Cycling sportswear that meets the multiple functional requirements of thermal comfort, biomechanical protection and aesthetics is highly demanded by cyclists. These multiple functional requirements lead to innovations in cycling sportswear design based on multi-disciplinary knowledge integration and fusion of art and technology. A theoretical model for cycling sportswear design is developed in this paper to model the design process by systematically integrating different knowledge and identifying the relationships between them. This model demonstrates that the design innovation of cycling sportswear is the fusion of aesthetic design with thermal and biomechanical functional design, which meets cyclists' demand for wearing comfort, relief of muscle fatigue and beautiful appearance.