Thanks for the info Andy, but I was already planning on layering fiberglass as well! I didn't know all that and now I'm very glad I chose what I'm trying...

More pictures!
 

:thumb:Time to add some more photos!


http://farm7.static.flickr.com/6140/...f0df7c2957.jpg
rear quarter view by cbchess, on Flickr

http://farm7.static.flickr.com/6175/...a97519dcf9.jpg
Frame in stand by cbchess, on Flickr

http://farm7.static.flickr.com/6177/...7bdd3956f8.jpg
Front view by cbchess, on Flickr

http://farm7.static.flickr.com/6143/...a858ee4598.jpg
Rear disc brake by cbchess, on Flickr

http://farm7.static.flickr.com/6015/...7c14045064.jpg
Bottom Bracket detail by cbchess, on Flickr

do you plan to sand down your lugs? And again, tell me how it rides after your sure it's safe for a real ride!

Yes I wanted to make sure it rode well before I did my finaly coat. I made the mistake of doing the final coat and then realizing I needed to add more carbon fiber layers. So I've added about 6 more layers and now I need to do a final sanding and gloss coat. I plan on doing somekind of valspar or poly coat on the raw bamboo as well.
Its been raining like crazy since I've built it up, so still waiting to ride it!

...dead head sticker on a cadillac....lol

don't look back... bah and now that songs in my head I almost commented on the deadhead sticker at first too though... and actually it's not bad looking at all, makes me think my jolly roger decal set might not be a terrible idea...

A lot more can be done with hemp or flax without just putting a gob of random fibers around the lug like the BBS used to do.
Their lugs were more likely failing because of lack of sufficient orientation of the fibers.
No matter what fiber choice you use an underlay of cloth in the chosen fiber makes more sense than just straight wrapping.
Unidirectional carbon cloth layed along the lines of the tubing and spanning the miter joints before wrapping goes a long way towards lasting lug integrity.
You can buy high grade Linen artist's canvas as an underlay for a natural fiber lug.
The source of your natural fiber is very important also. The way the fibers are grown and processed are crucial to the strength.
Keep in mind that modern phenolics used in very high stress areas are often based on Cotton or linen canvas or even paper in a resin binder.

I agree that fiber orientation is all important in a composite layup schedule. The "chop" method is borderline stupid. I've tried laying the hemp in using the orientation you describe for carbon and then over wrapping that as one would with tow, and it worked for a while. That said, I've been using hemp cord, string, cloth and raw fiber for various things for about 10 years now and the problem with the hemp is that it stretches under heavy impact and then doesn't recover. Over time the bike (or whatever) turns floppy, or fits loosely, etc. It is simply not the best option for structural applications. I use hemp as an overlay (money layer) over a carbon structural layup.

I guess I should add that the BBS tests tested 5 different layups (if memory serves) and experienced failure due to repetition in all cases. As a result of the testing they developed the carbon tow method that they use today.

I'm skeptical. Hemp doesn't stretch to that degree and it should be locked in the resin matrix. If the whole system is done properly it shouldn't be possible to apply enough tensile or compressive strength to the lugs to get that type of failure.
Nothing wrong with giving up and taking the easier route if it seems safer though.
A fibre resin matrix has the potential to reach into the 30000 psi range depending on resin choice.
That foam block technique with the matrix over the top looks downright scary.

Hey guys, some of you may remember the thread I created a year or two back about bamboo. Well I'm back and still without a frame, however I will be building one soon. Now the part that may matter to you is that I will be dumping some of my test results and data for the benefit of the community and potentially for the benefit of me (which will hopefully come in the forms of suggestion or ideas).

This morning I heat treated a piece of Moso Bamboo with a propane torch until it became nice and browned. Which I then sectioned and took to my university's microscopy lab where I took some pictures at 40x of some heat treated and non heat treated samples.

Moso Bamboo:
https://lh6.googleusercontent.com/-i...007011203a.jpg

Heat treated cross section at 40x:
https://lh3.googleusercontent.com/-g...4/DSC_0001.JPG
https://lh5.googleusercontent.com/-X...4/DSC_0007.JPG

Note, the little silver bits are actually pieces of metal which got lodged into the bamboo while sanding it to get a better finish for the microscope.

Non Heat treated Moso at 40x:
https://lh6.googleusercontent.com/-6...4/DSC_0010.JPG
https://lh4.googleusercontent.com/-i...4/DSC_0014.JPG


If anyone has any questions or concerns please let me know and I'll do my best to address them as quickly and accurately as possible.

Canaboo

An epoxy matrix is about 95% mechanical bond, hemp is full of natural oils especially the raw hemp fiber (that I used). I shouldn't need to state this but, you know that smell when you open the bag, that's the oils making that smell.

As a result of these 2 facts you can safely assume that hemp will never be fully adhered to the epoxy matrix. It can move within the matrix. I'll offer you an easy tensile test as well. Take one strand of hemp and pull it apart with your hands. It's not easy but you can do it, or at least I can. Now take 1 strand of carbon fiber and try the same thing. The carbon strand should cut your fingers off before it breaks. It also has nothing on it to inhibit the bond.

