Disclosed herein are embodiments of delivery capsules for delivering prosthetic implants around the relatively tight bends of a catheter. In particular, disclosed herein are delivery capsules including a tubular layer for holding the heart valve, a frame enclosing the tubular layer and an elongate element coupled to the frame for allowing the tubular layer and frame to expand. For example, the frame may be biased to expand and withdrawal of the elongate element from openings in the frame can release the frame to expand into a larger diameter. Another embodiment includes a helical wire wrapped around the capsule for easy delivery through bends and a second helical wire that is advanced between windings of the first helical wire to selectively stiffen the capsule for withdrawal. Other embodiments include sock-like capsules that can be crumpled into shorter lengths by pulling a pull line attached to the capsule.