Difficulty Analysis: The Ingredients of Movement

"That hold is tweaky."
"That foot is too high."
"That move is huge."

Is it so simple? What makes movement hard? It's easy to try a move, "feel" how hard it is, and simply end your analysis there. However, climbing is a technical activity, and the levels of complexity are almost endless. Many of the best routesetters simply intuitively know what's hard about a move, and over time that skill can be developed. But it will help to have some of the basics down to make off-the-cuff setting, tweaking and offering forerunning advice easier. Here's a few of the basics of understanding what makes a move feel hard.

Mechanical Advantage

Mechanical advantage is the term used to describe a move that can be altered in difficulty, significantly or subtly, by a subtle tweak in body position. Here are the major points of mechanical advantage, and the type of moves for which they might apply.

Straight arms - The quintessential example can be found in every coaches' rallying cry to "straighten your arms!" Straight arms use the musculoskeletal structure as a support system, rather relying on the inferior lactic-acid-vulnerable forearm muscles. Any method that allows the climber to achieve straight arms can provide considerable rest opportunities. Three of the easiest contributors to a rest position are: Holds facing straight up and down with feet directly below them; holds facing inward in a dihedral; and holds facing outward on an arete. These rest spots can be quickly tweaked or eliminated by changing the directionality of the restable hold to something less mechanically preferable.

Hold factors - the "incutness" or depth of a hold can allow for significant mechanical advantage, by giving the climber more breathing room in their body position. Larger holds, even slopier ones, provide some mechanical advantage by letting the climber's larger hand and arm muscles do the work without having to redirect their energy and tension through the smaller muscles of the fingers.

Plumb line potential via body position - a mouthful, but the best way of describing what is essentially "ideal body positioning." The best way to understand is simply to look at two angles when considering a move. Angle 1 is the angle of the climber's arm when holding the hold, or more accurately, the angle of a line drawn from the climber's center of gravity to the center of the hold. Angle 2 is the plumb line of the hold. The smaller the difference between these two angles, the more mechanical advantage exists in the route. Often moves with massive discrepancies between these two angles end up feeling "tweaky" or just plain difficult. Plumb line is without question the fastest way to make a route more difficult. A tiny twist in the directionality of a hold takes only a few seconds (compared to at least a minute to change out a hold or foothold) and can change a move from comfortable to desperate instantly.

Ankles - One sometimes overlooked mechanical advantage is the ankle. The larger the foothold, the easier it is for a climber to use the big muscles of their leg, rather than redirect tension through the complicated and smaller muscles of the foot. Huge feet with bad handholds is a great way to test or train finger strength, but simply won't force the climber to engage their core as much as vice versa. In dihedrals, this mechanical advantage can be a nightmare, as feet usually considered completely awful can be enough for the climber to relax their ankle.

Traveling

Travel is my catchall word for the physical movement factors of a move. A frequent complaint among shorter climbers is that moves are too big. Being able to watch a climber try a move and understand specifically which part of the move is giving them difficulty can be a powerful asset for a routesetter. Working efficiently with forerunners for competitions and being able to communicate with and appease a gym community will both require cultivating the ability to understand why a move is "big."

Travel time - the duration of time that the climber must maintain or create body tension or momentum to execute a move. Some moves are better done quickly, and some slowly. Generally speaking, more vertical or slabby routes will be forgiving and allow longer duration movement; simply because of the imposed demand on the body to maintain tension, steeper walls require more alacrity. In some cases, such as unwinding from a deep cross through on a steep wall, the movement must be executed in a manner many climbers refer to as being simultaneously slow and fast. In many cases, a move will have a tipping point, where the move can be executed in a static manner up to that point, and the climber must alter their position to create momentum and complete the move.

