The "Do It Yourself" LED Bike Light Guide

Triple SSC P4 Light
Trail 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.

Several projects are documented here as well as some general information and comparisons to other types of bike lights: halogen, HID, etc. Hopefully you will find this information useful and take advantage of it to build your very own LED bike light.

Dual Cree MC-E Light... build pics up soon!

Dual MCE

Update (09/08/2009) 

The Dual MC-E worked out wonderfully last riding season! It provides a tremendous flood of light in front of your bike. Some people might think that it doesn't have enough throw, and I have mixed feelings about that, but for riding tight winding trails it's perfect. I exerimented with another idea, which was to mix one Cree MC-E with one Seoul Semiconductor P4 LED in a housing similar to the one shown above (with less heatsinking). That light, which I call a Hybrid design, provides more throw and uses less power. Most of my fellow riders love the Hybrid.

Each MC-E is being driven at 500mA and the two MC-Es are wired in parallel with each other for a total of 1000mA, which is perfect for using the single 1 amp Buckpuck. The four dies of each MC-E are wired in series. The light runs fine with my 14.8 Li-Ion pack and draws about 12.5 watts from the battery pack. This should still give me around a 4 hour run-time.... this light uses just a little less than 1 watt more than my Triple SSC light.

I will be posting more photos (build pics and beamshots) soon!
Until I update more info on the Dual MC-E light, you can read up on it at this thread on the MTBR.COM Bike Lighting Forums.

MC-ELedil Boom

Anyway my current intentions are:
2 x Cree MC-E  (
MCE4WT-A2-0000-000M10, Cool white, 430 min lumens,WC Tint on 20mm Star)

2 x Ledil Boom Reflectors ( one spot and one medium )
2 x 700mA Buckpuck drivers ( or one 1000mA driver)  I ended up using a single 1 amp Buckpuck.
Other thoughts... I ordered stars that are individually addressable per LED die. That means I can wire it however I want, but I'll probably go with each MC-E's 4 dies in series. I'll be wanting to use my existing 14.8v Li-Ion battery pack, so we'll have to see if 14.8v will be enough to drive the 4 segments wired in series. It's gonna be on the edge so, I have also considered just running 3 of the 4 LED dies in each MC-E. I don't know what that will do to the beam. I did some figuring on voltage, current, power, and output and you can see the results in this spreadsheet. Anyway, my current plans, based on those calculations, are to wire each of the MC-Es in series, and run them at about 500mA each. It should give me about 1100 lumen of output before I subtract losses for the optics, driver efficiency, and thermal degradation. So I hope to at least be spewing over 900 lumen from the light running at 500mA. The total drain from the battery will be 1 Amp.  The light should only draw about 13.2 watts, giving me a little under 4 hours runtime with my 4 Ah battery pack. I also believe that limiting the drive current to 500mA will help the heat buildup issue that is apparent with these devices having 4 LED dies close together.

I'm still working on a design for the housing, but it will be similar to the all-aluminum "achesalot" housing with a few new approaches and more heatsinks. I'll still be using the square aluminum tubing and I will still have to work a few things out after I receive the LEDs and reflectors, but I think it should turn out pretty cool! Check back on my progress every week to see where this project is at. I hope to finish by Thanksgiving if all of the parts come in.

Thanks for all the kind e-mails and requests for an MC-E project. I'm not sure I would have started this project if you guys hadn't kept edging me on :)

Below is a photo (unfinished at the time of photo) of an offspring from the Dual MC-E project. I called it the Hybrid, because it uses two different types of LEDs: one Cree MC-E and one SSC P4. The reason for its existence is that the Dual MC-E is real floody and the SSC-P4 with the IMS20 refelector has great throw, so I decided to combine the two for a light that has an all around good beam with ample flood and throw. Another side effect is that the light runs cooler and requires less voltage and overall battery juice. I slap this on my helmet and it's really all I need. I can put the dual MC-E on the bars as well, and have a ridiculus amount of light.


The Hybrid is wired like this: the MC-E's 4 dies are in series-parallel and that is in series with one SSC P4.

Hybrid Diagram

Click here to see comparison shots I took back in the spring between a Light & Motion HID and the two lights below.

