How viable is the use of 60 cm Dyneema slings in a Magic X anchor system?

Domenic Marrone


In recent times, one of the most contentious issues within the climbing community is the building and form of belay anchors. Self-equilibrating anchors have seen a rise in popularity with the Magic X being one of the most common. Despite the popularity, the Magic X breaks the “no extension” rule of anchor construction. This means if one of the anchor points fails the system will be shock loaded with the weight of the climber. Therefore, this paper presents a simple mathematical model to show if this anchor system should be considered as an option. The results show that for a 30 cm fall, a force of 11.4 kN is exerted on the sling and anchor point. Whilst this will not break the sling, there is high chance of causing the failure of the last remaining anchor point. Consequently, this system should be only considered for high strength anchor points such as bolted sport climbing routes.


Sports; Physics; Mechanics; Material properties; Rock climbing

Full Text:



Kirkpatrick, A. & Coley, D. (2013). High - Advanced Multi Pitch Climbing. Akreative.

DMM (2010). DMM Climbing - Knowledge. Available at: [Accessed 21st February 2019].

Schlessingerman, A. (2003) Mass of an Adult. The Physics Factbook (and references therein). Available at: [Accessed 21st February 2019].

DMM (2019). DMM Climbing - Dynatec 11mm. Available at: [Accessed 20th February 2019].

DMM (2019). DMM Climbing - Wallnuts. Available at: [Accessed 20th February 2019].


  • There are currently no refbacks.
We use both functional and performance cookies to improve visitor experience. Continue browsing if you are happy to accept cookies. Please see our Privacy Policy for more information.