Use of elastic for opposition pieces

[catbirdseat]

JosephH's thread on modified gear got into talk of using elastic cord for opposition pieces. This is something of which I've never read or even heard about. It is a very interesting idea to me for a couple of reasons.

 

First opposition pieces can take quite a bit of time to set up to get the tension just right. The use of elastic could save time. Also, use of opposition with inelastic slings can potentially cause triaxial loading on biners or mechanical leverage, depending on the geometry of the placement. Use of elastic on an upward facing piece can allow extension of the downward facing piece to reduce strain while still preventing rope wiggle from displacing that piece.

 

Of course I could foresee instances in which elastic would be disavantageous as well. Some placements would not tolerate ANY change in direction. Thus, an inelastic sling would be preferred.

 

Are there others who have used this system or would care to comment on it?

[Dru]

I hold the lid on my rubbermaid of climbing gear with a bungy cord.

[Blake]

I usually use the bottom piece of an opposition placement merely to keep the top piece in place. For example: I've got a totally bomber chock of some type that will hold any downward pull just fine, but if it is able to walk up/out i wouldn't trust it. I'll stick a nut or cam or something down below and then clove hitch both pieces together, and then maybe tie a fig-8 on a bight or something with the remaining sling length and clip that to the rope. In this case I think elastic to maintain tension might be very usefull. I'm not sure how easy or practical it would be to tie elastic cord between various pieces while on lead though, but I guess if you have a good enough stance to build an anchor with pieces in opposition, you probably are pretty stable right where you are.

[Bill_Simpkins]

Takes no time at all to set up the tension. Use a clove hitch on each piece. Lossening and tightening clove hitches is super easy when you pull on the middle strand.

As you know cloves can be tied and adjusted quickly with one hand. I could tension 2 pieces correctly with a sling and two clove hitchs in about the same amount of time it takes to throw on a piece of elastic.

Plus you should tension the pieces with a full strength sling anyways in case one fails. So you have to tension a sling either way.

[JosephH]

The original thread is at:

 

Gear Modifications...

 

Just so there is no misinterpretation of my intent here, let me be clear that the elastic cord in no way substitutes for sling with respect to either loading or restraint of pieces in opposition - the elastic just makes it easier to set opposition pieces and holds them while cloving or otherwise adjusting the opposition setup.

 

Again, the elastic cord just holds the pieces in place while you get it set up. This is particularly handy when a bottom piece of opposition wants to fall out and requires another hand until the setup/slings are adjusted. While there may be times when I allow a little slack in the sling with the elastic holding the pieces together until the sling is loaded, it never more than and inch or so at most - more than that and I rethink everything. Oh, and regarding "in the time it would take to throw an elastic on.." - I don't "throw it on", it's already there, I just drop a sling loop or a sling and elastic loop (note: compared at full lengths, the elastic cord is about an inch shorter than the sling so there is always tension even if an elastic loop is dropped along with a sling loop).

 

I got started doing this to help insure my roped solo anchors hold and aim the way I want them to once I depart from them. Sometimes I would come back down to second the pitch and find all the jostling of the rope had inadvertantly moved things in ways I didn't much care for and the elastic cord kept things in place. Then one day on a pitch I didn't need the elastic draw I ended up using it in an opposition setup and now I carry two draws configured this way at all times just for opposition setups; it makes setting them up a quick, easy, and one-handed affair. You are right, though, I have never seen or heard of another person doing this, but it has always worked well enough for me that I always carry them...

[Blake]

Joseph, I think you just need to expand your secret stashes of perfect fitting rocks, and you'd have ready-to-go anchors all around beacon.

[catbirdseat]

Thanks for the clarification, Joseph. It makes perfect sense.

[chirp]

The original Tri-Cam brochure espoused the use of bungee to aid in the stabilization of 2 opposed T-cams.

I will scan the info if anyone wants.

It's definitely a valid and intriguing part of the game and I am glad to see this information being brought to light.

Tech funk !

 

Much more interesting than reading endless articals on quickdraw biner gate configurations.

[fenderfour]

I was taught an interesting way to set two pieces in opposition. This works best with pieces that are relatively close and oriented with an upward and a downward piece.

 

Set you pieces (one up, one down) and each gets a biner. Clip a double (or triple) sling into the lower piece. Thread the entire sling through the upper biner. Pull the sling tight and wrap the sling around the upper biner, being sure to thread the sling through the loop coming from the lower biner. Keep wrapping until you are left with the appropriate sized loop, add biner and use.

 

The sling is clipped to the lower piece, so it's not going anyhere. It's wrapped around the top biner enough to create a great deal of friction, and it's looped back through itself, increasing the friction, so the top piece isn't going anywhere.

 

A downward pull will put most of the force on the upper piece due to all of the friction. An upward pull will put most of the force on the lower piece.

[catbirdseat]

Yep, I know about that one. ChrisW taught it to me. It is very fast.

[JosephH]

The original Tri-Cam brochure espoused the use of bungee to aid in the stabilization of 2 opposed T-cams.

I will scan the info if anyone wants.

It's definitely a valid and intriguing part of the game and I am glad to see this information being brought to light.

Tech funk !

