Runner for height access systems secure people while climbing on antennas, towers etc. The runner is released by pulling a lever. In case of a fall, the lever will be pulled down and the runner blocks. But in case of a fall back or a knee-jerk catch for the lever, conventional runners do not block. The user is in danger of a deadly fall. The SPEED’s security bolt is hidden in the housing, protected from unwanted access. In case of a failure of the pullback feature, the runner reaches a maximum speed of 4 m/s. When exceeding this speed the especially developed Micro-centrifugal-force-brake swivels out the bolt and the runner blocks.