Marco
There are a lot of reasonsing and philosophies about what fits with backpacks. Pehaps the strongest point made is “Try on Lots of Backpacks.” If still in doubt, choose the tallest size between two equivalnly comfortable packs…it will put more of the load on your hips/legs directly, bypassing the spine and shoulders.
Different people will also advocate different framed packs. No frame, internal frame and external frames. All fit a bit differently. Raw measurements do not take this into account. The shape of a frame and harness system can also influence fit. Straight frames are never fully comfortable. Curved frame sheets tend to hug your back better, with less additional weight in padding. Stiff, tubular frames can restrict hip movement while hiking, important for comfort while walking.
Width of a backpack makes a big difference. Tall and narrow, vs, short and wide. Often these are chosen for a more specific purpose. Narrow packs seem to be better for climbing, and bushwhacking. Wider packs (and more compact loadings) can be better on flatter, open trails. You should pay attention to the size of the pockets (if any) and how vulnerable they are to snagging. I find narrow 11″-12″ pack-body width comfortable. Wider 13″-14″ pack-bodies can catch on all sorts of things on narrow trails.
The overall use of load lifters is a rather controversial subject. Like belt stabilizers, they are designed for keeping the loaded pack near your center of gravity. Lets face it. All the load goes on your feet and legs. There is no such thing as a magical “load” lifter. (Hydrogen filled ballons and bags do not count, these are add-ons.) Putting them at 45 degrees “above” your shoulders, or straight across your shoulders, or at 70 degrees above your shoulders doesn’t do a da*n for carrying the loads. They DO help manage any “overload,” though. Keeping the weight close to your body will reduce any “pulling back” with the loaded pack.
Compression straps can help by keeping a load more stable and “rattle” free. Also, they help keep the center of gravity closer to your body. They also keep the pack stiff and nearly self supporting, resulting in a better carry, generally.
Center of gravity seems to be in two major types with packs. The first is the overall COG. It will force you to lean forward to balance a load while walking. This will ALWAYS happen with any load on your back. The second COG is forcing the pack to pivot on the wast belt. This will put stress on your shoulder harness. The two combined, can be quite uncomfortable. This has more to do with loading, than fit, though.
The packs COG, load lifters, torso strap, and shoulder straps can all combine to put a lot of stress on your chest. Women pick up early on this with any pressure on the breasts becoming quite uncomfortable. These all conspire to reduce breathing. In high exertion activities, such as hiking or climbing, this is bad. You should NEVER feel like the pack is restricting your breathing. Often this is just a matter of adjustment, Sometimes, these things can conspire and will do this, regardless of the adjustments. Aarn front packs, indeed most front pack arrangements, fail in this regard. Your chest will move up and out while breathing. Any pressure on your breathing will cost you energy or pain on the trail. Reduce as much as possible the weight on the shoulder harness. In the video, he mentions 65% of the weight should be on the hips. I would rather say “as much as is possible.” The shoulder harness should never have more than 3-5 pounds of load on each strap…enough to stabilize the pack while walking, climbing, or twisting between trees on a bushwhack. Taller packs will twist and turn against you, putting additional strain on your chest. A deeper 7-8″ thick pack will change the COG and pull against your chest. Overly tight load lifters will pull weight agaist you shoulders, putting more weight and more pressure on your chest. We all need to breathe. With a 20 pound pack load and a good waist belt, as much as 80-90% of any of my pack load is on my hips. Indeed, my shoulder harness/torso strap is just tight enough to stabilize the pack against the load. Wow! I can breath!
Keep the heaviest items low in your pack. This will move the packs COG closer to the waist belt and reduce the need for loading on the shoulder straps. The next heaviest items should be loaded close to your back. and as low as possible. ready items (lunch, sweaters, jackets) should be placed on top. This also makes them readily available. If your tent is the heaviest single item, it should be placed where? In the pack and on the bottom of course. Or, get a lighter tent, so you can put it next up, in the pack,ready to be used in wet weather. If you have trouble with pack collapse, try rolling it tightly and placing it upright, next to your back. There are tricks you can play with gear to help the pack be more comfortable. But there is no fix for an ill-fitting pack. If you do not have the correct size pack, then all the tricks in the world will not make the pack fit better. I would avoid the weighted bags at REI or EMS when checking the load ballance of a pack. These are usually very dense pushing the weight and COG very low. You would do better to simply take all your gear, and laod it to get a good idea of how the pack will carry. They will not usually complain, but tell them you are looking to buy a new pack. Often they will help!
