How to Build a Bamboo Bicycle

Step 5 Epoxy it all together

Time to get dirty!

I used epoxy from fiberglass Hawaii called Aluzine (it is a 2 to 1 epoxy specially formulated for surfboards and has some UV inhibitors in it). Why? Because I had a lot of it left over from a repair to my windsurfer.

I used two different kinds of hemp fibers. I used raw hemp fibers (or semi-processed) and hemp twine (drawn out - semi-twisted, comes on a spool). The raw hemp seems much stronger so I used that as the bulk of the joint and then used the twine to tighten up the lashings.

Mask the frame off carefully. Prepare all the joint areas (clean and dirt free, heavily sanded or rasped for an extra-rough surface).

The process is pretty messy and requires a lot of patience and finesse. Wear gloves and start small - small batches of epoxy and small amounts of lashing. I mixed up a small pot of epoxy and then dipped my fibers in it. I then wrapped it on the joint and followed that with a dry piece of twine. There was enough epoxy on the raw fibers to completely wet out the twine. Practice and you will get it.

I got my hemp from www.downbound.com

Of course you can use kevlar, carbon fiber or fiberglass.

Comments

[swimmer321]

so after you wrap the joints of the bike in the hemp, can you sand it down to make it look nicer? the calfee bamboo bike joints are really really nice and clean-looking. How can i get that look?

[peligro]

I think the author intentionally had the joints look fibrous. If you soak the hemp cord in epoxy, once you put it all on the frame it should fit a lot smoother than in these pictures. And you will definitely be able to sand it down, it just won't be easy. Once the epoxy has cured the hemp/epoxy matrix acts like any laminate in that it is a relatively homogeneous material. It should be solid throughout.

[chriscook42]

Thats what Im wondering. It is almost as if the hemp and stuff was melted into a single material. But you are right- it is a much more appealing look.

[chriscook42]

After further analysis it seems calfee probably did hemp and then fiberglass on top of it. The fiber glass could be sanded and I think that couldve made that look.

[kklaw]

I would be careful with sanding through any of the hemp fibres, that is where the tensile strength of the joint comes from. The epoxy provides a matrix that helps to evenly distribute the forces throughout the joint but the fibres need to remain intact to provide any tensile strength. Chris's idea of a layer of fibreglass on top for cosmetics and some protection is often how fibreglass is applied. This is why carbon fibre must not be scratched, its structural integrity is severely compromised if any fibres are broken. This is a great project, I'm excited to try it with carbon.

[mpenn]

I saw his finishing technique in a tv program. all he did is us a dremel to get a smoother shape. then he did a crap load of filing and sanding.

[Guillaume648]

Hello, I wonder how many hemp (Kg ?) and epoxy (Kg ?) you've used for these 5 jonctions ? Thanks !