Mass of supermassive black holes (left) (estimated from central stellar velocity dispersions) and inner slope of the stellar component of the rotation curve (right) (tracer of central stellar mass concentration) as a function of mean pitch angle. The red dashed straight line (left panel) corresponds to the fit from the tight correlation presented by Davis et al. (2017): their values are consistent with ours, but we do not find such a strong dependence of the pitch angle on M_BH. Different colours correspond to different spiral types, as indicated in the legend.