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How I built a carbon bike frame at home (and a bamboo frame too)

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Picture of How I built a carbon bike frame at home (and a bamboo frame too)
I have built this carbon composite MTB frame four years ago using simple building method which is described in this Instructable. Of course, this method is not suitable for mass production, but if you plan to build just one or two frames for yourself, it is sufficient and you can build your own frame of a high quality. The feeling of riding a self-made frame is great!

After years of riding, the frame is still okay and I am still alive too, although I prefer riding my bike equipped by the bamboo/carbon frame, which I have built using the same method described here. Until now, several frames have been built by this method in the world.
 
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Step 1: Few important things you need for building the carbon frame

Picture of Few important things you need for building the carbon frame
1. Frame jig - it is used to hold all parts in their exact position. I have built the frame jig from scrap wooden rods and some lathed parts and connected with screws. You can also build e.g. adjustable aluminum jig, where you can make the frame geometry according your needs. As a template of a frame dimensions for construction of a jig, I have used my bike frame that I rode before. The completed jig was stiff enough and guaranteed the position and the alignment of the metal parts during the construction of the foam core.

2. Metal parts - they include an aluminum bottom bracket shell, head tube, short seat tube, cable stops, rear dropouts and a rear brake bosses. The used thin walled tubes and cable stops were made on a lathe, for the carbon frame I have purchased rear dropouts and brake bosses from the bike parts supplier. I have made them by water-jet cutting for the bamboo frame. I prefer to use 7075 Alloy for the metal parts. It is good to have all aluminum parts anodized, as then you do not need to wrap a light layer of fiberglass around the aluminum tubes and part of the rear dropouts as an insulation between the aluminum and the carbon against galvanic corrosion.

3. Foam core - I have used polystyrene foam to make the core of the carbon frame. But it is better to use extruded polystyrene, or polyurethane foam, which is more rigid. Later I have used the polyurethane foam which is normally used for insulation of the outer walls of buildings.

4. Materials for laminating - I have chosen a bi-directional woven carbon cloth (180 grams per square meter). I have used MGS's L285 epoxy resin with hardener 285 for laminating. For the carbon frame I used about 3.8 sq.m of the fabric, for the bamboo frame about 2.0 sq.m. You can also use uni-directional carbon for the base layers and use the bi-directional carbon just for the outer layer.

5. Supplies - I used plastic kitchen foil for covering the workbench during the wetting out the carbon, latex gloves, a small digital scale for weighing of the exact volume of resin and hardener, cups for mixing, paint brushes for wetting out, lots of electrical tape, sand paper and a good respirator during sanding.

6. Patience - the more the better

Step 2: Making the core

Picture of Making the core
After I have built the frame jig and all metal parts were secured in the jig, I began to make the frame core.

I had polystyrene foam rods of the necessary diameters, made simply by using hot wire foam cutter. The cross sections of the main rods was circular, the chain stay and the seat stay were elliptical. I have wrapped these rods with one light layer of fiberglass to increase their rigidity.

In this picture you can see the aluminum parts in their exact position. The polystyrene top tube and down tube is already bonded with carved small pieces of polystyrene for the next sanding. In the front of the picture on the ground the chain stay was being prepared for sanding (to achieve proper shape) and bonding.

Step 3: Making the core 2

Picture of Making the core 2
After adding all of the polystyrene rods I have sanded all of the added small parts in the places of rods connection areas to achieve soft shapes. After that I have wrapped these junctions with one light layer of fiberglass. After the curing of the epoxy resin, I have softly sanded the whole surface.

After finishing the frame, you can melt the polystyrene out of the frame by using acetone, so you can save about 90 g of the weight. I didn't do so, as I think the core helps to dampen the vibrations and shocks.

Step 4: Laminating

Picture of Laminating
I was a little bit afraid before I have added the first layer because of lack of experience. I only had theoretical and little practical knowledge of how to do it, but by following the instructions on how to mix the epoxy and how to wet out the carbon cloth it went okay. I have wetted out the pieces of carbon and I have added the first layer on the foam core. I have tried to cut as large pieces of carbon as possible. For each tube, I have used one big piece with overlapping about 1 cm.

