/ External Frames
Hip Belt (Women)
Internal or External Frames -
the Debate Rages On
Americans might be interested to know that in Scandinavia, the
external frame pack is more commonly used in the backcountry.
Here in Canada., the internal frame pack, as well as a series
of variations on that theme are the rage. In the United Kingdom
(U.K.), "ramblers" carry internal frame packs almost
exclusively. As usual, there are advantages and disadvantages
to both designs. It's up to you to decide what's important based
on your intended use, the perceived comfort of each design,
and how you prefer to carry your gear.
What is an External Frame Pack?
An external frame (EF) pack is a design where the frame is fully
exposed on the outside of the pack, and the pack itself is attached
to the sides of the frame using straps, aluminum pins, or other
methods. The frame material of choice is aluminum, mainly due
to its light weight, though there are variations. The Coleman
Peak 1pack frames constructed entirely of plastic, which provide
a significant amount of flexibility while walking. The pack,
straps, and hip belts are attached to the frame using buckles
slid through holes on the frame providing a maximum amount of
adjustability. Meanwhile, the basic Camp Trails frames are straight
welded aluminum affairs with aluminum cross-members. Some of
these designs utilize plastic separators between the cross members
that allow the shoulder straps to be adjusted up or down to
compensate for various torso lengths.
A basic external frame pack - the Camp Trails "McKinley".
A rigid aluminum frame with a hip belt attached directly to
the frame provides a basic "carrying" configuration,
but little flexibility. If you're an occasional backpacker,
this may be all you need.
Frames are generally slightly curved in a gentle S-shape down
the sides, with cross members attaching the two sides together.
Some frame designs also utilize a "lip" or shelf on
the bottom, which enables the pack to stand on it's own when
put on the ground and provide greater protection against unknowingly
losing a sleeping bag if it's not lashed securely to the frame.
The frame generally separates the pack from the back by an inch
or so. Since there is ample room for air to circulate between
the back and pack, EF packs are generally considered to be "cooler"
to carry in warm weather, with the minor downside being that
their greater distance from the back can also make them marginally
harder to balance on your back.
Some frames may also include a cross member that extends beyond
the top of the pack. This "extension" can be used
to lash extra equipment on top of the pack, or make it easier
to remove the pack from your back by providing another grab
point to lift the pack off your back. The downside of the frame
extension is that it can get caught on trees and branches when
traveling off-trail. Even on-trail, some trail maintainers frequently
forget to clear enough headroom for trail hikers, which can
increase your chances of hitting branches. And during rainy
or snowy conditions, branches can be weighted down. A frame
extension can give you a cold or frosty shower if branches are
hanging low overhead. Once again, it's a trade-off. Do you want
more options to attach gear on the outside and make it easier
to remove the pack, or travel "more compactly"?
What is an Internal Frame Pack?
An internal frame (IF) pack is a design where the frame is contained
inside the pack. Frequently, the "frame" is nothing
more than two aluminum, plastic, fiberglass, or composite "stays"
that run vertically from the top to the bottom of the pack.
In more advanced packs a ridget frame sheet is incorporated
.They provide the primary means of support for the shoulder
straps and hip belt, and some basic structure to hang the pack
So what is the IF pack style? An IF pack always includes a large
integral compartment on the bottom for your sleeping bag. This
provides greater protection from the weather (since the bag
is actually inside the pack) and eliminates the chance the sleeping
bag will be lost in the backcountry, or gouged/damaged while
traveling through brush. In wetter locations, such as canoe
trips., this is a major consideration and benefit.
There are generally fewer pockets on the outside of an IF pack,
but many more lash points to attach equipment. This is likely
to compensate for the loss of lash points that might have been
provided by an external frame. Often, extra pockets can be purchased
separately, and are often fully detachable. Many IF packs also
utilize "compression straps" designed to compress
the pack if it is not fully loaded. Whereas the EF pack provides
a rigid frame on which to hang the pack, IF pack structure is
often provided by the gear inside the pack. If the pack is not
fully loaded, the compression straps eliminate the extra space
by compressing the entire load into a smaller, tighter package.
Since the sleeping bag compartment is integral with the pack
itself, IF packs are larger in appearance and heavier. Since
the pack is carried right against the back, it is generally
hotter to carry in the summer, but easier to balance. Regular
users of IF packs may actually find these packs to be "over
padded", and some designs allow the user to remove lumbar
padding and other padding on the back. Others may find the padding
an added benefit and comfort.
IF packs also carry lower on the back, which increases balance
further and minimizes your chances of catching the top of the
pack on branches. Manufacturers have incorporated a variety
of design enhancements such as quick-wicking fabrics and "ribbed"
padding designs to help in making the pack cooler to carry.
And since the entire pack is carried against the back, there
is a greater surface area involved in transferring weight between
the pack and body. On EF packs, the weight is typically carried
at only three to five points on the pack frame. With IF packs,
you get a better sense that the pack is "draped" over
your body - almost as if you're carrying someone on your back.
External Frame meets Flexible Body
Clearly, the greatest challenge to backpacking comfort is faced
by manufacturers selling EF designs. A rigid aluminum frame
locks together the opposing movements of the hips and the shoulders
and minimizes the twisting action of the torso. In some cases,
manufacturers have used a variety of techniques to address this
incompatibility of motions, and in some cases they haven't.
Camp Trails has stuck with a straightforward design in their
basic pack models. The shoulder straps are permanently attached
to the horizontal cross-members near the top of the frame, and
the hip belt is permanently attached to the bottom of the frame
with nylon webbing and grommets. The back is separated from
the frame using padded panels that can be adjusted for tautness.
The frame is rigidly welded and provides no "flex".
This is what I call the "basic" frame pack design,
which has remained unchanged for close to thirty years. The
design is perfectly adequate for carrying equipment into the
back country. However, a perfectly rigid frame with permanent,
non-flexible attachment points "fights" against the
natural motion of the body. This design has a tendency to tire
the user quicker and increases the potential for sore muscles
in the shoulders and hips. If you're looking for a greater degree
of comfort, you might consider some of the EF design variations.
The more refined Camp Trails models and Coleman Peak 1 packs
are constructed entirely of plastic. This provides a maximum
amount of flexibility in the twist motion. Depending on the
attachment method for the hip belt, the amount of up and down
motion (compression) possible at the hips may be limited. We've
not attempted to cover all the countless design variations associated
with EF packs, just provide you with a sampling.you've probably
determined by now, FLEXIBILITY is the key to EF pack comfort.
The more a pack moves with your natural body motion, the more
comfortable it's going to be on the trail.
Internal Frame meets Flexible Body
Body motion considerations are much simpler with IF packs. Since
the vertical stays are typically the only rigid part of the
pack, a great deal of freedom of movement is afforded by this
design. This is why you rarely (read, almost never) see someone
cross-country skiing or mountaineering with an external frame
pack. In most cases, the only resistance offered by an internal
frame pack is by the equipment loaded inside. Often, equipment
is loose enough to provide the necessary freedom of movement
at all critical points on the body - at the hips, torso, and