Knot for backing to fly line?

[teezer]

I put a loop in the backing and the fly line, then loop to loop them. I use a bimini twist for the backing (not as hard as you think) and the fly line I double the line over and put two nail knots about a half to an inch apart. Use 6 to 10lb test mono for the nail knots, this way the mono digs into the fly line coating. You could then coat the nail knots with pilo-bound if you want to make it slide thru the guides easier. I have never had a problem and have tested it while catching hardtails.