Below are the Triple SSC (Seoul Semiconductor)  P4 (all aluminum housing) and the Copperhead (aluminum-copper hybrid) lights. Within this site you will find step by step instructions (with many photos) for building either light.

Triple SSC P4 (U bin) with L2 Optics

The Triple, All-aluminum housing (above) is a refinement of my original square tube light design. Each time I build a light I learn a thing or two. So far I've built a dozen or so of these. Some for me, some for friends, and a few to sell since quite a few folks seemed interested in that. It seems that I can't even make minimum wage  for my time spent building them, so I will not be building anymore to sell once the few I have are gone... sorry. But really, it's more fun to make the light yourself anyway! I certainly don't mind answering your questions!

The Copperhead

The Copperhead, shown above, is the most recent light that I've built. I was wanting to do something with the copper end caps and I'd seen several variations on lights using them. It was a fun project, and the light definitely has the "steampunk" look! This design is also a little easier to build than the all-aluminum square tube housing, but it weighs about 35-40g more than the all-aluminum light. (130g vs 170g). Some folks have pointed out the potential for corrosion between the aluminum and copper components, but in this particular build the pieces are actually separated with some Arctic Alumina Adhesive, which physically isolates the two metals. I have not noticed any apparent corrosion after several months. The biggest drawback to the Copperhead is that I do notice it a little more when wearing it on my helmet... but it's not a real show-stopper. It's probably lighter than some of the commercially available "helmet mount" lights.

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. 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.

Triple SSC on Helmet
Triple SSC on my 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 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.

small cree
Cree XR-E on a Star

Stack of Lights

A stack of finished and partially finished LED bike lights.

Construction Zone - The section of this site most people come here for!

It's fairly simple to construct your own LED bike light if you have basic electronics knowledge, some soldering skills, and some propensity toward being able to errr... construct things. I will try to arm you with the basic knowledge, tools and techniques needed and set you on your way to DIY LED light construction! But first, the usual disclaimer: "I will not be held responsible for any damage to yourself, your personal property, or anything else for that matter, as a result of using the information contained within this web site."  Now that that's out of the way, let's get started.

LED bike light construction can be broken down into the following areas:
  • Building the all-aluminum square tube light housing (detailed instructions with photos) and a means for mounting on the bike/helmet. This is typically the most difficult area in bike light construction.
  • Building the Copperhead Bike Light (detailed instructions & photos)
  • Electronics and LED selection - this will cover both the LED choices and the required circuitry to drive them.
  • Optical considerationsIn my earlier days of bike light construction I was convinced that using reflectors was the way to go. LED flashlight experts said that they were more efficient and offered more throw. This information is probably true, however as I continued to experiment, I discovered that I liked the flexibility of being able to choose from quite a few different optical lenses that were available. I discovered that by mixing different optical beams in my triple LED light that I could achieve just the right beam pattern for my riding style. For trail riding I like the combination of 2 x 15 degree and 1 x 5 degree lens (in a triple LED light). There's no reason you can't mix reflectors and lenses. I have one light that has two 15 degree optical lenses and one 5 degree reflector. Most lenses are only about 90% efficent, meaning you will loose about 10% of your total lumen output in the lenses, while many reflectors are said to be a little more efficient. So when calculating your actual lumen output from a light, you must subtract for the loss introduced by the lens or reflector. So if the lumen output from your 3 LED totals up to about 720 lumens, you'll have to subtract about 72 lumens that are lost in the lens, resulting in only around 650 lumens output. So why use optics at all? You must control where the light is concentrated in order to make the light beam usable... 
  • Thermal management - we must keep our LEDs from frying. LEDs can get hot! You should never apply power to your LED without it being thermally attached to something that will wick the heat away. Thermal management is important, and is basically why most LED bike lights are constructed from aluminum... it is pretty good at dissipating heat away from the LEDs. My earlier LED bike light designs incorporated heatsink fins similar to what you might see on your computer's CPU chip. It seems that I remember reading somewhere that about 3 square inches of exposed heatsink area per LED watt is a general guideline for heat dissipation. So if our total LED light wattage is 11 watts, we should have about 33 square inches of exposed aluminum to dissipate the proper amount of heat away from the LEDs. My triple LED light design has a total of 17 square inches of exposed aluminum surface, all of which is thermally connected to the LEDs.... woefully inadequate until you take the airflow provided by the moving bicycle. Operating my light without air moving across it will result in an overheat condition! I will expand the TM section more later, because it is important. Nearly all major LED manufacturers have PDF documents available that offer excellent TM guidelines and advice... I recommend that you read them!
  • Installation of the LEDs, electronics, and power connectors (photo guide for a Triple Cree)
  • Battery considerations - we could have put this within the electronics section, but since it's external to the light itself, we'll discuss batteries separately. Most high power LEDs require about 3.7 volts at 1A to power them (it varies from LED to LED). With 3 LEDs wired in series (the recommened way), that's a total of around 11.1 volts. Using a buckpuck style driver consumes about another volt, so a total required voltage for a 3 LED system is just over 12 volts, minimum. You might get buy with a 12 volt battery, since when fully charged, many are 13.8 volts, but as they drain down you will probably notice some dimming of your light (a 12v will work fine if you're building a dual LED light). A 14.4 volt Ni-Mh (Nickel Metal Hydride) or a 14.8 volt Li-Ion (Lithium Ion) rechargble are the recommended batteries for this triple LED light. Since the voltage is higher than required, the current draw will only be about 0.75 Amps. As the battery voltage gets lower, the current draw will increase.
The main parts of my all aluminum triple LED light housing.
SSC P4 on a Star MCPCB