Trust me, I wanted hemp to work, I used to own/operate a head/hemp shop in the Keys and I really wanted hemp to work, which is why I use it as a money layer. No one wants it to be functional in this regard more than me.

It simply is not suitable for advanced composites as stand alone structure.

That said...do whatever you want. If you have some magic touch and it works for you sweet. If I were doing that though, I would expect to be doing a lot of warranty work.

Andy

Before using any natural fiber I wash it several times with a degreasing solution and rinse it with acetone after a final drying. That greatly enhances the bond.
Just poppiing open a bag of natural fibres that you have no idea of how it's been handled and processed is likely a poor recipe for a lasting bond.
Having said that I don't actually use hemp in particular for the reasons you state. Linen is much cleaner and just as strong. There are several other choices that glue much better with less effort at cleaning them first. Abaca, Coir, Ramie etc.
Linen in particular is used in some pretty advanced high pressure situation composites.
So is cotton canvas.
It can be done.

Touche'

Right on. I'm just explaining why from my point of view it has a high chance of failure. The resin system I use (Mas) directs against using acetone for prep (with any surface). There are obviously other resin systems for which it is fine (goujon, sp, etc). It's funny because I feel like there are many different ways of making the same part, and none of them are necessarily wrong. Take your earlier statement about not trusting foam, As a professional laminator nearly every part I've ever made has had a core material involved (I like Divinycell H80). The foam they use is bad news in less than the 10# density, although I don't know the weight of their foam. We just work differently and it sounds to me like you've done your homework and research and simply came to a different conclusion than I did. Respect.

Andy

I'm not saying foam composites aren't a good idea I would just want to "make" the foam around the lugs rather than inserting the bamboo into the foam blocks.
By "make" I mean glue the bamboo with miter joints and then make a fillet joint with micro-baloons or mlled fibre of some sort so there is a considerable amount of structural integrity and then lay the reinforcement on top of that.
The acetone warning that many Epoxy manufacturers cauition against using may be referring to the typical re-claimed acetone that is readily available. That can be contaminated with several other substances, oils in particular that will interfere with a bond.
It is possible to get "virgin acetone" from Aircraft Spruce that doesn't have this problem. You could check with MAS and see if that is a possibility.

bump
I wanted this thread back on the first page. I got a new batch of bamboo for my next frame. This new stuff is MUCH thicker in the walls of the tubes and should make a much better frame. The first stuff I used, I cut myself from a neighbors yard. I have noticed tha it is some of the smallest bambo growing around here. I think I mistakenly picked some of the most flexible bambo possible.

The new stuff is super thick and should be nice and stiff.

I also got a bunch of 2" carbon fiber tape - woven carbon fiber cloth. This will help strengthen my joints a lot more than just plain carbon tow of my first frame. I also got some 2" Kevlar tape a bit cheaper than the carbon tape.
The carbo and Kevlar tape is not sticky, it is just is called tape. The stuff I got is 2" wide and woven in a 90* pattern.

On that note another *bump* and an update, I'm going to do some experimenting with the oven method and cutting up a frame this weekend then tacking it up and seeing if I can get it anywhere near correct alignment. If that works out well enough, I'll have to order my first batch of epoxy.

How are you guys bonding the metal components to the bamboo? I work with glass/epoxy for high performance sail boats and am bamboo Bike frame curious. Was hoping to one day attend the B.BikeStudio build sessions and see first hand how it goes. Wanted a hybrid frame with disc brakes, IGH & CarbonBelt drive. They did not have their frame & component design ready for all that yet.

A miter joint and good metal prep are necesary for the sturdiest lugs. A thickened all purpose Epoxy is best for tacking and forming slight fillets before wrapping.
The BBS is ready for the build you want now.
They don't use miter joints which likely explains the hemp lug failure.

getting closer to build #2

For structural bonding and coving (filleting) toughened epoxy is the best choice. It has more flexibility which helps in failure avoidance. It is also more expensive than a laminating resin and you probably won't use enough in 1 or 2 bikes to justify the purchase.

The second best route (read as cheapest and functional) is adding filler to your laminating resin and using that for bonding and coving. It has it's own pitfalls though. If you use microballoons or q-fill, for example, as your thickening agent you will get a brittle, easily breakable bond and fillet. Most manufacturers will have recommendations for their resins.

I have to back up Canaboo on the prep. Prep is everything when working with epoxy. Different materials require different prep. Once again it is usefull to check with your epoxy manufacturer as they will have tested various methods with various materials and will know the best approach for their epoxy.

My BBS kits is being prep'd.