 

Much more interesting than reading endless articals on quickdraw biner gate configurations.

 

Yes, please scan it that would be interesting. I've always adherred to the premise that there are no unique ideas - someone else somewhere is having the same stinking thought as you; but what we see are the unique individuals who dare to bring those ideas to life...

[RuMR]

bolts make the perfect opposition piece...hahahahaha, guaranteed not to fall out and you don't even need the downward pull piece...

 

[Rafael_H]

Set you pieces (one up, one down) and each gets a biner...A downward pull will put most of the force on the upper piece due to all of the friction. An upward pull will put most of the force on the lower piece.

 

I hope I am not missing smth. If each piece is holding mostly on its own, why have opposing setup at all? Is this for the (belay) anchors? I thought opposing is necessary for horisontal placements...

 

Please elaborate. Thanks.

[fenderfour]

I was tought this method mostly for use at anchors, but I have used it on lead once. This could also be handy in an area where the terrain goes from not-so-steep to steep.

 

You could use this on horizontally opposed pieces, but the angle between the pieces ends up being almost 180. This would greatly increase the force on both pieces if you fell. Someone better versed in the physics of anchors could explain this part better than me.

[JosephH]

I thought opposing is [only] necessary for horisontal placements...

 

was tought this method mostly for use at anchors, but I have used it on lead once. This could also be handy in an area where the terrain goes from not-so-steep to steep.

 

Someone better versed in the physics of anchors could explain this part better than me.

 

Well, let's talk about that...

 

Opposition placements aren't anything special; they're just a normal, common sense way to insure a placement is solid even if a given piece has one or more deficiencies such as:

 

1) It might lift out of its placement as you go by it or move above it:

 

This case is all about the importance of properly slinging a placement of any type (even cams). For those of you who have mainly sport climbed with quickdraws this is a fundamental change in the way you operate and think about clipping. Every piece you place will be affected by the rope moving in and out from the rock face and pressure from the rope to one side or the other due to the path of the route relative to the placement. It is imperative that a piece not be adversely affected by the rope as you pass it. This is typically done by slinging it appropriately with the correct length of sling or if that is insufficient then you need to lock it down (or otherwise in place) with another piece in opposition so the primary piece stays secure in it's placement.

 

2) It won't stay in the placement by itself unless held in a specific direction

 

Sometimes you find a good placement that will hold a fall fine, but the damn piece simply won't stay in the placement on its own to do it. This is a typical use for a piece in opposition.

 

3) It is not sufficient by itself (a placement only good in pairs - typical in horizontals)

 

There are times, rare though they may be, when one piece by itself won't cut it. I usually run across this in either horizontals or when dealing with a lot of small pieces. Once I did a circle of eight micro stoppers, then equalized them all to the center point with a sling, and then attached a screamer to that. No three or four of those pieces would have held a fall, but the eight together held quite a few of them while we worked the route higher to a solid cam. In horizontals the concern is if you fall on a piece and swing towards and past it you will pull it. To that end horizontals are usually protected by two opposing pieces.

 

4) It is only good for a [narrow] specific direction of pull [by the rope or a fall] on its own:

 

You have to consider the effect on a piece of both rope movement while climbing and the direction of the force applied to a piece in a fall. Particularly pay attention to the force vector of a fall - both during the fall and once it is fully loaded. Make sure a piece will hold in the right position for both circumstance and use an opposition piece if necessary.

 

Again, slapping in the odd piece in opposition to prop up or insure another piece should just be a common part of your trad leading repetoire. There are lots of books out there on the topic so read up and drag an old traddy out to plug in a bunch of examples for you to clean.

Edited January 19, 2005 by JosephH

[catbirdseat]

Set you pieces (one up, one down) and each gets a biner...A downward pull will put most of the force on the upper piece due to all of the friction. An upward pull will put most of the force on the lower piece.

 

I hope I am not missing smth. If each piece is holding mostly on its own, why have opposing setup at all? Is this for the (belay) anchors? I thought opposing is necessary for horisontal placements...

 

Please elaborate. Thanks.

This particular setup is most often used as an omni-directional as the first placement set after leaving the belay, when you really want to protect the belay by having a bomber placement that won't jiggle out as you go by it. It is good when you want something that absolutely won't pull out when the rope is pulling out and up when you fall on a higher piece, that is to prevent zippering.

 

So basically, it is a situation where the upper piece would hold a downward fall just fine, but might jiggle out from rope drag and the lower piece might fall out by gravity.

[Rafael_H]

1) It might lift out of its placement as you go by it or move above it:

2) It won't stay in the placement by itself unless held in a specific direction

 

Ah, wasn't thinking. Agreed, and both have happened to me, been lucky. Once fought a Metolius to not go perpendicular to wall, got pissed (hanging all the while) and replaced with Alien. Never thought of opposing (dumbass).

 

4) It is only good for a [narrow] specific direction of pull [by the rope or a fall] on its own:

 

Yes, have been there too so placed a "head-piece" and went on to a better spot. Been lucky, huh.

 

I guess you have to be running 20mi/wk and swimming and doing yoga to hang on one arm constructing this things Hats off.

 

Thank you!