Zip Line Cable Tension
The tension of a zip line refers to how tight the cable is. Cable tension is extremely important in zip line installation because it directly affects the performance of your zip line. It controls the speed, the riders altitude, and the amount of strain the weight of the rider put on the anchors while fully loaded. Knowing how much tension to put on your cable can be difficult, especially with so many zip line kits for sale online. The good news is, cable tension will vary from backyard to backyard and it is easily changeable.
Speed:
When a zip line has a higher cable tension it will start fairly slowly but increase in acceleration as the rider descends the slope in the ride. This will allow the rider to maintain a consistent, safe speed until the end of the ride.
It is similar to a ball being rolled down a hill with a gradual decline, it will start off slowly but pick up speed as the inertia from the weight of the ball pushes it downward.
A zip line with lower cable tension will start faster, but will quickly run out of speed towards the end.
Think of a ball dropped into a large bowl; starting out quickly as it drops into the low point, but slowing down as it has to travel uphill over the second half.
*If your zip line rider is too slow, you must tighten your turnbuckle and add more strain to the line.
* If your zip line is riding too fast and you have some room to adjust, try giving it some slack.
Altitude:
The tension of your zip line cable will directly affect the height in which the rider will travel above the ground. If you tighten the cable it will rise your cable higher, if you give it slack it will bring the cable lower. You must also account for the riders weight when making these adjustments. You must also keep in mind that height adjustments on your anchor point can also raise or lower the rider’s path.
Anchor Strain:
When a rider is applying their weight onto the cable it can be multiplied depending on how high your cable tension is. Be sure that your anchors are sturdy enough to withstand multiple weight loads, and always double check your installation manuals to double check that you do not provide too much tension on your cable line, this could jeopardize the safety of the cable and also the equipment. You can check out our guide to make sure your anchor is safe.
*A quick tip is to try to allow your cable, while the rider is present bearing weight, to land below the end anchor by about 2% of the zip line's total length. For example: The trolley on a 100 foot zip line, on it's very lowest point, should be approximately 2 feet lower that where the end point of your zip line anchor is. Assuming you are on flat land, if your starting zip line is 7 feet high, then have then ending point 2 feet below at 5 feet high. This sounds fairly complex, but you can eyeball it fairly easily.
Achieving Tension:
For zip lines that are less than 150 feet, you will be able to achieve proper cable tension by hand. Be sure to wear gloves and pull as hard as you can after wrapping the cable around the ending anchor. Have a friend secure the cable by putting on cable clamps.
For zip lines that are 150 feet or more, achieving the proper cable tension by hand can be a very challenging experience. We recommend using a come-along or some other type of mechanical winch that can crank your zip line tight. You can attach a winch or other ratchet device to a small loop at the end of your cable and pull it around your anchor until you've reached the desired tension. A cable grab can also be used to pull the cable up the tree for anchoring. You can make adjustments using a turnbuckle which is included in almost all zip line kits. If not they can be purchased here.
You can also email us and ask an expert at chris@ziplinestop.com!