What determines the wt of the fly rod? For instance, I have two old fiberglass fly rods that have lost their information about the wt the rod is designed for. Is there any way to determine what the rod is designed for, or is it just something that is pulled out of the air? These are not high dollar rods as compared to today’s rods, in fact I just picked them up at a garage sale for a few buck a couple of years ago. I am just curious as to what wt they are designed for. How does length come into play on the rods design and wt rating? Let here from some experts or anybody with an opinion.