hi guys

i am trying to design a tandem bike with two riders seated side by side.....but what i cant get quite sorted out is.....if we have two separate chain drives driving a common rear axle.......and the two riders are exerting different torques.......then will the rider exerting lesser torque contribute to the rotation of the rear axle or not?.....i know it is a silly question yet...i wud like some clarification....