headlights available for $115. Yeah, that's expensive, but it's less than the 2 watt LED lamp used on dynamo systems! You can construct a simple HID system for well under $200.

History
This site evolved from a set of plans I wrote back in the 1980's for a 78WH lighting system. I also had a side business manufacturing and selling lighting systems for a while, but it was too much work for too little money. These systems were sold with a choice of three headlights, 1) a 55W automobile driving light with an H3 quartz-halogen bulb, 2) a 35W automotive driving light with a bayonet incandescent bulb, and 3) a 14W sealed beam. From time to time I would get e-mails asking for these plans; I resurrected them from their Wordstar DOS format, updated them, and put them on a web site.

What About Generator (Dynamo) powered lights?
High power (relatively speaking) dynamo powered lights will cost you over $350 in the U.S. (6 watt dynamo plus front and rear lamp). As even the U.S. distributor for Busch and Muller concedes (regarding dynamo systems), "they are not as bright as the high end high power battery systems." A debate rages on whether or not the 3W dynamo systems are "bright enough," but other than a few die-hard dynamo zealots, all the experts agree that a 2.4-3W headlight is not sufficient for safe riding.

Location Makes a Difference
In the periodic "lighting wars," advocates of dynamo lights will inevitably cite Amsterdam, or other cycle-friendly cities, as examples of why bright lights are unnecessary. Using glib comments such as 'dark is the same here as there,' or 'the laws of physics don't change between localities,' they fail to look at the big picture and fail to understand the differences of demographics, politics, education, and history.

Some of the reasons that location makes a difference are as follows (not all reasons apply to all locations of course):

• Strength in Numbers. The more people cycling the safer the cycling environment, and the better behaved the drivers. The whole concept behind Critical Mass is Strength in Numbers.

• Speed. Look at the speed of bicycle commuters in various countries. In Amsterdam and Beijing, the average speed is about one-third of that of the typical U.S. commuter. It can be maddening to be riding that slow if you're not used to it, but you have to go with the flow. Low power lights are more acceptable at very low speeds. As Forrester writes: "The maximum safe speed for Dutch voonerven has been given as 8 mph. Average travel speeds on Dutch urban bikepaths are universally described as very slow, probably below 10 mph. On the other hand, speeds of American bicycle commuters, now easily measured with electronic speedometers, typically are in the 16-22 mph range. Dutch cyclists tolerate their low speeds for two reasons: travel times are not great because they travel short distances and motoring is so inconvenient that it would probably take longer. American cyclists would not tolerate Dutch speeds because of the longer distances they must travel. The facilities, traffic rules and speed-controlling attitudes that are acceptable to one nation are obviously unacceptable to another."

• Street lighting. Street lighting in European cities is usually very good. In the suburban environment of the U.S., street lighting is often poor or non-existent. For example, one street I used to ride on fairly often was El Camino Real from Palo Alto to Redwood City. For whatever reason, Atherton (one of the cities along El Camino Real) decided that they did not want their section of this busy thoroughfare to have any street lighting. To safely ride through Atherton it is necessary to have bright lights.

• Facilities: Countries, such as the Netherlands, have extensive systems of bicycle paths and bicycle lanes to separate bicycles from the rest of traffic.

• Driver Education. In the U.S., the driving test is perfunctory, unlike in countries like the U.K. and Scandinavian countries. In the U.S., it is vitally important that, as a cyclist, you ride more defensively, part of which includes using bright lights at night.

• Driver Experience. Many parts of the U.S. have a disproportionately high number of adult drivers that learned to drive late in life, and that are from countries where the relationship between bicycles, vehicles, and pedestrians is based on size and intimidation, where drivers believe that they always have the right of way. Visit China, Taiwan, or India for verification!

• Social attitudes. As Forrester writes, "The different physical and economic histories produced the expected social attitudes. In America, since cars were obviously the most convenient means of transportation, the person who did not drive was considered a failure unable to afford a car. Americans did not possess the European tradition of genteel poverty. In American eyes, those who cycled were economic and social failures. While there was considerable class-consciousness about European cycling, as about all European social life, cycling still had sufficient utility in the cities and the country towns that cyclists were not automatically rejected by society, at least until recent decades."

