Since I don't care for rubber band belts on e-machines, I'm not sure I'd like them on a treadle. Someday perhaps I'll run across one and give it a try, but for now I'll just use the leather ones.
I've seen some of those braided leather shoe laces for hiking boots and like that. Never thought of trying one.
Just like substitute needles there's a substitute for belts too. Cool.
Joe