What you don't see at first glance, however, is the huge manufacturing effort behind the new bikes: A frame like that of the new Big Mountain R.X750 or Enduro R.E750 consists of 1,046 carbon blanks, each one carefully developed and designed in its shape to withstand the loads of the associated frame sections. A layer of carbon consists of two layers with a combined thickness of 0.2 mm, depending on the necessary wall thickness and component, several are laminated on top of each other.
Elaborate and careful work by hand
More than 60 hours are required from the laying of the first carbon layer to the finished painted frame, and the entire production process is characterized to a high degree by meticulous manual work. Around 35 specialists have the frame in their hands during this time and dedicate themselves to its completion with great precision in their area of responsibility.
The entire production process is based on close cooperation between the ROTWILD developers and the engineers at the frame builder. This is because once the new design has been completed, the development phase begins on site, which lasts a good six months. A major focus of this phase is the construction of the layers, the alignment of each individual carbon layer and the running through of testing requirements for all components. In addition, before series release and the start of production, extensive testing with prototype frames takes place alongside road tests. The frame spends several days per test procedure on a test rig and undergoes several 100,000 load cycles. These dynamic load tests of individual components and the entire frame include fatigue tests, e.g. swaying, the control of stiffnesses and the impact behavior.
Precision in every step of production
The production of a frame is divided into several process steps, starting with the cutting of the carbon layers. After a rough cut, the exact shape is cut using CNC-controlled cutting machines until the more than 1,000 blanks are ready for each frame. Then the actual lamination begins.
Here, the specialists join together layer by layer according to the exact specifications of a layout plan. Reusable silicone molds serve as the basic shape, but metallic components such as the swingarm bearing are also wrapped with several carbon layers in this way - the experts refer to this as "preforming". The left chainstay alone consists of 99 individual carbon blanks that are laid by hand. Nothing happens here by chance, quite the opposite. In addition to the number of carbon mats placed on top of each other, the alignment of the fiber orientation is of great importance. This follows the preceding simulations of forces.
Working with molds
The finished components are placed and fixed in a metal mold that somewhat resembles a baking pan. Then the whole thing goes into the oven, where under high pressure and temperatures of around 80°C the frame is given its final shape and stability. Careful work is also required to remove the frame from its metal mold. Subsequent manual finishing involves cleaning off burrs and removing the hoses and silicone components required for molding from inside the frame.
A special feature of the new ROTWILD bikes: due to the complexity of the frame, it consists of two parts, so for each frame size two molds are necessary for the main frame. These weigh several hundred kilos each and consist of over 30 individual parts.
After curing and cooling, the two-part main frame is assembled into one component and the surface is smoothed. The entire production process is accompanied by permanent quality controls. Each individual component is intensively inspected and checked for accuracy of fit and processing tolerances.
Check again and again
An important step and a special feature is the recurring check in the X-ray machine; spot checks in the production process allow a view inside the frames and thus a permanent check of the production processes.