Advanced Trad Anchors > Part 2 of 5 > The Sliding-X

This article about the sliding-X knot is part of the book - The Trad Climber's Guide To Problem Solving.

VDiff trad climbing self rescue book

The main advantage of using a self-equalizing anchor is that it continues to distribute the load equally between the anchor pieces as the loading direction changes. This maintains a lower force on each piece, therefore decreasing the likelihood of anchor point failure. This is especially useful when equalizing marginal pieces of lead protection.

The main disadvantage of using self-equalizing knots at the anchor is that if one piece fails, the whole belay shifts. This shift is barely noticeable on a well set up anchor. However, with some setups the sudden jolt could cause you to lose control of your belay device. Be careful where you use self-equalizing anchors and make sure to tie appropriate extension-limiting knots to reduce the possible sudden shift in belay position.

If two micro nuts are equalized with an overhand knot as shown, it is likely that one of them would take most of the force of a leader fall.

This could be due to a slightly off-centre adjustment of the knot, or a slightly different loading direction (you may not fall directly downwards). If the fall generates 4kN of force, it will cause the 3kN piece on the right to fail.

equalize climbing anchor

This will put 100% of the force on the remaining piece, which will most likely cause that to fail too.

equalise climbing anchor

If the same two micro nuts were equalized with a sliding-X, the knot would self-equalize during the fall and distribute 50% of the force (2kN) onto each nut. The nuts would then be much more likely to hold the fall.

sliding-x climbing knot

The Sliding-X

The sliding-X is useful for:

- Equalizing two pieces of trad gear as part of a more complicated anchor
- Equalizing two pieces of lead protection
- Equalizing a two-bolt anchor for top roping

Step 1
Clip a sling through two pieces of gear.

Make sure the sewn section of the sling is near the top of one of the pieces so it doesn’t interfere with the sliding-X knot.

Step 2
Twist the sling 180 degrees and then attach a carabiner to it. The central point will now be equalized even when the pull comes from different directions.

sliding-x equalizing climbing anchor

Step 3
Position the central point where you want it. Unclip the sling from one piece and tie an overhand knot near to the central point.

This is known as an extension-limiting knot. The closer to the central point you tie them, the less the anchor will extend if one piece fails.

Step 4
Clip the sling back into the piece.

equalize climbing anchor sliding x

Step 5
Repeat steps 3 and 4 with the other side.

You can now adjust the overhand knots so they are as far down as possible while still allowing the central point to move freely where it needs to.

sliding-x trad climbing anchor

If one piece fails, the central point will shift as shown.

how to tie a sliding x climbing anchor

1) It’s essential that you twist the sling in step 2. If you don’t, the central point can become completely detached from the anchor if one piece fails.

how not to tie a sliding x climbing anchor

2) It can be difficult to clip another carabiner into the main point of a sliding-X when it is weighted. If you must do so, make sure you have clipped the carabiner through the sling in exactly the same way as the original carabiner. A much better alternative is to use the quad anchor.

Sliding-X Variations

There are many ways of incorporating the sliding-X into an anchor. However you do it, make sure that if any piece failed, the resulting anchor shift:
- Is minimal
- Causes the remaining pieces to re-equalize
- Will not cause you to lose control of the belay

The following arrangement uses one double-length sling to equalize three pieces.

Step 1
Clovehitch a double-length sling to the lower right piece.

how to tie a sliding-x climbing anchor

Step 2
Clip the sling through the upper right piece.

how to tie a sliding x climbing anchor

Step 3
Add two extension-limiting knots.

how to tie a sliding-x climbing anchor

Step 4
Clip the sling into the left piece.

Adjust the knots so they limit extension while allowing for some directional movement.

how to tie a sliding x climbing anchor

Step 5
Put a 180 degree twist in one of the master point strands and clip a carabiner through both loops as shown.

how to tie a sliding x climbing anchor

VDiff climbing self rescue book

You could also equalize four pieces by clovehitching another piece on the left.

You may need to adjust the extension-limiting knots after adding the fourth piece.

how to tie a sliding x climbing anchor

If your belay consists of one bomber piece (the bolt) and four mediocre pieces (the micro nuts), you could use an arrangement like this.

This method equalizes the pieces so the bolt takes 50% of the load and the four micro nuts take 12.5% each.

how to tie a sliding x climbing anchor

Advanced Trad Anchors > Part 3 of 5 > The Quad Anchor

The 'Quad Anchor' is an anchor system which self-adjusts to keep an equal force on each anchor point. It can be better than other methods of equalizing in certain situations.

Self equalizing quad anchor


- Distributes the load equally between the anchor pieces. This puts less force on each piece, therefore decreasing the likelihood of anchor point failure.

