Abstract: A transmission system (1), for instance of a bicycle, is described, comprising a drive wheel (2), a driven wheel (3), and a coupling chain (4) having a first chain half (4C) and a second chain half (4D). The transmission system is provided with a measuring device (6) for providing a measurement signal which is representative for the torque transmitted by the coupling chain (4). This measuring device (6) comprises a transverse force sensor arranged within the span of the coupling chain (4) in the form of a wheel (10) rotatably mounted on a supporting arm (20), which wheel touches the first chain half (4C) and the second chain half (4D). The measuring device provides a measurement signal which is a measure for the component (Fv), directed substantially perpendicular to the plane (L) defined by the rotation axes of the drive wheel (2) and the driven wheel (3), of the resultant (FDR) of the transverse forces (FDC, FDD) exerted to the sensing wheel (10) by the chain halves (4C, 4D).