For a nice photo-essay on Amsterdam bicycling see http://www.ski-epic.com/amsterdam_bicycles. On the subject of the pervasive use of dynamo lights, the author writes, "EVERY bicycle in Amsterdam is outfitted with a dynamo powered head lamp, where the rider has to pump extra super hard and the head lamp shines dimly. If you are younger than 35 years old, you probably have never seen one of these in the USA, we have very bright headlamps for bicycles that add much less weight and do not increase resistance. I haven't seen a single dynamo powered bicycle in San Francisco in over 20 years. Once I saw a "Simpsons" (animated comedy) episode where Bart turned on his dynamo bicycle headlamp and could barely make forward progress-> in the USA these dynamo powered headlamps are considered a JOKE, but almost a quarter million bicycles in Amsterdam all have them."

Editorial

Making Your Presence Known
Riding safely at night (and even in the daytime) means doing everything possible, within reason, to make yourself visible and your presence known. Your life depends on being visible to vehicles. This is the U.S. we're talking about here, complete with lunatic drivers (both drunk and sober); elderly drivers who should not be driving in the daytime, let alone at night; and inexperienced drivers (young and old) who may look out for other vehicles, but don't look for pedestrians and cyclists very carefully, even in the daytime. It's a place where motorists that engage in serial red light running, and that never stop for pedestrians in crosswalks, will complain bitterly about a cyclist not coming to a complete stop at a stop sign.

Except for yahoos and drunks, most motorists don't intend to behave badly around bicycles--they are simply clueless. Even non-clueless motorists, including myself, get very upset when I have a close call with a bicyclist that is not visible at night. On the other hand, motorist behavior when they see a highly visible bicycle is truly amazing. They don't crowd you, they don't cut you off, and approaching from the rear they arc around you giving you plenty of room.

Stadium Lights
Advocates of inadequate lighting, that are unable to present coherent reasons for their position, will often claim that I am advocating that bicyclists install desk lamps, stadium lights, nuclear reactors, etc. on their bicycles. Such an exaggeration shows just how weak the position the poor light advocates is. No one is saying that you should tow around a car battery that powers dual 130 watt off-road driving lights. There are both commercial and home-made systems that will make you very visible without going to ridiculous extremes. Cyclists that have gotten away with inadequate lights for years are fond of pointing to themselves as proof that in fact their equipment is just fine, but of course all it proves is that they've been lucky so far.

Discover the Pleasure and Safety of Night Cycling
Many cyclists are discovering the enjoyment of night and early morning riding. The weather is cooler, the traffic is much lighter, and a ride before or after work is a great way to start the day or unwind after a grueling day. I especially enjoy a post-dinner ride to a coffee house because I can pretend that I'm in Amsterdam or Taipei instead of San Jose.

In the 1980's I used to lead all night bicycle rides for a local bicycle club (Western Wheelers). These rides started at 2:00 a.m.. We rode throughout Silicon Valley with no problems other than one drunk coming out their house and hurling a beer bottle at us (he missed). I also led the same type of ride up in San Francisco, riding through North Beach (including Lombard Street), Chinatown (with a 3:30 a.m. restaurant stop), downtown (via the Stockton tunnel), Fisherman's Wharf, Golden Gate Park, and across the Golden Gate Bridge. It was wonderful riding through San Francisco on virtually traffic-free streets (if anything, people were scared of us!). Take back the night!