- Provides two independent attachment points for the belayer and climber. This helps to prevent carabiners from jamming up at the same master point.

- The two attachment points adjust laterally, meaning that the anchor remains equalized even when different directions of pull are applied at the same time. This is useful during multi-pitch belay changeovers, or if the route traverses in or out from the belay.

- On multi-pitch routes where you have bolted anchors that are approximately the same, you can speed up your anchor building by keeping the quad tied.


- The quad will extend slightly should either anchor point fail. This can shock-load the remaining piece(s).

- Since the quad needs to be doubled up, it is difficult to equalize anchors where the placements are far apart.

Best Situation To Use The Quad Anchor

To equalize two bomber anchor points such as a two-bolt anchor.

How To Tie The Quad Anchor

You Will Need:
* 2, 3 or 4 solid anchor points
* A cordelette
* 3-5 screwgate carabiners

Step 1
Double over a cordelette so there are four strands of cord. Make sure the double fisherman’s knot of the cordelette is near one end.

Climbing cordelette

Step 2
Tie a ‘load-limiting’ knot on one side of the cordelette. This can be either an overhand knot or a figure-8 (The figure-8 is easier to untie after loading. The overhand uses slightly less cord).

Climbing cordelette

Step 3
Tie another load-limiting knot on the other side and clip both ends of the cordelette to the anchor points with screwgate carabiners. Make sure the knots are fairly even when the anchor is weighted in the direction of loading. The four-strand ‘master point’ should normally be around 12 inches long.

These load-limiting knots minimize the distance the cordelette drops if one anchor point fails. The closer you tie these knots to the master point, the less shock-loading is applied to the remaining anchor point.

If the strength of your anchor points are difficult to assess (e.g: older bolts), you should move the overhand knots closer together. However, this also reduces the lateral range over which the quad self-equalizes.

Climbing quad anchor

Step 4
Separate the four strands of the master point into two doubled strands.

Climbing quad equalizing anchor

Step 5
Attach yourself to two of the master point strands (using a clovehitch on a screwgate carabiner).

If belaying in guide mode, attach your belay device to the other two master point strands.

Belaying in guide mode with a quad anchor

It is important to only clip into two of the master point strands. If you clip into all four, you could become completely detached from the anchor if one point fails.

Dangers of the quad anchor climbing

VDiff self rescue course

Equalizing 3 or 4 Anchor Points

To equalize three anchor points, simply split one of the double-loops, attaching one loop into each piece. You will need to re-tie the load-limiting knots to equalize these pieces since they will probably be at varying heights.

Do the same with the other side to equalize four points.

Quad anchor rock climbing

Sometimes it can be difficult to equalize three or four points correctly, as this uses up a lot of cordelette. In this case, consider equalizing the furthest away pieces with a sling to create two anchor points. Then attach your quad to those.

Quad anchor with slings and cordelette rock climbing

Using The Quad as a Top Rope Anchor

You can use the quad anchor to set up a top rope. This is useful if you want to top rope two different routes which are immediately next to each other, but share the same anchor. The quad will self-equalize for both of them without needing any adjustment.

As always, make sure your anchor meets the requirements of the six point rule before you set up a top rope.

Step 1
Clip a screwgate carabiner into two of the master point strands.

How to make the quad anchor rock climbing

Step 2
Clip another screwgate into the other two master point strands.

How to equalize rock climbing anchors

Step 3
Clip the rope through the screwgates and fasten them.

It is important not to clip a carabiner through all four strands (see above).

Self-equalizing anchor rock climbing top rope

Trad Anchors – Part 2 of 4 > Equalizing Gear

This 'Equalize Trad Anchors' article is part of the book - Trad Climbing Basics.

VDiff learn to trad climb e-book book

Equalizing Trad Anchors - The Basics

Let's assume you've got two incredibly good pieces of gear or two bolts at the anchor. The easiest way to equalize them together is by using a long (120cm or 240cm) sling, or a cordelette (a loop of 7 or 8mm cord).

Step 1
Clip the sling or cordelette to both pieces of gear, using screwgate carabiners. Pull it down in the middle so both strands of sling are equal.

trad climbing anchor equalized

Step 2
Tie an overhand knot in it. This creates a central point.

equalize climbing gear overhand knot in sling

Step 3
Clip a screwgate carabiner into the central point.

trad climbing anchor equalized

An overhand knot in your sling will equalize the anchor pieces in a basic sense. However, it must be tied in a way which meets the following three criteria:

1) Each piece of gear only takes around 50% of the total weight of the belay.
2) The anchor is set up for the direction that the 'pull' will come from.
3) If one piece of gear was to fail, the other would not be shock loaded.

