Understanding structure-mechanical activity relationships (SMARs) in polymer mechanochemistry is essential for the rational design of mechanophores with desired properties. To date, SMAR studies have predominantly focused on covalent mechanochemistry. For example, the stereochemistry, regiochemistry, and substituent effects in various mechanophore scaffolds, such as benzocyclobutane, 20,70 cyclobutene, gemdihalocyclopropanes, naphthopyran, furan-maleimide, spiropyran, and the more recent pterodactylane mechanophores, have been shown to significantly influence their chemo-mechanical coupling. One key mechanism for enhancing mechanochemical reactivity is a "lever-arm" effect, where variations in the polymer backbone structure and/or the structure of the handles connecting mechanophore and polymer act like a molecular crowbar that can modulate mechanophore activity by changing the ∆R parameter associated with Bell theory. However, SMARs in noncovalent mechanical transformations remain underexplored in polymer mechanochemistry. We are particularly interested in developing a fundamental understanding of the chemo-mechanical coupling in the recently introduced configurational mechanophores. In this study, we quantified the transition forces (F*) for mechanical atropisomerization using single-molecule force spectroscopy (SMFS) for the first time to characterize mechanophores M1-M3 (Figure ). The previously reported M2 structure showed an F* of 197 pN ± 12 pN, corroborating its high mechanical activity suggested by earlier indirect evidence. Using Bell's approximation as an intuitive framework, we hypothesized a "lever-arm effect" to fine-tune the mechanochemical reactivity in diarylethene atropisomers. For a subset of mechanophores M1-M3 (Figure and) which undergo mechanistically similar transformation of atropisomer stereochemistry, M3 features the longest rigid structure-the 'lever arm'-between the polymer attachment site (where force is applied) and the rotational chiral axis (the 'fulcrum'), maximizing the ∆R and thus, requiring the smallest force to adequately reduce the activation barrier for atropisomerization. Conversely, M1 comprises the shortest 'lever arm' and requires the highest force. This anticipated activity trend is confirmed by DFT calculations, SMFS, and ultrasonication experiments. Remarkably, for M3 which incorporates the longest lever arm, its F* is further reduced to 131 pN ± 4 pN, a 33% reduction from the record of previously reported M2 structure. This study offers fundamental insights into the chemo-mechanical coupling between atropisomer stereochemistry and force and provides design principles for highly sensitive mechanochemical transformations which could enable the study of previously unobserved nanoscale mechanical processes.