An enhanced model of a bowed string is developed, incorporating several new features: realistic damping, detailed coupling of body modes to both polarisations of string motion, coupling to transverse and longitudinal bow-hair motion, and coupling to vibration of the bow stick. The influence of these factors is then explored via simulations of the Schelleng diagram, to reveal trends of behaviour. The biggest influence on behaviour is found to come from the choice of model to describe the friction force at the bow, but the other factors all produce effects that may be of musical significance under certain circumstances.