Travel distance - simply the physical size of the move - but notably, not as it appears to many climbers. For instance, if the left hand is low on an undercling at waist height, and the right hand on a crimp above head height, moving to the next hold a few feet above the climber can be a body-height-sized move. However, if the crimp allows for a match, the size of the move is cut in half. This principle is why matchable holds are a huge no-no for forcing sequences (unless the match is the intended sequence) - and, due to the size of kid-fingers, why it is more difficult to set problems that are equitable for children and adults.

Body Position - the effects of body position on travel can't be easily summarized, but the most prominent effects are:

• Twisting during travel - some moves will require the climber to twist in or out while making momentum in another direction. This allows the climber to maintain hip-wall proximity, maximize reach, and prepare to create tension in the body position that the next hold necessitates.
• Traveling with the lower body - ankle, knee, and hip extension are all different factors in creating more distance in a reach during travel. Some moves will necessitate or favor different methods of reach - for instance, with big footholds, many climbers neglect to fully extend their ankle, because it is comfortable in the relaxed position. Climbers who are unused to slab climbing often don't have the trust and tension necessary to extend their ankles all the way. And, contrarily, many climbers on a steep wall will lack the body tension to extend through the knees and hips fully while moving upward.
• Traveling with the upper body - reaching by extending the shoulders and elbows is a given, but for some moves, proper posture can affect a climbers reach. Often the trunk can be rotated one way at the hips, and another at the shoulders, to provide a bit more reach. This occurs frequently during heel hook moves on aretes and during the opening movement of a big barn door move. Other times, the two work in tandem.

Momentum

Momentum is a crucial part of any move, no matter how static. Even an extremely secure, slow move requires generating force on a vector. Being a successful climber requires having a robust knowledge of generating, controlling and canceling momentum. Being a good routesetter depends upon being able to force the climber to call on that knowledge.

Generation through the elbows - necessary for some moves, but far fewer than the average climber thinks. There's a good chance if a climber thinks a move feels hard, they're starting with their elbows and following with their legs. Getting climbers out of this habit is an age-old problem for routesetters. For hard undercling moves, elbow generation becomes a necessity, as the legs will often be fully extended just to be in position.

Generation through the shoulders and back - for gym rats with chronic burl-itis, #2 after elbows. On the steepest walls, creating swing before a move, performing come-in moves and many forms of foot cutting movement necessitate shoulder momentum. Often flexing at the elbows first is not possible, as the holds are poor and it will result in a loss of body tension.

Generation through the hips - hip extension is a popular way to start moves, especially moves that trend sideways. Pulling in with the hips to rock over a foot before pushing off of it is also a common use of hip momentum.

Generation through the knees - generally speaking the most powerful momentum generation tool in a climber's toolbox. Many moves start at the knees. Placing feet to the side, angling them obtusely, or otherwise hindering vertical footwork can help to cancel out knee momentum.

Other methods - the "nod" move, notably, is used by some strong climbers with great success. The pogo or "moon kick" would also be a great example of an unorthodox method of momentum generation.

Setting a problem that requires multiple types of momentum is a good challenge for a setter, and can provide a well-rounded power testpiece for climbers.

Accuracy and Precision

How "accurate" a move must be can be a huge factor in discerning why the move is difficult. Major players in the precision requirements of a move can be:

• Speed and momentum - the more momentum a climber has during a move, the harder it is to hit a hold perfectly, without over- or undershooting.
• Body positioning - coming out of or in to very specific body positions can be stressful on the accuracy of a move. Hitting gastons can be notoriously picky on body position, and getting the shoulder and hip positioning right can be mentally complex enough that hitting the fingers right on the hold becomes difficult.
• Hold size, obviously, is a factor in precision. Slapping enormous feature-slopers doesn't usually require a ton of precision, except in cases where overshooting will bring the climber off of their launch hold. Outdoors, slopers can require precision down to the individual grains in the rock. Indoors, requiring that level of precision on slopers is difficult (but possible.) When setting for precision, many setters will automatically retreat to pockets, and the benefits for that tactic speak for themselves.

