The FEI’s Eventing Frangible Device Working Group has introduced updated standard for frangible cross-country fences. The team spent six months reviewing slow-motion video of horses jumping fences, and took into consideration testing performed by British Eventing, MIM at Chalmers University (SWE), and the Transport Research Laboratory (TRL).

A frangible/deformable fence is a fence that is designed to break and/or deform to help prevent somersault falls that are induced by contact of the horse with the fence. Frangible/deformable fences operate either by removing the fulcrum point on the fence over which the horse rotates, and/or by limiting the impulse that the fence exerts on the horse

This is the second version of the standard and has two main changes from the previous version:

• Adding requirements for the amount of energy needed to activate the fences. These were based on a combination of energy and angular momentum, including inputs from jump speeds, height and flight duration.
• Using a 40 kg kettle bell pendulum instead of a 120 kg pendulum impactor.

Recent research indicated that an activation energy of 250 Joules (J) for front rails and 400 J for back rails is required to further reduce the risk of somersault falls when the horse strikes the fence. Currently, the activation energies of typical frangible fences are up to circa 490 J measured with a 120kg pendulum.

Many somersault falls occur when a horse forelimb strikes the fence. To more closely match a typical event horse forelimb in both energy and momentum when striking a fence, the lower mass kettlebell pendulum was proposed. This pendulum has the additional advantages that it is low cost and easy to build. This should help enable the development of prototype fences because fence manufacturers will be able to easily make a kettlebell pendulum at low cost and trial new ideas that they have.

Beginning January 1, 2021, all newly manufactured devices must comply with the Updated Standard V2. Devices manufactured according to the previous standard specifications can be used until December 31, 2021.

“It is important to note that realistic infield assessment to ensure fences don’t break too easily has been strongly debated and agreed with the Frangible Working Group understanding the importance of balancing safety with true cross-country.”