Nate,

Can you share your design process with us? I'm always curious how people calculate what materials to use when they build ziplines.

Are you using rope or cable for the line? How are you attaching the anchors to the trees? How do you determine the angle of the line? How do you determine the line tension?

Tom,

I'd be happy to. I use steel stranded aircraft cable (galvinized, 7X19 construction), anywhere from 3/16" to 3/8" in diameter. A majority of what I sell are short 100'-150' lines, called Mammoth Zip Lines, with a handle bar and a harness for safety. These are much like the 'Fun Ride' kits you would see at a Toys-R-Us, with the addition of a harness. The rider never goes more than 5-10 feet off the ground, and coasts down the cable until they come to the ground. The kits come with a lead rope as well, so an adult can guide smaller kids down, as they just sit in the harness. The kits can be used many different ways, some customers use them to get down from treehouses, some string them over swimming holes; they're really versatile.

The kit I'm working on now (called the Mammoth Deluxe) is designed for longer distances, and for rigging higher off the ground. The rider can reach the launching platform by ascending a fixed rope, a climbing wall, rope ladder, stairs, whatever, zip across, and then rappel from the end or clip onto the next zipline. The cable is anchored to the trees by wrapping a heavy duty nylon sling aroung the tree, and clipping the thimbled cable to the eyes. In addition, a safety cable is wrapped around and clipped to the line, in case the nylon strap fails. Tension is kept off the safety cable to protect the tree.

As far as slope- I usually recommend a 5%-10% drop from start to finish. It's really quite flexible. As long as the rider has the ability to control their speed with a braking device, the only issue is to make sure it's steep enough to reach the end.

Line tension is also flexible. A very tight line will start out slower, and continue to pick up speed til the end. A loose line will start out very fast, the rider
dropping quickly, but will slow down at the end as they pass the low point of the cable and start going uphill. I use turnbuckles or heavy duty ratchet tie-down straps for tightening the cable.

Braking devices- right now, the best thing I can find has been regular work gloves, with an extra padding of leather stitched into the palm. The rider simply applies friction to the cable behind the trolley to slow down. I'm also working with a machine shop in the Portland area to come up with a braking device that can be inserted into the Petzl Tandem trolleys.
I sell the Petzl Tandem Speed, Tandem Cable, and Trac pulleys for the longer kits, and make my own trolleys for the short 3/16" cable kits.

After many a Saturday afternoon, the zip line is finally up and running. Here are some photos, as promised.

Ascending to the launching platform (you call this SRT, correct?)



View of top platform.



Going for the ride.



Bottom Platform.

Quote Oldtimer “Everyone has the right to make its own mistakes to learn a new business...”

We are talking about bringing people doing high risk activity on Zipline.do you think everybody has the right to bringing people playing Zipline and make its own mistake experiment?

Keep balance
Elliot

Hello Elliot, you missed the sarcastic undertone part of my posting and Tom Dunlap's post. ( Kind of read between the lines). In this country every one has the right to do anything they want as long as nobody gets hurt or injured. If someone gets hurt (badly) them you will provably get a law suit by some lawyer that will take everything including your house and small kids to make you pay for the damages. Even if it was not your fault or the user did not follow the proper safety rules or operational instructions. You better have LOTS of Liability Insurance but in any case you can held liable for killing someone and that is a criminal act in most states in the USA. So take it easy and be careful with those zip lines.

connecting biners in a chain is not a good plan. You should have a soft _link_ between the biners. Look at rock climbing quick draws,

Also, consider using double auto locking biners like the Petzl ball locks instead of screw gate biners.

Using hands as a braking device near the pulleys is asking for trouble. What do you plan on doing when glove gets sucked into the pulley? Scary and dangerous!