ABSTRACT Cellular adhesion via the formation of molecular bond clusters is a fundamental biological phenomenon. Cell adhesion forces can be measured by various advanced techniques with adjustable probe stiffness. To quantitatively understand how the stiffness of a loading device may influence the measurement of these forces, we consider an idealized theoretical model of a cluster of molecular bonds that are subjected to an applied tensile load by a Hookean spring. In this model, the rebinding and rupture of individual molecular bonds are governed by stochastic master equations. By deriving an exact expression of the rebinding rate and directly solving the master equation, we find that the conventional moment method provides incorrect predictions for this problem. Moreover, the measured adhesion strength of a molecular bond cluster exhibits strong dependence on the stiffness of the loading device and the bond number when the stiffness value is close to or smaller than the effective stiffness of the bond cluster. Thus, an improper selection of the stiffness value of the loading device may lead to measurement uncertainty. Monte Carlo simulations are performed to verify the proposed analytical results.