hmm, i cant see your pic Allen,...
and......WARNING! WARNING! FUNGUS CAN WEAKEN BAMBOO!
I just broke the top tube of my bamboo mtb frame! i think what happened is it cracked on a jump, as i heard the shuddering sound of splitting as i landed in a big pothole,
rode it home fine, then the next day i jump on it off a curb and the bike litteraly split in two!!!!
the downtube got pulled right out of the lug once the top tube broke near the end, leaving the front end of the bike in my hands and the rear on the street behind me!
On examination of the tube i noticed thin black lines coursing through the wood, also visible on the surface if you know what you are looking for. now i know what to look for, as it is obvious the fungus had eaten the bamboo well before i flame cured it, and applied polyuethane varnish to the interior...
i am really really bummed about this, but am slowly getting over it. I have completely dis assembled my first two bikes and am trying new anti fungus treated bamboo sources .

Sorry about that my server is fakakta. Here they are again posted off of another, better server.





Mine shattered because when the rack hit the ground it twisted the rack's mount off of the downtube.
Since all the fibers in the bamboo run in one direction the downtube could not handle the lateral torsion.

I plan on lining the insides of the pipe with carbon fiber with the grain of the carbon on a 90º bias to the bamboo's fiber.

Sorry you had a failure as well. We are not the only ones to have failures in early prototypes. Don't be too downtrodden. Persevere, and it will all come together. At least they are cheep to build.

Polyester amide polyol <--Google up that string. It makes for a very interesting read.

Both of you have built incredible bikes. I LOVE the track bike. Some day I will own a bike under 20 lbs.

Just a couple of questions.
Has anyone used fiberglass instead of hemp for the joint material? It's strong, available and cheap.

Could this joint wrapping technique be used with steel or aluminum tubing?

I've not seen fiberglass used, carbon fiber yes, but not glass.

Yes, The technique can be used with metal tubing. However one still needs to miter your pipes, and do a lot of prep work. And, my personal opinion is that welding, or braising is the best technique to join metal to metal.

I plan on building a bamboo frame over this summer. Ive been following this thread and all others I could find. Allen not sure if you mentioned it. But I read that filling the bamboo rods with that expanding foam used for insulation helps increase the rigidity of rods. What do you think about that? Also the use of Tonkin instead of black bamboo? Is there a significance difference.

I haven't used Tonkin cane as yet, can't help there. I have used Moso, it splits readily, it may be ok for a trailer though.

I haven't heard about using expanding foam.
A few of the things I've read about are Polyester amide polyol, and lining the inside of the pole with carbon fiber.

Google up Polyester amide polyol, and you will find a bunch of articles about strengthening bamboo.
For lining the inside of the pole (haven't had the time yet) I plan on using pre-preg carbon cloth laid on a 90º bias to the bamboo's fibers, and cutting an inter tube (and then glueing the ends shut so I have a straight length and not a doughnut) to use as the bladder to press the carbon to the bamboo's interior surface.

Hs anyone priced a split bamboo fly rod lately? .........If you think carbon fiber frames are expensive .............not a practical process for cheap frames.

Apples and oranges.

Split bamboo rods are expensive because they are extraordinarily labor intensive to build.
Many more labor hours go into making a fly rod than a bamboo bicycle frame.

The raw bamboo poles are inexpensive.

yes and besides, I don't think you'll find a fly rod that has the diameter you'll need. Like AllenG said, you're better off getting raw bamboo poles. I can't remember what I used, I think it's tonkin and it's been holding up. Single speed and just over 17#.

here are some links to places that sell bamboo https://www.bamboocreasian.com/bamboo...FQQRswodL3F8mw
and
www.bambooforever.com

I have appreciated all the information in this thread. my friend and I are planning on making some bikes and i was wondering about a few things. how did you mount cable guides, brake posts/mounts and water bottle cages? is drilling holes in the bamboo for these things something to be avoided? Thanks, bummer on the breakage.

Gotta break em to learn how to repair them.

I drilled into the bamboo for the water bottle mounts. It did not seem to bother anything.
Glue will not adhere to the skin of bamboo. You have to sand the skin away wherever you want to glue.
For the water bottle mounts I used as long of a boss as I could find.
Scored the outside of it to give the glue a surface to grab, and then soldered a boss reinforcement to the boss proper before I glued them in place.

Ideally, make your own boss reinforcements out of an old downtube, and about the size of a quarter to give you a large glue surface.
Note the size of the bosses that Calfee uses.


For cable mounts and guides, they will pop off if they are just glued to the frame (at least that is what I ran into). Same fix though, braise them to a small pice of metal tube and then glue that larger surface area to the frame.

If you are running canti brakes then I would recommend the Voodoo canti brake bosses. They have ears which make it very easy to fiber them to your frame.

Voodoo canti mounts

AllenG, where did you get those Voodoo canti mounts? And is there another place to get bike parts other than nova cycle?

thanks

Sure, no problem.

You can get them directly from Voodoo.

There are quite a few framebuilding supply houses.
Nova
Henry James
Paragon
Ceeway
And many I'm leaving out

You can also buy parts directly from Voodoo, Surly, and others, as well as many custom framebuilders. I see you are already signed up at FrameFourm. Several of them sell parts.

Love the work on these bikes!

Got a question about the dropouts and the chain/seat stays for you guys...

How much metal do you have on those dropouts that is inserted into the end of the bamboo tube? Seems that you would need a bit more than the 1cm or half inch that many dropouts (as purchased) would give you to be a strong enough bond. I would have thought that welding on 4-5cm (2 inches) of metal rod to allow for greater insertion (no funny jokes, ok?) would be a lot stronger?

What was your solution?

I am using an "off the shelf" dropout kit for carbon. I got them from nova cycles and all I did was make sure that the dropouts fit inside the diameter of the chain/seat stays (if I measured how deep it went, I would guess about 1 to 1.5 inch). then I glued the inside and layered cf on top of it. Here's the link for the kind of dropout I used from nova:

https://www.novacycles.com/catalog/pr...oducts_id=1347

I welded on a few inches of pipe.

Thanks Masterofnone and AllenG.

My engineering brain knew that there had to be more to bond on to, but none of the pictures I could find that detailed works in progress showed that area before it was assembled.

I'm working on a project of my own and this thread (and the links and leads from it) have been invaluable to my research.

AllenG, I can't seem to locate those canti mounts on voodoo's website. Did you go through a distributor to get them? I like the ones you used. There's an engraving on the arm of the picture above, maybe that's the company making them? Let me know.

thanks

They are not on the web site.
I shot them an email and asked if I could buy a set.

AllenG, thanks I'm in contact with him now.

How are you keeping your bike warm these cold days? I haven't brought mine in from the garage, but I have it wrapped up with cloths and egg crate.

I keep my bikes stacked against the wall in my studio. Also I'm in Georgia.
I did have a piece of unused bamboo that was on my front porch split from top to bottom the other day when it went down to 18ºF. It was an untreated piece leftover from my original stock. The wood I used for frames I smoked and flame treated. It does not seem to be affected by the cold as yet.

I wrap mine with sod and water it daily. The roots add necessary rooty strength, otherwise, bamboo will break.

Cool!

You know though... bamboo grows really quickly... I could actually see making a 'growing jig' to grow the bamboo in the shape of a frame and working from there; no lugs needed.

Yeah, but you would have to wait 5 years for it to mature and be ready to ride....