As far as selecting and fitting a pack to yourself, it's not rocket science but you have to be informed. Read, read, read! I hate the current incarnation of Backpacker magazine but their gear reviews are still worthwhile and can help narrow your choices. Every April they published an extensive gear guide that can be quite helpful. Their opinions are based on measurable things like durability and workmanship but also on subjective things that I often disagree with. Note that they are currently enamored with ultralight equipment and that influences their recommendations (until the ultralight thing became popular, a 28 cu. ft. tent was considered a one person, now it's two - and folks haven't shrunk).

Although pack makers offer very specific fit instructions, in general - you fit a pack by sizing or adjusting six components: 1) the frame, 2) the distance between the shoulder straps and the hip belt, 3) the stabilizer straps (often incorrectly called “load lifter straps”), 4) the hipbelt, 5) the load lifter straps (or load transfer straps – these are actually stabilizer straps as well) and 6) the sternum strap.

The steps to using these components are:

1) Sizing the frame correctly. Have someone measure your back with a flexible tape measure from the seventh vertebrae (this is the first prominent vertebrae felt as a finger is run downward from the base of the skull) to the point on the spine that's at the same level as the iliac crest of the hip bone. The crest is the point at which the hip bone can be felt at the side sticking out. If the maker offers three sizes and you're between 16" to 18" you’re a small. If you’re 18” to 20” you’re a medium and if you’re above that, you’re a large or tall. Most women will never have a back length shorter than 14” or one longer than 19” and most average 17 1/2”. If the maker only offers two sizes, if you’re at or below 19” you’re a regular and above that a large. If you fall somewhere between 18 3/4" and 19 3/4" you're really in between sizes and should try both to see how they fit and feel when weighted.

2) Loading it. A backpack, both standard and ultralight, must be loaded with about 20 lbs give or take. The weight in an internal frame should be loaded so that the heaviest weight is placed even with a top of the hips when the pack is on. Our store used special weight bags. To do this, put a sleeping bag in the bottom, where one would be carried, and place the heaviest items just above that. In an external frame, the weight placement isn’t as crucial. Weighting the pack allows the hipbelt to settle on the hip bones or proper fit.

3) Make whatever adjustments are recommended by the maker to lengthen or shorten the distance between the hipbelt and shoulder straps. On externals this is usually done with plastic spacers located on vertical rods that are in line with the shoulder straps or an extendable frame of some sort. On internals this is done by adjusting some kind of yoke that the shoulder straps are sewn to. When correct, the hipbelt should rest about an inch above the iliac crest (the protruding bones of the hip) and the shoulder yoke (where the straps attach to the pack) should be about two inches below the top of the shoulders.

4) On most modern packs, both internal and external, you'll find a pair of straps that run from the shoulder straps to the upper part of the pack bag or frame. These are the stabilizer straps. If the pack is sized correctly, and the harness is adjusted correctly, those straps should run from a point on the shoulder strap even with your clavicle (protrusion of shoulder blades) up to the pack to form a 45 degree angle between the top of your shoulder to the pack when viewed from the side. These straps are usually sewn low on the shoulder strap and are run through a buckle that can be slid up or down to adjust the departure point at the clavicle.

On the pack, the bag is often fitted with two buckles to lower or raise the attachment point to form the 45 degree angle. ALWAYS LOOSEN THE STABILIZER STRAPS BEFORE TIGHTENING THE SHOULDER STRAPS WHENEVER USING THE PACK! If you tighten the shoulder harness with the stabilizer straps already snugged up, you’ll pull the top of the shoulder straps into a “V” leaving a gap between your shoulder and the strap. This puts a significant amount of pressure on your clavicle while also contributing to the pack’s instability. So loosen the stabilizer strap and then tighten the shoulder straps by pulling the webbing of the shoulder strap BACK AND DOWN UNDER YOUR ARMPIT.

5) The load lifter straps of the hipbelt should also be loose before connecting and tightening the belt and then pulled tight. Again, if you don’t do this, the hipbelt will be pulled into a “V” away from your hips, leaving a gap and putting pressure on the front of your hips. When you pull these straps tight, you’ll feel the weight in the pack rise up and into the small of your back.

6) Make sure that after the hipbelt and shoulder straps are tightened, the top of the hipbelt is about an inch above your hipbones so that the belt is resting on top of your hips. Too low and it will reduce circulation to your legs. Make sure the shoulder straps drop approximately 2” below the top of your shoulders, down your back, before joining the pack. THEN, snug the stabilizer straps on the shoulder straps until you take all of the slack out, that it meets the pack at a 45 degree angle, and just till it barely begins to rise off the top of the shoulders.

7) Finally, locate the sternum strap. This strap has one half mounted on one shoulder strap and has the male end of a Fastex buckle on one end. The other half is mounted on the other shoulder strap and has the female part of the Fastex buckle on it. One of these straps will also be elasticized. These halves clip together to join the shoulder straps by running across your chest. Both sides are mounted on a plastic “slider” that can be moved up or down to raise or lower the position of the strap. Locate it slightly above the breast bone but no higher. Large busted women may have to move it a bit higher but it should not be anywhere near the hollow of the throat. THIS STRAP IS IMPORTANT. It redistributes about 20 percent of the pack weight carried by the shoulders to the large chest muscles. It also greatly reduces pack sway. Of course, this is far less of an issue with the light loads of an ultralight pack. Tighten this strap till slack is gone and it is barely beginning to snug up. ALWAYS UNCLIP THE STERNUM STRAP AND HIPBELT BUCKLE AND LOOSEN SHOULDER STRAPS WHEN CROSSING A STREAM. If you go down with these all tightened it is nearly impossible to shed your pack.

I think that should do it for fitting a pack to yourself.