Intro: Embedded Bike Rim Lights
In this instructable I will show how I installed LED lighting in the rim of my bicycle. If you are into bikes and or hacks, you may have seen other bike lighting hacks. If not, check them out. Below is a summary with links and my own comments regarding the designs.
Glo bike with phosphoresent paint from Glo Nation - https://www.instructables.com/id/Night-Bike/
If you garage your bike during the day, the paint wont charge well when it comes to time to ride at night. Also if you are riding in a major city it is likely that there will be so much light polution that you, and everyone else wont see you glow percivebly more brightly.
Project Aurara - http://vimeo.com/23544972
POV - https://www.instructables.com/id/SpokePOV%3A-LED-Bike-Wheel-Images/
My lights are installed into the rim. Not stuck to the spokes. I believe that this conserves the astetices of the bike during the day (system is almost un-noticable during normal lighting conditions). Also the chance of accidentily getting something caught in the system and ripping it off are considerable reduced.
Batteries are on the hubs (no power for the lighting comes from the frame). This eliminates complex, high tollerance and low cycle contacts featured in other designs. A dowside is that each hub has its on supply making recharging more of a involved task. The major upside is system isolation so that the wheel can be swapped to any other bike.
Expandability. This first instructable covers basic on/off lights. I plan to build on this instructable with more interactivity using the same components with minor modifications.
This is an instructable, I will share all my experience and failures so that you dont repeat them and get a near or better result easier than I did. Please share any design/ construction technique inovations. Share alike!
If you follow my instructable you will be drilling many holes in your rims. Use older rims if you have doubts. I dont believe the perforations will significantly weaken the rims. The valve hole for the tyre is much bigger than the 5mm hole we are going to make. If the rim is going to fail it will be there. That said I did this hack on my old crappy rims so I wont be too upset if they fail.
You will also be required to seperate the rim from the spokes and hub. And of course, if you want to ride the bike again, and not just look at a pretty ring of ligts, you will have to put it back together. Wheel building is not covered here. I will refer you to some resources when appropriate. Give it a go! its not too hard and you will get another life skill badge.
This is a labour intensive hack. Plan, make the jigs, and modularise your work to save time and be prepared to put in some hours!
Step 1: Equiptment and Materials
• Soldering iron and other basic misc. electronics tools.
• drill press
• electric hand drill
• bandsaw (hand for making the drill jig, not essential)
• 5 and 6mm drill bits (dont use cheap ones. They will go blunt) black=carbon=good *usually
• spoke wrench (you will need to buy this from a bike store. DO NOT USE PLIERS OR A WRENCH OR ANYTHING ELSE) Mine cost $1.50
• scrap 18mm ply (or other suitable material for drilling jig)
• LEDs colour and number to suit
• battery holder
• resistors 3 to 330 ohm (dependent on the number of LEDs)
• 2m of red black 22AWG wire.
• male and female 3.5mm stereo jack (or your own jack solution)
Step 2: Undo That Wheel!
Take off the tyre and inner tube and tube tape. Unscrew the nipples (hehe) and keep them in a safe place.
TIP> tape the outer intersections together to conserve the lacing pattern and save time later. I did this for half of the spokes. They were reinstalled quickly. The rest were reinstalled twice.
mark the rim with a pencil where you intend to drill and recheck. In my wheel I installed 18 lights to a 36 spoke wheel. This is one led for every other space in the rim. I reccommend this number as a maximum. You need to leave out LEDs for the rim joint and tyre valve, so if you try to do the full 36, there will be gaps in your LED chain. with 18 the spacing is greater but even. Also 18 is still alot of work!
Step 3: Building the Jig Drilling
The jig is essential to make the work easy, accurate and repeatable. When errors are uniform, they arent errors.
The sketchup model i used to conceptualise the jig is attached for reference. Basically its a sandwhich of three 18mm plywood sheets. The center supports the outer edge of the rim and the two side pieces provide lateral support and clamping pressure.
To setup the jig, put an large drill bit in the chuck the same diameter as the valve hole. Place the wheel in the jig so the valve hole is in the centre of the jig. Align the jig to the drill using the bit to center it. Clamp the jig down to the platen of the drill press.