While it was still wet, I have wrapped over the first layer of carbon tightly with electrical tape with sticky side up to provide compaction during curing. I could wrap tightly thanks to the aforementioned light layer of fiberglass, which has increased the rigidity of the foam core significantly. Before wrapping, I have perforated the tape with a pin over the whole surface. This squeezed out excess resin after wrapping.

You can also use perforated heat-shrink tape for the compaction, or use vacuum bagging technique, but for me this was the easiest and sufficient method. According my rough measuremets, the ratio of carbon/epoxy was about 50:50.

This image shows the excess resin after wrapping.

Step 5: Laminating 2

Picture of Laminating 2
In this picture, you can see the frame after the first layer was added and the electrical tape was removed. It began to look like a real bike frame. Approximately four-five hours after first layer had been done, I removed electrical tape lightly and I added another layer, and again, I wrapped it over with the tape. I have tried to make as many layers during the day as possible, because after it fully cured overnight I had to softly sand the surface for the next layer. Before the last layer I have bonded the rear brake bosses and have reinforced them with few carbon layers.

Step 6: Laminating 3

Picture of Laminating 3
During the construction, I have combined the layers diagonally and cross-wise. On the top and down tubes and seat tube, there are 9 layers; on the chain stay and seat stay there are 11 layers. The high stress areas were covered with additional 6-8 layers. I have added two more layers as I initially planned just for the safety, but if I built this frame again, probably I would not add them again. I have sanded the surface carefully before the last layer.

This is the picture after the last layer of carbon. Finally I have let the frame fully cure for a few days at about 50°C at the heater.

Step 7: Finishing

Picture of Finishing
After removal of the fully cured frame from the jig, I have cut the excess carbon and I have sanded the entire surface. Also I have bonded the cable stops and then I have sandblasted all the visible aluminum parts. I have added a few layers of wet epoxy, with sanding between each layer. The sanding is the worst part of building the frame, don't do it in your living room... The whole surface was polishing for a better look. But it is better to spray some quality clear varnish over the surface.

Step 8: Finished bike

Picture of Finished bike
This is the finished bike with my homemade carbon frame.

Step 9: Building the bamboo/carbon frame

Picture of Building the bamboo/carbon frame
I have seen many amazing constructions made of bamboo and I have always wondered why such light, strong, stiff and elastic material is not widespread used for building of bicycle frames, although such frames were built already hundred years ago. Since I have finished my carbon frame, I was thinking about using bamboo for my second frame. Later on, I have found an article describing a bamboo frame Craig Calfee built for himself a few years ago. At that moment I was fully determined to build it too.

One year later I have built the bamboo frame according the same method as I built the carbon frame. This was a little bit easier, as I did not need to laminate the tubes.

Step 10: Building the bamboo/carbon frame 2

Picture of Building the bamboo/carbon frame 2

The most difficult part of building the frame was to find quality bamboo rods. It took me much more time than the building itself. I have visited several dealers in near surroundings and I have tried to find appropriate rods of the necessary diameters among huge amount of bamboo. Finally I have found few rods I wanted, but frankly speaking, next time I will build such a frame, I'll rather grow my own bamboo, or fly to Asia for it. The rods for the top tube, down tube and seat tube are some Chinese species of bamboo; I was not very satisfied with the quality of the surface, which was rather scratched and there were also a few woodworm holes in it. The rods I have selected for the seat and chain stay were some other species from Malaysia. Unfortunately the seller was not able to tell me what species it exactly was. During breaking tests of these bamboo rods I found out that when I filled the inside with the polyurethane foam (which added only few gram of weight), the rigidity increased mainly of the rods for the seat and chain stay, which are the most critical parts of this frame.

Step 11: Building the bamboo/carbon frame 3

Picture of Building the bamboo/carbon frame 3

The frame building itself was quite quick. I have used the frame jig I made for my previous carbon frame. Bamboo rods were fitted in miter joints together with aluminum tubes (bottom bracket shell, head and short seat tube) and bonded with epoxy. The junctions in the rear part of the frame I have made from polyurethane foam and the following laminating process of the joints with epoxy resin and woven carbon cloth was practically the same as for the carbon frame. The bamboo rods, in the place of connection with the carbon were machined, so there were small shark teeth which guaranteed that the bamboo will not loose. Also it is important to have well dried bamboo, so it will shrink later minimally.

