Internal backpack frames are hidden and covered with the fabric and outer layers of the backpack. Some internal frame backpacks may have the frame between the inner and outer layer. Internal frames are usually made of small V-shaped pieces of aluminum connected together. External frames surround the pack portion of the backpack, are visible from the outside, and may be more rigid and larger.
According Nomadik.com, a hiking and camping based site, until the 1970s, the external frame backpack was standard. But this changed with the introduction of internal frame backpacks.
A key benefit of the external frame backpack is that packbags or backpacks can be attached to the frame. Additional smaller bags and pouches also can be attached to an external frame, enabling the user to expand the amount of storage space on the frame.
The internal frame backpack has several advantages over the external frame. Internal frame designs tend to be smaller and weigh less. The center of gravity is closer to the wearer's natural center of gravity, which allows for better balance and movement. The internal frame also is more flexible than the rigid external frame design.
Consider whether heat can become trapped more easily between your back and the internal frame's backpack material. This may cause discomfort during extended use. An external frame leaves space between the wearer's back and the fabric.
Some users find that an external frame backpack holds more items and is easier to load and unload due to additional compartment space. Internal backpacks are designed to be compact and may have fewer compartments and access zippers than external frame backpacks.
While internal frame backpacks help the wearer maintain better balance and center of gravity, external frames allow heavier loads to be spread out over a larger frame area. This distribution of weight can help the wearer manage heavy loads and more gear.
While internal frame backpacks may be more widely used, their designs are more complex than rectangular shaped external frames. Therefore prices generally are lower for external frame backpacks.
External frame backpacks can present difficulties when hiking on less-traveled trails and over extremely rugged terrain. An external frame sits further away from the wearer's body, which can cause you to lean too far back. Because the frame is wider, it can get caught or rub against rocks and trees in tight trail areas.
According to Nomadik.com, the internal frame backpack is more widely used and favored by hikers than the older external frame model. While both continue to be available, there is the potential for external frame backpacks to become phased out of production.
