Falling on static ropes is dangerous they say. It sounds painful, but how painful? We tested semi-static nylon rope, a very static polyester rope and a high-tech super static abrasion-resistant rope on the drop tower.
Disclaimer: Don't lead with a static rope. It is dangerous and could stop you so fast it breaks you, the rope, or just straight up kills you. I guess if the rope broke you die either way.
So why would we test this?
I've had my dynamic rope get stuck where two ropes were required to rappel and my other rope was static.
To exit a canyon up a vertical/steep side
Some alpine climbing situations where only a skinny static rope is available
The wrong rope was mailed and you didn't realize it was static! We have an EPISODE about that happening with a dirty return at Dicks Sporting Goods.
What's Normal?
Climbing at the gym or on a 1 pitch sport route can generate around 2kN on the climber and 4kN at the anchor. See our GYM FALLS EPISODES about that. The highest force we got so far is with a 290lb guy falling with the belay device bolted to the wall and he got 4.44kN and the anchor saw 7.16kN. This is all with a dynamic rope that absorbs the force and these forces are super good enough for you and your gear.
Fall Factors?
Not all falls are created equal. How far you fall is irrelevant, as long as you don't hit the ground. Falling 3 feet can be super dangerous if you only have 2 feet of rope between you and what's catching you. That is a fall factor FF1.5 (3/2). A 10 foot fall in a gym with 30 feet of rope going up to the quickdraw and back down to your belayer is a FF0.33 and that is why it is soft.
Where can you get a FF1 or FF2? Starting pitch 2 where you can fall past your belayer OR having a personal anchor that you get too high on and drop hard onto it. The only thing you have to worry about when you start on the ground is the ground. Your FF is super safe enough.
We get some gnar forces with just a FF0.3 testing these static ropes but remember if you got a FF1 it gets more than gnar. If you fell just 3 feet but only had 3 feet in the system it's just as bad as having fallen 20 feet with 20 feet of rope in the system. It doesn't matter. It's all the same FF1 and when we did test a FF1 we literally broke the rope.
Our Test
We dropped a 200 lb weight from 4 feet above the last "protection" to simulate a lead fall with the climber's last piece just below their feet. The GriGri belay device was bolted to the post at the bottom to have some consistency though it was a non-dynamic belay making the force higher than if a person belayed it. We estimate that 25 feet of rope was out and the weight fell 8ft. That makes the estimated fall factor ~0.32x.
The Ropes we tested were:
Nylon Dynamic 9.8mm
Nylon Beal Spelenium 10.0mm Semi-Static with half of the dynamic rope's stretch
Polyester Imlay Canyonero 9.2mm Static AF with 1/4 of the dynamic rope's stretch
Technora Sterling Canyon C-IV 9.0 static rope with 1/3 the dynamic rope's stretch
Results
How can you mitigate risk if forced to use a static rope as a lead rope?
Place gear immediately and often after leaving the belay
Give a dynamic belay (use a belay device that can slip and jump when catching the climber)
Assume you'll die and you are just getting the rope fixed for the follower
See What Hz
For years, some viewers have complained that our dynamometer doesn't refresh fast enough to capture peak force. The Line Scale 2 in fast mode was only reading at 40hz or 40x per second. When we built the drop tower, we got an S-beam Load cell that can read at 10,000 Hz! These falls gave us insight into how fast the refresh rate needs to be in order to capture the peak force. We counted the number of refreshes that captured our peak force and divided that number by 10,000. If we only got 4 cells on our spreadsheet that showed the peak force, we would need 10,000 / 4 =.2,500Hz to capture accurate data. If our peak force was consistent over 180 cells, then 10k/180 means 56hz would have given us accurate data
How many hertz do you need to capture a 0.3 fall factor fall on a dynamic rope? 23! This validates the gym fall experiments we did in the past! However, for the semi-static ropes in a 0.3 fall factor fall we needed 36-85hz and when we did the fall factor one with our most static rope, we needed 550 hz. Luckily, being aware how a faster load cell could help, we steered the design of the LineScale3 to read at 1280Hz making it the fastest all in one load cell on the market. You can get our exclusive discount code on our GEAR page if you want to do your own experiments.
What's Next
If climbing gear blows, does it at least help slow you down???
