Any disadvantage to a 10 ft rod vs a 9ft?

[Silver Creek]

As in many things related to fly rods, the answer lies in the physics of levers. The disadvantages of a 10 foot fly rod over a 9 foot is less pinpoint accuracy for dry fly fishing, and less useful in smaller streams unless you are dappling or bow and arrow casting.

A longer rod is basically a longer lever. The longer the lever the greater the mechanical advantage, but the less precise control you have over the end of the lever. For example, try writing your name by holding the end of a paintbrush that is 6 inches long and one that is 4 feet long. You will have more control of the end of the shorter paintbrush. Greater control of the fly rod tip translates to greater accuracy in casting.

For accuracy alone, you want a fly rod that is long enough to give you enough mechanical advantage to cast the distance that you need to, but short enough to give you the maximum control of the rod tip. Ever wonder why 9 foot fly rods are the most popular? It is because they offer the ability to cast as far as most people need and with sufficient accuracy.

The advantages of a longer 10 foot fly rod like casting further, keeping more line off of the water for direct line nymphing, the ability to mend more line, etc. are tradeoffs for the loss of accuracy over the 9 footer. You need to decide whether the positives of a longer rod outweigh the loss of casting accuracy.

I use a 10 footer for larger rivers, but an 8 - 8.5 footer in my local waters. So in big water, the advantages of a longer rod, especially for nymphing, outweigh the loss in accuracy.