A stent delivery system can include a core member, an introducer sheath, and a microcatheter. The core member can have a first section and a second section distal to the first section. The second section can have a bending stiffness per unit length that is less than a bending stiffness per unit length of the first section. The introducer sheath can have a lumen configured to receive the core member therethrough. The introducer sheath can have a length of at least about 80 cm. The microcatheter can have a lumen and a proximal end configured to interface with a distal end of the introducer sheath for delivering the core member into the microcatheter lumen.