Step 12: Building the bamboo/carbon frame 4

Picture of Building the bamboo/carbon frame 4
When I have built this bamboo frame, I was interested in how would it differ from my carbon frame. Above all I have expected that thanks to the unique properties of bamboo, as a natural composite, the frame would be more able to absorb road shocks and the ride would be more comfortable.

After three years, I can write that the bamboo frame fulfilled all my expectations. The frame is excellent and still okay. Compared with the carbon frame it really does dampen vibrations better and the ride is more comfortable.

The connections of the bamboo rods with the carbon joints are still rigid without any problems. I know I can expect the bamboo to shrink or split sooner or later, but I hope that thanks to the used method of securing the mutual connection between the bamboo rods and carbon joints it should not loosen in the case of shrinking and the splitting of bamboo can be easily repaired.

I love riding this bike!
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So i am looking at building the full carbon frame and with my experience in carbon fiber we built and entire robot out of it for my schools robotics club and it was in multiple parts and we made joints for it then slid the carbon tube on the joints and wrapped it but it looked crappy in the areas that were wrapped how did you cover the areas where parts connected to make it look like one solid part and not lashed together with strips of carbon fiber. Also do you have an Instructable for making the frame jig?

ericwlff2 months ago

These are really cool. I have to build one now...

J.J.M7 months ago
Gmather@live.ca
J.J.M7 months ago
Hey can who ever wrote this please email me at gmathet@live.ca. I would like to talk
ShaneFox111 months ago

I have interest in building a carbon fiber BMX race frame. I was hoping to gather more Intel prior to starting. Your info is terrific. I have a few more questions before starting. Can I pick you brain a bit please?

pixel51 year ago
great instructable!two questions:
1) where did you buy your supplies?
2) how strong is the frame?
akhil121041 year ago

very nice explaination thanx

but can u tell us more about the joints at courners .. how to made them??

Hi there! Could you please give some more detailed information on how you joined the bamboo to the corner pieces? (I'm new to this and don't really understand the process) Thanks, and great work on the projects!

rravi31 year ago
How do I build the jig to make the bamboo bike, also do you know what the price range of this project is?
Thank you,
and awesome project too
sanchits2 years ago
hello I would like to built one of these carbon or light weight bikes can you please guide me. Would like to take this as a part of my project, I recently graduated as mechanical engineer and worked on a car design project before but building a bike would be a new challenge for me. Please let me know how can I proceed.

Questions

1. Is there any standard global sizing for bike
2. Currently I am using Catia V5 what kind of factors and calculations do I need to consider?
3. what is the weight of your frame?


srichie2 years ago
While the cost of carbon frames keeps getting very low, and is now pretty much affordable, bamboo frames are still a rarity, and priced accordingly. I'd love to see quality bamboo frames being affordable and widely available. Some day...
ithica20122 years ago
hi i think if u have seald the bamboo with a good quilty resin or varnish then it should last a very very long time my favorit fishing rod is a 85 yr old bamboo thats as flexable as if it were new beautiful job by the way
jfaylor3 years ago
i am going to build a carbon road frame and i need to know where do you get your carbon along with what thickness, type, modulus, how much carbon thank you
aamaral3 years ago
Hey, congrats for your instructable. A piece of art, really. Im into doing one for myself. About the weight, how much for the carbon and the bamboo frames?
apaterson13 years ago
how would i attach disk breaks to it? and is it easy enough to paint with ordinary paint? by the way amazing job!
For the disk brakes, just buy drop outs with mounts build into them. I assume that you mean spray paint when you say ordinary paint, and as I have yet to do this instructable, I don't know how well that would work on it. In general, it can be hard to get a good paint job with spray paint it, as I found out on my steel frame. I wouldn't use spray paint personally. Hope I helped!
apaterson13 years ago
is the bamboo frame suitable for cross country mtb riding?
SeaFire703 years ago
I was thinking that it might be great for a fixed gear bike. My concern would be about the stress around the the bottom bracket and chain stays when skip breaking the bike, with both frames.
I like the valuable information you provide in your articles. I’ll bookmark your weblog and check again here frequently. I am quite sure I will learn many new stuff right here ! Best of luck.
Harley Fenders

The blog was absolutely fantastic! Lot of great information which can be helpful in some or the other way. Keep updating the blog,looking forward for more contents...Great job, keep it up..
Carbon Fiber Bicycles , Carbon Wheel Sets



Just got to say what a great artice this is a what a fantastic finished product, cheers for sharing.

