Carbon Fibre Bicycle Frame

The objective was to investigate the use of structural optimisation as a design tool for the construction of a carbon fibre bicycle frame. A frame was modeled as a free form monocoque structure with single sided installation of the rear wheel. The aim was to reduce the very high vertical stiffness of a traditional diamond frame while increasing lateral and torsional stiffness. Weight was to be minimised but with all previous strength requirements still fulfilled.

The Carbon Fibre Bicycle project was initiated as a Master of Science (MSc) thesis work at the Department of Aeronautics, The Royal Institute of Technology, Stockholm. ALFGAM Optimering supplied the optimisation software and also participated in the actual calculations.

A total of 112 design variables were used in the combined shape and lay-up optimisation. Five different load cases were used simultaneously with a number of deflection constraints to control frame behavior. The calculations indicated advantageous increase in torsional and lateral stiffness (by a factor of 1.5) and decrease in vertical stiffness (by a factor of 5) in comparison to the reference frame.

Weight was lowered from 2.00 kg to 1.4 kg. A manufactured prototype of the frame complied well with calculated results.


Structural optimisation can be used on complex free form structures. It is invaluable when optimal stacking sequence and lay-up thickness are to be determined.