I am going to use a short piece of seat tube and attach the collar to that.
I do like Brano's bamboo seat post, although I'm going to use a regular one.

Don't mind the questions at all. Do keep in mind this is my first frame, and it hasn't proven it's not a wheeled punji stick yet.

dont mind the questions at all. looks like bamboo bike building is the new thing, this thread could be a good resource for many.
i used a short piece of steel tube inside the seattube too. cant really see how else you would do it, i dont think the bamboo holds up to well to internal pressures like that, it would probably crack...
my next frame is going to bee 100% iron bamboo, so i will see how it compares to the first one in terms of stiffness. the first one is actually plenty stiff, but i havent taken it to the track for all out sprinting yet...
whats a punji stick?

ouch!

thankfully, even if enough force were applied to the frame to break the bamboo, it would split and shatter, not break into sharp pointy pieces.... right?

It's my understanding that only carbon bikes actually explode. ;)

More Update:
Ready to start the lugs
http://awcg.com/Allen/Bicycle/X1/Wrapped.jpg

Lugs dry
http://awcg.com/Allen/Bicycle/X1/UnWrapped.jpg
Next I'm going to sand the lugs and smooth them with bondo.
Being that this is my first frame I take no shame in using bondo to give the lugs a final shape.

Learned a lot building this frame. The Mark II will be done differently.
For one my vacuum pump died, so I used tape. The next will be done in a vacuum bag.
Another change will be I will add filler to epoxy and will smooth the joints (such as around the seat stays and seat tube) before I wrap the lugs.
Other than the fact it's ugly nothing is wrong with this frame, it's perfectly rideable and I'll will build it up.

I'll post a pics of the bondo work as it progresses.

great! not ugly at all.
what fiber did you end up using?
i just took my boo bike on its first critical mass ride here (we call it "pedalazo"), it was an instant hit, even the traffic cops were oggling it and asking me to make them theirs!
i look forward to see pics of your finished build, is it a 29er? ss or fixed?
congrats on a great job, you are almost done!

Chapaneco,

It's a 29er. I'm not going SS or fixed, I have an internal geared hub to hang on it.
Went with hemp (sourced it from here)
^^^
Another change I'll make on the next frame is I'm going to spin the fiber into twine first.

Did you or would you consider finishing your bamboo with tung oil or clear coat?
I know I'm going to paint my lugs, but I don't know how a finish coat would adhere to the bamboo.

Oh and thanks, seeing your bike lit the fire under me to finish this one.

Not ugly at all. You'll have to give us a full update on how it rides and of course pics of the built up bike.

You have both inspired me and I will be building one of these in the fall.

Did you put on a metal brake bridge? Or does the hub have a roller or coaster brake?

I've been thinking about doing a road frame, and have been thinking about whether it would be better to bond on a metal brake bridge, drill a bamboo bridge that I could cut a good miter on or something else entirely.

I'm going with canti brakes, the bosses are not yet on the frame. The brake bridge is made of bamboo. Not sure how long it will last, but it seems solid enough that it should take a good while to break if it is going to.

the polyurethane thet spilled onto my bamboo was easily removed with a penknife, indicating that varnishes will not adhere well to the unsanded exterior of the bamboo. i am sure this is thanks to the wax that the bamboo has as a natural coating, which makes it waterproof and bug proof! the good news is you really dont need to treat the exterior. I did completely cover the inside of the bamboo with a polyurethane varnish to keep bugs out as well as avoid rapid changes in the bamboo's water content (which is what causes cracking!!). I have heard tung oil works well for this purpose as well, but you have to soak the bamboo in it for a while, the interior is the important part to coat, as the exterior is covered in natural wax. In Columbia, they soak the bamboo is diesel for 48 hours. this seems to work too, especially for tropical bugs.

ps. why not buy hemp twine, already spun? but will this soak up the resin properly? or are you going to soak it first, then quickly spin it into twine as you wrap?

I treated the bamboo by smoking it. My neighbor has a smoke house for curing hams, left the bamboo in that for a period of days. Some of the pieces split (only about 10%), I discarded those and used the intact wood I had left.

I bought the fiber thinking I would use it in raw form. I'm going to spin it first and then soak the spun twine. The hemp soaks up the resin very readily, dipping the twine into the resin should thoroughly coat it.
I believe using the hemp in twine form will make it easier to control and will make defining the ends of the lugs easier as well.

