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twins vs single rope - friction in belay device
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Peter_S


May 15, 2011, 9:36 PM
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twins vs single rope - friction in belay device
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Hi!
Any experience in using thin twin ropes vs single ropes in terms of friction in the belay device? I am going abroad for a month, and have twins (7.7mm...so thin) stashed there. A bit of rock climbign is planned, so I wonder....My partner feels insecure holding falls (ATC) on my 9.6mm rope, and would hate to have less friction. I used halfs frequently before, which were much better to hold, but thin twins?

Thanks,
SM


justanotherclimber


May 15, 2011, 10:06 PM
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Re: [Peter_S] twins vs single rope - friction in belay device [In reply to]
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Two twin lines is over 15mm of rope- not really an issue if you have a device with teeth and a glove. There are specific devices on the market- or there were, anyway, like the DMM bugette and petzl reversino (not in production, but you might find one out there) that were designed specifically for twins.

You may also look into the mammut alpine smart- locking assist device for half/twin ropes.


(This post was edited by justanotherclimber on May 16, 2011, 8:36 AM)


iknowfear


May 16, 2011, 1:04 AM
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Re: [Peter_S] twins vs single rope - friction in belay device [In reply to]
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Peter_S wrote:
Hi!
Any experience in using thin twin ropes vs single ropes in terms of friction in the belay device? I am going abroad for a month, and have twins (7.7mm...so thin) stashed there. A bit of rock climbign is planned, so I wonder....My partner feels insecure holding falls (ATC) on my 9.6mm rope, and would hate to have less friction. I used halfs frequently before, which were much better to hold, but thin twins?

Thanks,
SM
Stating the obvious:
Be aware of what kind of Biner you use with an atc. The bigger and rounder the biner, the less friction you have.

Cheers


JimTitt


May 16, 2011, 2:45 AM
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Re: [iknowfear] twins vs single rope - friction in belay device [In reply to]
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iknowfear wrote:
Stating the obvious:
Be aware of what kind of Biner you use with an atc. The bigger and rounder the biner, the less friction you have.

Cheers

Really? We have done pull tests with both 10mm and 12mm diameter karabiners and canīt detect any substantial difference in the holding power.
In theory the change in diameter is more or less cancelled out by the change in angle on the incoming and outgoing sides of the plate and testing bears this out.

To the OP:- The only plates which give reasonable results this thin are the DMM Bugette (not the Bug!), the not yet available DMM Chicane and the possibly the Reversino though I havenīt tested this. And of course the two lines used as one HMS which is pretty standard.

Jim


billl7


May 16, 2011, 5:24 AM
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Re: [Peter_S] twins vs single rope - friction in belay device [In reply to]
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I usually use an ATC and also feel insecure belaying on a 9.6 mm. Relatedly, I find rapping with an ATC on double 9's to be challenging (I weigh 190 lbs) - have to do other things to get enough friction. I am certain you will want a different device for 7.7 mm cord although I don't have one to recommend.

Bill L


billl7


May 16, 2011, 5:34 AM
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Re: [JimTitt] twins vs single rope - friction in belay device [In reply to]
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JimTitt wrote:
We have done pull tests with both 10mm and 12mm diameter karabiners and canīt detect any substantial difference in the holding power.
This is not the same thing but ... I have found that a rap on double 9's with an ATC is much more managable using two HMS biners side-by-side rather than one of the same style of biners. Edit: Of course, that's a bit more extreme of a difference than in the testing you mention.

Bill L


(This post was edited by billl7 on May 16, 2011, 5:36 AM)


iknowfear


May 16, 2011, 5:49 AM
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Re: [JimTitt] twins vs single rope - friction in belay device [In reply to]
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JimTitt wrote:
iknowfear wrote:
Stating the obvious:
Be aware of what kind of Biner you use with an atc. The bigger and rounder the biner, the less friction you have.

Cheers

Really? We have done pull tests with both 10mm and 12mm diameter karabiners and canīt detect any substantial difference in the holding power.
In theory the change in diameter is more or less cancelled out by the change in angle on the incoming and outgoing sides of the plate and testing bears this out.