The following is an outline of the process i used to make some centering guides (screws that fit into the spoke holes). It is very difficult to describe and probably could be done in a better way. Refer to the photos and video for details and leave comments if you find a better way.
use a cordless drill to drill through two adjacent spoke eyelets either side of the valve hole and main drill bit. you just need to leave a mark for later. Take out the rim and remove the jig from the platen. Drill through the remainder of the eyelet holes. Install wood screews in the reverse direction. I used many layers of heat shrink tube to make the guides snug to the spoke holes.
Drill the rim on the drill press. the video below shows the process.
Use a drop of oil on the boring surface
Set your press to the lowest RPM
Step 4: Soldering and Electronics
Solder the LEDs
I made mine in 3 sets of 6 to troubleshoot, add redundancy and minimise failures. A better idea is to make a continuous ring and then make a jump in the middle so a break in the line somewhere will not take down all the LEDs
put on a good record and settle in, your making bike (read: christmas) lights.
Drill two 5mm holes in block of scrap wood a little further than the spacing between your drill holes in the rim. use these holes to support the LEDs while soldering. USE parallel wiring. This increases the redundancy of the circuit, and keeps the runing voltage down (current will be high).
Here is my youtube video if you need it. http://youtu.be/cS1QoyAOxyI
I used a cable with very thick insulation for my first set. This made installation of the tyre very very difficult (I ended up using an older softer tyre in the end). Try to use thin wire to minimise the space used in the rim recess.
Selecting the Resistor
LEDs are a weird electrical component. They have a voltage drop but no internal resistance. they are not like a normal light, they are a diode. What does this mean? if you forward bias them they will light up and act like a short circuit. This means that they will allow whatever amount of current the can to pass through them. You need a resistor in series to limit the current drawn by the LEDs
for more detail refer to the spark fun tutorial. http://www.sparkfun.com/tutorials/219
I will go through my design, if you use a different type of battery and or number of LEDs. you will need to change the resistor.
A LED has a maximum current of 20mA per LED.
I am running 18 LEDs in parallel so my target current is 360mA (18 x 20)
I am using two 1.2v 1000mAh Ni-Cd AA cells in series to drive the circuit.
V=IR, where V =2.4v, and I = 360mA
R = 2.4 / 0.36
R = 6.66667 ohms
You may want to experiment with the voltage and resistors to get the best result. Just bear in mind if you blow one of the LEDs in the wheel it will be very hard to replace. Also if one goes, it will force more current onto the rest. So you may get a snowball effect of all the LEDs frying one by one as they shift current.
It would be a very good idea to test the lights before sticking them in the wheel. Check the current with a multimeter.
Step 5: Fitting the LEDs
Fit the LEDs into the rim. I suggest supergluing them down as you go. Tape the cables down temporary to avoid them jumping out. Pass all the cable ends through the hole for the power input jack. Solder on the Jack and test the LEDs again to ensure they are working as before.
Step 6: Rebuild the Wheel
if you followed my advice and taped the spokes in their position before disassembly of the wheel reassmble should be quite quick. If not or you are building a new wheel I suggest doing a bit of research before taking this on.
As wheelbuilding is not my expertise I will refer you to someother resources
You tube: http://www.youtube.com/user/thebiketube?feature=watch
I will leave it at that. You know how to google.
Rember to line the valve hole up with a set of parallel spokes!
Step 7: Finishing
After another test of the LEDs, confirm that the LEDs are glued securely and tape down all the cables. Try to keep the cables down low or tyre installation will be more difficult.
Mount the battery pack near the hub. I have simply zip tie-ed mine near the hub. A better solution is definately possible.
Mount tyre and tube as normal.
Step 8: Enjoy!
Viola! You are a Tron biking legend.
Ideas for expansion:
Use UV LED lights in white rims or phosphorescent painted rims might get us closer to the Blackberry add look. Wear black pants.
Use brighter higher specification LEDs (the ones used here are garden variety cheapies)
Add some kind of switching effects (coming soon).
Use SPI addressable LED strip and $$$ to add more functionality.