How to Buy a Backpack Anatomy of an Internal-Frame Pack

How to Buy a Backpack
Evolution of the Threadbare Spud Sack
By Robert Earle Howells
Picture, if you will, a really crummy backpack - say, a burlap bag chock full of russet
potatoes with a pair of hemp-twine shoulder straps sewn on. Sure, it'll carry your load.
But spud-induced gravity will wreak agony on your shoulders. The straps will gouge
your epidermis. And the load will sway with every stride until it becomes an obnoxious
tail wagging you, the masochistic dog.
With this image in mind, it's easy to appreciate the design elements that make a modern
internal-frame backpack an impressive conveyor of payload. Through the evolution of
trial and error, the shoulder-slung sack has given way to a complex composite of foam,
aluminum and plastics conceived to minimize the effort of hauling potatoes and other
essentials. These contemporary packs came in all shapes and sizes, from ungainly
expedition models to slimmed-down day versions, but the elements that distinguish the
better ones are consistent across the board. So what makes the apotheosis of the
breed so great? Peel back some Cordura and take a look inside.
Anatomy of an Internal-Frame Pack
The framework.
Even that stupid potato-sack pack could be made reasonably comfortable if we could
put a large percentage of its weight on the hips. The bones of the pelvis can bear a far
heavier load that our relatively wimpy shoulders. Obvious solution: Add a hipbelt. But
how to get the weight onto the belt? The standard approach is to use one or more
aluminum stays, curved to fit the bend of the spine. The stays extend from the top of the
pack down to the hipbelt, typically two stays in a V-shape that meets near the center,
i.e., the small of the back. The stays transfer weight effectively, yet the pack remains
flexible (which is, after all, the primary advantage of an internal over the old-fashioned,
rigidly framed external). Many packs add a framesheet across the back. The
framesheet, usually made of high-density polyethylene (HDPE, a flexible but strong
plastic) stiffens the back of the pack for even better weight transfer, but at some
sacrifice in flexibility. It also prevents sharp, bulky items from poking your back.
The hipbelt.
Weight transfer is for naught unless the hipbelt, the receiver of this load, is up to the
task. That means one that fits (more about fit later) and has just enough stiffness to
support a load without sagging. A soft-foam hipbelt may feel great in the store, but after
a few miles down the trail it will begin to bottom out and your hips will feel the pressure
of the load. One that is too firm can bruise your hips. The most sophisticated hipbelts
are a Dagwood sandwich of different grade foams-open cell for tactile comfort, closedcell
for support, compression-molded foam for even firmer support. Some add a layer of
HDPE. A good hipbelt will compress progressively, like the shocks on your mountain

ike. Look for one that cups over your hipbones, which maximizes the amount of
weight-bearing surface area.
Shoulder Straps.
Here too you want to avoid too-soft foam. Another bad sign: puckers in the foam or in
the sheath that covers it. These puckers will turn into hot spots against your skin out on
the trail. The best pack makers have mastered the art of bending, curving, and covering
foam without these dreaded creases- but, of course, you have to pay for such
craftsmanship.
Back panel.
A sweaty back is an unavoidable consequence of carrying a load, but a good back
panel can mitigate the soggy-back syndrome. Some use firm, compression-molded
foam with grooves built in to permit a cooling airflow. Others use a swatch of soft,
reticulated foam (it looks highly perforated) that does a decent job of dispersing sweat.
Some do away with back padding altogether: Your back stays cool; just pack soft stuff
against your back to stay comfortable.
Pack bags and construction.
Every major maker of packs uses good quality materials and stitches them together with
all the requisite back-stitching and bar-tacks so that a pack is very unlikely to fall apart
during years of normal use. Cordura nylon, nylon packcloth, ballistics nylon, and
proprietary materials (generally similar to Cordura) are all plenty strong and abrasion
resistant. Of more concern is the design of the pack bag- and this is largely a matter of
personal preference.
Most packs designed for more than a weekend on the trail are top-loaders. The
advantage: You can overstuff a pack up top by using a built-in extender, which gets
capped off with a floating top pocket. And most packs offer a bottom sleeping bag
compartment, so you can access your snooze sack without hauling everything else out
in the process. But if you really want convenient access to your belongings, get a pack
with a zipper on the main panel- either a side zipper, or for the best access, a full
horseshoe.
Don't be seduced into thinking a flotilla of external pockets make for a better pack than a
clean, nearly pocketless design. A multitude of compartments may help you stay
organized, but they add weight and complexity. They also tempt you to add weight
around the perimeter of your pack, instead of inside and close to the back where it is
least likely to impede movement. I prefer a simple, single front pocket, big enough to
hold a rain jacket, or a hinged 'shovel pocket' for carrying wet or bulky items. Add a
couple of water bottle holsters and/or a sleeve inside to hold a hydration bladder, and
you have all the extraneous compartments you really need.
Up top, it's handy if the aforementioned floating top pocket removes and converts to a
fanny pack for day hiking or a summit push. Most packs have this feature. Fine touches

