American Alicia Dana was dominant once again in South Africa, finishing nearly five minutes clear.
Two medals will serve as an excellent boost for Darke as she starts to look ahead to the Paralympics in Rio after two fourth place finishes at the recent world championships.
Also in action for the Great Britain Cycling Team on day two were Craig McCann and Hannah Dines who finished in fourth and fifth place in their respective T2 races.
McCann’s result was particularly impressive in his first world cup event for the team while Dines finishes a year which has seen her make a real impact on the international stage with another solid performance.