Legalese
Nothing can eliminate the dangers inherent in riding a bicycle. No lighting system can completely eliminate the dangers inherent in bicycle riding at night. In no way do I intend to imply that use of a bicycle lighting system built according to these instructions will reduce or eliminate the dangers inherent in bicycle riding at night. Bicycling can be a dangerous activity regardless of the time of day due to unpredictable, inattentive drivers, as well as by poor cyclists . I assume no liability for accidents, death, or injuries incurred as a result of using a a system built according to these instructions. You should take following precautions to lessen the danger:

• Check state and local laws regarding the use of high wattage lights on bicycles, and regarding flashing strobes (as well as legal colors). In most states, flashing red lights (i.e. LED blinkers) are not legal, but flashing amber lights are fine. Most LED blinkers can be set to steady-on if law enforcement objects to the flashing mode.

• Always carry spare batteries, bulbs, fuses, and the tools and knowledge to install them.

• Carry a legal back-up lighting system in case your primary system fails. Check state laws regarding bicycle lighting requirements to ensure that the back-up system is adequate.

• Ensure that the system is properly attached to the bicycle. Check mounting brackets, Velcro straps, wiring harnesses, and rear rack attachment hardware every time you ride. This is especially important because if the system fell off, or if the wiring harnesses became tangled in the spokes, it could cause you to crash. 

• Check wiring harnesses for fraying or breakage. A short in a wiring harness will cause the fuse in the system unit to blow. 

• Ride safely and obey all traffic laws. Ride defensively. Anticipate the actions of inexperienced, poor, and reckless drivers. 

• Wear reflective clothing. 

• Properly wear an ANSI or Snell approved bicycle helmet.

• Install a loud horn on your bicycle (audible devices are required by law in some places)

• Make sure that your bicycle is in safe riding condition.

Seeing versus Being Seen
There are two things you have to consider when riding at night:
     1. Seeing the road
     2. Being seen by motor vehicles (as well as pedestrians and other cyclists)

Being Seen
On streets that are well lit you need lights that will make you visible. The best lights for this are xenon strobes. You can put a red or amber xenon strobe on the back of your bike and a clear xenon strobe on the front. You'll still need a low wattage front headlight to remain legal. A xenon strobe is similar to what's used in a camera flash. An electronic circuit charges a to a high voltage and then discharges it through a xenon tube. Xenon lights are incredibly bright considering their relatively low current draw. Xenon strobes are visible in areas with a lot of ambient light, and are even visible in the daytime. Avoid low-intensity LED blinkers which are cute, but not very visible except in total darkness.

Seeing
On darker streets you need to be able to see the road in front of you. How far you need to see depends partly on how fast you ride. For quartz-halogen lamps, a good rule of thumb is a minimum of 10 watts, then an additional watt for every mph over 10 mph. So at 20 mph you should have a minimum of 20 watts. To reduce the amount of watt-hours you have to carry around, it is a good idea to have two headlamps, and select either or both depending on your needs. This is why commercial lighting systems often offer dual lamp systems, i.e. one 20 watt and one 5 or 10 watt headlamp, or two 10 watt headlamps.

Myths and Facts About High Quality Rechargeable Lighting Systems
I added this section because there are so many myths being promulgated by individuals who are very much against the use of bright, high quality bicycle lighting systems (because they don't use them, and think everyone should live their lives the same way they do). As these people create more myths, I'll add to this section. Some of these people are fairly desperate, and make all sorts of amusing accusations, and I include these in this section for your entertainment.

Myths and Facts Section

The Optics Debate (and field of view)
Headlights intended for use with dynamo systems are designed to work with the lower intensity 2.4-3.0 watt lamp bulbs. They use a tightly focused beam that illuminates directly in front of the bicycle, but that doesn't provide much illumination to either side.

The Optics Debate

Cost
You can equip your bicycle with very good quality lighting without spending a fortune. In some cases this may require that you do a bit of work to connect a battery to a light through a switch, but it's not rocket science. This section looks at how much you'll have to spend.

Cost Section

Sourcing
As an electronics hobbyist for most of my life, and an electrical engineer who frequently is involved in prototyping, I am very familiar with component sourcing. Non-engineer types often have no idea where to buy the parts at reasonable prices and are shocked when they see how much parts cost at places like Radio Shack or Fry's. This section tells you where to buy components.

