If your boss/wife has handed you a flying fox or zip line installation job and you’re trying to figure out what wire to order, this is the article for you. Getting the cable selection wrong isn’t just a compliance problem, it can get someone killed. Here’s what you need to know.
The Standards to which You MUST Build
Commercial flying fox (sometimes called a zip wire) installations in Australia are governed by AS 2316.2.1:2025, which came into effect in December 2025. If you’re starting a new install in 2026, you’re building to this standard, no exceptions. Operators with existing installs have until December 2027 to comply, but that’s not your problem if you’re doing a new build. If the flying fox is in a theme park, tourist venue, or any high-throughput amusement setting, AS 3533.4.2-2013 also comes into play. Your certifying engineer will tell you which applies, but you need to know both exist.
Why the Cable Has to Be Bigger Than You’d Think
Here’s the part that trips most people up. You might look at a 100 kg person and think “I just need a cable rated to hold 100 kg.” That’s not how it works. And Galvanised Wire Rope behaves differently when compared with Stainless Steel Wire Rope. The molybdenum content in Stainless Steel Wire Rope resists chloride pitting that will eat through galvanized coating fast in a salt air environment. Conversely, G316 stainless is softer than G2070 galvanized, it wears faster under trolley traffic, and it stretches slightly more, so tension will need more regular monitoring. And stainless products cost a LOT more than galvanised products.
Trigonometry and Angles
When a vertical load it applied to an approximately horizontal cable, the horizontal loading is a multiple of the vertical load divided by the angle (from horizontal) of the cable which is the triangulation effect. If that angle is zero (as in a perfectly horizontal wire), the horizontal loading is infinite (because you are dividing a load by zer0). The larger the angle, the lower the multiplier of force. Using a 2% mid-span vertical drop (sag), as an industry standard – the angle from horizontal is 2.29 degrees.
Static vs Dynamic Load
So when someone is suspended on a zip wire cable, the cable doesn’t just carry the person’s weight vertically, the tension gets multiplied horizontally at the anchor points. Under standard installation conditions the horizontal tension at the anchors is approximately 12.5 times the vertical load – in static conditions.
Putting a 100 kg person on a Zip line can generate a peak dynamic load of 6 kN (611 kgf) (the maximum allowable under the standard), and the horizontal tension on that cable and its terminations can hit 75 kN (7647 kgf). That’s why the correct/safe diameter cable must be used on a commercial zip line.
Including a Safety Factor
On top of that, AS 2316.2.1 mandates a minimum safety factor of 3, meaning the cable’s Minimum Breaking Strength (MBS) must be at least 3 times the combined pre-tension plus maximum dynamic load. Conservative engineers will push that to 5 or 6, and for good reason: fatigue and degradation eat into that margin over time.
Which Cable Do You Actually Order?
Here’s the short version by span and use case. Each recommended diameter should be treated as a minimum guideline. Larger, stronger, and higher-grade wire can be also in each example as well.
- Short Span (<= 25m) domestic or private use: 10mm 7×19 Galvanised Wire Rope. G1570, G1770, and G1960 are adequate, however Marine Grade G2070 is recommended for durability. All meet the residential play equipment standard of 68.7 kN MBS.
- Long Span (> 25m) domestic or private use: 12mm 6×26 or 6×25 FI+IWRC Galvanised Wire Rope. G1570, G1770, and G1960 are adequate, however Marine Grade G2070 is recommended for durability. All meet the residential play equipment standard of 68.7 kN MBS.
- Short Span (<= 25m) Standard commercial challenge course or flying fox: 11mm Galvanized 7×19 or 6×24 FC Galvanised Wire Rope. G1570, G1770, and G1960 are adequate, however Marine Grade G2070 is recommended for durability. This is the baseline for AS 2316.2.1 commercial compliance. Both options offer high flexibility, good fatigue life.
- Long Span (> 25m) or high-throughput commercial install: 6×26 or 6×25 FI+IWRC Galvanised Wire Rope or 12mm Compacted (Swaged) 1×19 Stainless Steel Wire Rope. Stainless Steel wire is the premium specification choice. The compacting process flattens the outer strand profile, which means the trolley rides on a smooth surface rather than individual wire crowns. The result is less wear on the trolley and the cable, significantly less noise (up to 70% quieter), longer service life, and around 25% higher MBS than a standard rope of the same diameter. It’s the right call for anything built to last.
Maintain and Inspect
Once the cable is installed, it needs regular inspection. The discard threshold under AS 2316.2.1 is more than 10% of total wires broken within a length of 8 times the cable diameter. For an 11mm 7×19 rope, that’s any section of 88mm with 14 or more broken wires. If you find it, the cable must come down and be replaced.
Additional Considerations:
Coastal or marine environment:
There is a very Simple Rule:
- Inland, away from the coast: galvanized G2070. It’s stronger surface-wise, more wear resistant, and significantly cheaper.
- Coastal, marine, or industrial chemical environments: 316 stainless, full stop.
Don’t Skimp on Terminations
The cable itself is only part of the equation. The terminations are considered the Critical Component and are primarily where commercial zip lines fail.
Wire Rope Grips are (at best) temporary: Wire rope grips (bulldog clips) are not acceptable for permanent commercial installations. As the cable cycles under dynamic load, it undergoes constructional stretch — the diameter shrinks slightly, the grip loses clamping pressure, and the cable can pull through. WorkSafe Queensland has issued explicit warnings on this guideline following documented incidents. If a certifying engineer signs off on galvanised wire rope grips as a temporary or interim measure, they must be double-throat (fist) grips, torqued to AS 2076-1996 spec with a torque wrench, marked with paint across the nut and saddle for slip detection, proof tested at twice rated capacity before first use, and re-inspected at no more than 12-month intervals.
Swage Sleeves are permanent: For any permanent install, you need hydraulically pressed ferrule terminations (originated by Talurit and also known as “mechanical splices”) completed in a controlled workshop environment, or qualified resin/metal socketing. Every termination also needs a heavy-duty steel thimble to protect the rope, stabilize the radius at the bend point, and spread the load of the fixing point.
Review Installation Details
- Slope: the maximum allowable riding slope is 3% if you’re only using a stop block. With a certified bungee or dynamic brake system, you can go to 6%. Beyond 6% is prohibited.
- Turnbuckles: never install with the turnbuckle more than 80% open or 80% closed. Always use lock nuts. Leave a 20% adjustment margin each way so you can compensate for thermal expansion in summer and contraction in winter. Steel cable moves more than you’d expect across the Australian temperature range.
- Tree anchors: if you’re rigging to live trees, you must use synthetic round slings, not wire rope slings. Wire rope will girdle and kill the tree over time, and a dead anchor tree is a structural failure waiting to happen. The sling should be around 15% longer than the tree’s circumference. Trees used as structural anchors also need annual arborist sign-off under AS 3533.4.2.
Conclusion
The right cable for the job isn’t the cheapest one that’ll hold the load on paper. It’s the one sized to the actual tension forces, specified to the environment, terminated correctly, and compliant with the current standard. Get the details right before you order and get a certifying engineer to sign off on the design before anything goes in the ground.