Rappel rack and Rope wieght

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Rappel rack and Rope wieght

Postby ianreuter10 » May 14, 2015 10:29 am

Up to this point in my vertical caving career I have been using a microrack with dual hyperbars however, I am planning on doing some bigger drops in the near future, and simulating the expected rope weight on my backyard rope system I find it almost impossible to descend on my current rack. I'm about 5' 10" and weigh about 120, and with a 45 pound weight tied on the bottom of my rope I was completely stationary, unless I physically pulled up the rope and created some slack in the rope. I'm looking into getting the SMC Stainless Steel Rack Kit with 90* Eye 14" from on rope one. Im just wondering if you guys could give me some insight into whether this rack is long enough to provide enough distance to space out and add and drop bars, enabling me to descend safely and efficiently on a 45 t0 50 pound rope. The link for the rack is here: http://onrope1.com/store/index.php?p=pr ... &parent=14
Thanks
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Re: Rappel rack and Rope wieght

Postby GroundquestMSA » May 14, 2015 10:58 am

How large of a drop are you anticipating? I think that 11mm PMI weighs roughly 8 pounds per hundred, so you are simulating about 600' of rope weight. I think that most people who do that sort of drop do move up from a micro rack to a 14", at least. I see no reason why the rack in the link would not be completely adequate.

I am roughly the same size and weight as you. I've also been using a micro-rack for short pits and playing with added weight in the tree. I have been able to descend smoothly with 80 lbs. of rope weight (giant air compressor) below me. You didn't say what sort of frame you had. I started with the short (8") frame and found that I was too light to get a smooth ride out of that. The 10" made a huge difference and that's what I'm using now. If you have a BMS micro-rack, you can buy a longer frame from the manufacturer (Carol Basset, who will "tune" it for you), though I got one more cheaply from GGG, which considering your location would probably be the better choice.
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Re: Rappel rack and Rope wieght

Postby caver.adam » May 14, 2015 3:05 pm

If you are doing 600 feet of rope, the main reason you should upgrade from a microrack is heat. A microrack can get very hot over long distances. Hot enough to glaze the rope. Or cause you to lose control. I know someone who has used water to cool their microrack on a long drop but I would not recommend it.
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Re: Rappel rack and Rope wieght

Postby Chads93GT » May 14, 2015 4:26 pm

A 14" rack is plenty long and good for drops up to 1100', if not more. On 4 bars you will be able to spread them out completely.

But you can glaze a rope even on a long rack.

I melted my PMI at Valhalla the last time I was there on my 18" bridge day rack, I was going a little fast. As I climbed I was picking balls of nylon off the rope all the way up.
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Re: Rappel rack and Rope wieght

Postby Scott McCrea » May 14, 2015 7:48 pm

Heat is mostly a result of speed. Go fast enough and any device will glaze or damage a rope. Rappel at a reasonable speed and you can maintain a nice temp with any device.

With your weight, I would recommend a 14" rack. You are going to need plenty of spreading space. You might even consider spacers. If you're not sure how or why they work, as a knowledgeable vertical caver for a demo or at least do a search here.
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Re: Rappel rack and Rope wieght

Postby PatB » May 14, 2015 9:07 pm

My buddy is about the same weight as you. He borrowed my micro rack, short frame, when doing a large drop in Georgia. He said he had to feed rope the whole way. I use the same rack, but the one with the longer frame, like Groundquest mentions from Carrol B. I'm not a racer on long drops. I try to enjoy the scenery on the way down and ponder if I should just stop and change over so I don't have as far to come back up... I think you'd be fine with the longer BMS rack, but you'd definitely be OK with the hyperlink you mention. You'll have your cave pack clipped to you for a little extra weight. You'll go faster with the stainless, so start out with all your bars rigged and then take them off one at a time if you're not moving.
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Re: Rappel rack and Rope wieght

Postby ianreuter10 » May 15, 2015 1:07 pm

Hey guys,
thanks for all the input. It sounds like this rack will do the trick so I'm gonna pull the trigger on it. My current rack is the BMS micro rack with a 10.5in frame. It sounds like some of you had have a lot more success rappelling heavy ropes on this rack, so I might have go outside and give it another shot. Ill definitely be getting the 14in one though, as I'm sure no matter what it will definitely be a smoother ride. If I'm still having trouble with the 14in rack ill look into the spacers. However, I'm curious if replacing the 2nd bar with titanium bar would possibly do the trick as well, as On Rope states it has a lower coefficient of friction.
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