It is well understood that mechanical forces induce versatile chemical reactions in polymeric materials at the molecular scale. The types of reactions that can be triggered by mechanical energy range from simple heterolytic or homolytic bond breaking to unexpected and otherwise forbidden chemical reactions. This opened up the field for synthesis of compounds with predetermined mechanochemical reactivity, so-called mechanophores. However, the prediction of mechanochemical reactivity of polymer chains or mechanophores is very difficult by experimental means, so that computational methods became indispensable to investigate the induction of chemical reactivity by mechanical force and to streamline the design of new mechanophoric components. While most computational methods that allow incorporation of an external force afford a priori knowledge of the expected reaction mechanism, the Constrained Geometries Simulate External Force method (CoGEF) only affords knowledge of the reactants. The CoGEF method allows to investigate the mechanochemical strength of covalent bonds by density functional theory and, recently, it was validated as a predictive tool for mechanochemical reactivity. While multidimensional approaches are also available, the classical 1D-CoGEF method is the most prominent approach to study mechanochemical reactions due to its simplicity and broad availability.