I bleached a pair, one stayed in for a month the other just over a fortnight. It cleaned them fine but unevenly dissolved a top layer and left a skin of mushy powder and all needed sanding and still isn't right. A bit like peeling off masking tape and bits off paint come up, that kinda surface was left. Try it for a week and see how you get on. And greasing those hubs before is really essential, bleach will pit them like buggery....