In this project i tried to replicate Revolights. Concept is very simple. Ring of light on a wheel and only LEDs facing ahead light up. Unlike the Revolights my light has battery mounted on bicycle frame and not on a wheel. My light isn't using any "smart" technology, every LED has its own brush that makes contact when facing the right direction. Check the video to see the result. Before i go into details i want to mention that a lot things mention may be altered for your bicycle since each bike is different. Also this build requires some technical skills.

Step 1: Step 1: LED Modules

Here is list of things you are going to need:

PCB
24 SMD LEDs (5630)
paperclips
M3 screws
M3 tap
Li-po battery
5.6 ohm resistor
switch

First thing to do are LED modules. I'm using 12 LED modules around a wheel. Each module consist 2 LEDs and it connects them together. there is nothing else on it. It serves rather mechanical purpose than electrical. I'm uploading my design in Eagle CAD however i highly suggest measuring inner width of your bicycle fork and width of your wheel. If you're using V-brake make sure the modules aren't going to hit that. There are many ways to create PCB. I used laser printer and a laminator. I'm sure you can find a way. Since the design is so simple making the PCB with sharpie is fine even protoboard would work just keep in mind you need to make 12 of them so plan ahead. Once you have all 12 PCBs ready just solder LEDs in place. Make sure negative lead goes to the pad touching the rim. If i was able to solder those with 12€ soldering iron anyone can do it!

Bicycle_light.rar
Download

Step 2: Step 2: Wheel Modification

Now we need to attach those LED modules on a wheel. The modules are mounted with M3 screws in holes we need to drill and tap. Before you start make sure there is room for screws to sit inside of your rim. Now mark twelve position where you're gonna be drilling. If you have 36 spokes like me just make a mark, skip 2 spokes and make another one. When drilling the holes use 2.5 mm drill. Likely scenario is that your drill and tap isn't going to fit between the spokes and you will need to remove them. try avoiding this scenario. removing spokes and putting the back on is real pain in the a**. I believe it is possible to solder the modules directly to a rim which usually a aluminium alloy. I didn't have luck with soldering but that's probably my soldering iron.... Anyway now it's time to tap the holes. Just take M3 tap and start taping. Don't forget to use lubricant. I used WD40 although it's not recommended. If you have all holes taped and tested you can put the wheel back together and screw your LED modules in the holes you've created. Note that painting the modules silver makes them blend in with the wheel.

Step 3: Step 3: Mount for Brushes

It's time to make the ring with paperclips. Just draw it on a PCB and cut with dremel. I made it the same diameter as hub on my bike just so it blends in nicely but you can change the diameter if you want. The 12 sections on the ring don't need to be precisely cut since paperclips will determine when when they make contact. Take your paperclips and straighten them. Now bend the end of the paperclips in a sharp angle. Solder them onto the PCB as shown in the picture. Mount the ring on a wheel using zip ties.

Step 4: Step 4: Switching Mechanism

The conductive pad is just PCB cut in a way it makes contact with paperclips. Most bikes have several mounting holes for brakes, racks, etc. . Try designing your pad so you can mount it on one of these holes. if you can't just do what i did. My pad is mounted with the lock nut for wheel. The problem is that my paper clips would hit the fork first and bend too much before touching the pad so i needed to raise it. To do that i just used some scrap pieces of pcb and superglue. Once that was done it was time to bend the paperclips. I wanted to make them the same shape but each one turn out differently. If your paperclips brake loose from the ring just solder it back on in position you want it to be. You want to bend them in a shape like on the picture so the wheel can rotate both directions.

Step 5: Step 5: Wiring

Now it's time to wire it all together. Take a wire and solder one end to one of the LED modules then run the wire on the closest spoke. Use superglue to keep it in place. The other side of the wire gets soldered to a paperclip. To determine which one, rotate the wheel in a position where the module is in position where it should start lighting up. Find paperclip that is just about starting to touch the conductive pad and and solder the wire to that paperclip. The positive terminal of battery will be connected to the pad in series with 5.6 ohm resistor and on/off switch. Negative terminal needs to be connected to the wheel. connecting it to a frame won't be enough since bearings don't provide good electrical connection. Since I mounted the ring on one side of the wheel, I still have room on the other side so I decided to mount negative terminal there. The assembly is just improvised screw held down with nut and piece of metal making contact with hub of the wheel. You can use paperclip to make this connection. I attached wires to the pad and the improvised screw and ran them up the fork next to steering wheel where i had little bag. i stuffed battery, switch and resistor in it. Generous amount of superglue makes sure connections won't break and foam keeps everything from moving inside.
I will going trough comments so feel free let me know what you think.