An analysis of the various harmonic orders of the inertia forces in offset slider-crank mechanisms is presented. The formulas given here are valid for all practical values of eccentricity ratio (ratio of offset to length of connecting rod) and crank to connecting rod ratio. The influence of the latter ratio on the force components is evaluated with infinite series, whereas such is not the case for the eccentricity ratio. Rules for the full or partial balance of harmonic components of the first or any other single order are given.