To the OP:- The only plates which give reasonable results this thin are the DMM Bugette (not the Bug!), the not yet available DMM Chicane and the possibly the Reversino though I havenīt tested this. And of course the two lines used as one HMS which is pretty standard.

Jim

Hi Jim,

Hmmm, interesting that your test do not correspond to my my own limited experience. I felt(!) that an ATC with Peztl Oval (Round edge) is much more dynamic than with my old Camp ScrewGate... Will try to look at it tonight, and look at my biners and post up the details, although this will still be n=1 :-)

cheers,


JimTitt


May 16, 2011, 5:56 AM
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Re: [billl7] twins vs single rope - friction in belay device [In reply to]
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We also tested with two 10mm krabs which gave about 20% more power, we didnīt try 2 X 12mm ones because this would be pretty uncommon as most people only carry one, certainly you would get even more increase as the rope will be forced into the underside of the plate more.
However, as I noted in the tests, this forcing into the underside of the grooves can have some very unpleasant effects on the rope and damage the sheath if the bottom of the plate isnīt well rounded as is the case with a number we tried.

Jim


billl7


May 16, 2011, 5:59 AM
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Re: [JimTitt] twins vs single rope - friction in belay device [In reply to]
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JimTitt wrote:
We also tested with two 10mm krabs which gave about 20% more power, we didnīt try 2 X 12mm ones because this would be pretty uncommon as most people only carry one, certainly you would get even more increase as the rope will be forced into the underside of the plate more.
However, as I noted in the tests, this forcing into the underside of the grooves can have some very unpleasant effects on the rope and damage the sheath if the bottom of the plate isnīt well rounded as is the case with a number we tried.

Thanks for the info, Jim. Cools my ardor a little for such configurations.


bearbreeder


May 16, 2011, 9:55 AM
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Re: [Peter_S] twins vs single rope - friction in belay device [In reply to]
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im actually looking at getting the mammut alpine smart version for thinner ropes

assisted locking ... i just need to find one ... hmmmmm


juho.risku


May 17, 2011, 1:07 AM
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Re: [Peter_S] twins vs single rope - friction in belay device [In reply to]
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All depends on belay device as well as rope itself. Similar diameter ropes sometimes can have more / less friction, for instance for me Beal Joker has felt more slippery than slightly lower diameter ones.

If uncertain I would definitely try out first and find such high friction belay device that your partner is comfortable belaying with. Someone already suggested Reversino, but there are quite a few others as well. I have good experiences of Petzl Reverso 3 (compatible down to 7.5mm twin ropes), others which I was able to come up wit fast that are also compatible with thin ropes (down to 7.5 twin): Mammut Smart Alpine, Vader Alpine and Vader Light, Simond Cubik, Toucan and Toucan 2, Petzl Universo and Verso, Kong Ghost, Trango Jaws and finally DMM Bugette.

In case you're interested of comparing their specifications, here's a link: http://www.tribevine.com/...pe%20Belay%20Devices


JimTitt


May 17, 2011, 1:46 AM
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Re: [juho.risku] twins vs single rope - friction in belay device [In reply to]
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I know you want to promote your website but all you are doing is regurgitating manufacturers specifications, not any test results.
The OP wanted a high friction device with twin ropes and a few on your list are definately not in that category!

Jim


juho.risku


May 17, 2011, 1:58 AM
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Re: [JimTitt] twins vs single rope - friction in belay device [In reply to]
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Sorry if I upset you or someone else... hopefully the info wasn't totally useless. It was intented to be used as a starting point what to look for while in search for more information + there are reviews of products as well (so not only manufacturers specifications).

Btw. Personally, I think that any device intented for very skiny ropes, i.e. 7.5mm, is by definition high friction one.

To ellaborate more on high friction device issue itself: I've used both Reversino and Reverso 3 (+ ofcourse several others that do not fit into definition of high friction device), which both in my opinion work well what comes to friction on skiny ropes... though I do consider Reverso 3 better (Reversino is just too small, but definately high friction one).


