Cables going into rotating handgrips

The shifter and brake cables break easily on a handcycle if those same cables have ends planted into brakes levers or shifters that reside on a rotating handgrip.  The usual cause is that the cables repeatedly bend at the spot of entry into the lever or shifter.  I have built a long holder for the cables that always keeps the loop of cable above the shifter and brake lever.  In addition I have added spring coverings to the cables at both places where excessive bending can occur.  The springs should extend the radius of the bends thus slowing the pace of breakage.