Introduction: Bamboo Carbon Bike
Step 1: Supplies
Bamboo: bamboobikesupplies.com they have a kit with all the pre-made iron bamboo.
Carbon: I bought 3 miles of 12k tow from eBay for about $65. It took about 3/4 of a mile to build the whole bike. Lots of left overs.
Frame: steel motobecane bike that I got for free. I wish I would have found a steel bike with a standard BB not a Swiss BB.
Epoxy: west systems 2 part from westmarine and 2 part tacking epoxy from hobbyrrtgbcy supply.
Sandpaper: 60 grit
Polyurethane: for bamboo
Gloves, stirring sticks, mixing cups, electrical tape, rags
Components: Craigslist and online
1 major tip use a cut piece of bamboo with slits in the end and wrap this in carbon for wrapping the bike. Tie the carbon in a not at the end so it can't slide through the cracks. This made wrapping in tight places 10x easier.
Step 2: Making a Simple Jig
I made a simple jig with a 2" by 4", a flat piece of particle board, 1 L bracket, I threaded rod, and a few nuts to put on the end. This provided a sturdy base for me when I was cutting the frame into pieces.
Step 3: Cleaning the Frame
Put the frame on the jig or stand and give it a thorough cleaning and sanding on the joints where epoxy and carbon will be mating to. This will ensure you get a nice very strong bond. You can also use some paint stripper to remove paint for this process. Let the stripper sit long enough, it will make your life easier. Be sure to grease then stuff the BB and the head tube with a clean rag. This will make sure no epoxy gets into the threads. I had a bit of epoxy get in the threads, and I found this out near the end. I had enough grease on everything that the epoxy just chipped right out.
Step 4: Cutting the Frame
Start off by making 4 main cuts. As seen in the pictures above, cut above the BB, the top tube, and the two rear stays. Be sure to leave plenty of room for the bamboo to slide on over and bond to the metal. Make sure to only make these cuts or else you are at risk of losing the frame geometry. Use a sawzal or a hacksaw to cut these joints.
Step 5: Cutting and Framing the Bamboo
This part is not difficult but you don't want to screw it up badly. I cut the lengths to what I thought they should be, then used a round file to give them their shape and fit together properly. My fit was not where near perfect but that is okay because the carbon covers any imperfections. I used hobby 2 part glue because it gets hard after 2 minutes this makes tacking the frame together very easy. Remember you have room to slide the tubes around a bit because they are overlapping the steel sections that are being kept.
Step 6: Cutting the Down Tube and Forming Bamboo Down Tube
Once the glue is dry on the other sections you have maintained the geometry and are able to cut out the down tube. Make sure you leave significant pieces of tube on the remaining frame because you have to be able to slide the new piece of bamboo in between here without breaking the frame. Once you have made that cut, size the bamboo appropriately to fit in here with as much overlapp as you can fit on both sides. Wrap one side in electrical tape which acts as a stopper. That way you can ensure equal tube overlap on both sides. Also cut and mold a small piece of bamboo as the rear brake bracket. This is a structural and functional piece of the bike. Use electrical tape to hold the whole frame together. I decide to leave the rear horizontal stays and wrap them in carbon later for looks. the bamboo rods they sent me for that section seemed a bit puny for my liking. In hind site I think they would have been plenty strong.
Step 7: Wrapping the Frame in Carbon
Once you have whittled down the outside of the bamboo with a knife only at the joints, you can begin to wrap the frame in carbon. I used 12k tow and west systems epoxy for all the joints. Start by mixing up a batch of epoxy and brushing it on the joint your wrapping. Do strands lengthwise in each direction a few times before you begin wrapping. Then wrap randomly around this, through there, over this, this will improve the strength. Then at the end wrap everything evenly and coat epoxy on the top. Make sure there are no areas that are dry without epoxy. Put 3-5 layers on each joint. You can layer the carbon so that you have nice smooth filleted transitions. Back wrap the epoxied joints in electrical tape to squeeze out unused epoxy. Let drive for 5 or so hours before removing tape don't test strength until glue has fully hardened after 24 hours. Be sure to use quick dry hardener to reduce wait time in between layers.
Step 8: Sanding the Carbon
Once I was confident in my frame strength I began hand sanding the whole frame with 60 grit sand paper. I sanded every joint until it was good enough, to my standards. Be sure to wear a mask, long sleeves, and long pants for this step. You will kick yourself if you don't, you will be itching all night. Sand a flat spot on the front and back of your brake mount on the rear stays. This makes attaching the brakes very smooth.
Step 9: Gluing on Emblem and Drilling Hole in Brake Strut
I used the original emblem from the motebecane I used, reprinted it and glued it to the front tube. I feel like every bike needs something there. For the hole in the brake strut I just sized up a drill bit to the brakes I had and drilled a hole. These are really the fun finishing steps.
Step 10: Coating Bamboo in Polyurethane
I coated all the bamboo with two coats of polyurethane to ensure the bamboo was sealed properly. Do one coat then wait 4 hours to do the next. Use any type of brush for this step.
Step 11: Coat Joint in Epoxy
I then coated the joints in epoxy to give it a nice shiny finish. I only did one coat for this step. I have the emblem a light coating to protect the paint from chipping.
Step 12: Finishing the Bike
I decided to make the bike a single-speed for now, later to convert to a 20 speed. I put spinergy carbon 700c wheels with dura ace brakes. I also put carbon bars and a carbon fork on the bike. Nashbar sells a 1" carbon threadless fork for $100, that are awesome. I got a origin 8 singlespeed crank with a sram chain. Brake levers are nice tektro ergo brakes.
Step 13: Riding the Bike
The frame is awesome and very stiff, I love riding it. It rides exactly like a carbon bike, stiff and responsive but forgiving on the body. My plan is to manufacture some all carbon and bamboo bikes and start my own business sometime soon. I obviously have a different method in mind to build my next frame, to reduce overall weight. This bike is awesome though, and quite the accomplishment when your done.
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