Welcome to my web site dedicated to providing info on building your very own DIY LED bike light. Each year the technology just gets better, but the basics are the same: High power LEDs provide a tremendous amount of light for their size and weight and they are incredibly durable and last a long time.
This site provides a great deal of information on building an appropriate housing for an LED bike light and covers the electronics, optics, and batteries that will be needed to complete the project.
Why we Need Bike Lights
Riding singletrack in the dark is, without a doubt, the most fun you can have with clothes on. Trails that you know like the back of your hand in daylight seem like the dark side of the moon (there is no dark side of the moon really, as a matter of fact it’s all dark).
Your perception of time and distance become distorted, you’re never quite sure where you are. When alone, the mind can play cruel tricks, it always seems like there’s something strange over there… no, it’s over there. Just keep telling yourself that healthy wolves don’t attack humans, and give thanks for your wonderful light.
Group night rides are very special too, more social than daylight rides somehow. When the bunch pauses, turns out their lights and grows quiet, you really feel like you’re out there, way out there. Everyone’s experience is unique, but you are there together, and a bond is formed. 24-hour races… whoa, don’t get me started…
Well, that’s why we nightride, anyway.
There are three reasons for using bicycle lights:
- So that you can see where you are going at night.
- If you only ever ride at night on well-lit streets, then you will have less need for a powerful a lighting system than if you ride off-road.
- So that other road users can see you.
- Lights should be visible from a wide angle so that you are visible to the other road traffic on twisty roads and at junctions. LEDs have a much narrower field of view than normal bulbs – some LED lights get around this by having several LEDs pointing in different directions. Clipping an LED light to your body or helmet means that you can be sure that it will be pointing in the wrong direction for at least some of the time.
Flashing lights catch the eye – in a shop for instance – but it can be difficult to judge distance from them. They can be useful on dull days to get the attention of a motorist, when it is light enough to see a cyclist once you have noticed that they are there. There have been stories about drunk drivers hitting cyclists after getting mesmerised by flashing LED lights. I don’t know if they are true.
Bicycle reflectors are cheap, robust and very effective most of the time. Unfortunately, they are useless if a light isn’t being shined directly at them. This means that reflectors alone will still leave you vulnerable to two of the most common cycling accidents – with any traffic at junctions or with pedestrians on shared cycle paths [see Effective Cycling, John Forrester, MIT Press, 6th Edn, p331]. Reflectors are well worth having in case your lights ever give up, but you shouldn’t rely on them.
Fluorescent clothing is good for increasing your visibility during the day. At night dayglo colours are much less conspicuous – reflective clothing, and 3M Scotchbrite in particular, works much better. Don’t assume that hand signals will be easy for other road users to see at night.
- Because the law says that you have to.
- Legal requirements vary around the world, but its safe to say that it is always going to be possible to improve on a lighting system which meets the basic legal requirements and its easy to make it much worse.
Where do LED bike lights stand in terms of brightness compared to HIDs and Halogen?
I guess this question is better answered now that I have posted the beamshot comparisons at the top of this page (although I apologize that I don’t currently have a halogen light to compare). When I first started this site, a couple of years ago, I was comparing LED bike lights to halogen-based systems, and now I’m comparing them to much brighter and more efficient HID systems!
The light shown below is my triple SSC P4 (U bin). I ride with many riders who own L&M (Light & Motion) HID lights (a great system by the way) and I would not trade my homebuilt light for one of theirs.
Why not, you ask?
Well, I can turn it on and have it at full brightness, instantly… HIDs, which are arc lamps, must ramp up to full brightness and that takes nearly a minute. Also, I can instantly adjust the brightness of my light to whatever level I choose. It’s certainly nice to be able to dim (or completely turn off) the light when riders stop at the trail heads waiting on others (it’s not good for HIDs to be turned on and off frequently).
When you don’t need as much light, dimming the light also extends battery life. Speaking of battery life, a triple LED light running at 11.8W is about the same brightness as the L&M HID running at 13.5W… so the LED light will have better battery life… it is more efficient.
Another cool thing, is that I can change out optical lenses pretty easily if so desired. Although I’m real happy with my current lens configuration, various lenses can be mixed and matched on the 3 LEDs to offer different types of beam patterns to best suit my needs.