Other factors

Obviously there are myriad other elements that come into play for movement difficulty - to name a few, I've ignored balance, breath control, endurance factors, and only glossed over the basics like hold size and distribution, countless aspects of foothold placement, etc. But this should be a good start to being able to analyze what makes a move 'hard.'

Summary

Morphology in combination with the factors in this article makes the entire topic exponentially more complicated than can be covered in a blog post. Climb with a morphologically diverse group of climbers and you will quickly recognize patterns to which moves each body type struggles on. Developing that intuition is the only way to learn how to do some of the most basic tasks required of a routesetter:

1. To set movement that is equitable for different body types, and still performed the same (or similarly)
2. To understand, without having to ask or watch someone try it, what makes a move feel difficult
3. To be able to accurately and quickly look at, analyze and constructively criticize a boulder problem (an extension to #2 in that it requires actual communication)
4. To be able to change a move to add or remove difficulty in the most efficient possible manner.

I will probably return to this overwhelmingly complex topic some time in the future. For now, happy setting!

Movement Analysis: The Frog Pinch

The frog pinch is a pretty specific move, so I thought it would make an excellent candidate for my next movement analysis. I set this move on accident a few times, but the first time I forced it was at the level 2 USAC clinic, with E-Grips' Myorcan Tufapinch. I was somewhat on the spot, since I was setting it specifically for Chris Danielson himself. However, I didn't struggle with it and actually found it fun and intriguing to set. Since then I've set the move a few times with increasing success. The first thing you need to know about this move is that unlike the last movement analysis, this move might be a bit unintuitive - it's more technique than power. Lots of climbers do not have the hip flexibility and lower body tension necessary to quickly grasp this move when they encounter it. That being said, it's most logical to set this move on a slightly harder route, where climbers are likely to see the move as a challenge instead of a frustration. Gym rats hate this move. Flexible strong females, techy people and Smith junkies will eat it alive.

Basic Summary

The gist of the frog-leg is a move where the climber has to create body tension by compressing their legs towards each other. This means a few things off the bat. First, the hand holds need to be poor enough that the climber will fall if their feet aren't secure. If the climber can dyno or campus past the move, it's a no go. Second, The number of feet available needs to be limited; actually, it needs to be one - the pinch. Third, that foot option needs to have zero upward foothold potential. If the climber can use the top of the foot even as a poor smear, they will drop their other leg and make the move without using the frog.

Black denotes the start holds and route trend.

Generally the move works best when the climber is traversing over the frog pinch footholds, because it's hard to generate upward momentum when your legs are both pinching. Since that upward motion would make the move a lot more upper-body dependent, it could ruin the equitability of the sequence. I have found the easiest way to set the Frog Pinch is by having the climber do a cross move from a wide open position. We're going to have them start on the big pinch and a small right hand crimp by hand foot matching their left heel on the pinch from the ground. This sets the climber up for the frog by having half of the body position implied by the time they get to the move.

Starting position.

After they pull on, they'll bump their left hand from the big pinch to the first left hand sloper (Hold 2.) At this point they are creating compression with the three holds.

The opening move, to the first sloper.

Moving their left hand to Hold 3 is not an option because of distance, so the climber knows they need to move their right hand. The logical option is to create compression to replace the right hand's tension by using their right leg - for some climbers this will mean automatically adopting the frog position.

Creating compression with the feet - the Frog Pinch.

Then the climber can cross through to hold 3. Optionally, an extra (very poor) hold can be added above hold 1 to help this body position transition.

Crossing over - not too much upward motion, mostly moving laterally.

The route can go lots of directions afterward, provided none of the holds used in later sequences are accessible from the opening moves.

Hold Considerations

Basically, we're talking about four holds. One big start pinch, one small start crimp, and two non-matchable directional slopers / sloper pinches.

The right hand starting hold, doesn't matter much, as long as it's poor enough to prevent moves from being skipped. Placing it facing straight up will make the opening move easiest; placing it horizontal to the right will make it quite hard. Straight down or left will make the move (almost) impossible.

