Chemical reactions usually proceed through radical, concerted, or ionic mechanisms, yet transformations in which these three mechanisms take place at the same time are rare. In polymer mechanochemistry a mechanical force, transduced along polymer chains, is used to activate covalent bonds in mechanosensitive molecules (mechanophores). Cleavage of a C–C bond often follows a homolytic pathway but some mechanophores have also been designed that react in a concerted or, more rarely, a heterolytic manner. Here, using 1H- and 19F-nuclear magnetic resonance spectroscopy in combination with deuterium labelling, we show that the dissociation of a mechanophore built around an N- heterocyclic carbene precursor proceeds with the rupture of a C–C bond through concomitant heterolytic, concerted, and homolytic pathways. The distribution of products likely arises from a post- transition-state bifurcation in the reaction pathway, and their relative proportion is dictated by the polarisation of the scissile C–C bond.