Allen, your frame looks great! This is a very interesting read.

East Hill

allen,
just staring at your frame for a while, looks great!
i keep wondering why you built it with such long chainstays. i am currently building a cargo bike, and the chainstays will be only a bit longer than yours, to get the rear wheel under the weight of the giant rack its going to have.
my main concern with the long chainstays is flex. i will be very interested in hearing how yours turns out. and what is the reason you designed it this way?

To fit the fat tire. My mountain bike's chainstays bend inward to accommodate a large size tire. I did not want to try to bend the wood on my first bike and since this bike is intended as an upright cruiser I don't mind the long wheel base. I'm curious about flex myself. I'll have it built up in a week or so.

http://video.google.com/videoplay?do...46950791304015
^^^
Interesting video about bending bamboo

How is your frame? Has the flex or ride changed as you've put on the miles?

I'm also intending to build a long-tail. One thing I don't care for with my XtraCycle is the handling characteristics when I have a lot of weight on the snap-deck. With the weight up high the handling becomes pretty twitchy. To improve that I'm thinking of going with a small rear wheel, 24 or maybe even 20 inch.

--A

{edit}
For a proof of concept experiment I bent a 1 1/2 inch piece of bamboo the other day. As the video shows I filled it with sand, but I only have a small torch with a fine flame tip. Although not absolutely necessary a larger torch would have been very advantageous. It took some time but it is possible. Bamboo will take and hold a bend. It does bounce back, so you would need to make a jig to be able to repeat the same bend in two pieces.

http://awcg.com/Allen/Bicycle/X1/Bent.jpg

wow, that video is from monte blanco, veracruz, where some of the bamboo for my bike came from!
i am going there next month to source some more bamboo and observe their techniques.
i think thinner culms, such as for chainstays, are easier to bend, prolly no sand needed. a friend also had an idea of training the bamboo to grow into the shapes you need, you could potentially grow a whole bike, even insert the bb and headtube at the right times and have the bamboo envelop them, growing the bamboo into a jig! you would have to wait 4 years for your bike, but it would be pretty wild!

The sand helps prevent splitting. It keeps the pressure inside the culm even, otherwise it will try to crimp and then split.

Four years is not much longer of a wait time than for a Vanilla. Form grown--it would be an astounding bike.

in response to your previous q. about my bike's handling. if anything, i think i have noticed a stiffening of the frame overall in the last couple of weeks. it seemed more absorbent of road vibration at first... i am also noticing many things that i would like to improve upon for the next project, although nothing major.

Update:

In the spirit of full disclosure, here are a few images after sanding, before paint.

http://awcg.com/Allen/Bicycle/X1/Sanded.jpg

http://awcg.com/Allen/Bicycle/X1/SeatCluster.Sanded.jpg

http://awcg.com/Allen/Bicycle/X1/Headtube.Sanded.jpg

I have a few touch-ups here and there, but it gets painted tomorrow.

I like your giant fork and spoon. and bike too

nice, did you do the sanding by hand?
id be interested to know if it creaks (not cracks)
mine creaked alot at first, like an old ship. the creaking has deceeased as i put the miles on, now it wil only rarely creak under strong stress, like pulling hard on the bars to pump up a big hill.
maybe there is a way to minimize this, i feel it has to do alot with the original tacking, i used epoxy like you. next time, i am trying gorilla glue first, and a closer preliminary wraping of the joints with very very fine fiber...
oh, and what are you using as filler after sanding?

Bondo. It'll crack eventually.
On the next one I'll use some translucent 3M Scotch Weld mixed will filler powder.

I did the sanding by hand. Cut long strips of sandpaper and did it shoe shine style.
Oh and I used a drimmel a small amount, to shape around the seat cluster.

Fantastic job on the frame.:):):) Guess I'm too late but was going to suggest not sanding the lugs down too much...and forget the bondo. The hand wrap look gives the frame some rustic charm and matches the bambo. I like the idea of using hemp twine around the lugs as a final coat - serious rustic charm there. You can still do it mind you...get some thin twine and wrap around the lugs in a tight uniform pattern followed by more resin. Clear coat the entire frame and you're styling!