The probe‐surface interaction underlying the ‘‘shear‐force’’ distance control commonly used in near‐field microscopy has been studied in detail by measuring dither resonance profiles and approach curves in vacuum and liquid helium. Simulations based on a nonlinear oscillator model considering the probe geometry, its elastic properties, adiabatic short‐range probe‐surface contact, and the surface tilt angle, are in excellent agreement with the experiments. We prove conclusively that a nonlinear bending force mechanism with parametric mode conversion is responsible for the observed phenomena.