Shown below is a photo of one of my triple SSC P4 lights with dimmable 3021 buckpuck driver and L2 optics mounted onto my trail riding helmet.
I started building LED bike lights in 2005 and have had good success with them. My main purpose for building these lights was nighttime mountain bike riding… and I like to tinker with things. During the winter months, the daylight hours are just too short to find time to ride during the work week, so many of us have taken to riding the trails at night.
Many of my fellow bike riders have nice, bright HID lights that they forked out big bucks ($400+) for. I had a hard time justifying spending that much on a light, so I started out with some home built halogens back in 2003.
The halogens worked okay, and offered a good lumens per watt value for bike lighting, but then I discovered the new (at that time) superbright Luxeon LEDs and began to consider their use in bike lighting. Once I built my first triple Luxeon III LED light, the halogens were tossed out for good! Luxeon LEDs are currently being outperformed by the Cree and SSC LEDs, but there’s a good chance they’ll be back in the race eventually.
What does an LED bike light offer that a halogen does not?
More lumens per watt. (I didn’t say more lumens per dollar… but we’re getting there!) I consider about 10 watts as the most drain that I want on my battery pack because I want it to last as long as possible and I do not want to carry around a huge battery pack. A 12 volt, 10 watt halogen MR11 lamp puts out around 190 lumens whereas a 12 volt, 9 watt Luxeon bike light (3 x Luxeon III, 3 watt emitters) puts out about 240 lumens. Recent technology with the Cree XLamp XR-E emitters will double that output number with even less current draw from the battery.
The XR-E is said to offer 160 lumens of output at 700 mA. So a bike light containing 3 XR-Es should output 480 lumens, drawing 700mA at 12 volts, or about 8.4 watts. That’s 57 lumens/watt… not too bad!
Cree recently announced that they will be offering LEDs with 80 lumens/watt by late 2007. Can you imagine a 9 watt bike light that puts out more than 700 lumens? So by the end of 2007, LEDs will have even overtaken HIDs in terms of lumens/watt. [Edit 11/25/2007, I’ve left my original text above, and guess what? We’re there! It’s actually more like 700 lumens at 11 watts though]
- Ability to configure beam pattern with various optics and reflectors. You can buy a few different beam configurations of halogen lamps, but the availability of optics and reflectors for Luxeons and Crees are quite good, and the ability to mix these within a single, multi-LED bike light makes for a really customizable beam that meets your riding needs.
Lighter weight – of course this depends on the construction of your light, but the emitters themselves are very lightweight and don’t require a big ceramic socket to plug into. Some lightweight aluminum will do fine for mounting the LEDs and dissipating their heat.
- Longer run time (less current drain on battery for equivalent amount of light) – absolutely. You would have to nearly double the halogen watts to get the same amout of light as a modern LED bike light. For example: a triple Cree XR-E light = 480 lumens @ 8.4 watts while a halogen MR11 = 400 lumens @ 20 watts). [Edit 11/25/2007, a 3x Cree XR-E (Q5 bin) light = approx 700 lumens @ 11 watts]
- Better, whiter (less yellow) light – the color of light is really a subjective matter. But to most people, the whiter light of an LED will be more pleasing and will also be perceived as more light output even with less actual lumens of output.
- Less heat – while the LEDs do generate heat and require heat management as a consideration, the halogens get much hotter. I could always smell mine burning the paint (or something) off of the lamp housing… even in cool weather. The aluminum cased LED lights that I’ve built barely even get warm to the touch while bike riding.
- Longer life/less prone to failure
LED Versus HID
This is a hot area of debate on many bike lighting related forums. I personally don’t have anything againt HID lights and often recommend them to people who are looking to purchase a very bright manufactured bike lighting system. But as I mentioned earlier, I feel that the latest generation of LEDs offer the ability to have an LED bike light that is just as bright as an HID light and is more flexible and power efficient. Here’s a list of my other best MTB headlights for night riding.
Building your own light offers even more flexibility. You can choose the number of LEDs (typically 2 or 3) and the type of optics to determine what type of beam you will have emitting from your light. Building these lights is rewarding and for some even addicting! No really, I can stop anytime… “my name is Allen, and I built my last bike light over two months ago… OK, OK, I modified one last week.”