Modern carbon fiber bicycles are sold in only a few different sizes because the tooling is expensive. However, every person is different and rides in a unique way. Therefore, customized bicycles are required for the optimal enjoyment and performance of cycling. Custom bicycles can be very expensive due to the manual labour involved when fabricating without tooling. ideas2cycles has developed a process that allows the use of modern materials and joining methods in custom bicycles without the need for expensive tools. The solution is casting metal nodes for joining carbon fiber tubes. The tooling is printed using a voxeljet VX1000 printer.
There are two reasons why projects such as this one can be implemented: In the first place Antin is a graduate engineer who has required know-how, and secondly he knows about the digital production methods which allow for the cost-effective implementation of putting creative ideas into practice. In this context, Antin bases the concept of the bike frame on a simple but ingenious design, and combines the various frame tubes with exactly calculated sleeves. An magnesium alloy is used for the precision casting parts to save on weight.
The process starts with simulation-based design. Load cases and boundary conditions are defined and topology optimization is performed. The optimal shape is then transferred to a CAD model that contains the tailored dimensions for each customer. The tooling is designed and the casting process is simulated. When the design is ready, the STL files of the tools are sent to a company (Hetitec Oy) for printing. Within a week the tools arrive at the foundry and the casting can be done. Difficulties in casting the metal matrix composite (Al-SiC) material led to a failed first attempt. Changes in the mold design were required, but fortunately the fast lead time of the molds meant that the problems were quickly solved. The successful nodes are post-machined and bonded to carbon fiber tubes. The bike is now ready for a test ride!
"We have tried a variety of methods for building bike frames according to customer specifications in single batch sizes. The 3D printing technology turned out to be the simplest and most cost-efficient method," says Antin. The clever guy from Finland e-mails the CAD data for the sleeves to the voxeljet service centre. Here, a 3D printer quickly prepares the plastic models for subsequent precision casting in a fully automated process without the use of tools. The plastic molds are as precise and true-to-detail as prescribed by the requirements.
Kim-Niklas Antin already envisions the bike production of tomorrow: "The customer will select his favourite frame from a set of basic types, which is then customised to his requirements in CAD and subsequently printed using the 3D printing method – and that´s that."