Parts/Source List for a Triple Cree XR-E from a couple years back.
Just replace the XR-E (P3 bin) with some XR-E (Q5 or R2 bin) and you're up-to-date!

Many people have requested this. It is a little difficult to put a parts/sourse list together, because (1) I build variations on the light and (2) my sources change from time to time. Anyway, here is a typical parts list of a Triple Cree XR-E light that I have built. I do not endorse any of the sources below, but they are just some that I have used. I'll try to recommend multiple sources where applicable.  I spent about $110 (US) building the Triple Cree. You can probably do it for a good deal less now.

Another thing people ask:  "is there one place I can get all of the stuff from to save on shipping?" And the answer is "no." Cutter Electronics might be the closest thing to that, but they are in Austrailia, their prices are a little higher, and it takes a while to get stuff from them (just my opinion).
  • 3 XR-E (P3 bin) + 3 Ledil optics + S&H = 62.11  Cutter Electronics in AustrailiaDealExtreme.Com
    • Dealextreme is cheaper and faster than Cutter, but you'll have to get lenses elsewhere.
    • So, another source for optics is, but you have to email or call them to order. I have not used them yet, but I've heard from others that they are friendly and that their prices and S&H are reasonable.
  • 1 nFlex controller + S&H = 30.18  TaskLED
    • the bFlex controller is probably the one to use these days... was not available when I ordered nFlex.
  • 1 momentary contact switch = 2.65  RadioShack
  • 1 size M, DC power connector = 2.15 RadioShack
  • 1 foot of 1" (1/16" thickness) square aluminum tube = 4.50 (Lowe's hardware dept) - I think I had to buy a 4 foot section
  • J-B Weld (used less than 1/10) = 6.00/10 = 0.60 (Walmart or auto parts store)
  • Arctic Alumina Adhesive (used about 1/3) = 7.00/4 = 2.35 Sandwich shoppe  CoolerGuys
  • Wire (24 ga), and solder = 2.00 (Radio Shack)
  • 2 #8-32 hex head screws + washers + rubber washers = 2.00 (Lowes,  Home Depot, or Ace Hardware)
  • Rubber grip for bottom of helmet feet = 1.50 (Walmart, Lowes,  Home Depot, or Ace Hardware)
  • 1/16" thick plexiglass - Local hardware store (Lowes,  Home Depot, or Ace Hardware)
  • Clear silicone caulking - $2.00 - Local hardware store or Walmart.
  • 3 Seoul P4 LEDs (U-bin)   DealExtreme (sells on a star MCPCB) , Sandwich Shoppe (sells bare emitters)
    • Recommended optics for use with Seoul - 20mm L2 (2x15 degree, 1x5 degree) from LedSupply
      • Roadies always want more spot light than off-road mountain bikers, so consider 2x5 and 1x15
    • Don't forget holders for the optics:  (Luxon III or Star Optic Holder)
  • 3021 or 3023 (wired) Buckpuck LED Driver from LedSupply
    • You can save a few dollars by using a simple 3021 or 3023 wired Buckpuck (about $20 + S&H) as opposed to the bFlex. The only deal is that you have to choose the drive current you will be using. 1000mA works well for Seoul P4 or Cree XR-E as long as you are able to keep the lights cool (keep pedalling man!). In some ways I actually the prefer the simplicity of the 3021/3023 buckpuck over the bFlex, but it really depends on what you're looking for.
    Battery Pack ( this could cost more than the light itself )
        I use 14.8V, 4A Li-Ion packs. A battery pack and charger will run you around $85 - $95. I've bought from the following two sources without problems:

