Ultralight backpacks are generally lighter than mainstream backpacks with external or internal frames. They typically weigh less than 2 pounds. Although there are some exceptions, some UL backpacks are slightly heavier than 2 pounds.
Ultralight backpacks were traditionally frameless. However, many UL packs that you can purchase today have optional pack stays. These are aluminum rods or carbon fiber rods that slip into the back pockets of the pack to stiffen it and allow you to transport heavier loads (25 to 40 lbs). These also shift more weight from your shoulders onto the hip belt (see my post on Reframing Internal Frame Backpacks).
But UL packs are different from other backpacks because of their design and how they are packed. Let’s start with the anatomy of a backpack.
The basic design of most UL packs is the same:
- Large main compartment
- Roll top closure and not top pocket or floating lid
- Two side pockets
- Large open front pockets, made of either mesh or solid fabric to provide greater durability.
- There are many attachment points all around the pack’s perimeter.
A UL backpack is suitable for 3 seasons. You can store all your gear in the pockets outside of the pack, including water bottles, rain gear and snacks. The main compartment is sealed off and everything else goes into the main compartment. People who use UL backpacks store their shelter outside their packs. This allows them to set it up faster than they need to open their main compartment. If you have to set up shelter in the rain, this will help keep your clothing and sleeping bag dry.
You can easily move around the day by placing all your items on the outside of your pack. It’s addictive. I don’t like internal frame packs that have almost everything in the backpack. You need to stop more often to dig it out.
One of my favorite features about UL packs, is the ability to set up ad hoc rigging systems with the external attachment points. This is great if you have a fishing pole or tent that you want to attach to your pack. Crocs, a platypus, extra water, or a sleeping bag. This flexibility is also available if you have an external frame backpack. However, I don’t think it is as useful on internal frames packs. It really limits the utility and value of packs that can be used in different ways.