[ INTERNAL FRAME BACKPACK ]
Internal frame packs are constructed with a resin or aluminum frame sewn into pockets in the harness of the bag. Often the frame consists of two “stays” running vertically along the backplate. Aluminum stays are meant to be moulded to the shape of your back. The bag is designed to carry all your gear internally with only pockets and accessories attached to the outside. Some smaller packs may offer the option of attaching a sleeping bag stuff sack to the top or bottom. Like the external frame packs, it is important to correctly size your internal frame pack. Some models offer a range of pack sizes and some offer adjustable or replaceable stays.
The opening to the bag is an important feature. A small opening aids in weatherproofing but makes packing and unpacking more difficult. A wide opening is handy but the longer zippers or extra fasteners are often more prone to trouble. Be sure that the zipper or fastener for the opening(s) is not at a place that will receive a lot of stress when the bag is packed and carried. If the zipper breaks you might not be able to close the bag! Most larger bags will offer two or more compartments inside the pack. This will assist you in placing heavier items in the proper place, and keeping all your kit organized.
The benefits of an internal frame pack are:
a. comfortable harness that can be adjusted and moulded to you;
b. a bag that holds its load close to your back and close to your centre of gravity;
c. easy to pack bag; and
d. the lack of projections and protrusions from pack make trekking in forests and through tight spaces easier.
The disadvantages of this design are:
a. hard to move equipment from one person to another;
b. hard to carry large or awkward objects;
c. with the backplate pressed against your back, care must be taken while packing to pad sharp or hard objects; and
d. ventilation is restricted across your back.
These characteristics make internal frame packs a good choice for treks with light to medium weight packs through forest or hilly terrain. Internal frame packs are excellent for climbing and mountaineering where range of motion and a lower centre of gravity are important.
