The elastic shock cord inside your poles helps make setup quick and painless. Maybe you’ve never thought about it, but the shock cord is more or less a giant rubber band, except that instead of being in a loop, the shock cord is linear and runs the length of the poles.
The length of shock cord is less than the total length of poles, so that the elasticity causes the poles to “snap” together when unfurled. While this isn’t necessarily a new thing in the industry, it’s an important part of set up so you can set up quickly, don’t lose poles, or mix up their order (this matters more for variable diameter pole sets, obviously). There are two secrets to getting the shock cord right in NEMO products: material type and length.
From a materials standpoint, the rubber in the shock cord needs to retain its elasticity over the lifetime of the tent, as well as for the environment of use. For cold weather tents, we generally switch over to a different shock cord whose rubber can still be compliant at extreme temperatures. From a length standpoint, we use an algorithm to determine the length of shock cord for each pole set so that the aluminum ferrules self-assemble with appropriate force. If the length of shock cord is too short, there is a constant force stretching out the shock cord which will wear out the material prematurely. If the shock cord is too long, then the pole segments might not fully assemble, compromising the structure’s strength.
If you’re eating up all this information and yearning for more, check out this video from physics grandmaster, Richard Feynman, about a completely different way to think about rubber/elastic bands.