Holds 2 and 3 should be semi directionals so they can be easily tweaked to make the move feel more natural. The fastest way to make the move harder is to make the holds face outwards more, making the climber more reliant on compression and less on being able to actually pull down against gravity. I've found the most natural way to set the move is to have Hold 2 be basically straight down or just a bit left (since the climber will be using it the most.) The optional bump hold should face gently right, so the climber will struggle to bump their left hand from the start hold to hold 3, making the intended sequence more obvious. Hold 3 can be oriented depending on your next sequence, but I try to have it face slightly rightward with a decent thumb catch and keep the route trending left. This also makes it harder to skip moves.

The frog-leg foothold is going to be the centerpiece of the route. I'll emphasize again that this pinch can't be smearable! The three holds I've set this move on are the E-Grips Bubble Wrap Pinch, the Tufapinch and the Atomik Granite Pinch. The granite pinch was the most smearable, but also the most comfortable heel hook for the start. The Tufapinch is quite hard on anything steeper than about 20 degrees. There are several other holds that could theoretically be used for this purpose.

Troubleshooting hold choices:

• Thumb catches can generate a lot more compression than you might think. Consider using holds with no or poor thumb catches.
• If the climber can't pull off the ground, try moving your centerpiece pinch hold down (or in) a bit, or making your right hand starting hold better by rotation or hold change.
• If the climber can smear on top of the centerpiece hold, either it's too low or too good, hold 2 and 3 are too good, or your terrain isn't steep enough.
• If the frog-leg is uncomfortable, watch someone climb it and try to rotate the frog pinch so it points directly at their ideal center of gravity during the move. Just rotate it for fun if nothing else - a five degree shift makes the move completely different. Experiment. Rotating the pinch hold has been the final step of tweaking the move every single time I've set it.

Terrain Considerations

This move works on just about any terrain, but it's easiest to keep the climber from smearing on top of the pinch hold on a wall at least 20 degrees overhanging. Slabs and vertical faces it's just too easy for the climber to forego compression in favor of balance. On a steep enough wall, the hold has to better than the ones I outlined - Lapis volumes are a fun alternative, if you have them; although the move at that point is less like a frog pinch and more like stock gymnastic roof climbing. In fact, I think doing the move on a gently overhanging wall where it feels new and foreign is what makes the move so interesting to set and climb.



Possibly the best place to set this move is on a staggered overhang, if you have one near the ground. In this scenario you can move the entire setup up and down until you find the appropriate average angle to make the move "go." I didn't figure this technique out until I had set the move several times - it's much easier on this type of terrain, so it's a good place to start.

Movement Analysis: The Drive By

(While I finish up some posts in progress about the "routesetting biz", here's a post I wrote this summer. An ode to a move..)

I've been thinking a lot about the drive-by. It's been popular lately on the competition circuit:

Battle in the Bubble (3:30)
Teva Games 2009 (0:28 / deeplinked)
World Cup Vail 2010 (4:45)

Recently, I set a route up the front 45' of our boulder that featured a big drive-by lunge at a jug. It was a fun experiment at setting that move. First, I'll talk about the technical, boring aspects of the move. So if you're just interesting in learning how to set it quickly, head on down for the skinny.

Much like a standard dyno, the gist of the move is basically two steps: one, to force the climber to create momentum in one direction, and then two, to have them cancel it out when they hit the target hold (i.e. hold the swing.) What separates a drive-by from a stock one handed dyno is the momentum goes in stages: first one direction, then upward, then arcing back in the other direction as the climber hits the apex of their move. In other words, their free hand will look sort of like a clock hand swinging around from 6 to 12. The more momentum created, the bigger the clock face, the harder the move.

Basically, you can start with a sidepull lockoff, with the other hand around center mass (i.e. not very good to pull with) and good feet directly under the climber. Then, move the target hold high enough that the climber has to release body tension and perform a bit of a pop to snag the hold. This is closer to a stand-up than a drive-by, but I think it meets the technical qualifications.

