When you get a backpack, first get a general feel for it. Adjust the suspension to approximately the right length, loosen the shoulder straps, pack the bag (try to pack as if you're fully loaded), then put the bag on. Bend over to secure the hip belt, tightening it as much as possible without affecting your breathing. Then give the bag a little shake upwards, and simultaneously pull the shoulder straps diagonally backward with both hands—but not too tight. Finally, straighten up.
The properly adjusted backpack should have its base at the lower edge of your normal waistband, covering about half of your buttocks. The feeling should be that the bag is sitting on your hips, while the shoulder straps mainly serve to stabilize rather than bear the main load. Jump up and down a bit—check if your center of gravity wobbles (most likely due to poor packing or unsecured side/strap adjustments), or if it shifts backward. If you feel a strong pulling sensation, aside from packing issues, the adjustment strap between the upper part of the shoulder straps and the back panel might be too loose. Tighten it to form roughly a 45–60 degree angle. Repeat the adjustments until the desired fit is achieved. Then wear the backpack for about 30 minutes. If your back doesn’t feel uncomfortable and the overall experience is quite comfortable, great—your backpack suits you well. If repeated adjustments still leave you uncomfortable, it may simply be that this particular backpack isn’t right for you.
Also, some people prefer to secure the hip belt firmly against their hip bones, as long as it doesn’t hinder walking. Others find it more comfortable to have the belt covering only half of the hip bones. Some might even get friction marks on their hip bones. But never secure the belt too high, around the abdomen—that way, when you tighten the belt, you might end up struggling to breathe out.
Finding the right torso length for you: Your height doesn’t determine your torso length. To measure your torso, take a soft measuring tape and measure from the seventh vertebra of your spine (starting from your neck, there are several protruding bones) downward along the contour of your spine to the lowest point of your hip bones. To locate that point, place a hand on each hip and point with your thumb to the lowest spot.
The line connecting your thumbs is the measurement you need. If your torso is shorter than 0.45 meters, you typically should use a small carrying system; 0.45–0.50 meters calls for a medium-sized system; and anything above 0.55 meters requires a large carrying system.
Reducing hip pain: It’s the hip belt—not a waist belt—that does the job. It should sit on your hips (the outward-projecting pelvic bones extending from your waist to your thighs), transferring the weight to your skeletal structure. Because of this bone connection, the belt is padded. Make sure the padding at the front doesn’t press against you—you’ll need some space to fasten it properly.
Some shoulder straps extend from the backpack like a big Y, others like an H. Some allow you to adjust them to fit your neck and shoulders. The shoulder straps should position the backpack just below the tops of your shoulders. From there, they should form a snug jacket-like fit against your shoulders. The bottom of the straps should leave at least a palm’s width of space under your armpits so they don’t ride up. If these straps don’t match the contours of your neck and shoulders, they may pinch and leave bruises.
Adjusting the load lifters: Set at a perfect 45-degree angle, the load lifter straps help shift weight away from around your shoulders—or even transfer some of the weight from your shoulders to your hips. Once your hip belt (note: the hip belt) and shoulder straps are correctly adjusted, it should feel as though a strap runs from the top of your shoulders all the way to the frame, pulling it taut.
Don’t let your chest strap restrict your breathing. This strap and buckle connect the two shoulder straps and control where the pressure rests on your shoulders. Move the strap up or down to find the most comfortable position. Keep your head free—if your backpack is overloaded or packed too high, you won’t be able to look up at birds or clouds. Adjust your lid or top pocket so it tilts away from your head.
The best way to coordinate your load is to pretend, when buying the backpack, that you’re preparing for a long, cold hike. Pack everything you’d need into a canvas sack—including food (allow 1–2 pounds per day)—and load it into the backpacks you’re considering as finalists. Then walk around with that load a few times.