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Lowest piece: forces in fall?


Original Post
Old lady H · · Boise, ID · Joined Aug 2015 · Points: 290

A low first piece of gear goes in to protect against an upward pull.

If the lead falls, and the belayer is pulled tight to this piece, is it then getting slammed by both the climber and belayer in an upward pull?

The top piece has the weight of both, once they are hanging, but I hadn't thought about the bottom piece taking a hit from a belayer "falling up".

Two "hits" to that piece, maybe? The first when the belayer hits, the second from the lead stopping?

Thanks! Helen

FrankPS · · Atascadero, CA · Joined Nov 2009 · Points: 275

The topmost piece takes the force of the fall; none of the lower pieces see any of that force, except for whatever outward force they may see from failure to extend, traverses, etc.

The belayer getting lifted and hitting the lowest piece would be very rare.

Not sure where you got the idea that the lowest piece protects against an upward pull. It may have a slight upward angle, but is more outward. Properly placed and extended, the lower pieces will prevent a bottom-up "zipper."

My two cents.

Patrik · · Unknown Hometown · Joined Jun 2010 · Points: 30
FrankPS wrote:

Not sure where you got the idea that the lowest piece protects against an upward pull. 

  Only if you sport climb will the lowest piece protect against an upward pull!

Old lady H · · Boise, ID · Joined Aug 2015 · Points: 290

Sorry. My knees hurt, apparently that's where my stegosaurus pea brain resides today.

Lowest piece needs to resist an upward pull?

Best, H.

Tony K · · Pa · Joined May 2017 · Points: 0

OLH keeping it simple general rule of thumb for trad climbing ....gear should be placed to resist an upward pull ......this is done by adding  quick draw, runner, sling ect.  By doing that you allow the rope to move freely without moving your piece of gear

rocknice2 · · Montreal, Quebec · Joined Nov 2006 · Points: 3,028
Old lady H wrote:

A low first piece of gear goes in to protect against an upward pull.

If the lead falls, and the belayer is pulled tight to this piece, is it then getting slammed by both the climber and belayer in an upward pull?

The top piece has the weight of both, once they are hanging, but I hadn't thought about the bottom piece taking a hit from a belayer "falling up".

Two "hits" to that piece, maybe? The first when the belayer hits, the second from the lead stopping?

Thanks! Helen

Typically the force on the top piece is 1.66 x the force of the falling leader.  That's because of friction at the top biner. Without friction it would be 2 time the force. 

So now let's say the belayer is nice and light. They get pulled up without even trying. They get pulled up until they come to an eqilibrium with the falling climber, at 1:2\3. 

Worst case scenario is there is no belayer. The strand is directly tied to the bottom piece. It would see 2\3 or 66% of the force generated by the falling leader. Once you add a counterbalance (lightweight belayer) the amount the bottom piece needs to hold is lessened by the amount the belayer is taking.

It's generally a bad idea to place a piece very low. Even to protect an upward pull for future pieces. The best resolution is to stand against the wall under the piece in question. Usually a nut. Once the leader gets in a multi directional piece higher up then it's usually safe to move away to a more comfortable stance. Since the first piece isn't critical any more.

Edited because my tablet can't spell worth shit.

B Owens · · Unknown Hometown · Joined Sep 2011 · Points: 60
rocknice2 wrote:

Typically the force on the top piece is 1.66 x the force of the falling leader.  That's because of friction at the top biner. Without friction it would be 2 time the force. 

So now let's say the belayer is nice and light. They get pulled up without even trying. They get pulled up until they come to an eqilibrium with the falling climber, at 1:2\3. 

Worst case scenario is there is no belayer. The strand is directly tied to the bottom piece. It would see 2\3 or 66% of the force generated by the falling leader. Once you add a counterbalance (lightweight belayer) the amount the bottom piece needs to hold is lessened by the amount the belayer is taking.

It's generally a bad idea to place a piece very low. Even to protect an upward pull for future pieces. The best resolution is to stand against the wall under the piece in question. Usually a nut. Once the leader gets in a multi directional piece higher up then it's usually safe to move away to a more comfortable stance. Since the first piece isn't critical any more.

Edited because my tablet can't spell worth shit.

Besides conservation of gear, why?

AndrewArroz · · Unknown Hometown · Joined Jan 2016 · Points: 10
Bowens wrote:

Besides conservation of gear, why?

Angle of pull. 

Old lady H · · Boise, ID · Joined Aug 2015 · Points: 290

And, if it's extended enough to mitigate that, it might be totally useless to help with a fall.

