WARNING: If you are not comfortable with being stopped by strangers and answering their questions about your bicycle, this is not the project for you. And DEFINITELY do not build the spoke lights.
Step 1: Gather Your Tools and Materials
- Bamboo: I used 1 7/8" diameter for the down tube, 1 3/8" for the top and seat tubes, 15/16" for the seat stays, and 1 1/16 for the chain stays. All values are approximate, and anything close to those should work.
- Carbon Fiber Tow: I got 5000 meters of it off ebay for 50$. I have enough left over to build at least 4 more bikes.
- Epoxy: I used West Systems 105 resin and 205 Hardener.
- Old Bicycle Frame: I chose to cut apart an old frame for the lugs, rather than buy new ones. Using an old frame also lets you get away with not building a proper jig.
- Propane Torch: For heat-treating the bamboo.
- Basic hand tools: Saws, a decent knife, a drill, a rotary tool.
- Electrical Tape: For compressing the carbon fiber while the resin hardens.
- Aluminum angle bar: For making a simple stand to hold the frame in place.
- Threaded rod and nuts: For holding the dropouts in place in the stand.
- Spar Varnish: For finishing the bamboo.
- Paint remover: For stripping the old frame.
- Sand Paper: For sanding, of course!
- Rubber Gloves: For working with epoxy. Apparently, you can develop a nasty allergy from too much skin exposure to the hardener. You will need at least 50 pairs of these.
For the lights:
- 4 square wooden dowels
- Drill and 1/16 drill bit
- 80 LED's: I used 3mm orange ones
- 2x 9V battery clips
- Resistors: To run the orange LED's off 9V, I needed 20x 30 Ohm resistors
- Electrical tape
- Soldering Iron
Step 2: Preparing the Bamboo
To start, use a long metal pole such as a gardening stake to punch out all the nodes. If you do not, the heat can cause the nodes to explode. Light your torch, and begin heating the bamboo, node at a time. You will know when you have heated it enough, because the green will suddenly turn tan or brown. Obviously, try not to actually burn the bamboo, or you will weaken it.
After you have torched the bamboo, it is probably best to let the poles sit for a month or so to let the rest of the water escape. Once my bamboo was dry, I sanded it down past the outer skin. In my opinion, the bamboo looks much better this way, as it has a beautiful gold color under the skin. I sanded down the nodes even with the rest of the bamboo as well.
Step 3: Building a Stand
I screwed two pieces of aluminum angle into a 6" wide plywood board to hold the bottom bracket shell in place. To hold the rear dropouts, I used a threaded rod bolted to the wooden base.
Step 4: Preparing the Donor Frame
To get the frame ready, strip the powder coat off the head tube, BB shell, and dropouts using paint stripper. Beware, this is pretty nasty stuff. Use it outside, and try to keep if off you.
To avoid using a jig, the order in which you remove the bike's tubes is very important. You have to be able to retain the bike's geometry for everything to align and for the bike to track straight. I started out by removing the chain stays. By removing them first, the dropouts are still held in place by the seat stays, and no other part of the frame is affected.
Step 5: Adding the Bamboo Tubes
Step 6: Adding the Bamboo Tubes, Cont.
Step 7: Adding the Bamboo Tubes, Cont., Cont.
I chose to used really wide diameter bamboo for the down tube. I really like how it looks, and it adds a lot of stiffness to the frame. The down tube was mitered and tacked into the frame just as the other tubes were.
Step 8: Wrapping the Joints
To start out, mask of your frame. This makes cleaning up the tubes much easier, but be sure not to wrap over the tape at all, or it will be impossible to remove.
Wrapping the carbon fiber is best done a little bit at a time. I found that the easiest way to wrap was to paint some epoxy on the joint, wrap one or two layers of carbon around the joint, and then paint more epoxy on top of the carbon. Repeat these steps until the joint is too soft to wrap much more. When you have finished with the carbon fiber, wrap the entire joint in electrical tape, sticky side up, to compress the joint as it dries. Once the epoxy is dry, remove the tape, sand the surface of the joint lightly, and add another layer of carbon. Continue this process until the joint looks sturdy. When you are wrapping, be sure that you have fibers in all directions. If you just wrap circularly, the joints will only be strong in one direction. This can lead to cracks or even joint failures later on. To fix this, I cut lots of short strips of tow and laid them lengthwise on the joints, before wrapping circularly around them. I alternated one lengthwise layer and then one layer around. I have no idea how much carbon fiber is necessary, but it is better to have really thick joints than too thin joints.
Once the joints are strong enough, sand them down to a smooth surface. This step is not necessary, but it makes the joints look infinitely better.
Warning: Epoxy dust and carbon fiber dust are not good for you! The carbon fiber will irritate your skin and eyes (and probably your lungs), and epoxy is just not nice stuff, so be sure to do all your sanding outside, preferably with long sleeves and a breathing filter.
Depending on your frame's geometry, you may want to add a chain stay bridge to stiffen the frame. Also add a brake bridge, and cable stops, if you need them. For both these parts, I cut the tubes out of thin bamboo, and wrapped them heavily with carbon fiber.
While you are wrapping, occasionally check to make sure you have clearance for your back wheel's cassette. I found that I had to remove a significant amount of bamboo and carbon to get them to fit.
If you are going to have a derailleur or rear brake on your bike, you can attach cable stops with carbon fiber as well. To make the cable stops, I cut short segments of very thin bamboo, and glued a metal cable cable cap into the bamboo. I then glued the assemblies to the bamboo frame on the down tube, and wrapped around them them in carbon fiber. For the brakes, I decided to run housing all the way along the frame, so I did not use cable caps. I just cut short segments of bamboo to guide the brake cable and glued them along the top tube.
Step 9: Touching Up the Joints
Step 10: Finishing the Bamboo
First of all, sand down the bamboo, and remove any epoxy that might have gotten on the tubes. To finish the bamboo, I chose to use some spar varnish left over from my boat. Since this stuff it durable and flexible enough to be used on masts and spars, it should work quite well on a bicycle. I thinned the varnish with mineral spirits, and applied about 10 thin layers of it. Other people have used tung oil to finish bamboo instead. I have only used it on wood, but, while it looks very good, it does not provide a hard coating like varnish does.
Step 11: Making a Head Badge
Step 12: Build Up Your Bicycle
I built mine up with a mixture of new and vintage parts. I bought a new carbon fiber for from Nashbar on sale for 52 dollars. I highly recommend you get a carbon fork, simply because they perfectly match the carbon on the frame. I got my brakes on ebay for 24 for the pair, I already had the wheelset, bars, shifters, derailleur, and cranks I used, and I got cables and housing from my local bike store.
Step 13: Light Up Your Bike
The spoke lights are based off a very simple circuit. Each one is composed of ten sets of four LED's and a resistor in a series, in parallel. I chose to use 3mm orange LED's because they were for Halloween.
Step 14: Building the Lights
Step 15: Building the Lights, Cont.
Step 16: Light 'er Up!
Step 17: To Conclude
Please note that this Instructables is entered in the bike contest, and the MakerBot contest so please vote for me when the time comes! 500$ to REI could fund the components for building an even cooler bamboo bicycle, and with a 3D printer, I could print headbadges, so I don't have to arduously grind them out of steel.