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Belay Device Friction Test

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Following up on their climbing shoe rubber friction test, Spadout has recently released a belay device friction test. While highly unscientific not rigorous, this is at least a nice starting point for an objective debate over which tube-style belay device is best (they did not test auto-blocking devices). Their overriding view on the tests were:

We believe two key factors that distinguish belay devices are the range of friction the device can provide as well as the maximum friction it can achieve. You want low friction when feeding the rope and high friction when locking-off.

The friction study ranks a large group of popular belay devices on a numerical scale based on several criteria in their tests using different diameter ropes.

A locking carabiner was clipped to a bolt and each belay device was attached to the biner. The rope was passed through the belay device. The slack on the â??climberâ? side of the device went around a pulley and was attached to a 50 lbs weight. The weight and the pulley allowed the belay device to feed and settle naturally. The â??handâ? side of the belay device was attached to a spring scale to measure the force.

The force on the spring scale was recorded. This test was repeated 10 times (resetting the slack on the â??handâ? side between each test). After doing ten feed tests, the spring scale was moved to the lower lock-off test position and ten more tests were performed.

I was pleased to see that my all-time favorite (and current) belay device, the Trango Jaws, was ranked first in the testing. I’ve tried many belay devices and I’ve always come back to the Jaws. Specifically, I feel the deep V shaped grooves on one side provide high friction and nice fall catching for even the most heavy climbers. Flip it over and the side without the grooves gives you much less friction for easy rappels. Any thoughts on this study? What’s your favorite belay device?

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5 Comments

  1. for me it’s definitely the trango jaws. my climbing partner weighs more than twice what I weigh. I tried a number of different belay devices before settling on the jaws. I can easily and smoothly belay my partner with the jaws, far more so than with any other device I’ve tried.

  2. I wouldn’t call it “highly” unscientific, that’s unnecessarily harsh. Their methodology is perhaps a little basic to fully explore the performance of the devices they tested, but it’s a reasonable start without making things too complicated. Furthermore it’s repeatable as they’ve fully disclosed their methodology and they’ve provided their results data for us to draw our own conclusions.

    All things considered it’s a worthwhile start at objective performance testing and comparison for a complex category of devices and certainly not worthy of being derided as unscientific.

  3. Pete, you have a valid point. “Highly unscientific” are not the right words for what I was trying to imply.

    Probably the better phrasing would have been “not rigorous” because by definition they did use the scientific method thus making it scientific.

    Post has been edited and thanks for calling that to my attention!

  4. Hi Tom
    You may not be aware that this test was completely discredited on rockclimbing.com recently and for good reasons:-

    The tester appeared to have no knowledge of the fundamental principles behind this type of device and failed to realise that a static test will give meaningless results.
    The results are wildly innacurate, with some devices being given a braking power 50 times that of others which both theory and practice tell us is not the case.
    The results contradict the findings of other highly regarded tests by qualified, independant testing authorities such as the German TÃ?V .

    The test as it stands is completely wrong in almost every respect, gives a false picture of the relative effectiveness of an essential piece of safety equpment and has no place in climbing-related literature.

    I am an English engineer, living in Germany and owner of Bolt Products manufacturing rock anchors (bolts) for climbers. I have no commercial interest in any of the manufacturers concerned, do not produce any similar article to those tested and have no connection with the author of the test.
    I have however over the years done some work on the theory and testing of belay devices and in my profesional opinion the test is completely worthless.

    (I have an unpublished paper on belay devices which includes all the required information and basic theory if you would like to confirm this for yourself or obtain a third party opinion)

    Yours
    Jim