Devices and methods for transferring forces down a catheter shaft while also maintaining an open fluid pathway are disclosed. In some of the designs, inner and outer members of the catheter interact, allowing improved transfer of forces down the catheter shaft. These designs also allow for maintenance of a fluid pathway along the length of the shaft, including at locations where the inner and outer members are interacting with one another. Structures are disclosed which extend at least a portion of the length of the shaft, allowing improved force transfer and resistance to kinking. Structures are also disclosed which specifically allow for inner and outer members to engage one another at at least one point along the shaft, improving the transfer of forces down the shaft.