Thick or Thin Rope?

What’s the smallest diameter rope I can use for sport climbing?


“What’s the smallest diameter rope I can use for sport climbing?”


Most rope manufacturers offer a 9mm single rope and even a model that dips down to 8.9 or 8.7mm. These smaller ropes are lighter and slither through carabiners with little friction, suiting them for times when you need to minimize weight and rope drag. Naturally, there are trade-offs. Thin ropes aren’t as durable, can cut more easily and are more difficult to grip and belay with. A skinny rope also might not be compatible with your rap/belay device.

I like to use a 10mm(ish) cord for projecting and wall climbing. When it is time to send or onsight, I switch to a thinner rope. Realistically, a thinner rope mostly gives you a psychological edge, with the weight savings really noticed when the rope is in your pack.


This Gear Guy question appeared in Rock and Ice issue 248 (February 2018).

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