Making the sidepull (the launch hold) a worse hold, or pivoting it downwards, will increase the difficulty of the second part of the move, and make the move feel more dynamic. Because they will have less purchase on the launch hold to control their body position once they start generating momentum, they will have to rely on the target hold to regain stable positioning.

Let's say you're using a left hand side pull, to the left of the body. Moving the feet to the left and keeping them low will make the move a simple "pop" with no drive-by element. Moving the feet further to the right can make the move very desperate very fast. The climber will use their poor right hand hold to rock over their footholds, then jump straight up. Their body will naturally curve left, hopefully snagging the target hold near the apex of the jump. With a sufficiently poor launch hold, this effect can make the move more of a drive-by dyno.

By altering the other hold, the one that will be released to grab the target hold, we can also dramatically change the body type of the move. As it moves past the climber's center of mass and closer to the launch hold, it becomes harder to rock over the feet and push off to begin the move. Moving it too far the other direction makes the swinging/rotating element of the move much less significant.

One of the keys of truly forcing the move is the directional nature of the off hold. Pivoting the launch hold affects the body positions created after the move has started, but pivoting the other hold (the hand you're reaching with) has drastic effects on the "setup" body position. Making the off-hold an undercling or opposing sidepull will give the climber a multitude of body position options, and maybe even let them attempt the move with their other hand. If you make that hold a gaston, they are forced to lay back on the launch hold and their body positions are constrained.

Finally, you can alter the target jug's position to change the amount of swing. Moving the target jug just a few T-nuts horizontally past the launch hold's vertical position can often change the move from a compressed, tight foot-cut with a bit of 'oomf' to a massive screaming-banshee 90-degree one-arm swing.

Sample layout

Here's a super simple example of forcing a drive by on a semi-steep to steep wall. In this case, you climb into the move from the right. It doesn't matter what the start is, so long as the holds are either necessary feet for the drive by move, or unusable for the drive by move. Remember, you want to limit the climber's options.


(Directionality indicated by the curved side of the hold.)

Hold analysis:

- In this case, hold A is a huge jug facing right. It's crucial that hold A is a great hold, but it should be low profile - very difficult to heel hook. For instance, the top hold in this set by Voodoo. Another great candidate would be the E-grips wonder hole.

- Hold B is a shallow edge or pinch, and shouldn't have a lot of bite to it. If it's too incut, the climber will be able to get opposition purchase for a heel hook. The lunar flats by E-Grips might be a good choice. A small thumb catch on hold B helps a lot with being able to hold the swing on the big move - alternatively, leave it off if you want to force them to cut the off hand and move into a one hand swing.

- Hold C can be anything you want. Just to figure the move out, I suggest a massive jug. My favorite jugs right now are the Teknik Supervillains.

Sample movement


Movement analysis:

#1. Left hand comes in to hold A as a gaston. Feet are on start holds or around terrain.

#2. Right hand matches into hold A.

(Left foot steps high onto the right foothold.)

#3. Left hand moves to hold B.

(Swap feet and move left foot to left foothold.)

#4. ("the" move)
- Keeping the left hand/arm extended for as long as possible, the climber rocks their body over the footholds by locking off the hold A jug, creating rightward momentum.

- When they reach the apex of the rockover, the climber straightens their legs, creating upward momentum.

- Right hand departs hold A. As it extends to grab hold C, the left hand's grip on hold B is holding them into the wall, causing their momentum to shift back left.

- The right hand latches hold C and the opposition between hold B and C is used to cancel out any remaining leftward momentum.

As you can see, one single move can require several body positions to set up. In this case, you could replace hold A with a smaller hold, make the feet into crimps that were start holds, and you'd have essentially the same move. The gaston/match is just to break up potential left-right-left monotony.