to look for if you think you might need them: Ice ax loops, crampon patches, and lash
points so you can strap on weird bulky things like snowshoes.
As for capacity, the 5,000-cubic-inch neighborhood should suffice for most of us- that's
generally enough for a long weekend to a week-long excursion- and you can typically
pile on another thousand cubes by way of the top extender. Figure on spending $200 to
$420 for a quality internal-frame pack.
Pack Fit
The best contemporary backpacks are virtually bespoke garments compared to the offthe-rack,
one-size-fits-most models of yesteryear. Of utmost importance here is torso
length, so the pack rests just right on your hips without doing a potato-sack number on
your shoulders. It shouldn't sag, nor rest so high it squeezes your kidneys. Look for a
pack that comes in two or three sizes, AND offers fine-tuning adjustability. Cheaper
packs often come in one size. Though they may offer a ladder-adjustment to raise or
lower the shoulder straps, the fit will be approximate at best. As a smallish (5' 8'') guy, I
have to drop the shoulder straps way down to get them to curve just right over my
shoulders- which usually means that the junction of the straps, where they join the back
of the pack bag, pokes me in the small of my back.
Besides overall pack sizes, the best packs offer different sizes of hipbelts and shoulder
straps- hipbelts that match the greater flare of feminine hips or the lesser flare of male
hips; shoulder straps narrow enough not to gouge slender folks in the armpits, wide
enough to disperse a load better than, say, the hemp twine of our potato pack. When
you've boiled down your choices to one or two packs, seek out the factory-trained packfitting
expert at your mountaineering shop to nail down the fit. Because today's packs
have so many adjustability features, this is almost impossible to do unaided. Then walk
around the shop carrying each pack, loaded with the full amount of weight you intend to
carry on the trail. You'll feel the best pack grab onto your back like a pet monkey, with
no discernible hot spots, and the load will feel so perfectly distributed that you'll wonder
if you forgot something. You should be able to sashay your hips freely, swing your
shoulders fully, and raise your legs in majorette's parade step without ever feeling
drawn off balance.
Daypacks
If you've followed the lesson thus far, you understand why I hold little regard for the
average book-bag style daypack. Most are just zippered potato sacks in pretty colors,
with virtually no load support. That's fine if all you're carrying is a sweater and a Norton's
Anthology, but if you're out for a full day with the ten essentials in tow- i.e., if you plan to
carry more than ten pounds or more than about 2,000 cubic inches- you need a
daypack that can bear some weight.

At the very least, get one with a hipbelt. Not just a narrow strap of nylon webbing, but a
two-incher, ideally with some padding. In the absence of an internal frame, a contoured
fit can transfer a light (say, 20-pound) load quite well. Look at the back of the pack; does
it curve in any way similar to human anatomy? If so, it will angle the load onto your hips,
preventing droop and sway. A lightweight framesheet will aid the operation. When you
get up around 3,000 cubic inches (the size you'll need for a long day of ski touring or
foul-weather hiking), the pack should emulate a full-size internal frame, with a
framesheet and/or at least one aluminum stay.
Unless I'm going to be climbing or scrambling, I like a daypack with at least a couple of
external pockets- under a light load, they're not much of a balance-inhibiting concern-
plus at least one internal pocket for little items such as notebooks and car keys. Other
features such as ice ax loops, shovel pockets, and hydration pouches are a matter of
preference, but I think some provision for lashing on extra items is important. At the very
least, you may need to carry a soggy rain jacket that you don't want stuff inside with
your peanut butter sandwiches. As with full-size packs, don't resort to guesswork. Take
along all ten essentials and then some when you go to try on packs. Give them a realworld
test. Unless you can afford more than one daypack, buy for the heaviest, bulkiest
load you can imagine carrying. Someday you'll need it. Till then, even if you'll only be
carrying a big sack of Idaho's finest, you might as well do so comfortably and gracefully.
Robert Earle Howells has been a correspondent for Outside Magazine for 11 years and
is the editor of Outside's annual Buyer's Guide. He started backpacking in the Sierra 25
years ago, and still frequents the Sierra as well as his local San Gabriel Mountains. Bob
taught mountaineering classes for the Sierra Club in the early '80s, which is when he
was turned onto gear geekdom.

