When I operated the Little Lehigh Fly Shop customers would ask for a short fly rod for their petite wife. My response was if you want your petite wife to move a large boulder do you give her a long lever or a short lever?
Long, obviously; remember that guy named Archimedes?
A fly rod is a simple lever. Ease of casting, mending and fish fighting improve as the fly rod gets longer. Longer is better! I see good anglers fighting to reach a “riser” on the opposite side of the stream with a short rod!
Conversely, rods over nine feet can be cumbersome and as you add length you add guides increasing friction between line and guides.
I’m comfortable with a rod length of nine feet. My rod length goes down if the canopy I’m fishing under demands it. When fishing a laurel canopied stream you may opt for a five or six foot rod. Don’t go to one of those little streams thinking you will hold your nine foot rod further up. You will create a teeter totter. One end of the rod teeters, one end totters, and you impart shock waves to the line and lose control.
It’s always amazed me that a trout can completely devour your fly yet the fly will come out of its mouth. But get your fly within four feet of a willow and it will hold on to your fly for all eternity.
Bottom line; buy a rod as long as the canopy you are fishing under will allow.
For every foot of length there should be one guide, plus one. For example, an eight foot rod should have one guide for each foot (8), plus one. Total nine. This formula doesn’t include the hook keeper or tip top.
The rod should be properly splined. When a graphite rod is constructed, graphite fabric is wrapped around a mandrel and a backbone or spline is formed.
Take the top section of your two piece rod; place the thick end on the table. Hold up the tip with one hand the press down and roll with your other hand. You’ll feel it hop. That’s the spline. The guides should be in line with it.
For fishing most trout streams, I suggest a slow rod that loads (bends or starts working) with minimal line out. I want a rod that loads for short distance casting and will still propel my line across the stream. For bigger water I use a stiffer faster, rod.
Choose a rod designed to cast a line appropriate for the size fly you usually cast. A rod built to cast a 3 weight line is great for tricos and midges but a 6 or 7 weight is appropriate for large flies like Hex’s and streamers.
I think a five weight is a good compromise and in a pinch you can use it for light warm water fishing.
Those are some basics. You can find expensive rods without these characteristics. You can find inexpensive rods with them.
Look for these basics in any rod you buy, and then consider the aesthetics.
Point to remember
The size of your hand doesn’t change with the length of the rod,
The rod grip shouldn’t either.