- 1). Check for reliable gear. A zip line requires components in good condition with the appropriate weight-bearing ratings. That does not mean a person can use something lying around the house---unless the person happens to be an experienced climber. The first check, therefore, focuses on the integrity of each component. Manufacturers specify load ratings and use restrictions in product descriptions and sometimes on the products themselves. Stay away if the neighbor with the zip line says the rope came from Grandpa's attic or he bought the hardware and harness at a yard sale. When age and previous use represent unknowns, safety issues exist.
Gravity is the force that makes a zip line fun.Sean Murphy/Digital Vision/Getty Images
Check for fraying or "give." A zip-line setup with a rope, rather than a metal zip cable, should use a static line (rope designed with minimum "give") and show no signs of fraying. Fraying suggests overuse or misuse. A dynamic line, or rope that stretches, involves safety issues for two reasons. First, if an object is near the zip line, the weight of the rider could cause enough stretch that a collision with the object might occur. Second, if the low point of the line comes close to the ground, the rope could stretch so much that the rider might hit the ground.
- 3). Check to ensure that the hardware on the zip line is a pulley or trolley. Using a carabiner or other device that rubs the rope as it moves, rather than rolls along it, creates friction. Friction not only wears out the rope, but it also takes some of the fun out of the ride because it slows down the rider. Another danger is that the friction can cause the carabiner to get very hot.
A chest harness eliminates the danger of the rider going head down.Digital Vision/Photodisc/Getty Images
Check the harness for comfort, coverage and strength. A harness commonly used in rock climbing loops around the waist and legs and has a connection point to the hardware just below the waist. Although it may be used for riding a zip line, it requires the rider to use upper body strength to remain upright. In contrast, a harness that also loops around the chest and has a connection point at the chest keeps the rider upright. Harnesses generally allow for some adjustment, but they do come in sizes, so make sure the fit is comfortable. Tug on it everywhere to test the strength.
- 5). Check for RENE. Climbers rely on the acronym RENE as a reminder of how to rig anchors for ropes. As described on the Climb a Rock website (see Resources 2), RENE stands for Redundancy, Equilization, and No Extension. Redunancy means that the zip line must have at least two anchor points at each end. The zip line would connect to two lengths of webbing, for example, each of which attaches to an immovable object such as a tree. Equilization means that when the rider gets on the zip line, both anchors take equal loads. No Extension means that if one anchor fails, the load transfers to the other anchor with no shock or swing. So even if one anchor fails, the rider has a smooth ride.