Introduction: Building a Carbon Fibre Bamboo Bicycle From Scratch
Look no further for a free-range, organic, and gluten-free mode of transportation! Bamboo bicycles not only look resplendent, but they also provide fantastic road vibration absorption, higher strength to weight ratio than steel, and similar stiffness to aluminum. With a bit of time and sweat, you can be riding out into the sunset all thanks to your wonderful craftsmanship.
Thanks to all the bamboo bicycle builders below! Definitely couldn't have done this without the help of your instructables!
Build a Bamboo Bicycle (And Light it up!) by ben_k
How I built a carbon bike frame at home (and a bamboo frame too) by Brano
Bamboo Bike #2 by BAMBOOBIKER
Building a Recumbent Bamboo Trike Frame by kentdvm
Step 1: Materials List and Cost Breakdown
Before we begin, let's get a few housekeeping items out of the way. Below is a rough list of materials and equipment recommended for this project. The corresponding costs are an estimate if you need to buy all parts brand new. You can definitely cut down on costs by purchasing used bicycle components, or using a donor frame for the lugs instead of buying new ones.
Bamboo Poles (from Bamboo World)
• 3 = 1" by 8' poles (for 2 seat stays, 2 chain stays) @ $1.19 ea
• 4 = 1.5" by 8' poles (for top, down, and seat tube) @ $4.27 ea
Approximate Pole Diameters
• Down tube - 46 mm
• Top and seat tube - 35 mm
• Seat stays - 24 mm
• Chain stays - 27 mm
Carbon Fibre Lugs (from eBay & Coast Fibretek)
• 12k carbon fibre tow (I used 1-2 lbs of my 4 lb spool) @ $62.35
• West Systems 105A Resin qt @ $44.35
• West Systems 205A Fast Hardener .44 pt @ $22.65
• West Systems Mini Pumps 300ABC @ $18.95
• West Systems 404 High Density Filler 15.2 oz @ $16.70
• 4 rolls of electrical tape @ $0.63 ea
Total (all materials): $167.52
Total (cost of materials used for frame*): $94.50
*I only used about half of the carbon fibre and epoxy, so I have enough for at least another bike.
Bicycle Frame Parts (from Nova Cycles)
• Head tube OS chromo 36.0SM x 200 @ $7.87
• Bottom bracket lugless shell 69mm @ $4.25
• Rear track dropouts @ $17.29
• Seat tube 28.6 x 9/6 x 650 @ $15.95
Frame Jig (from Home Depot)
• 2 = construction wood 2x4x96 @ $2.95 ea
• 1 = 1/4-20 x 36" threaded rod @ $6.99
• 12 = 1/4" washers @ $0.11 ea
• 16 = 1/4-20 nuts @ $0.29 ea
• 1 1/2" wood screws @ ~$4
• Various ABS PVC pipe fittings (to hold frame parts and keep epoxy out) @ ~$10
Bicycle Components (from various sources)
• FSA Hammer Heavy Duty Headset - 1 1/8" threadless @ $15.00
• Vuelta aluminum headset spacers - 1 1/8" x 10 mm @ 2.00 ea
• Kalloy 28.6 x 350 mm seatpost @ $23.00
• KMC Z410 1spd chain @ $8.00
• Pake Track crankset - 130 mm x 46t x 165 mm 1/8" @ $61.00
• MEC mountain pedals @ $21.00
• Kalloy SC-201 bolt-on seatpost clamp - 28.6 mm @ $7.00
• Jagwire basics lined brake set @ $3.00
• Tektro R540 caliper brake front @ $25.00
• Tektro RL721 CX brake levers @ $15.50
• Pake Straight fork 1 1/8" threadless @ $63.00
• Fyxation rodeo bullhorn bar 25.4 mm x 40 cm @ $25.95
• Ora road stem 80 mm x 84 deg 25.4 mm @ $19.38
• Vuelta ZeroLite track wheelset 700c @ $92.25
• 700 x 23 tires and tubes @ ~$40.00
• Plumber's torch
• Flint spark lighter
• Kitchen oven
• Jigsaw (or chop saw)
• Power drill (or drill press)
• Dremel tool
• Hand saw
• Round and half-round rasps
• 60, 80, 120, 220, 400 grit sandpaper
• Organic respirator and a well-ventilated area - Epoxy fumes and carbon fibre dust are not good for you or your lungs
• Safety goggles - Carbon fibre dust and eyes don't bode well together
• Full body coveralls - Carbon fibre dust is extremely itchy and may cause rashes
TOTAL COST OF BICYCLE FRAME: $150
TOTAL COST OF PROJECT (not including tools): $700
Step 2: Getting Into the Right "frame" of Mind!