JimTitt


May 17, 2011, 3:28 AM
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Re: [juho.risku] twins vs single rope - friction in belay device [In reply to]
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I was going to edit my post to point out I have a commercial interest in one of the devices I mentioned as the designer.

To design belay devices one naturally tests a large number and we can definitively say which have more friction and which less with all thicknesses of rope, reviews based on personal opinion and perceived braking power are often proven to be incorrect when tested.

I omitted the BRD from the list of possibles.

Jim


juho.risku


May 17, 2011, 3:36 AM
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Re: [JimTitt] twins vs single rope - friction in belay device [In reply to]
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I'd actually be very interested of the test results of different belay devices... any chances of getting to look at those? What were the devices you tested?

+ You're absolutely correct in what comes to reviews. They're definitely not the same thing as real tests... though test settings are also often simplifications. For instance, ice, water, wear and dirt may change the game quite a bit. I'm pretty sure that also the rope (not just the diameter, but other factors too) could affect the results.


(This post was edited by juho.risku on May 17, 2011, 3:56 AM)


JimTitt


May 17, 2011, 4:54 AM
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Re: [juho.risku] twins vs single rope - friction in belay device [In reply to]
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The differences water, ice and wear make have been investigated over the years but are of course rope characteristics, not belay device characteristics.

Different ropes have their own characteristic but we test in a way to discount this and at the same time give us information on how various ropes perform but the same as our device tests this is commercially useful and valuable information so as usual will never be published unless someone else does the tests or buys the information.

To be published the tests need anyway to be repeated under the supervision of an independent person since we could be accused of bias.

Weīve tested over 40 devices.

Jim


jackmarr


May 17, 2011, 7:06 AM
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Re: [justanotherclimber] twins vs single rope - friction in belay device [In reply to]
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I am thinking of halfs/twins for my next rope to save the hassle of carrying a tag line on long routes and other reasons (such as my wife is way lighter than me). Our Bluewater, though lovely, has had a tough year and a half. But I am addicted to the GriGri for sport with solid pro, and prefer not to use an ATC like device (except on trad ice etc). Anyone have any experience with the mammut alpine smart- locking assist device for half/twin ropes mentioned or could suggest a lock assist for twins/doubles? If it is good, I would be sold.


iknowfear


May 17, 2011, 7:36 AM
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iknowfear wrote:
JimTitt wrote:
iknowfear wrote:
Stating the obvious:
Be aware of what kind of Biner you use with an atc. The bigger and rounder the biner, the less friction you have.

Cheers

Really? We have done pull tests with both 10mm and 12mm diameter karabiners and canīt detect any substantial difference in the holding power.
In theory the change in diameter is more or less cancelled out by the change in angle on the incoming and outgoing sides of the plate and testing bears this out.

To the OP:- The only plates which give reasonable results this thin are the DMM Bugette (not the Bug!), the not yet available DMM Chicane and the possibly the Reversino though I havenīt tested this. And of course the two lines used as one HMS which is pretty standard.

Jim

Hi Jim,

Hmmm, interesting that your test do not correspond to my my own limited experience. I felt(!) that an ATC with Peztl Oval (Round edge) is much more dynamic than with my old [strikethrough]Camp[/strikethrough] Salewa ScrewGate... Will try to look at it tonight, and look at my biners and post up the details, although this will still be n=1 :-)

cheers,

ok, so I had my partner belay me with an old ATC-XP and a Petzl Oval and my Old and pointy Salewa Biner. Two falls from the same point. Rope was old and thick. He said that the Salewa was harder to give rope and generally provided a little more friction - YMMV.

Cheers,


mattm


May 17, 2011, 8:22 AM
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Re: [JimTitt] twins vs single rope - friction in belay device [In reply to]
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JimTitt wrote:
iknowfear wrote:
Stating the obvious:
Be aware of what kind of Biner you use with an atc. The bigger and rounder the biner, the less friction you have.

