How to Build a Bamboo Bicycle

Intro: How to Build a Bamboo Bicycle

I saw a picture of a bamboo bike and decided I had to have one. I found out that professionally built bamboo frames cost a few thousand dollars so I decided to build one myself.

I had a lot of fun and I hope that you can make one too by following these instructions.

The bike I made is a track bike for commuting to work. The bicycle was inspired by Craig Calfee who makes much nicer bamboo bikes. I really wanted something with a minimum of fancy technology and carbon fiber (although I sprang for the carbon fork). I used epoxy and hemp fibers on all the joints (no pun intended). The track bike also makes it easy in that it is a very simple bike - no gears, cable routings, rear brake or derailers.

Disclaimer: Death or serious injury can result from a bicycle frame failure. Using new and untested techniques is risky. Be smart.

Some links to check out before you get started:
Brano's instructable on carbon and bamboo bike building
Craig Calfee's bamboo bike project
Calfee bamboo bikes
Bike Forest BikeCAD
The forum for info on bamboo and heat treating it

The basic steps:
1. Figure out what type of bicycle you want
2. Get all of the parts and bamboo
3. Heat treat the bamboo
4. Tack it all together
6. Epoxy it all together
7. Build up bike
8. Ride off into sunset

STEP 1: Pick the Bicycle Frame You Want to Build

If you are a real bike nerd you will love this step. You are now a frame designer and get to think about things like bottom bracket drop, chain stay length and head tube angle.

I suggest using an existing frame as a template (if you have one you really like).

If you feel ready to test your skills of an artist go to www.bikeforest.com and use the BIKECAD program. It is a free, online frame designing program.

Another good source of information is the Paterek Manual, which is actually for steel frames. Paterek goes into detail on how to size a frame based on body measurements and what each change in geometry means as far as road handling goes.

Once you have your geometry picked out draw your frame on a large piece of paper.

STEP 2: Get Your Parts and Bamboo

There are some parts that you simply can not use bamboo for (maybe you can, but I didn't)
These are:
1. Dropouts
2. Bottom bracket shell
3. Head tube (I tried bamboo and it did not work - too wobbly)
4. Fork

I chopped the dropouts off an kids bmx which are very similar to track dropouts. The bottom bracket shell was cut out of a wrecked road bike frame. The fork I ended up getting was a carbon road fork from Nashbar. The pink one was just for sizing purposes.

The bamboo:
I had no idea what to get so I went to my local bamboo nursery and bought some hefty green pieces of bamboo. The size I chose was about the same diameter on say an aluminum bike.

STEP 3: Heat Treat Bamboo

Sometimes being impatient pays off!

The bamboo I bought was green and freshly cut. I realized that it would have to be dry before I could use it but I wanted to use it right now! A brief interweb search tought me that bamboo can be heat treated. So I busted out the trusty old blowtorch and got to work on some test pieces.

Holy cow, heat treating bamboo is amazing. Steam and water literally spews out the ends. Sorry I don't have a picture of this (I was using both hands and recently broke up with my girlfriend so nobody was there to take pictures).

Practice on a few pieces first. The trick is to heat the bamboo evenly and slowly. The two step process worked best for me. The first step is to turn the green sections to a light brown. The second step is turn the light brown sections to a dark brown.

I also had a few dry pieces (already light brown) and only treated them once to get them to a dark brown color.

Another thing, I only did one section at a time (from one node to the next).

Heat treating turns relatively soft bamboo into a super hard material. It is incredible. My wood saw had no trouble cutting the green bamboo but I had to use a hacksaw to cut the treated bamboo.

STEP 4: Tack Frame Togther

Now that you have heat treated the bamboo you need, cut, miter and tack the frame together.

You may choose to use a jig to hold everything in place. I did not use a jig so I am not going to go into that here. I don't know much about jigs so don't even ask.

I used the full size drawing and built directly off of that using spacers and standoffs to get everything in the right position.

Use a good half-round wood rasp to miter the joints.

Make sure that you use trigonometry to figure out the length of the chain stays and seat stays. What is drawn on the paper is a projected view.

Rough up the bamboo where the epoxy will go.

Rough up the metal too and stick it all together using 5 minute epoxy or your favorite glue.

Once it is all stuck together very gently put the wheels and fork in place and check alignment. If it looks good you are ready to move to move to the next step. If not

Note: The bamboo headset shown was not a good idea. I had to ream it out and insert a steel head tube because the headset cups did not seat properly in the bamboo and gave a scary wobble when turning corners! Start with a metal head tube and save yourself the hassle. The picture does show how rough your bamboo joint areas should be.

STEP 5: Epoxy It All Together

Time to get dirty!

I used epoxy from fiberglass Hawaii called Aluzine (it is a 2 to 1 epoxy specially formulated for surfboards and has some UV inhibitors in it). Why? Because I had a lot of it left over from a repair to my windsurfer.

I used two different kinds of hemp fibers. I used raw hemp fibers (or semi-processed) and hemp twine (drawn out - semi-twisted, comes on a spool). The raw hemp seems much stronger so I used that as the bulk of the joint and then used the twine to tighten up the lashings.

Mask the frame off carefully. Prepare all the joint areas (clean and dirt free, heavily sanded or rasped for an extra-rough surface).

