An elevator system includes an elevator car and a counterweight fixed to a traction device. A drive pulley moves the traction device. A bottom tensioning apparatus is fixed to the counterweight and to the elevator car. A tensioning weight tensions the bottom tensioning apparatus. In an end position of the counterweight, the elevator car can continue to move when the traction device is moved further by the drive pulley. This moves the tensioning weight at half the speed of the elevator car, for example. A measuring device is provided for the tensioning weight for detecting such a motion of the tensioning weight. This allows a triggering of an emergency stop of the elevator car.