How To Buy A Backpack
The keys to buying a backpack are fit and capacity. While fit should be determined by your body
type, capacity (the types and amount of gear a pack is capable of carrying) should depend on
intended use and length of trip. Here is what to look for to determine what backpack is right for
you.
Pack styles and uses
The more weight you carry, the more supportive your pack needs to be.
� A waist or lumbar pack or small daypack is best if you are taking a short hike with little gear
� If you'll be carrying a bulky or heavy (10 pounds or more) load, or if you plan to be out for more
than a day, consider an internal or external frame pack
� Both internal and external frame styles have a harness system comprised of shoulder straps and
a hip belt; compression straps pull the pack and load closer to the body
Internal frame
� Refers to a support system that is built into the interior of a pack
� Internal frames transfer a large percentage of the pack's weight onto the hips, which can bear far
heavier loads than the shoulders. This frame style is comprised of a hip belt that works with an
internal suspension system.
� The internal frame suspension system usually consists of one or more aluminum or carbon fiber
stays that curve to fit your spine
� The stays extend from the top of the pack to the hip belt, and their job is to stabilize loads and
transfer weight to the hips
� Many models also include a framesheet, often made of high-density polyethylene, to stiffen the
back of the pack and allow for better weight transfer
� Internal frames offer better balance because of their low profile and close-to-the-body fit
External frame
� The first generation of framed packs
� They feature a rigid support system, or framework (usually constructed of tubular aluminum), to
which a pack and harness attach
� External frame packs transfer weight and stabilize loads, but are much more rigid than internal
packs
� Usually have a wider profile than internal frame packs. On an open trail where balance isn't a
critical factor, this should present no major problems, but in the backcountry, the frame could
snag on branches or get tangled in brush.
� Because the rigid frame keeps the pack away from your back, such models tend to be
comfortable when used in hot weather
� Usually less expensive than their internal frame counterparts because their design and production
is less complicated

Daypacks
Daypacks are ideal for carrying light loads over short distances.
Sizes
� General purpose daypack capacity range is from 500 to 2,500 cubic inches
� In daypacks of 3,000 cubic inches or more - for ski touring or a long day of hiking--look for models
with a framesheet and at least one internal stay
� A padded hip belt and padded, contoured shoulder straps are also nice to have
Features
� The features you choose should be based on your intended activity
� Outside mesh pockets are handy for carrying water bottles, snacks, field guides, or wet shoes or
clothing
� Easy-access pockets are good for storing cameras, GPS receivers, or other items you want to
keep protected, yet accessible
� A daisy chain, nylon webbing that offers multiple lash points, is good for securing small items
� An external bungee cord is handy for securing a jacket or rain gear to the outside of the pack
Sport specific packs
Many daypacks have sport-specific features to accommodate specialized equipment.
� Back-counrty skiing
A model with loops or straps for hauling skis will probably be more comfortable and useful than a
general-purpose pack
� Inline skating
Packs with a larger cargo area to hold your skates or an outside loop to attach your skates
Plenty of room for helmet and protective gear
� Bicycling
These packs generally sit lower on the back to provide a lower center of gravity
A special pocket or compartment to stow a helmet
Outside mesh pockets to accommodate cycling shoes or water bottles
� Snowboarding
Extra-durable rear pocket, usually made of Hypalon, Kevlar or heavy-duty Cordura, to
accommodate a snowboard, snowshoes or avalanche shovel
Streamlined, narrow-profile design that won't hinder balance and maneuverability in the
backcountry or on the slopes

Hydration packs
Hydration packs are designed to provide an ample supply of water while you're on the move.
� A bladder, or reservoir, usually made of food-grade plastic holds the water
� This is placed into a specially designed waist pack or low-profile day pack
� Users drink the water via a hose equipped with a non-leaking valve
Styles and uses
� Hydration packs were originally used by long-distance bicyclists and runners who required lots of
water, free hands, and who couldn't juggle lots of water bottles
� Now they are commonplace among skiers, snowboarders, hikers, inline skaters, climbers,
triathletes and adventure racers
� Daypack styles offer the largest bladder capacity as well as varying degrees of storage space
� Waist pack styles generally have smaller bladder and storage capacities
Features
� Reservoir capacity
Generally run from 1 to 3 liters
Your choice depends on intended use
� Insulation
Recommended to keep water cool in warm weather and to prevent freezing in cold weather
� Fill weight
Measure of what the bladder weighs when filled
Most indicated weights pertain to empty reservoirs
� Wide-mouth reservoirs
Accept ice cubes and make for easier cleaning
� Moisture-wicking fabric on shoulder straps and back panel for added comfort
� Sculpted shoulder harness for better fit
� Reflective trim
Return To Top
Materials
� The most popular--and durable--technical pack materials are found in the nylon family: Cordura
nylon, ballistics nylon, ripstop nylon, and nylon packcloth, which are all:
Very durable
Strong and abrasion resistant
Many feature water-repellent or waterproof coatings or treatments
What to look for
� Backstitching and bar tacking in high-stress areas, such as around zippers, pockets, and external
loops and webbing
� High-abrasion areas, such as pack bottoms, should be reinforced with a strong material such as
Kevlar, Hypalon, or heavy-weight Cordura
� Back panels made of reticulated or compression-molded foam covered with a breathable, wicking
fabric to disperse perspiration and enhance airflow