Sourcing Section

Watts Versus Lumens
Technically, a watt is a unit of power, not light. Lumens are a better unit to use because the lumen is weighted to how the human eye responds to light. This table compares different lamps, their power consumption in watts, and their light power (luminous flux) in lumens. This section looks at illumination.

Watts Versus Lumens Section

System Recommendations
While each person's needs may vary, here are some suggestions for lighting systems.

Buy one set of Optronics MR16 based driving lights, one 10W narrow flood MR16 lamp, one 20W flood MR16 lamp, a 5AH sealed lead-acid battery, a dual-rate 1000mAH charger, a 12 volt Xenon strobe tail light, a frame bag for the batteries, connectors, a plastic box for the switches, and three switches. As an alternative to the MR16 lights, buy two 14W sealed beams. I prefer the latter solution but it is a bit more work to construct.

For a budget system, use one 5AH battery, one 14W sealed beam, one xenon strobe, and one dual rate charger. You can construct something for less than $50.

For an HID system, buy a TrailTech HID (flood), a 5AH sealed lead-acid battery, a dual-rate 1000mAH charger, a 12 volt Xenon strobe tail light, a frame bag for the batteries, connectors, a plastic box for the switches, and three switches.

You will have to figure out a place for the battery pack and a way to mount the headlights to the bicycle. I prefer mounting the lights to the front reflector bracket (use a rectangle of aluminum or wood for two lights, but for one light you can mount it directly to the bracket). The batteries can be placed in a frame bag, seat bag, or rack-top bag.

I am less enthusiastic about NiMH systems because of the need to parallel AA battery packs in order to provide sufficient current to the lamps if going over 16 watts or so. Using C or D cells will work, but is very expensive because C & D cells are much more expensive per AH then AA cells. Also, it is rather a pain to build the AA packs with a battery holder due to the tiny solder tabs on the holders. While parallel AA packs solve the cost and current issue, you have to charge the packs separately which is a pain if you want to charge your batteries overnight (unless you buy two chargers).

Headlights
This section looks at selecting headlights for a home-brew lighting system.

Headlights Section

Headlight Mounting to Bicycle
This section looks at methods of attaching headlights to the bicycle. This has traditionally been a source of frustration to people building their own systems. You want to mount the headlight securely and neatly. No hose clamps (jubilee clamps) or U bolts!

Headlight Mounting Section

Taillights
This section looks at selecting tail lights for a home-brew lighting system. The few good LED flashers are very expensive, but an excellent xenon flasher can be purchased for less than $10.

Taillights Section

12 Volt or 6 Volt
This section discusses the trade-offs between a 12 volt system and a 6 volt system. A 12 volt system is usually the better choice.

12 Volt or 6 Volt Section

Batteries
There are many types and capacities of batteries to choose from, with various trade-offs of weight, cost, and size.

Batteries Section

Switches
This section looks at switches and enclosures. Choose carefully to avoid a kludgey, unreliable system.

Switches Section

Connectors
Use connectors to make your system modular. The battery, headlight, and tail light can all be connectorized. This section advises on the best connectors.

Connectors Section

Soldering
You're going to have to do some soldering in order to get reliable connections.

Soldering Section

Run Time
Calculating run-time is complex, because battery ratings are not always as they appear. Sealed Lead Acid (SLA) batteries have amp-hour ratings that are based on very low current discharger rates, and at higher rates the ratings are less.

Run Time Section

Charger
This section looks at various types of battery chargers.

Chargers Section

Who Can Build This 
Construction of this system should only be undertaken by a reasonably well mechanically inclined person. You should be able to solder, know your way around Home Depot and Radio Shack, and know how to use drills, Xacto knives, Dremel tools, heat guns, etc..

Parts list (note that there are multiple possible sources for most of these items)

Parts List Section

Electrical and Mechanical Construction
This section details the construction of a system.

