the sheath just needs to be tight enuff that it never moves under any condition, the cable does the work, and can't if the sheath is loose, but the friction on the cable is 'built in' - if it doesn't hold against the return spring, you've got too much spring tension, which is a common thing resulting from general wear, prompting folks to put "better" springs on to get a quick/complete pedal return - also don't lube the cable so it "works easier"
Bill
