A transcatheter delivery system including an expandable transition element is disclosed. As one example, an assembly may comprise a prosthetic valve and a delivery device. The delivery device may comprise an outer shaft with a distal end portion forming a sheath adapted to enclose the prosthetic valve therein in a radially compressed configuration; an inner shaft arranged within the outer shaft and including a nosecone arranged at a distal end of the inner shaft, the nosecone arranged outside of the outer shaft, at the distal end portion of the outer shaft; and an expandable transition element adapted to expand from a non-expanded state within the outer shaft to an expanded state outside the outer shaft, wherein, in the expanded state, the transition element forms a continuous transition from the nosecone to the prosthetic valve when the sheath is moved away from the nosecone to uncover the prosthetic valve.