Capacity
The capacity of a backpack is measured in cubic inches. The size you need depends on what
you'll be doing and the amount and type of gear you want to carry.
� For a warm-weather weekend trip (two or three days), look for a pack in the 3,500 to 4,500 cubic
inch range
� For a week-long trip or more: 5,500 to 7,000 cubic inches
� Avoid using a pack that is too big. Most people tend to fill available space, which makes for a
heavier than necessary load to haul.
Fitting tips
Your height has little bearing on what size pack you should wear; it's your torso length that
matters.
� If the pack is too long, it will sag onto your rear end
� If it's too short, it won't support your lower back
Determining your proper pack size
� To determine your torso length, measure from the seventh vertebra (the bony protrusion at the
base of your neck between your shoulders) to the small of your back (level with your hipbones)
For torso length less than 18" (45 cm.), your suspension size will likely be Small
For torso length between 18" and 20" (45-50 cm.), your suspension size will likely be Medium
Torso length over 21" (52.5 cm.), your suspension size will likely be Large
Determining your hip belt size
� The hip belt should cup your hips and when cinched tightly, the pads should not touch
Women with straight or narrow hips may prefer a standard hip belt
Women (and men) with more curve to their hips should choose a women's-specific model
Shoulder straps should anchor to the backpack just below the seventh vertebra and the crest of
your shoulders. They should wrap comfortably, yet securely, around the shoulders and should be at
least 5" below the armpit.

�
�
Hiking & Backpacking Site
Megan Kopp
BellaOnline's Hiking & Backpacking Editor
How to Buy a Backpack
Disintegrating hipbelt, holes in the body, sadly worn straps – it was time for a new overnight
backpack. Walking into a local outdoor equipment store, I asked the staff member what I should
be looking for – after all it had been a few years since I last bought more than just a daypack and I
needed to know if anything important had changed. His answer was simple: comfort.
Well, he was partly right. But there are a few more questions you need to ask yourself when
buying a backpack because, as you’ll soon discover, there’s a whole lot more than just comfort
involved when it comes to choosing the right pack.
Are you going to use it for weekend trips or are you planning to through hike the Appalachian
Trail? The amount of weight you plan to carry points you in the direction of the size of bag and
suspension system best suited to your needs. Packs (in Canada) come in litre capacity – 56, 62,
77, 89 – know what you need to carry your gear.
Is height an issue? It is for me! I’m short and finding a pack to fit was a challenge. While the
shoulder strap height could be adjusted, I really had a time finding a pack that wouldn’t ride the
back of my head when the straps were at the shortest setting.
Internal or external frame? External frames used to be commonplace. They were relatively
inexpensive, capable of carrying heavy loads, worked well on well-cleared trails and offered good
airflow between the pack and the back. Internal frames have taken over in popularity, offering
less bulk, lower center of gravity and greater stability in rougher terrain.
Do you need multi pockets in order to stay organized? Additional zips and pockets are great, but
they add overall weight to the pack.
Material also adds weight – can you make do with ripstop nylon (light) all the way through or do
you really need a waterproof tarpaulin fabric bottom? How, when and where you backpack will
help make the decision a little easier.
Can you settle for pared down straps or do you want a beefed up suspension? Do you really need

a zip-off fanny or day pack, built-in hydration pockets and bladders, crampon pocket, shovel
pocket…? Be aware of what you really need versus accessories that you think are cool.
Are you concerned with appearance? Some people are (can’t say as I’m normally one of them,
but I’ve got to admit that one pack with fine red and white check was not in the running based on
looks alone – it made me nauseous just looking at the thing!).
Buying a pack is an investment that will stay with you for years, take your time, ask questions
and make it right.
A Few Words of Advice:
Put weight in the backpack (preferably in the store) and walk around. This will help you get a feel
for the fit and point out any obvious pressure points.
Try and buy a pack from a store that offer a one or two month return policy (that is, if you take it
home and find you’re sleeping bag doesn’t fit in the bottom with enough room for clothes, food,
sleeping pad, pots, pans, stove, etc… you can return it in the same condition without penalty).