A stent delivery system for treating bifurcations is provided. The system has a low profile and provides substantially predictable translational and rotational positioning. In one embodiment, the system includes a fixed wire balloon catheter and a partially attached side branch lumen, wherein the side branch lumen is attached to the catheter at a crotch point. The location of the crotch point is predetermined so as to provide substantially predictable positioning. Several embodiments of the system are described for various types of bifurcations and vessels.