Downhill, cross-country, road, track, BMX, cruiser: the possibilities of bicycles are endless! Seeing as I already have a road bike, I yearned to make this one special. A fixie seemed like a reasonable solution, undoubtedly adding to the mix of hipster vibes spewing out of this project. I searched through Google for different styles of track frame geometry until I settled on dimensions for the EAI Bareknuckle frameset.
Option 1: Model the frame in SolidWorks
I modeled the frame in SolidWorks, starting with a 2D sketch of the geometry. I created a 3D model using surface lofts to figure out the actual tube lengths required for mitering, which happens to be slightly different than the standard tube lengths you get from spec sheets. Alternatively, I could have used weldments to model the frame, and the benefit being you can output a cut-list of the required tubes. This requires more upfront effort to setup (but provides more ease in the long run if multiple frames will be made), so I opted for the former method.
Option 2: Use BikeCAD, an online webtool
If you're not comfortable with using or learning modeling software, there is a free and easier alternative. BikeCAD is a simple solution where all that's required is plugging in the numbers for your desired frame. BikeCAD offers both free and paid versions, but the free one will be sufficient for this purpose. Follow the online tools and you'll have your custom bicycle frame in no time at all.
Option 3: Find a donor bicycle and use its existing frame geometry
An even easier method would be to skip this "building a custom frame" nonsense and just use an old bicycle. As long as the lugs are in working condition, you can cleverly replace the tubes to preserve the geometry without requiring a proper jig (just as ben_k did with his bamboo bike).
Step 3: Bamboo Treatment Can Quickly Turn Into "heated" Discussions.
I purchased my poles from Bamboo World in Chilliwack, BC. These are of the Tonkin species, which is also used for making fly fishing rods. Iron bamboo is another popular choice due to its high wall thickness. Some species are more prone to splitting than others, so research and testing is advised before using it for your bicycle!
My poles were already processed and kiln dried, but other builders have harvested their own bamboo (when still green). When choosing poles (dried or new), it is imperative to check for any signs of hairline cracks. The last thing you want to do is to purchase unusable bamboo. I bought more than I needed, as some bamboo poles will split or be deemed unusable after further inspection.
Preparing the Poles
I cut the poles to the approximate dimensions, adding around 5 cm to the overall length as a safety net. It's easy to remove more material, but quite difficult to add extra!
Moisture and bamboo is equivalent to orange juice and milk: good things don't happen when the two combine. The purpose of heat treating the bamboo is to remove as much moisture as possible. I preheated my kitchen oven to around 150 F, then placed the poles in for about 10 minutes. I then raised the temperature to 275 F and baked it for another 20-25 minutes. This ensured the temperature of the bamboo rises in thoroughly and in equilibrium to effectively reduce the moisture content. The smell of bamboo was quite lovely, and I have grown to enjoy its sweet aroma.
After baking and letting the bamboo cool, I used a plumber's torch to further treat the bamboo. This removed any residual moisture and hardens the sugars near the surface. The flame should never be stationary, otherwise it will burn the bamboo. Move in smooth arcs, constantly rotating the bamboo for an even heat distribution. You want to darken it so it's a nice deep brown, similar to a nicely roasted marshmallow. I highly advise practicing on a test piece of bamboo to surpass the involved learning curve.