Cheers

Really? We have done pull tests with both 10mm and 12mm diameter karabiners and canīt detect any substantial difference in the holding power.
In theory the change in diameter is more or less cancelled out by the change in angle on the incoming and outgoing sides of the plate and testing bears this out.

To the OP:- The only plates which give reasonable results this thin are the DMM Bugette (not the Bug!), the not yet available DMM Chicane and the possibly the Reversino though I havenīt tested this. And of course the two lines used as one HMS which is pretty standard.

Jim

My Chicane is on pre-order! Can't wait.

Now the next question is when the "next thing" will come out for "guide style" device with Autoblocking features and the Chicane variable friction design...


Partner rgold


Jun 7, 2011, 6:47 AM
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Re: [jackmarr] twins vs single rope - friction in belay device [In reply to]
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I have limited experience with the Mammut Smart Alpine on 8.5mm half ropes (Mammut Genesis).

Handling requires more effort than with plate-type devices, and might be problematic if the ropes are not properly stacked---pumping slack for leader clips against significant hanging rope weight will probably be less than satisfactory. This may not be too serious an issue since rope stacking is generally essential with doubles and twins anyway.

A deal-breaker for me is that the device badly twists ropes on rappel. If you are willing to carry a separate device for rappelling, as I am not, then this would not be an issue.

The rappel twisting properties caused me to retire the device before catching any leader falls, so I can't comment on its assisted locking effectiveness.


markcarlson


Jun 7, 2011, 9:47 AM
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Re: [Peter_S] twins vs single rope - friction in belay device [In reply to]
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Peter_S wrote:
Hi!
Any experience in using thin twin ropes vs single ropes in terms of friction in the belay device? I am going abroad for a month, and have twins (7.7mm...so thin) stashed there. A bit of rock climbign is planned, so I wonder....My partner feels insecure holding falls (ATC) on my 9.6mm rope, and would hate to have less friction. I used halfs frequently before, which were much better to hold, but thin twins?

I have only used half ropes as well (8.5mm), but I did notice a considerable increase in friction when using the BD VaporLock for belaying compared to a round stock biner.

As long as your belay device says it handles 7.7mm ropes, you should not be too bad off. If your belayer is worried, a pair of leather gloves works wonders. Especially if you have to do any free-hanging rappels with a heavy pack!


donwanadi


Dec 30, 2011, 1:06 PM
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Re: [rgold] twins vs single rope - friction in belay device [In reply to]
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rgold wrote:
I have limited experience with the Mammut Smart Alpine on 8.5mm half ropes (Mammut Genesis).

Handling requires more effort than with plate-type devices, and might be problematic if the ropes are not properly stacked---pumping slack for leader clips against significant hanging rope weight will probably be less than satisfactory. This may not be too serious an issue since rope stacking is generally essential with doubles and twins anyway.

A deal-breaker for me is that the device badly twists ropes on rappel. If you are willing to carry a separate device for rappelling, as I am not, then this would not be an issue.

The rappel twisting properties caused me to retire the device before catching any leader falls, so I can't comment on its assisted locking effectiveness.

I'm interested in this device but the rope twisting is a concern. The instructions seem to indicate it is used to abseil in a very similar fashion to a plain old ATC. What causes the twisting?

Thanks


Partner rgold


Dec 30, 2011, 5:16 PM
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Re: [donwanadi] twins vs single rope - friction in belay device [In reply to]
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donwanadi wrote:
I'm interested in this device but the rope twisting is a concern. The instructions seem to indicate it is used to abseil in a very similar fashion to a plain old ATC. What causes the twisting?
Thanks

I don't know what causes the twisting. I have heard from others that they have not had serious twisting, in at least one case with the same model ropes as mine. I went back and tried again and got the same major twists. The rappel is also really jerky, which I dislike, and it can be tiring to hold the handle up. Probably a poor rappelling experience even without the twists.

Since then, it has been pointed out to me that the Alpine Smart can be threaded "backwards" for rappelling. I haven't had a chance to try this, but it could be a solution. Less friction, but there is too much in the normal orientation anyway.


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