Methods and devices for bonding a balloon assembly, such as a balloon assembly including an inner balloon and an outer balloon, to a catheter shaft are disclosed. In some cases, a proximal waist of the inner balloon may be bonded to an interior surface of an outer tubular member of the catheter shaft and a proximal waist of the outer balloon may be bonded to an exterior surface of the outer tubular member. In other cases, the proximal waist of the inner balloon may be bonded to a reduced diameter portion of the outer tubular member of the catheter shaft and the proximal waist of the outer balloon may be bonded to the outer tubular member, such as a non-reduced outer diameter portion of the outer tubular member.