Some people on have complained about, but I've never had any problems with them.

Here is a beamshot comparison between my Triple Cree XR-E (P3 -bin) and a couple variations on my Triple Seoul Semiconductor P4 (U-bin). I'm sure with the newer Cree XR-E (Q5 bin) the Cree is about the same as the SSC P4, or possibly brighter.
Photo Journals of Some of my LED bike light projects:

Dual Luxeon V Light
    Here's my MTBR Thread on the Dual Lux V light.
Triple Luxeon III (TVIJ bin) Light
    Here's my MTBR Thread on the TriLuxIII light.
Triple Cree XR-E (P3 bin) Light
    Here's my MTBR Thread on the Triple Cree XR-E light.
Triple Seoul Semiconductor P4 (U-bin) 
    Here's my MTBR Thread on the Seoul P4 light.

Great Bike Lighting Forums: bike lighting specific discussion forum - many great contributors bike light specific forum - the original source for many LED flashlight tech discussions and they now have a bike light specific forum.
The old reliable Triple!
This was the first light that I built using triple SSC P4 LEDs... it was very good for its time... and still not a bad light at all!
I had a few of these light systems that I'd built to sell. It turned out to be a very non-profitable venture considering the time and effort involved in putting it all together, but at least a few lucky people got a good deal on a light system with Li-Ion pack and charger. I will not be building any more to sell, so please don't ask :)

Light, battery & charger

1 - Helmet mount 3xSSC P4 (u-bin) LED light w/aluminum housing, (2x15 degree, 1x5 degree) L2 optical lenses, Buckpuck 3021, 1 Amp controller with continuous dimming control. Includes 2 Velcro fasteners for attaching to helmet (red ones in this photo). The light has a very smooth beam that is perfect for trail riding, IMHO. This is designed for light on helmet and battery in backpack/camelback.
1  - 14.8v, 4A Li-Ion rechargeable battery (built-in overcharge/short/low voltage) protection
1  - 14.8v Li-Ion battery universal smart charger.
Battery and charger are brand new in box, and the light has one test ride on it.

Light output:  3xSSC P4 (U-bin) =  600 to 780 lumens (based on mfg ratings) or about 660 typical lumens on average. Now subtract about 10% for loss in the optics, and you get about 595 lumens as a typical output coming out of the front of these lights... not bad :)

Runtime: about 4 hours of bright light on a charge (at max brightness level)

Dimmable: the light is dimmable via an easily reachable knob on rear of light. Dim it down a little as a courtesy to fellow riders when talking at the trailhead, or lower the ouput to extend battery life.

Weight: 130g (light), 600g (battery)

Other interests:

Yes I do other things besides ride bikes, build bike lights and maintain this web site...

Me playing guitar ... video on youtube.  Here I'm playing my Godin ACS guitar with Roland GR-33/GR-20 synthesizers. The song is a Pat Metheny song called "Close to Home." (head chopped off and no bike light in picture :)

I like sailing too. Here's a photo of me sailing on my boat. Forgive me, it was a lazy day and I was only using the gib and didn't bother to raise the main sail.

I wrote my first iPhone app this year. It's called WxRadMap for Weather Radar Map. Check out the link for more info. You might find it useful if you ride in an area prone to thunderstorms and you own an iPhone.

Email me if you have any comments or questions.

   - Allen Chapman