The lugs are built up on the frame out of carbon or hemp fiber usually.

Durability is superb for a well engineered frame (including the species, age, and treatment)! Each frame is hand built, so the automated mass production is what I believe keeps the big boys from venturing here. A good set of calipers can tell you where to cut for the diameter your looking for. However, the culms are not always round, you just have to adapt and use this to your advantage.

you can see a youtube of my project by searching for "bamboo bike by phil webb".

Hey guys, I haven't given up on this project and plan to finish during my break between semesters.

The things I am currently thinking and wondering about are, which hemp fiber, raw, sliver, or a twine? Or should I just go carbon, and if so I have seen conflicting information. Some say to use tow and to just wrap, others say that a weave would be much stronger. I have also been thinking about taking a bike and just chopping it and slipping the bamboo over so I don't have to worry about alignment issues the first time around.

The raw hemp fiber will work the same as the finer fiber. I am now under the opinion that twine may leave air pockets or pockets of resin void of fibers. I think you can make a stronger product with fiber (make test pieces and destroy them to draw your own conclusions).

I personally find TOW line is easier to work with than cloth. I am unsure the differences in strength.

Sand the enamel skin off of the bamboo wherever you want the resin to adhere.
Cutting through the skin before you cut the tube will lessen the chance of the skin splitting.
Wrapping the cut in blue painter's tape before cutting will also help.

Bamboo is not perfectly straight. I think you will still have alignment issues if you cut up an old frame and try to make an internally lugged frame.

Use off the shelf (Nova, Henry James, Paragon Machine Works, etc.) metal parts (head tube, bottom bracket, dropouts) and mount them to your jig so they are properly aligned. Fit the bamboo between them.

Miter the bamboo the same as you would using metal tubes, then tweak the fit by sanding the miters so the bamboo lines up as you want.

Well I'm trying to get away with out a jig but do you think the scratch build is better (a more precise final product)?

I would have thought that the longitudinal fibre alignment of the bamboo tubes would compromise their torsional rigidity .

This is supported by data showing that bamboo has a typical ratio of EI / GJ greater than 8 where isotropic materials with moderate Poisson's ratios (eg metals) give values around 1.3. Since EI / GJ describes the ratio of bending stiffness to twisting stiffness, this says that the bamboo has about 16% of the torsional rigidity of an equally laterally stiff metal tube. Since the bamboo tube will have lateral stiffness less than or equal to that of a metal tube of the same diameter and weight, this gives it at best 1/6th of the torsional rigidity.

It is well known that torsional rigidity of frame tubes is extremely important for handling - you don't want the down tube and top tube twisting enough to pull the head tube out of alignment with the rest of the frame.

Am I missing something or is this another case of something which looks like a good idea but really isn't?

Mark Kelly, you obviously know a heck of a lot about materials than most of us do. I relish your question and hope for an answer from somewhere.

I'm building off of a level table, not unlike Otto's setup here: http://ottobelden.blogspot.com/2009/...struction.html

Contour, read through this thread too: http://www.bikeforums.net/showthread...on-fiber-build

Contour, if you're creative, you can get everything lined up appropriately with out an expensive jig system. It's not very practical, so it would not be efficient for mass production, but for one offs I'm sure you'll think of something.

Thank you,
phil

I made a bamboo bike recently and the process is remarkably simple. You can align by eye if you're used to doing any work that requires some experience with this. My bike tracks perfectly.
I used bamboo from a flower shop and a garden center and chopped up a few steel frames for the necessary parts.
I didn't bother with heat treating. Tests show that as soon as you heat bamboo to a darker color you significantly weaken it (although it does become stiffer).
You will notice that bamboo poles in a typical selection may be splintered and cracked or perfectly sound. Since the sound bamboo has probably been sitting for several years through a huge range of moisture and heat cycles without cracking you can be more sure it will continue to do so in the future.
Imported bamboo has already been fumigated twice for bugs so it is hardly necessary to do that.
A good finish renders it impervious to moisture and appeal to insects anyway.

For gluing I would recommend going by a proven Epoxy system. I like System 3. Resins. They have an appropriate Epoxy for every application in the process and though it may not matter they are all likely more compatible with each other than using types from several companies.
I wrapped the lugs with a combination of Fiberglass, Carbon cloth and Manila hemp(for the natural look).
You need to cover the metal parts with glass cloth before you wrap with carbon. As far as tow versus cloth, by the time you finish wrapping a lug with tow it IS practically woven.

As far as worrying about torsional stiffness, I wouldn't. If you try to bend or twist a short length of bamboo tubing it is unyielding. If you wrap your lugs well they will increase the stiffness. With the ends of the tubes locked in place and all braced against each other the accumulated strength of all the parts is incredible.
Once you build one you will start replacing all your other bikes with a homemade version. I'm working on my TT bike now.
Interestingly I'm probably riding the only bamboo bike in Toronto right now and people don't even notice it.

Canaboo, can we get some photos to drool over?

http://i399.photobucket.com/albums/p...5/CIMG4903.jpg
http://i399.photobucket.com/albums/p...5/CIMG4904.jpg
http://i399.photobucket.com/albums/p...5/CIMG4906.jpg
http://i399.photobucket.com/albums/p...5/CIMG4907.jpg
http://i399.photobucket.com/albums/p...5/CIMG4908.jpg
http://i399.photobucket.com/albums/p...5/CIMG4909.jpg


Here's a few. Sorry it's a bit dirty from riding on dirty roads. Not really drool-worthy but a good basher for rough roads. The parts are very low end in case somebody gets the bright idea of hacksawing it to get the parts.

