A vascular intervention device delivery system, such as for implanting a self expanding stent, includes a thumbwheel rotatably mounted in a handle. A catheter has a proximal end attached to the handle and a distal carrier segment for mounting a stent thereon. A retractable sheath is movable to a position retracted proximally to uncover the distal carrier segment. A pull with a curved cross section extends between the thumbwheel and the retractable sheath. An idler wheel with a perimeter notch is rotatably mounted in the handle proximal to the thumbwheel. A pin is movably in the handle between a first position received in the perimeter notch to block rotation of the idler wheel, and a second position outside of the perimeter notch to permit rotation of the idler wheel. The pull wraps around the idler wheel to return in a direction for being wound onto a spool of the thumbwheel.