[en] We show how the cancellation between the nucleon and Δ (1232) contributions to finite-energy sum rules for πN → πN amplitudes can be used to determine the πNN and πNΔ coupling constants. We then apply the same method to finite-energy sum rules for the rhoN → πN and rhoN → rhoN Reggeon amplitudes. A unique solution is found, for which the rhoNN helicity nonflip coupling vanishes and the rhoNΔ coupling is of the M1 type. The relative size of the rhoNN helicity flip and rhoNΔ M1 couplings is also in agreement with experiment