External frame backpacks are used primarily for backpacking trips that will require all of the essential equipment to survive be brought with you. There are many great reasons to have an external frame backpack for a trip. This type of backpack consists of a visible metal frame that supports a nylon pack. The pack attaches to the wearer via two thickly padded should straps and a padded hip strap that goes around the waist.this blog post
The frame distributes the weight over the shoulders and the hips to alleviate the spine from too much pressure. The external frame does carry a high center of gravity that makes it a little harder to keep balanced during activities. This does limit a backpacker to activities that require minimal balance control like walking. Biking and skiing are not recommended while wearing an external frame backpack.
The advantages of external backpacks are mainly due to their versatility. They do also offer better ventilation for the dorsal area than most backpacks because the pack is somewhat suspended within the frame taking pressure off of the back. The frame can be used to tie or strap on extra equipment like tents or cooking utensils. This makes them a necessity for solo hikers and small groups that might require one person to carry the extra equipment.
External frame backpacks have become less popular in backpacking as gear has become more compact. Many tents and large gear fold down to manageable sizes that do not require the external frame to attach to. People’s activity demands are also a factor that has created lower demand for external frames. Adding jogging and biking to a backpacking trip makes a smaller internal frame the better choice because of its lower center of gravity. Travel constraints also make it hard to lug the larger packs of trains and planes, especially for those traveling to Europe. The traditional backpacker will always have the external frame, but technology is slowly phasing out the need for one.