Backing is line used underneath your primary line to reduce the amount of primary line you need. With braided line, for example, you might need two spools to fill a medium to large casting or spinning reel. Backing is used as a core filler. Flyline, which is somewhat limited in length, almost always requires a backing.
Backing for your baitcasting reel is just plain old monofilament line. The backing size should change depending on the size of the braided line you use. There are no exact standards, but here is a general guide:
10 lb to 40 lb braid — 15 to 20 lb mono backing
50 lb to 80 lb braid — 20 to 30 lb mono backing
You need only a few wraps of monofilament on your spool to lock the braid in. If your using 80 lb braid with a 30 lb mono backing, the knot you use to tie the connection is very important. The knot has to be streamlined enough to slide through the small hole of the line roller. If you’re unable to get your knot streamlined enough, reduce the size of the mono backing until you can get the knot through the line roller. I personally prefer using an Albright knot, although many consider the Double-Uni knot to be the most common for this type of line connection. It too works very well.
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Captain David M Rieumont
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