Step 4: The "jig" Is Up...
With the bamboo ready to go, it's ready to start putting it all together.
I decided to make the jig out of construction 2x4's. If I money was not a problem, I would have used aluminum extrusions to make a versatile frame jig. Unfortunately, it was not within the scope of my budget so I settled with wood. It wasn't the greatest in keeping everything perfectly aligned, as a significant amount of eye-balling was involved. However, it did the job and materials were inexpensive.
Making the Frame Jig
Again, I used SolidWorks to model the jig based on my frame geometry and determine the necessary dimensions. However, it would be just as adequate to whip out your calculator and high school geometry to perform some algebraic mathrobatics. Either path will lead you to the same end result.
Mitering the Bamboo
The mitering process turned out to be an incremental, trial and error routine in order to account for the natural curves and features of the bamboo. I removed most of the material with a saw and carving tools, followed by a half-round rasp. Once all poles were mitered, I used 60 grit sandpaper to roughen the base of the poles to allow the epoxy and bamboo to bond. I also used a hand saw to create random grooves in the bamboo to improve adhesion. I then tacked the frame together using West Systems 105/205 resin and hardener with 404 high density filler to fill any voids and provide a solid foundation for the joints.
Step 5: Chance the "Wrapper"
I chose to use carbon fibre to create the joints, but hemp is also an option commonly used by other bamboo bike enthusiasts. I found my carbon fibre tow on eBay, being the 12K variety. It doesn't really matter what kind you buy, but the higher the value the more strands there are per string, meaning more efficiency for you. I chose this because it was the best deal at the time.
Constructing the Lugs
To construct the lugs, I coated the cluster with epoxy and wrapped carbon fiber tow in spiraling formations around the joint. It was necessary to perform multiple wrapping patterns to account for the uniaxial material behaviour of carbon fibre. After applying multiple layers of carbon fiber wetted with epoxy, I wrapped the joint with electrical tape (adhesive side outward) to compress the lug and squeeze out excess epoxy. After about an hour and a half, remove the electrical tape and let the lug cure. I learned the hard way that removing the tape after the epoxy has fully cured is quite excruciating...
Working on Aesthetics
After the wrapping process was complete, the lugs were shaped and sanded for aesthetic purposes. The lugs were overbuilt such that sanding away the top layers would not affect the structural integrity of the joint. Research was conducted along with discussing methods with bamboo bike hobbyists and professionals to determine how much material was needed for an adequate lug. An excess of carbon fibre was used for the bottom bracket as it is under the most stress during cycling, especially during sprints and climbing when the rider is out of the saddle.
Step 6: Hei! Adding the "finish" Touch
Woohoo you've made it this far!
Seat Tube Shim
I cut a small length of an existing seat tube to be nested inside the bamboo seat tube. I drilled a hole and cut a slit to clamp the seatpost. I used a half-round rasp to ream the bamboo to accept this shim. Once it fit, I secured it with epoxy.
Varnish and Protective Coating
To make the frame look nice and pretty, paint a thin layer of epoxy on top of the carbon fibre to bring out the shine. I masked off the bamboo and used a small amount of black acrylic paint to give it a nice clean transition from carbon fibre to bamboo. Yes, it may cheating, but you can hardly tell and the crisp lines are worth it.
I used Deftoil Exterior Wood Finish to treat the bamboo. I applied two coats, following the instructions on the container. Once dried, I applied four coats of gloss polyurethane to seal the bamboo and prevent any future moisture from entering the bamboo.
Step 7: Instructabots, "assemble"!
Now that the hard part is done, you are free to harvest the fruits of your labour! If you can build a frame, I'm positive you can assemble a bicycle. There are a multitude of existing resources that will help you if you require assistance.
Warning: This bicycle will garner significant amounts of attention. Beware of compliments and people asking about your bamboo creation!