These criteria are explained below.

VDiff trad climbing book

Criteria 1: The V-Angle

In theory, if you have two pieces of gear with 100kg hanging from them, each will take 50kg, right? Unfortunately not. This depends on the angle the sling makes just above the overhand knot (the V-angle). The smaller the V-angle, the smaller the force on each piece of gear.

You don't need to know how to calculate these numbers, but an angle of anything up to 60 degrees is acceptable. At this point, 58% of the total weight of the belay (the weight of both climbers) will go onto each piece. This is good.

trad climbing bolted anchor equalized

At 90 degrees, 71% of the force will go onto each piece. This isn't too good.

climbing bolted anchor equalized

At 120 degrees, each piece of gear takes 100% of the force! Never equalize gear with such a large angle.

trad climbing bolted anchor equalizing

You can decrease the V-angle by using a longer sling or cordelette. If you don't have one, you can extend a piece with a short sling.

trad climbing bolted anchor equalize

Criteria 2: Direction of Pull

Your gear needs to be equalized together in the 'direction of pull'. This is the direction that it would be weighted if your partner falls.

If you've climbed straight up to an anchor and will be standing or sitting directly below it, this will be straight down. But if you've traversed in to a ledge and the rope is running off to the side, the pull will be in that direction. You'll need to place and equalize the gear to suit that.

When you're setting the anchor up, think about the direction that the pull will be in. Tie your overhand knot accordingly, then test it by pulling hard in that direction. Are both strands of the sling taking the weight? If one is slack, then adjust your knot accordingly.

equalizing bolts with cordelette

Criteria 3: Shock Loading

Imagine hanging a heavy shopping bag from a nail on your kitchen wall. If you place it there gently, the nail might strain a bit, but it'll hold.

Now imagine extending that shopping bag with a piece of string. Hold it up high, then drop it. What happens? The increased force will likely break either the nail, string or bag, dumping your shopping in an untidy pile of broken eggs and plasterboard.

This principle is exactly the same at a belay. If one piece fails and the anchor isn't equalized correctly, all the weight of you and your partner will 'fall' onto the other piece, shock loading it. The extra force caused by shock loading could pull out or break the remaining piece.

There should be no slack in any part of your anchor, so that if any piece failed, there would be no movement or shock loading.

shock load climbing anchor

How To Equalize Three or More Pieces

The previous example explained how to equalize an anchor with only two pieces of gear. This is fine if both pieces of gear are absolutely bomber (such as a new bolt or a sling around a big, sturdy tree).

However, in most cases you'll be building trad anchors out of regular trad gear – nuts, hexes and cams. These are not as strong as bolts or massive trees, so you'll need to use more of them.

If you're not sure how many pieces of gear to use, see
The 6 Point Rule.

To equalize three pieces of gear, simply use a longer sling or cordelette. Pull two loops down and tie one big overhand knot in it. Then clip a screwgate through all three loops. You may need to fiddle with the knot slightly to get all strands to pull equally tight – often the middle one can go a little slack as you tie it.

three piece climbing anchor

If you have two pieces of gear close together but the other one far away, it can help to use two slings. First, use one sling to equalize the two pieces which are close together. Next, equalize the central point of that with the third piece of gear using another sling.

You may need more than three pieces of gear to make a secure anchor. Use the same method to equalize as many pieces together as you need.

If you don't have enough slings, you can use the rope as part of the anchor (this is explained in the next article).

trad climbing anchor equalized with slings

Cordelette Craft

If equalizing the anchor with a cordelette, it is typically better to create the central point at head to chest level. This provides a convenient workstation to attach yourself and belay your partner from.

The following methods describe a few ways to adjust the height of the central point.

trad climbing belay equalized with cordelette

Cordelette Craft: Keeping the Central Point High

Double Up
One or more strands can be doubled up. The double loops don’t stretch as much, so they may give the higher piece more than it’s share of the load.

Consider this when equalizing the pieces together.

trad climbing anchor equalized with cordelette

Tie a Knot
Tie an overhand in the cordelette to shorten it.

trad climbing anchor equalized with cordelette

Figure 8
Tie a figure 8 instead of an overhand at the central point. Or wrap the cord around itself one more time to create a figure 9.

When using any of these methods to adjust the height of the central point, make sure your V-angle does not exceed 90 degrees.

trad climbing anchor equalized with cordelette

Cordelette Craft: Extending the Central Point

If you would prefer to use a cordelette to equalize the anchor (rather than the rope), but it isn’t long enough, try extending the furthest away piece with a sling.

