How are they done?
04.01. define geometry
There is no bike that does it all. Therefore, you should decide at the beginning what is the main purpose of the bike and choose a racer, road bike, crosser, city bike, MTB, etc.
We can satisfy most wishes with the componets and pick either from a standard selection or check individual needs. For the frame design the wheel size and type of fork are to be considered. During the manufacturing process we will specify gear changing, type of brakes, and fenders for example.
With the frame jig we are able to adjust, adopt, create or modify the frame geometry to your individual needs.
04.02. choose the type of bamboo
Bamboo is a robust, multi-purpose material, but from more than 1000 species only a few of them are suitable to build bikes. We use slow-growing bamboo, that has a homogenous inner structure which prevents bursting. Similar to building wood, there is a necessary drying process after the harvesting which is important for the final quality of the bamboo.
Apart from the structural aspects there is a good range of visual variety.
We recommend: Tutul (tiger bamboo), Nigra, Tonkin, Boryana and Moso
04.03. use off the frame jig
Each frame has four fix points:
– head tube (which will carry the fork)
– seat tube
– bottom bracket shell
– drop outs
These metal parts have to be positioned in the frame jig. The bamboo tubes will be cut to the correct length and fixed with epoxy to the metal pieces.
04.04. Filling, sanding, bonding
After over night drying the frame can be taken out of the jig. We are now at the time consuming part of the manufacturing process. The quality of the frame is highly dependent on the quality of its joins. To give the webbing the best possible base we repeat filling and sanding with the epoxy-mix several times.
04.05. fixing the webbing
For our joins we use natural webbing instead of glass fibre normally used in carbon bikes. Various natural products are available, apart from cotton and hemp webbing we recently came across bark cloth, which is a fabric made from the Ugandan fig tree. (See Partners)
To gain the required stability we use at least three layers of webbing.
04.06. impressing the glue
In the next step the expoxy is impressed into the absorbent webbing. After the drying process the frame gains its stability. The following procedure is for long lasting and aesthetic reasons.
04.07. Filling, sanding, bonding again
We want to achieve clean and homogenous surfaces for weather resistance and to avoid unwanted build-up of dirt on the surface. The frame gets its final finish by either adding colour pigments or highlighting the natural finish of the materials.
Marine varnish is used (we used it for bike 02). But the natural appearance is best highlighted with transparent, semi-gloss car finish. It is put on in several layers and can be renewed after years.
04.09. fitting of the components
That is the most exciting moment in the manufacturing process when it all comes together, when the frame with its components transform to become a bike eventually…