Friday, March 22, 2013

How a Climbing Rope is Made

A new rope is such a beautiful sight!

I recently got a brand new Sterling Evolution 9.8mm rope for my birthday.  As I got home and took the rope out of the bag, cradled it, smelled it (is this normal?), and imagined all the great adventures I would go on with it, I started to wonder how it was made and how much weight it could hold.  I mean, I want to know how this lightweight and narrow rope is keeping me from being a pile of abstract art at the bottom of the crag.

Looks nice, but how is it made?

So, I went on an internet hunt for a video of the process and came across an awesome video by Sterling Rope athlete Joe Kinder and his factory tour of Sterling.  This video shows just how complicated it is to make something so strong.  The process of making a rope has been perfected with the help of machines that perform high speed intricate tasks and spit out a beautifully crafted rope.  The ropes also undergo some fierce testing of its tensile strength, as seen in the video (looks like my dream job!).  Check it out:

I came across the impact force measurement of the rope as well and saw that it had a value of 8.8 kN.  8.8 kN?  This number doesn't help out much unless explained.  I had to dig back to my college physics days on this matter.  kN stands for kilonewton (or 1000 Newton), which is the measurement of the force of an object (in this case a falling object).

The impact force measurement of a rope is the force that is transferred to the end of the rope.  For a climbing rope this force would be the climber.  The UIAA has a specific set of standards for a climbing rope. According to UIAA standards a dynamic rope is tested with a fall factor of 1.77 (maximum fall factor is 2 Fall factors explained here).  For a full rope a weight of 80 kg (attached to the end of the rope) is dropped 2.3 meters above a "clipping" point and the force generated is measured.  For a single rope, the peak force during the first drop must be less than or equal to 12 kN (using an 80 kg weight) and less than or equal to 8 kN for a half rope (using a 55kg weight).  Basically, you would want to have a rope that had a low kN number since this will be the force that is put onto your body during a fall and you would want the rope to absorb most of that force.  You definitely want this force to be as small as possible.  For more details on these tests check out the sites below:

Impact Forces

Rope Ratings and Definitions

So, the next time you head out to the crag with your rope, just think about all the science and technology that is put into the nylon threading that keeps you from going splat.