Alternatively, unfasten the double-fisherman’s bend and tie a figure-8 loop in each end of the cordelette. Clip the ends into the furthest away pieces and equalize with an overhand knot.

The disadvantages of this setup are a reduced strength on the outer pieces (one strand of cordelette is weaker than two) and there is no top shelf.

trad climbing anchor equalized with cordelette

Fall Factors and kN Ratings: What They Actually Mean

'Fall Factors and kN Ratings: What They Actually Mean' is part of the book - Trad Climbing Basics.

VDiff learn to trad climb e-book book

kN Ratings

kN ratings are shown on all your climbing gear: nuts, cams, slings and carabiners. kN stands for kilo Newtons. 1kN is about 100kg (220lbs for the Americans). So this nut will hold around 900kg.

Climbing nut with kilo newton kN ratings

This is Nelly. She weighs 850kg, so the 9kN nut would hold her weight – just.

But if Nelly climbed above the nut and then fell, she would put more force on the gear. This force would certainly exceed 900kg, causing the nut to break.

Every fall exerts a force greater than body weight – often many times more than your actual weight.

Elephant rock climbing with rope

Your goal as a leader is to reduce the potential force on gear, therefore keeping the climb safe.

The exact force generated depends on:
- The distance fallen
- The climber’s weight
- The length of rope in the system
- Friction through gear in the system
- How dynamic the belay is
- How dynamic the rope is

Elephant rock climbing

Fall Factors

The fall factor is the distance fallen divided by the length of rope in the system.

The higher the fall factor, the more force is applied to protection. This is why a bigger fall puts more force on gear.

If a climber falls 3 meters, when 10 meters up a pitch, the fall factor is 0.3.

If a climber falls 7 meters, when 10 meters up a pitch, the fall factor is 0.7.

rock climbing fall factors

Similarly, a fall taken close to the belay puts a much larger force on protection than the same length of fall taken higher up the pitch.

If a climber falls 2 meters, when 20 meters up a pitch, the fall factor is 0.1.

If a climber falls 2 meters, when 3 meters up a pitch, the fall factor is 0.66.

fall factor climbing

Warning - Factor 2 Falls
If a climber falls 2 meters, when 1 meter up the pitch (falling directly onto the anchor), the fall factor is 2. This puts a large force directly on the belay device which makes it hard to hold the fall.

It is important to eliminate the chance of a factor 2 fall by placing gear immediately off the belay.

factor 2 fall climbing

VDiff trad climbing book

kN Ratings - Top Rope Vs Leader Fall Forces

Most lead falls have a fall factor of 0.2-0.7 and generate 2-5kN of force on the top piece of gear.

When top-roping, the distance fallen is minimal, therefore the fall factor is near zero. The force on the anchor will be the weight of the climber plus part of the weight of the belayer (around 1kN of force).

If there is slack in the system, the force will be a little higher, but still significantly less than the typical forces on gear during a leader fall.

Kilo newton kN ratings and fall factors explained for rock climbing

kN Ratings - Forces on Climbing Gear

Most medium/large sized trad gear is rated to about 10-14kN. This is strong enough to hold the most enormous fall you'll ever take. In most cases, the gear itself won’t break.

The weakest link in the system is usually the quality of the placement or the rock it is in (e.g: a 14kN nut in a suboptimal placement may be plucked out with a 2kN force).

Warning - Micro Gear
Tiny 'micro' cams and nuts have low strength ratings and will only hold small falls. If you take a massive whipper onto a 3kN nut, it'll probably break.

If your route is protected by small gear, make sure to place plenty of pieces and consider equalizing them to make a stronger point of protection.

Micro nut kilo newton kN rating

Heavy Climbers

The heavier you are, the more force you apply to gear when you fall.

Heavier climbers should consider thicker ropes with low impact-force ratings, which can take more abuse than thinner ropes.

Heavyweights should beef up all anchors, place protection more often and make sure the belayer is able to take the load.

belaying a heavy climber

kN Ratings and Fall Factors Summary

It’s important for a leader to understand when potential forces may be high, and to place gear appropriately to reduce this. High forces can break micro gear, break the rock that holds bigger gear in place or pluck out poorly placed gear.

Extend gear when necessary to avoid rope drag. Rope drag reduces the effective amount of rope available to absorb the impact, which increases the fall factor. Never rely on a single piece of gear, especially if it has a low strength rating. If you're 'cruxing out' above unreliable gear, it's usually safer to down-climb to a place where you can rest and re-think your options.

The belayer’s role is to assist the leader in making these decisions. Often the belayer has a better perspective of the potential forces on gear. Let your partner know if they are creating a dangerous fall potential. You can also help by being ready to give an appropriate dynamic belay.