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What We Did
For the Rio 2016 Paralympics the New Zealand women’s Para cycling team used a custom-built carbon fibre tandem bicycle frame that omitted the additional diagonal tube used in many tandem designs. This choice provides aerodynamic benefits but requires other parts of the frame to be enhanced to provide adequate stiffness and strength. The resulting Rio 2016 frame design was stiff enough but was consequently also heavier than preferred. In preparation for the Tokyo 2020 Paralympics the Department of Mechanical Engineering at the University of Canterbury has collaborated with Zenyth Projects Ltd to design a new tandem frame that incorporates further aerodynamic refinements but is significantly lighter than the Rio 2016 frame whilst retaining adequate stiffness. Computational finite element analysis has been used to assess a range of frame designs under a standing start load case. Preliminary analyses of the Rio 2016 frame and two other existing tandem designs provided benchmark values for frame stiffness and guided the design of the new Tokyo 2020 frame. Two iterations of geometry for the Tokyo 2020 frame were analysed in detail, with the second giving significant improvement on the first. With the external geometry fixed the carbon fibre laminate lay-up was refined to reduce stress and optimise stiffness and mass.
Who Was Involved
Paralympics New Zealand, Zenyth Projects Ltd
Why It Matters
New Zealand has had an extremely strong representation of Para cyclists on the world stage. The NZ women’s paracycling team has won multiple medals at World Championship and World Cup events on both road and track. The weight of bicycles is crucial for any race format, and the University of Canterbury have helped to design a new lightweight paracycling tandem. The final design for the Tokyo 2020 frame is 26% (1.1kg) lighter than the Rio 2016 frame whilst retaining 70% of the torsional stiffness. The weight saving will result in a decrease in the time for a 3000m pursuit race of 0.15 s.
