Design of a custom racing hand-cycle: review and analysis.

PURPOSE: This paper describes the design, manufacture and evaluation of a custom hand-cycle with a Delta-style frame and fork steering. The state of hand-cycle design and future design directions are also examined.\ud \ud METHOD: The design of the custom hand-cycle was based on these criteria: Light weight, aerodynamics, climbing ability, ergonomic fit and the user's specific needs. We designed and built a custom hand-cycle for one expert user, therefore, the user's personal needs were key design drivers. The hand-cycle was evaluated by the user over three years of use.\ud \ud RESULTS: During three years of evaluation and over 8000 km of use there were two frame failures: (i) A crack propagated around one of the tubes connecting the mainframe tube to the headset tube; and (ii) a crack propagated around the circumference of the curved part of the main frame tube directly behind the seat. The first failure was repaired and after the second, the device was retired. The evaluation of this design serves as a basis for a new set of design criteria.\ud \ud CONCLUSIONS: Large amounts of frame flexion can indicate eventual plastic deformation and failure. Future hand-cycle designs should see the use of more advanced materials, finite element analysis software, and continued incorporation of bicycle technology and design innovation.\ud \u