Modulation of the solution conformations of N,N'-bis(benzhydryl)bispidine has been achieved by protonation. Conformers have been characterized by NMR spectroscopy using nuclear Overhauser effects and residual dipolar couplings. In contrast to the preference for the chair-chair conformation for the free base and the monoprotonated species, the diprotonated bispidine is revealed to exist as a mixture of chair-boat and boat-boat conformers. While boat-boat conformers of bispidines have previously not been detected, they are here observed to constitute up to 70% of the bispidine population.