The process is pretty messy and requires a lot of patience and finesse. Wear gloves and start small - small batches of epoxy and small amounts of lashing. I mixed up a small pot of epoxy and then dipped my fibers in it. I then wrapped it on the joint and followed that with a dry piece of twine. There was enough epoxy on the raw fibers to completely wet out the twine. Practice and you will get it.

I got my hemp from www.downbound.com

Of course you can use kevlar, carbon fiber or fiberglass.

STEP 6: Build Up Bike

Now you get to put in a bottom bracket and a head set. Stick on the cranks and chain, add the wheels and bar and the seat post.

Oh yeah, the seat post...

I thought my idea of having the seat post made out of bamboo was really cool. I spoke to my local bike guru who explained that the seat post is integral to the strength of the frame and advised that I insert a steel seat post into the bamboo tube. Luckily seat posts come in a wide range of widths. I folded a small piece of sandpaper in half (rough surfaces out) and wrapped that around the seat post to allow the bamboo to grip it. I then cut two slots in the bamboo to allow the seat binder to clamp the bamboo down on the seat post.

It all worked but then, crack! I guess the sandpaper was too much for the diameter of the bamboo and caused a small crack down the length of the seat post, almost all the way to the binding. I drilled a small hole to stop the crack spreading and now I will have to wrap the post in some hemp and epoxy.

I still rode it like this and it seemed ok but I am in the process of fixing it right now.

I also had to file down one of my joints at the dropouts to allow some clearance for the chain.

STEP 7: Ride Off Into the Sunset

So how does it ride? Like a stealth bomber! The ride is smooth and silky and very quiet. I never realized how much noise a steel bike makes as you go over bumps and potholes. The bamboo bike is quiet.

Riding around on a bike you built yourself is thrilling.

I am still a little nervous about it breaking but every week I am getting less freaked out about riding it. I think the bike needs a name so if you have any suggestions...

The bike is actually not that light. It weighs about what my steel fixie weighed when built up - around 18 or 19 lbs. I will weigh it again and let you know.

STEP 8: Sweet Pictures to Further Inspire You...

I took these of a Calfee bike parked outside the library - so awesome!

Comments

[katikitalas]

can you share drawing at [e-mail]

[Famorae]

Good day, I am working on this project as a student in my country and I would like for a few assistance.
what is the diameter of the bamboo you used?
what is the thickness of the bamboo wall
did you carry out any test on the bamboo before using?

[swimmer321]

so after you wrap the joints of the bike in the hemp, can you sand it down to make it look nicer? the calfee bamboo bike joints are really really nice and clean-looking. How can i get that look?

[karana]

You sand the exterior layers but it remains a solid lock. Practice on a test build to see what I mean. Getting fine and more slender look simply required taping or wrapping the hemp fibers really tightly with electric tape. It gets the joint to really get tight and strong.

[chriscook42]

Thats what Im wondering. It is almost as if the hemp and stuff was melted into a single material. But you are right- it is a much more appealing look.

[masseffectcat]

It's my understanding that, besides being very careful to wrap the joints as tightly/neatly as possible, Calfee overbuilds the joints, grinds them down, and does a final epoxy on the cleaned up surface. The overbuild is important, because it allows you to improve the aesthetic without reducing the strength of the joint. Just don't grind all the way through the overbuilt parts and it should be fine.

[chriscook42]

After further analysis it seems calfee probably did hemp and then fiberglass on top of it. The fiber glass could be sanded and I think that couldve made that look.

[kklaw]

I would be careful with sanding through any of the hemp fibres, that is where the tensile strength of the joint comes from. The epoxy provides a matrix that helps to evenly distribute the forces throughout the joint but the fibres need to remain intact to provide any tensile strength. Chris's idea of a layer of fibreglass on top for cosmetics and some protection is often how fibreglass is applied. This is why carbon fibre must not be scratched, its structural integrity is severely compromised if any fibres are broken. This is a great project, I'm excited to try it with carbon.

[peligro]

I think the author intentionally had the joints look fibrous. If you soak the hemp cord in epoxy, once you put it all on the frame it should fit a lot smoother than in these pictures. And you will definitely be able to sand it down, it just won't be easy. Once the epoxy has cured the hemp/epoxy matrix acts like any laminate in that it is a relatively homogeneous material. It should be solid throughout.

[karana]

Nice tips and exchanges. Here is mine. Finished a few days ago. But I had help. Hoping to make another using recycled dropouts and head tube next week.

[paolobertoncin]

great job

[bpurcell2]

Name 'Not just for smoking' as in , Hemp is;

[davidbarcomb]

This looks great! I have to try this one

[faceboogerz]

Where did you get all the dropouts joints from?cut out from an old bike or did you make them or did you order them?

[ayasbek]

Those dropouts were cut out of an old BMX. Now I get all my dropouts from these two:

Paragon Machine Works (www.paragonmachineworks.com)
or
Nova Cycle Supply (http://www.cycle-frames.com)

Hope this helps.

[faceboogerz]

Thanks yes your thread have been very helpful. ..and thanks for the two websites.

[cameronbrown]

Here is my finished bike, with a step by step writeup
http://www.cameronbrown.ca/blog/2013/09/bamboo-bike-build-part-3-final-touches/

[Kelly02]

It must be lighter than usual bikes. Nice work.

[dlu]

Hi~
I've a little Q:
How's ur bike now~?

[ayasbek]

I have stopped riding this one. My other bamboo bike has been sitting outside under a tarp for over a year now and still rides and feels great.