Abstract: A rotor blade assembly for a wind turbine includes a ring insert in the blade root section. The blade root section has a span-wise end portion defined by an inner circumferential component and an outer circumferential component, with a radial gap between the components. The ring insert is disposed in the radial gap and is bonded to the inner and outer circumferential components. The ring insert has an inner circumferential surface and an outer circumferential surface, wherein at least one of the inner or outer circumferential surfaces has a radially varying cross-sectional profile that increases bonding surface contact area between the inner or outer circumferential surface and the respective circumferential component of the blade root section as compared to a constant radius cross-sectional profile.