Thanks to its increasing strength and decreasing price, it is assumed that plastics can, in the future, take over metals for several applications. This opportunity is applicable in the frame of a bicycle. In this project, the design of a plastic bicycle frame for a normal man bike will be described.

To ensure ergonomic proportions, the existing frame of the Gazelle Heavy Duty NL C7 HMB (frame size 54) will be the starting point of this project.

Creating a frame from plastics instead of metal gives much more design freedom. Besides, a conceptual design can and should have a more futuristic appearance than standard bicycles. In the translation from the sketch to a 3D-model, emphasis is on deriving the right shapes and shading, cross sections, and transitions between surfaces.

A new plastic is created and applied with the strength properties which are 1,3 times as high as standard polyethylene. Forces are applied in the longitudinal plane of the bicycle showing that the chain stay tube is by far the weakest point. Furthermore, much stress occurs at the connections between more tubes. Especially in the connections of the bottom tube, this is very clear.

Several changes are made compared to the first concept on both technical and aesthetical level. The most important changes are as follows:

- The most striking difference is the extra line that is added at the bottom tube and the chain stay tubes. This line continues into the bottom part of the chain stay tube to ensure more body and strength in both chain stay tubes.

- A smoother and more logic transition is created between the bottom tube, top tube, and head tube. However, these points could still be more integrated into one shape.

- The bottom tube is made thinner to make it more flexible. The result is less stress in points where the bottom tube connects to other tubes.