Provided is a way of using an estimator to determine a force (Fz), which acts from the outside on a steering gear of a steering device in a vehicle by way of a steering linkage, wherein a motor for generating a steering torque is assigned to the steering device. This is achieved by estimating the force (Fz) acting from the outside as a function of an effective motor torque (tor_RAeff), wherein the effective motor torque (tor_RAeff) is determined as a function of a motor torque and an efficiency, the efficiency being determined as a function of the estimated force (Fz).