Chiral graphene nanoribbons offer a versatile playground to control electronic and magnetic prop-erties in a one-dimensional graphene nanostructure. Here, we report the on-surface synthesis of (4,1,4) chiral graphene nanoribbons (chGNRs) and characterize their structure, edge states and band gaps using scanning probe techniques and DFT simulations, the latter revealing a critical dependence on the environment of the electronic and magnetic properties of (4,1,4)-chGNRs. While gas phase calculations predict an open-shell ground state, the influence of the metallic substrate upon adsorption modifies the electronic properties as predicted by GW calculations. In this theoretical frame, the experimental band gap of surface-supported (4,1,4)-chGNRs can only be reproduced assuming a closed-shell configuration.