Electrical and Mechanical Construction Section

Back-Up Lighting
No, this doesn't mean lights for riding in reverse. It means that you should have a back up lighting in case your primary system fails for some reason. For a headlight, this can be as simple as a TwoFish LockBlock with a Mini-Mag-Lite. For a taillight, an LED flasher in addition to a xenon strobe, is a good idea.

Back-Up Lighting Section

Dynamo Powered Lights
The main purpose of this web site is to explain how to construct a high performance battery powered lighting system. I’ve gotten some not-so-nice e-mails, and seen some bizarre-logic Usenet posts, that promote dynamo powered bicycle lighting systems. These e-mails and posts also dispute the need for the greater illumination provided by higher power lights. I decided to add this section on dynamo powered lights, so the reader can get an unbiased evaluation of the pros and cons of dynamo powered lights.

Dynamo Lights Section

Flashlight Type Lights
Decades ago, a flashlight on the handlebars was a common type of bicycle light. Ironically, with the advent of new flashlights with very bright Cree LEDs, along with improved methods of mounting the light to the handlebars, this type of light is making a comeback. A Cree LED flashlight that costs $30, has equivalent light output to a bicycle light costing five times as much, and far exceeds the capability of most dynamo powered lights. There are many discussions of these types of lights on Candlepower Forums.

Flashlight Type Lights Section

Bicycles with Built-In Lights
A few commute bicycles now come with integral dynamo hubs, and front and rear lights. This section looks at this option.

Bicycles with Built-In Lights Section

HID Lights
HID lights are the best bicycle lights in terms of brightness and efficiency. Prices have fallen and you can now put together an HID system for less than the cost of a good dynamo based system. However you can spend a fortune on HID lights if you really want to, as evidenced by the German made Busch & Müller "Big Bang" (see http://www.bumm.de/index-e.html?docu/197e.htm) which sells in the U.S. for $953 (plus $3 for a wall plug adapter). I was all set to buy one, but I didn't want to pay for the wall plug adapter (c'mon Peter, you really could throw in a 50¢ plug adapter for free).

HID Section

LED Lights
LED lights offer long run time, but fall a little short in the brightness department.

.LED Section

Flags
Flash Flags help visibility.

Flags Section

Sound
Okay, we've discussed lighting, now what about sound? The prepared and properly equipped bicyclist has both a polite bell and an obnoxiously loud horn.

Sound Section

Cell Phone Charging
As long as you have a 12 volt system, you may as well keep your phone charged up.

Phone Charging Section

Battery Recycling
Surf over to www.rbrc.org. The RBRC is a non-profit, public service organization created (and funded) by the rechargeable power industry to promote the recycling of portable rechargeable batteries. As part of the program, all components of the products shipped back for recycling are broken down and re-used: for instance, the cadmium is used to make new batteries; the nickel and iron are used for new stainless steel products.

Wear a Helmet
While I am not a helmet zealot, wearing a helmet is a good idea.

Helmet Section

Caffeineation
While proper lighting is important for commuters, proper caffeineation is also crucial. Please visit Bicycle Coffee Systems for information on how to keep properly caffeinated during your ride. A major update to Bicycle Coffee Systems occurred in March 2005.

Caffeination Section

Commute Bicycles
If you are looking for the proper bicycle on which to commute, please visit Commutebike.com. Don't depend on the generator lighting systems used on these bicycles.

Conclusion
It is not difficult to construct a high performance bicycle lighting system, and it's much cheaper to build your own as long as you are reasonably mechanically inclined.

Links to other Bicycle Lighting Sites
I have explained what I do, and what I believe is best. Get some other views on the subject of bicycle lighting at some of these other sites.

Links Section

About the Author
Steven M. Scharf is one of Earth's leading experts on bicycle lighting. An electrical engineer by trade, he enjoys cycling and designing lighting systems. He lives in Silicon Valley and works for a small semiconductor company. He has bicycled all over the world, including Canada, Russia, Thailand, Japan, Taiwan, and China. See a list of his bicycle related web sites at http://www.nordicgroup.us/hosted.htm.

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