Schlüsselwörter: Aluminiumgusslegierung / Fahrradbremshebel / Zeitfestigkeit / Betriebsfestigkeit / Lastkollektiv / As part of the growing interest in the operation reliability of bicycles and their components design strength investigations were performed on a bicycle brake lever of an aluminium casting alloy. In addition to materials testing and FE-analysis the low cycle fatigue straight lines of the two spot samples, which differ in production periods, were determined experimentally. The low cycle fatigue straight line of the second spot sample of the brake levers has in comparison to the first one with a slope exponent of 5.5 a larger gradient. Furthermore this straight line is in the range of larger numbers of cycles. The reason for this is seen in a detectable changed casting quality. In the field of operational stability 2-step-block-tests were accomplished. Using Miner's rule the damage sums of the test results are larger than one. The experimental results are hence in safe area.Keywords: Aluminium casting alloy / bicycle brake lever / low cycle fatigue / operational stability / load spectrum / 1 Einleitung