I'm potentially the light belayer, so I do think about the rope angle, where I'll go in a fall, should we build me an anchor (usually no), what happens if they fall right now? A long list. 

Including getting creamed by my climber, and those first 3-5 pieces and ground fall and zippering (whatever bottom up is).

As I've been higher than my climber after a fall, I can actually see the possibility of being pulled to the first piece, especially if there isn't a bunch of rope out yet, or not much friction in the system (someone running it out).

Best, H.

S. Neoh · · Unknown Hometown · Joined Oct 2009 · Points: 0
Old lady H wrote:

As I've been higher than my climber after a fall, I can actually see the possibility of being pulled to the first piece, especially if there isn't a bunch of rope out yet, or not much friction in the system (someone running it out).

In situations involving light belayer / heavier climber, I have seen many instances of belayer going up to the first piece.  In fact, I might go as far as saying it is common place in gyms.  Less common outdoors but I have seen that too on sport routes.  I do not think I have seen it happen on trad but all dynamics involved are basically the same (when there are only one or two pieces of pro in) so one cannot rule that out either. 

I have only experienced this once first hand either as a climber or belayer.  It is not fun.

B Owens · · Unknown Hometown · Joined Sep 2011 · Points: 60
AndrewArroz wrote:

Angle of pull. 

I believe you are saying that, the lower your first piece, the sharper the angle of the pull will be in a fall (outward/upward force)?  Of course, your first piece should ideally be able to withstand an outward/upward pull. If that's the case, what's the issue?

Jon Frisby · · Brooklyn, NY · Joined Feb 2013 · Points: 100

get directly under their first piece and/or extend to avoid angling the rope sharply. /thread

AndrewArroz · · Unknown Hometown · Joined Jan 2016 · Points: 10
Bowens wrote:

I believe you are saying that, the lower your first piece, the sharper the angle of the pull will be in a fall (outward/upward force)?  Of course, your first piece should ideally be able to withstand an outward/upward pull. If that's the case, what's the issue?

You are correct.

Here's the concept. Lots of people (including me) have the urge to put the first piece right at the level we can reach standing on the ground maybe on tippy toes. So if my belayer is standing a few feet away from the wall and the wall goes up more or less vertically we're creating an angle that's probably 100-140 degrees. When the climber falls a few pieces up that angle between the bottom piece and belayer will create upward/outward pull on your 1st piece. Now, you're correct that a long sling on that same piece will alleviate the issue because the angle will be more obtuse, but let's also consider that a piece placed at 7 or 8 feet with a long, extended sling is now effectively placed at face or even shoulder level. In other words, useless for catching a fall. Better to just place your 1st piece a little higher. And extend it, too.

Serge Smirnov · · Unknown Hometown · Joined Oct 2015 · Points: 235

This is what Freedom of the Hills recommends:

(this diagram is presumably for belaying off the ground - in a multipitch scenario the anchor would have pieces both below and above the master point)

Nobody I know does this (for typical mass ratios, this method generates more force on the top pro piece), but the situation Old Lady H described sounds like a good case for it.

BTW one concern with letting the belayer hit the first piece of pro is what it does to the belayer's hands.

Old lady H · · Boise, ID · Joined Aug 2015 · Points: 290
Serge Smirnov wrote:

This is what Freedom of the Hills recommends:

Nobody I know does this (for typical mass ratios, this method generates more force on the top pro piece), but the situation Old Lady H described sounds like a good case for it.

Well, this old lady won't be doing that either. The important piece that would make that work reasonably, is a stance in front to really brace on. They show it, but I don't think many would really see that as such. It does illustrate the line you aim for, and having the belayer lined up with the direction of pull. This is what might be needed on an overhang, and I have seen a bolted ground anchor once at a huge scooped out wall!

Otherwise, anchors will be beside me, or in front.

Best is still not at all, IMO.

But yes, an anchor as the part to keep me from going up could be that low first piece. On a single pitch, I'm not sure it would really matter much to run into pieces placed solely to keep the belayer going up.

Best, OLH

AndrewArroz · · Unknown Hometown · Joined Jan 2016 · Points: 10
Serge Smirnov wrote:

This is what Freedom of the Hills recommends:

(this diagram is presumably for belaying off the ground - in a multipitch scenario the anchor would have pieces both below and above the master point)

Nobody I know does this (for typical mass ratios, this method generates more force on the top pro piece), but the situation Old Lady H described sounds like a good case for it.

BTW one concern with letting the belayer hit the first piece of pro is what it does to the belayer's hands.

I've done exactly this when having my 12-year-old daughter belay me. Also used a GriGri. 