Very nice!
What resin are you using?
What's your build process, tape, vacuum bagging?
How much clean up did you do on your lugs? They look swank.

More, I must have more.

Seriously, that's a sweet bike.

Thanks. I just tacked this bike together with the same resin I wrapped it with(MAS Epoxy). I had some carbon and glass tape which I used as an initial overlay of all the lugs and then wrapped them twice with the Manila. After the first layer cured I sanded them and then applied one more thin layer of Manila as neatly as I could, sanded them again and smoothed on one more layer of resin.
I used inner tube strips in place of vacuum bagging. That compresses the matrix and squeezes out the excess resin. After it cures the tubing peels off and the surface is very smooth and only needs any ridges of resin flattened.
I did sand the ridges of the nodes down since the bamboo wasn't the greatest in quality. That doesn't weaken it if you just knock off the lip of the node and don't try to completely flatten it. The bike is very stout. I can place my hands on the top tube and bounce my weight onto it with no signs of creaking or bending.

Hey canaboo. You have inspired me to build a bamboo bike like yours. I located a old centurian road frame that I will be using as a doner fot the BB, HT and dropouts. I'm having some trouble finding a source for the bamboo. I live in MA and can't seem to find any growing beside the road. The online places seem to require a fairly large minimum order.Can anyone point me to a good source of bamboo?

www.bamboofencer.com has bamboo poles. Tonkin is a good choice for smooth nodes and all around strength and resiliency. It's the type used for making fishing rods.
I managed to get some up here and it is incredible stuff.

Thanks for the info. I ordered the bamboo today.I also ordered all the neccessary metal bits from Nova.I am working on drafting a full size blueprint and building a jig so that I can start assembly when the material shows up. When it comes time to wrap the joints I will asking more questions on this forum because I have not worked with composites before.

AllenG, I liked the dropouts that Otto designed for his friend, they look very similar to what Calfee uses, at least in terms of the bolt adjustable angle. Been following this thread, kind of lurking, and the question that I have is what kind of drop outs are you guys using on your bamboo frames and how are you attaching them to the stays? It seems that most dropouts that I can readily find on the www are pre-made at a certain angle for the stays and not easily adjustable. I wold love to get my hands on some similar to what Calfee uses, or that Otto guy.

Part C1152 at Ceeway seems to be the best option I have seen. I haven't bought a set yet but the long plug-in section seems ideal. The angle is the biggest problem but it is usually pretty easy to select bamboo with a kink at a node so that you don't actually need the angle in the metal.

Another option is to buy four of the carbon seatstay adapters from Nova and drill a set of the aluminum road dropouts to bolt on. The shape looks like it would interface perfectly.

Bonding?
 

I'm using aluminum for the head tube and bottom bracket and steel for the dropouts. Do I need to wrap theese with fiberglass before using carbon tow? If so, should I apply the fiberglass before even tacking the frame together with epoxy ?

Yes, you need to cover them with glass first. You also need to etch the Aluminum to ensure a strong, lasting bond.
You will probably find it easier to tack the frame first and then cover the exposed metal with glass. You can then use the glass as a base structural layer by extending it onto the frame. A few pieces of glass extending from the down tube between the chainstays and up the back of the seattube and a few more from the downtube and split to overlap onto the chainstays will tie that area together. It is easiest to buy a few rolls of fibrerglass tape for this application. The finished edges of tape reduce the problem of the glass weave coming undone.
The exception may be the dropouts. If you insert them into the bamboo then the carbon wrap will only reinforce the bamboo without actually contacting the metal.
You of course have the option of sleeving everything into bamboo first which will eliminate the necessity of the insulating layer.
Your lugs can look a bit bulky if you go that route unless you use the thinnest walled bamboo.

Canaboo, can you explain what you mean by sleeving and how you did this?

Old Goat, what style of jig have you built or decided that you want to build? I've been looking at this instructable http://www.instructables.com/id/Almo...rame-building/ and plan on building an alternate form that he has at the end which allows tacking of the whole front triangle.

This seems like mostly a carbon fiber frame, not a bamboo frame.

I have a big cast iron table saw that has perfectly square edges. I plan to clamp some square aluminum tubing, that I have around from another project, to the table to create a vertical surface. I'm going to build the front triangle flat on top of a full size drawing and then stand it upright to build the rear triangle. This is just a preliminary plan and probably will change as the project moves into the "hands on" stage. I was a mechanic for 30 years before I retired so I "think" better with my hands than with my head!

By sleeving I just mean inserting the metal tube snugly into the bamboo tube and gluing it in position.
I'm not sure how this would be viewed as a carbon bike when the carbon is merely a lug reinforcement.

According to the frame testing Renovo has done and is shown on their website, all of their tested bikes are stiffer than the Calfee Carbon bike, which, having ridden both, I guarantee is stiffer than his bamboo.

Would be interested to see the weight comparisons. Probably easy to make something stiffer if it's significantly heavier...

I finally found some bamboo that was of high enough quality to build my frame. I just finished tacling the whole thing together and tomorrow I'll start wrapping with fiberglass and then on to the tow wrapping. I have a couple of questions about the wrapping process.
How many layers of the carbon toe should I be using ? If I use old inner tubes to compress the wrapped areas should I be leaving gaps between the sections of the tubes to allow the excess resin to squeeze out?http://bikeforums.net/attachment.php...hmentid=135644