And volume's not the only issue. Once, I knew "someone" who selected a pack because it was big enough to hold his load, but not too big. He forgot to check out the suspension. The first time he took it out, he soon found out that the 30 pound load in the nifty little 2.5 pound pack had caused the hipbelt to double over, and rendered the lightly padded shoulder straps virtually worthless. Doing further research, he discovered the maximum comfort rating for the pack was 20 pounds.

Be sure you not only get the right size for the volume of your gear, and also a suspension beefy enough to carry the weight of your gear comfortably. (30 pounds of ultralight gear weighs the same as 30 pounds of traditional gear, oddly enough.)