A rotary assembly for a turbomachine fan includes a disk rotatable about an axis; a plurality of blades fastened by their roots to the disk and extending radially outwards from the disk; and a plurality of inter-blade platforms, each extending between two adjacent blades and defining the inner profile for the flow section of the fluid passing through the fan. On their facing side faces, these adjacent blades present slides between which the platform can slide, these slides limiting outward radial movement of the platform.