There are several sites dedicated to how one should keep the weight distributed in the backpack to maintain a center of gravity closest to and keep it all balance. It is simple physics.
There are many reviews on youtube and other sites on the merits of Z-Packs. Some of the ultralight packers like the Z-Pack but many of them review that the pack is NOT comfortable with a load beyond 15 pounds. Again because of the center of gravity, if you are prone to bad or sore backs then I would NOT reccomend a Z-Pack unless you are going to carry a very, very light load. I would only reccomend an ultralight pack if you are fit and like to carry absurdedly small amounts of stuff. I believe that there is a trade off between humping insanely heavy and lunatic light.
Many professionals reccomend trying one in a STORE with weight and that is what I did for several hours over several visits to various stores before I found one that was most comfortable comparatively speaking - oh wait, I don't think you can do that with mail order.....Humph! I tried everything from light to ultralight to regular to heavy. There is a definite tradeoff in the light packs and thats comfort: thinner straps. So while there is a lot of hype about backpacks out there....the hype dissapates quickly when you can comparatively try on several packs.
I am going on my second Camino one year after I completed my first one and I will not be bringing an ultralight pack and thats my experience talking.
Hi, Ricardo; I appreciate your perspective on what you have found to be essential in your choice of backpacks. That will be of help to some who are considering just where to start looking for their first backpack purchase. You bring up some things that folks should think about.
I'd like to add a few of my thoughts and insights. I appreciate your consideration.
Before I comment on packs, I want to make sure that there are common definitions in use.
'Ultralight' in a backpack describes a 'base load' being no more than 10 pounds, which is all of the gear and equipment which is non consumable. The 'total load' with all consumables included will be under 15 pounds. This is for a hike of 5 to 8 days without a re-supply.
'Lightweight' is the definition of a backpack that has a 'base weight' of less than 15 pounds.
Five years ago, ultralight meant under 15 pounds and lightweight meant under 20 pounds. Time has changed both manufacturing processes and technology in materials.
Today, a pack for ultralight use would likely be a frameless pack, while one for 'lightweight' backpacking -- which in some models might not weigh much more than a frameless pack -- will most likely have a frame, either external or internal, while itself still staying within a 1.5 to 3 pound weight range.
Personally, I have not had some of the objections that you are concerned about. I have personally purchased and used many ultralight backpacks and the more 'standard' backpacks as well. I have also been hired by backpack manufacturers to extensively test their products -- which amounts to many different brands and models of ultralight and 'standard' backpacks. This has given me decades and thousands of miles of experience with backpacks.
I also follow the surveys of users. For example, although large numbers ( if not most), thru-hikers on the Pacific Crest Trail, Appalachian Trail, Continental Divide Trail and the Colorado Trail will use one of the brands of ultralight or lightweight packs, the typical and average load weight between resupply points is 15 to 25 pounds, and users still report good results and comfort of use from their packs.
With my ULA Catalyst and Circuit which I used on my Pacific Crest Trail thru-hike, and my Gossamer Gear Mariposa which I used on my Colorado Trail thru-hike and on both Caminos on the Frances, I find them to be quite comfortable with a wide range of load weights. They have some of the best shoulder harnesses and hip belts that I have seen on any backpack, even though they are used by both those who go 'ultralight' and 'light weight'. I have found the same with Six Moons Design, Granite Gear, Zpacks, Osprey Levity, and others.
When I was gear testing the Zpacks Arc framed packs, I found them to be comfortable out to 36 pounds of weight carrying.
When testing for a manufacturer, I will test with load weights beginning at 12 pounds, and then over the weeks or months of testing, that load will get increased to the point of discomfort. In order to be as consistent as possible between all of the brands and models of backpacks I test, I have identified for myself several parameters defining discomfort in order to make my impression as objective as possible for something that is highly subjective. This is not something that is 'objective' to what
everyone would experience, but just to give me a similar guideline to use for all packs that I am hired to test.
The manufacturers will use the information from all testers to help determine, from a broad base, their estimate of comfort ratings.
I do not personally care for the Zpacks arc frames, but not because of a deficiency in straps or waistbelts or padding to the back of the pack, but because I just couldn't tweak the darned things enough to make it feel 'normal'.... or more accurately, so that it didn't feel 'odd'. I could haul it around all day in comfort, but i never could quite forget I was wearing it. I always felt the urge to tweak the harness or adjust the waistbelt just to try and get past that 'odd' feeling.
The most comfortable pack I have ever worn was a Dana Designs (now evolved into Mystery Ranch) Astral Plane. It weighed-in empty at a bit over 6 pounds. It is the bar by which I judge how comfortable other packs are and their adjustability. By comparison, my Gossamer Gear Mariposa is just under two pounds and is just as comfortable carrying a similar weight load. Considering that the Dana Designs pack weighs a bit more than 4 pounds heavier than my Gossamer Gear pack, that means that instead of the 9.8 pounds of total weight I carried on Camino would have increased to 14.2 pounds using the Dana Designs pack.
Just as a point of information, when using the Zpacks, even at max weight loaded weight in the pack, I never had an issue with center of gravity. No more so, for comparison, to an Osprey backpack with a trampoline mesh back. The small gap of the arc with either brand of pack is more than offset by the superb shoulder harness and hipbelt systems.
