Chris Tan Death Products™ proudly present...

The Chris Tan Death Quickdraw Mark 2 - Rubber Bands

The original mission was to construct a shock-absorber ( screamer) out of components found on an average rack. Furthermore, the rig had to be "reusable". This has an advantage over mission-specific, shop bought shock-absorbers, which are "use once". Although some manufacturers offer a "return for a re-stitch" service, this is not really viable mid-route or if you are based in the middle of nowhere.

Following on from a suggestion on ukclimbing.com from Sandy Wilson, I spent £1.49 for a packet of rubber bands from Partners, to build myself a stretchy quickdraw.

Test Updates


Fig 1
Fig. 1

Components

You will need:

  1. A packet of 100mm x 6mm rubber bands. I bought mine from Partners for £1.49.
  2. Two karabiners.
  3. A roll of electrical tape ( Not pictured).
  4. One 60cm sling as the back up.

Note: Click on the pictures for an enlargement ( 1-2mb)


Fig 2
Fig. 2

Construction

1. Make the quickdraw using about 30 rubber bands. As the rubber band "dog-bone" ( the tape bit of a quickdraw) will be quite thick, ensure that the karabiner gates are facing opposite each other. This will load the rubber band "dog-bone" onto the back bars of both karabiners.

Fig 3
Fig. 3

2. Wrap some electrical tape round rubber bands to neaten things up and give the rubber bands some protection.

Fig 4
Fig. 4

3. Add the essential back up sling.

Note 1: All rigs must be backed up by a sling.
Note 2: You will want to extend this Death Quickdraw as it is very stiff and my lift your gear out.


The Theory

1. The stretchy quickdraw is used to connect suspect protection to the rope. In the event of a fall, the quickdraw will dissipate additional energy by stretching. This should ( in theory) reduce the impact force on the suspect protection, making it less likely to fail. The additional 60cm sling provides a backup in the event of the rubber band "dog-bone" failing.

Testing

2. Warning: Do not use this rig! These pages are provided for information only. I have NOT tested this rig in any way whatsoever.


Update and Test Results

3. 02 September 2007: I can proudly report that after some testing, I have used and fell on Mr. Fantastic in the field. I was climbing on Earl Crag 2 weeks ago, attempting a wet, green poorly protected slab route. We had already done 3 routes in the wet and it seemed like a good idea at the time! Mr. Fantastic ( backed up by a short 60cm sling) was clipped into a poor WC-00 cam placement about 12 feet up. I attempted the crux rock-over, reaching for a very small and wet crimp. Nope! Wasn't going to happen! I tried to reverse the move but fell about 3 feet above the cam. It's strange how you notice the little details but I saw Mr. Fantastic stretch then the cam popped. By this time, I was only 2 feet or so above the wet ground. The only thing hurt was my ego and there's a bum shaped imprint in the ground to mark the start of the route. Mr. Fantastic survived intact!

4. Things to note:

  1. I am not as lardy as I think I am. Mr. Fantastic was made out of 30 rubber bands. I think the cam would have held if I used fewer rubber bands.
  2. The number of rubber bands required will depend on:
    1. How heavy you are.
    2. How high above the dodgy pro you will need to go.
    3. And of course, how bad the pro is.
  3. I think a 10 rubber band for well-dodgy pro and a 20 rubber band version for mediocre pro will work for my weight, about 72kg. I would tend to err on a more stretchy version with fewer runner bands. Even if Mr. Fantastic fails, there is the backup sling. And the stretchy quickdraw would have at least absorbed some of the energy of the fall. As long as the poor pro holds, Mr. Fantastic is expendable!
  4. If you pull test a 20 rubber band dog bone, you will find it will stretch up to 45cm but will require a lot more effort to get it to stretch to 60cm. I would suggest adding a slip knot into the 60cm sling, just to shorten it slightly.
  5. Your poor placement must be good for at least body weight, plus a bit more. No matter how much energy Mr. Fantastic takes out of the fall, the pro will pop if it can't hold your body weight. Furthermore, the top runner with the rope running through it will behave like a pulley, so even at rest, the force on the top pro will be greater than your body weight. Google "Pulley Effect".

As with any Chris Tan Death Product™, usual disclaimers apply. Use at your own risk! < Usual laugh follows>

Note: Usual copyright & disclaimers apply. If you would like to use the information or any of the pictures contained in these pages, contact Chris Tan by first removing the Walnut.


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Last Updated: 22 May 2006