2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/4315I present some new results, from simulations and observations, of the constraints bar pattern speeds place on the dark matter content of disk galaxies.4 pages, 3 figures. Contribution to "Disks of Galaxies: Kinematics, Dynamics and Perturbations", eds. E. Athanassoula & A. Bosma, to appearAstrophysicstext