Circularity and Life Cycle Assessment of climbing holds made from recycled polyamide climbing ropes

With growing demand for sustainable, circular practices, the sports industry is under pressure to adopt circular economy principles and reduce its environmental impact. However, little is known about how circular design strategies affect environmental and circularity performance in sports equipment. Climbing holds are commonly manufactured from non-recyclable thermoset resins, generating significant environmental burdens and limited circularity. This study addresses the environmental impact and circularity of redesigned climbing holds through Design from Recycling, Design for Recycling, and Design for Durability.

Replacing thermosets with mechanically recycled polyamide 6 (PA6) reduced environmental impacts by 90% across key categories, including climate change, marine ecotoxicity, fossil resource depletion, and human toxicity. Short-loop recycling from climbing ropes showed lower environmental impact compared with long-loop recycling from automotive waste. Circularity scores align with environmental performance, with virgin thermosets below 0.1 and recycled PA6 scenarios above 0.9. Lifetime extension for recycled PA6 holds further reduced inflow energy demand, although these benefits were only partially captured by Material Circularity Indicator (MCI) values. Including mould use increases the impact of thermosets, as silicone casting moulds have a short lifetime. For rPA6, durable aluminium injection moulds reduced the impact per hold.

These results demonstrate that short-loop recycling of climbing ropes into climbing holds is a viable and scalable circular strategy. Next, combining Design from Recycling, Design for Recycling, and Design for Durability significantly reduces environmental burden. Additionally, combining Life Cycle Assessment (LCA) with circularity indicators provides a complementary perspective. LCA captures the scale of environmental benefits, whereas circularity metrics highlight structural improvements. These results show that circular strategies can support a more sustainable product design in the sports equipment sector.