that's one of the reasons why they make more than one type of heatshrink. I can't locate stuff locally that I'm happy with, that's why I rewire as much of it as possible, and just heatshrink, liquid tape the junctions. But to each his own... That link I posted above shows one type that is like a braided heat shrinkable covering. Now that might duplicate the appearance of some of the vintage gear and be a little more bend-y to boot.