Any tips or things I should watch out for during the home-build I'll be doing? I went through their video's once so far. I'm a bit concenred of the Balsa butt joints...my boat buidling experience says anytime you've got wood, esp. balsa, any water intrusion will rot it out. Also, the bamboo loads the balsa in compression...isn't it likely to permanetly compress the balsa over time?
I plan to swap over nearly all components from my Carbon Belt Drive, 11-spd Afline IGH and hydraulic disc brakes. If I like the setup I'll buy new components so that I have two complete bikes ultimately...potentially to sell one later.

I'd be watching everything and going above and beyond any prep work they recommend... The bamboo shouldn't compress the balsa since the carbon/glass lug will lock the bamboo from moving into the balsa.
The lack of proper sealing of the bamboo in their method is a real concern to me.
If you want to seal any of the bamboo, make sure it's the inside of the seat tube. Water getting down in there and sitting on that balsa is a recipe for rot in a high stress area.
Not sure what glue is being recommended for tacking but do yourself a favor and use proper glue.
You may also run into clearance trouble depending on your front 'belt ring' size.

http://bikeforums.net/attachment.php...hmentid=279390http://bikeforums.net/attachment.php...hmentid=279391http://bikeforums.net/attachment.php...hmentid=279392http://bikeforums.net/attachment.php...hmentid=279393http://bikeforums.net/attachment.php...hmentid=279394


Here are pics of a bamboo bike made by students in Singapore. This is prototype frame #3. The parts are mismatched because most are donated parts or purchased 2nd hand parts taken out from other bikes.

That is a really nice looking bikje despite mismatch! I love the burnished look of the bamboo and the look of the joints. Did you varnish the frame?

Just watch out for PANDAS! :roflmao2:

The video show them using JB Weld (5 min thickened epoxy) as the tacking glue. I'd prefer to use proper West System epoxy with a thickener. But it seems the tack up stuff isn't really supposed to hold loads after the carbon layup, correct?

One thing I noted they did not do which is definately not best practise in epoxy work...according to the Gugeon Brothers West System instructional guides, epoxy produces an amine compound during curing and this coats the surface as an "Amine Blush". You should never sand/file a freshly cured surface before removing this material...otherwise you just embed it into the sanded surface and it makes for a poor secondary bonding surface. Can lead to delamination of subsequent layers. The blush is water soluble so a damp rag or light spray & wipe will do.

What are people finishing their frames with if anything? I will ride in wet weather often. Like the idea of polyurethane but does it bond well enough to bamboo?

You would be better off using all West if you can get it. G5 for tacking and 610 for the dropouts. The tacking may not be supposed to hold loads but the demonstrated fail points with their technique is the juncture between bamboo and balsa. Just not enough correct fiber orientation in those spots.
I really don't think their process speeds things up over just mitering, particularly if you have some aptitude with tools. Mitering is a far more secure building method.
You shouldn't have to sand between lamination layers..... no reason you can't do all the layers in one go.
It seems that the BBS goes on the premise that the natural silica layer of bamboo is a good waterproof coating but it really isn't after the plant is cut. Plus every little nick in it is a wick for moisture to get in. Bamboo is very hygroscopic.
I have heard of them using Tung Oil but Tung oil is not very waterproof.
You would be wise to coat the frame more thoroughly if riding in wet weather. In order to do that you have to sand the shine off the outer layer or nothing will stick to it.
Also keep in mind that Epoxy is very sensitive to UV rays so if you don't protect them you can be sure your lugs are on borrowed time if the bike will routinely be in strong sunlight. The Epoxy will rapidly take on a muddy appearance.

I used epoxy with thickener for tacking and when cured the tacked frame was extremely strong on it's own: http://www.cameronbrown.ca/blog/2013...-wrapin-it-up/

Nice work there!
I'm 4 days into my build. Carbon wrapping completed. Sanding & filing now.
I still haven't decided on a finish. I like the look of your finish. Can you specify what you used and how you prep'd the bamboo outer surface?Had been considering a standard marine spar polyU...but worried it will flake off the bamboo surface due to poor adhesion.

Details on my progress here:
http://www.pbase.com/d30/bamboobike&page=1

Not bad for a solo effort. You'll probably want to sand and touch up with extra carbon rather than just filling voids with Epoxy. That is if you have any carbon left over.
You need to at least knock the shine off the skin of the bamboo if you want to have anything stick to it.
A nice natural finish is Lee Valley 'Varnish Oil" with wax on top of it. Requires maintenance but you don't have to worry about chipping or flaking.
You really should at least put a good UV resistant Poly or spar varnish on the carbon/epoxy. The 205 and 206 hardener based mixes go "muddy' very quickly in sunlight and that means your lugs are breaking down.

Yes, I'm familiar with the UV effects on the West System epoxies...I have done lots of work on fiberglass boats over the years. I will be using polyU on at least the carbon lugs. I'll take a look at the Varnish Oil. I ride in lots of rain herei n Vancouver....any concerns for this stuff?

The only location I want to fill in is the underside of the BB...there is a void formed by the overlaps of carbon that just looks ugly...but the setup is pretty strong there. The fill it will just be fore cosmetics.