The effects of wearing an airbag vest, under a motorcycle jacket, on injury risk during inflation and protection against impacts were investigated. An existing finite element airbag model was inflated under a motorcycle jacket model and the risk of rib fractures was evaluated by measuring chest deflection of the HUMOS2 model. Three inflators were used to increase the amount of gas injected into the airbag. Once inflated, linear frontal thoracic impacts centred over the 4th costal interspace were performed based on previous crash simulations. Ribcage and internal organ injury risk reduction were assessed by chest deflection and Viscous Criterion from simulations with protector and reference simulations without protection. No injury risk was noted due to the inflation of the airbag under the jacket for the three injected masses. Blunt impact simulations demonstrated that the level of protection was maintained or even improved wearing the airbag under the jacket. The benefits of the airbag were more significant for impacts against obstacles with larger contact surfaces and increased with mass injection. Coupling airbags and garments could improve the effectiveness of inflatable protectors and should be optimised to minimise injury occurrence and severity. The method proposed in this work could be used for future evaluations of other rider morphologies as well as garment types and sizes.