How Zip Lines Work

Zip lining takes some serious guts, and a willingness to ignore your better instincts about the science of racing down a thin wire at crazy speeds. Historic Banning Mills

On the movie screen, we see our hero (who looks like he couldn't balance his checkbook) as he suddenly realizes that the nearby crossbow equipped with line-shooting capability/ telephone wire/clothesline could propel him quickly from the top of the steep slope to the bottom of the canyon, where the bad guys/pretty girl/bad pretty girls are. He drapes his jacket across the wire, holds on tightly and down the wire he goes. The trip is so fast that the viewer only has a split second to wonder: Does that really work?

A zip line is, at its most simple, a cable that starts at a higher point than it ends. Using the natural decline of the slope, a person or cargo can travel down the wire on a pulley system that minimizes friction to help the rider accelerate. In the next section, we'll talk more about how a plain old wire can support the weight of -- and provide a ride for -- a gigantic person. Or, for that matter, how gigantic a person it can support.

And if you're able and willing, you can use a zip line pretty much anywhere -- provided you have some serious guts and a willingness to ignore your better instincts about the science of racing down a thin wire at speeds up to 100 miles (161 kilometers) per hour. But whatever part of the world you're in (or flying over, for that matter), learn the parlance: In Australia they're flying foxes, in South Africa they're foefie (sometimes written and pronounced "foofy") slides, while Costa Rica generally calls zip line adventures canopy tours.

Although a growing industry for zip lines exists among adventure travel tours and eco-tourism, you might be surprised to know the first modern group that used zip lines for utilitarian purposes in the past consists of people with a decidedly less reckless reputation than you'd imagine.

Behind the fun and games, there's some serious science. Let's race to the next page to find out more.