Definitely on my list of things to do when I get some time/space/money etc etc...
iluvcamaros3 years ago
Did you do anything special to the legs of the dropouts to create a better bond with the CF?
fzdome5 years ago
did you leave the foam inside the tubes? if yes would you have any idea how to remove it? are you a student of BME?
Would you not want to leave the foam in to keep it firm?
Looks like acetone might work
forum
just google polystyrene solvent (or whatever type of foam you used) then double-check to make sure that it won't eat your epoxy, too
gymgutt5 years ago
so how do you cure it at 50 c? at the heater ? is it a stove ? or ? thanks !
Ro]x[as gymgutt5 years ago
Depending on the epoxy you pick, it's likely not necessary to actually cure at high temperature, although it will certainly speed the process up. I used a series of heat lamps for several hours on my frame, but perhaps even halogen lights could work.
where from have you bought the metal parts? could you help me out with this ? it's the  only thing keepeing me from making one
 
I cut my headtube, bottom bracket and rear dropouts off of a bike from the garbage. I used a short (maybe 10cm) section of tubing for the seat tube insert; maybe it would have been better to make this insert longer.
Hi! If you haven't find your solution yet, now I try to give some advice. Try at Deda, or Colombus tubi. If you're from Hungary as i suppose from your nick, you may try it at Sopron. Ask Yasec, he imports Dedaccai frame parts to hungary. Another try is worth at Újpest, when you shall ask Zsolt Matuz. He often gets bike frames from italy, smetimes frame parts too. If neither them could help, or you don't want to spend a lot on bike frame parts (yes, these are quite expensive), then write an e-mail, and I can help you on machining frame inserts out of aluminium to make shaped closures right. I have some experience with composite materials too. If wanna ask then write an e-mail
Now I don't know if this will work but what I plan to do is purchase a cheap roadbike from goodwill or another resale store; and cut the metal pieces from that off and then use the flame pieces to mold my carbon fiber pieces- in theory the carbonfiber will fit perfectly into the metal!
This might work, but you have to remember that CFRP has different properties than steel or aluminum. The ideal tube diameter and thickness will be different for each material due to differences in tensile strength and stiffness.
 Have a look on the step 1 page, a few suppliers have been named.
yoguy1214 years ago
hey man do you know if a frame like this or the bamboo version would be a good bike for doing jumps and gaps with because with it being light and all do you think it could stand up to being pounded on and dropped
please respond
thanks and great build i hope to build one someday
and how much was the total build cost
thanks again
JT1014 years ago
What is the frame weight of this and the carbon fibre one? Beautiful!
history3234 years ago
Hey, this is really nice! Just wondering if the CF bonds directly to the metal components, or do you have to take some sort of extra precaution to make sure the metal and carbon fiber stay together??
Santorican5 years ago
I've been staring at this picture for a few hours and for the life of me I cannot figure out how you laid up the carbon fiber. Did you use some sort of cf tape or did you drape wet cf sheets around the core?
m_68 Santorican4 years ago
When you apply wet-of-resin-and-agent carbon fibre texture on any surface, and aligned by a brush or a paint roller-like instrument made of different size washers, then it STICKS to it, unless you choose a too curvy surface to apply. The texture will SURELY bend in one direction, like wrapping around everything round edged, for example a tube.
Then there are several processes to laminate it, the one what Brano described is a very effective and cheap solution. If you plan to apply carbon fiber (or glass fiber, or texalium) texture on a surface, you may do the same punch-made-holes method on 0.2-0.5 mm thick film, and then somehow pull it on the treated surface.
classtopher4 years ago
That is just about the coolest thing I have ever seen. Good work.
Wow. Nice frames. How long does it take to make one of these? Im planning on making a BMX like this.
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