B Owens · · Unknown Hometown · Joined Sep 2011 · Points: 60
AndrewArroz wrote:

You are correct.

Here's the concept. Lots of people (including me) have the urge to put the first piece right at the level we can reach standing on the ground maybe on tippy toes. So if my belayer is standing a few feet away from the wall and the wall goes up more or less vertically we're creating an angle that's probably 100-140 degrees. When the climber falls a few pieces up that angle between the bottom piece and belayer will create upward/outward pull on your 1st piece. Now, you're correct that a long sling on that same piece will alleviate the issue because the angle will be more obtuse, but let's also consider that a piece placed at 7 or 8 feet with a long, extended sling is now effectively placed at face or even shoulder level. In other words, useless for catching a fall. Better to just place your 1st piece a little higher. And extend it, too.

But that's not actually "bad" (which is the statement that I was questioning), is it?  Again, besides the need to conserve gear, a piece that protects only the first 2 moves can still be valuable if those 2 moves are difficult.  Also, many climbs start in a place where there is substantial exposure beyond just the first few feet of climbing on the pitch at hand.  For example, a climb that starts on a sloping ledge or a climb that starts by stepping across a small crevasse or gap.  Also, on a multi-pitch route, getting in an immediate piece (even if it's just while standing or hanging at the anchor) can prevent a factor 2 and also the awkward situation of catching the leader on the belayer's harness. 

In the situations above (which are quite common), as long as you make an appropriate placement (as in, one that can withstand an outward pull, not one that is just slung to avoid the pull), I'm not aware of a problem or reason that one should avoid placing the piece?  Am I missing something?

Serge Smirnov · · Unknown Hometown · Joined Oct 2015 · Points: 235
Old lady H wrote:

The important piece that would make that work reasonably, is a stance in front to really brace on. They show it, but I don't think many would really see that as such.

I don't see that as essential.  Your weight would be pulled up off that stance anyway.

S. Neoh · · Unknown Hometown · Joined Oct 2009 · Points: 0

Many of us have mixed feelings about ground anchor outdoors (they are fine indoors when available).  The issue against it is the belayer has quite limited mobility.  Just in the past 18 months I had to move very quickly from my belay stance twice to avoid being hit by dead  branches dislodged by water runoff-off/wind and inexperienced/unaware hiker and leader above us.  I wear a helmet even when belaying so I would have been fine, but nonetheless.  Also possible is dropped gear and broken/loose holds.  The latter happened just 3 weeks ago two climbs over from me.  The belayers scattered to avoid getting hit by a baseball size piece of rock from about 50 feet up.  Not sure if they could have gotten out of the way if hampered by a ground anchor.  There is no universally correct answer in this case.  One has to weigh all cons against all the pros to arrive at a decision which will likely be fine for one party but maybe not another.  Things like this are not as clear cut as we would like or want but that is reality.

Serge Smirnov · · Unknown Hometown · Joined Oct 2015 · Points: 235

Good point for belaying off the ground, but I *think* Old Lady H was talking about multipitch, where you don't have much mobility anyway.

S. Neoh · · Unknown Hometown · Joined Oct 2009 · Points: 0
Serge Smirnov wrote:

Good point for belaying off the ground, but I *think* Old Lady H was talking about multipitch, where you don't have much mobility anyway.

Whether one considers it good luck or bad, I also had stuff come off above me while at a belay on a MP route.  Without a "ground anchor" below me, I was able to make the most of the reduced mobility to lean heavily into the anchor in front of me, essentially pressing myself into the rock and minimizing my exposed profile to whatever that was flying my way.

A word about being yanked up to the first piece.  If this is a likely scenario, it might be more risky to belay with a Gri-Gri.  Counter intuitive, you say?  Well, that is what we thought too until we witnessed a belayer "drop" her much heavier climber to the ground while she was jammed tight against the first quickdraw which was pulling practically straight up (how's that for an upward pull?).    We rushed over (the climber was fine but shaken) to take stock of the situation.  It turned out the rope side biner of the lowest quickdraw was pressed so hard against the cam of the Gri-Gri that it prevented the GG from camming and locking the rope.  A very sobering observation.  In this case, if the belayer were using an ATC, had control of the rope and managed to keep her brake hand away from the quickdraw, the rope side biner would have likewise jammed into the ATC, hereby helping to arrest the fall instead of failing to cam and lock like the GG did.  If I had not witnessed the event first hand and was able to do a group analysis of the situation immediately after it happened, I would not have thought it possible.  

Guideline #1: Don't be a jerk.

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