Good afternoon!
When I began fly fishing, one of the most confusing things to me was the jargon associated with the sport. Many novice and even intermediate fly anglers are not familiar with the various sizes and uses of rods, line, leader, tippet, hooks, etc. This may seem like a rather dry subject, but the knowledge pays off when you know what kind of equipment to use, which should be tailored to the fish species you are seeking and the environment you will be fishing in. For instance, if you are fishing a small creek with low-hanging trees, choose a shorter rod of lower weight size. If you are fishing a large river like the Madison (in most spots) you might want to stick with at least a 5 wt.
To begin, the jist of rod sizes is that they run from a 0 weight (often abbreviated as "wt") all the way up to a 12 weight and beyond. The largest sizes are usually for saltwater species (EVEN MARLIN!). The general rule is that, the bigger the fish, the higher the rod wt. However, this is not always the case. Often larger brown trout (a particularly finicky and sought-after species) may be caught on a rod size of about 3-5, but could weigh 15+ lbs. This goes for trout in general, as they are the best at spotting a thick, glossy line below the surface and behind your fly, which can cause them to get spooked, brown trout all the more so.
Now, if you are fishing for brook trout in a small Appalachian stream, you certainly do not want to be using a 10 weight rod. Trust me, i fished a tiny stream out West for brookies once with a 9 ft 5wt rod and it was a circus - a miserably tangled, tree-hung, and high-hooked debacle, not to mention there was grizzly poo all around me and no phone service for miles! Even still, I have caught many rainbow trout with an 8 wt rod, but a 4-5 wt is more than capable of handling the lot and the occasional trophy swirling about the other end of your leader at any given time. It is often said that a 5 wt. rod is the most versatile size, so it is a great starting point.
If you are just starting out as a fly angler for trout, you should lean toward a rod in the 3-5wt range. Anything above a 5 wt may in most circumstances be more suited for steelhead, bass, or something of larger size. On the other hand, if you are tossing a tarpon pattern in the salt water flats, you will probably want at least a ten weight.
Next time, I will discuss the fly line, leader, rod balance. This is important if you plan on being an effective fly caster and want to catch as many fish as possible. So not only do you need to have the right size rod, but you also need to have it rigged with the corresponding line size AND the appropriate leader for the method of fishing you are undertaking, i.e., fishing dries, nymphs, streamers and so forth.
Use coupon code STREAMTEAM for streamers in the shop and/or DEEPSOUTHTEAM for shirts and see what happens! ;)
Thanks for reading,
-Daniel