Need to switch this to a traditional one-handed swing drive by? It takes about two minutes. Just use this variation on a theme:


Variation on a theme:
-Move hold A further to the right, so it's not directly over the feet anymore. This will make it hard to generate upward momentum, and easier to generate rightward momentum with a natural barn door.
-Rotate hold B to be more of a gaston. It's crucial that hold B can not be used to pull directly downwards.
-Now, move hold C right a few feet, and maybe down a bit.
-Optionally, start the problem from the left to reduce the chances of skippage.

Now, when the climber sets up, they're going to naturally want to go with their left hand, the hold that was on hold B. If hold C is further to the right than hold A, the move will most likely require a wild one handed swing.

Suggestions for playing with drive-bys:
- Move the feet and watch as the climber's amount of swing varies drastically.
- Tweak the angle of your launch and off holds, even if you like the move the way it is. The body position difference / amount of "try hard" required when you pivot your off hold 10 degrees can be quite a learning experience..
- Want to scare the crap out of your climbers? Drive by around an arete to a jug that can't be seen from the launch position!
- Mega-slow balance drive by on a slab. You definitely see the "clock hand" move if this is set correctly.

Happy setting!

If you guys like this style of post (analyzing a single move) let me know - it feels kind of dense, but I write a lot of these just for posterity and I'd be happy to post them more often.

Movement is Body Position

I think if you reduce all climbing to its basest elements, you'll find that body position is the prevailing factor.

Balance can be important on a route, but only because having the right balance or the right points of contact allows proper body position. Finding balance literally IS body position.

Distance is a function of difficulty on a route, but only because it means the climber must create a change in body position to find success. You can see this every time a novice climber "slaps" at a hold they can't reach, or a more adept climber turns their shoulder out and shoves their hip in the wall on a big lockoff.

Bad holds are frequently thought of as a good barometer of difficulty. But often body positions with better feet, different hip turnout, or more relaxed stances can make bad holds feel "restable." A good example of this is sloping crimps. On an overhang, sloped holds without the use of toe or heel hooks usually means keeping the feet lower will increase traction on the holds. When the climber goes to move their feet up, the holds become more difficult to hold on to - because of a change in body position.

Footholds are also used as a route's yardstick. Our local bouldering area has a lot of granite pebble smearing, which requires the foot to stay at a certain angle. This angle means the leg stays pointed in towards the wall, and your butt stays pointed out. If you pull your hips in too close, you might gain distance for a move, but the body position will compromise foot traction and cause you to fall. Again, body position is the building block of movement. If I were going to try to duplicate one of these routes, I know I'd need to keep the feet pretty awful. Solid feet that you can edge on allow the hips to come in farther, the heel to be raised further, and in general just allow the climber to do more.

It is functional to set routes that force movement based on balance, distance, hold type, etc. But I think setting by forcing moves that require specific body position is the most effective way to really make a climber solve a puzzle.

Applying this to routesetting is difficult. It's one of the things I try to think about most when I'm setting. If a route feels "classic," it's usually because the body position shifts a) feel natural, b) are not dramatically harder from one to the next and c) are less body-dependent.

I'll talk more about body position in a future post. For now, happy setting!

Definitions of Forcing Movement

As a preface, for this post general terms like "stronger climber," "better climber" etc. are interchangeable terms for what is really a vague system of measuring more factors than I could list. To simplify things, just assume that I'm referring to a climber who, for the relative grade, has an average ability in all areas of climbing: power, lockoff strength, technical aptitude, mental acuity, etc. I'll try not to use definite phrasing, because all things in climbing are relative.

One big question that will be discussed a lot on this blog is this: when routesetters talk about forcing a move, what are we really talking about?

There's several perspectives. As with all things climbing-related, the talking points of each point of view will vary wildly with the difficulty of the climb being discussed. Forcing a move on a V10 being climbed by a V10 climber, and forcing a move on a V3 being climbed by a V10 climber are different propositions with distinct obstacles; greater technical aptitude, raw power and breadth of experience allows V10 climbers to visualize, attempt and perform sequences that, regardless of the routesetter's intended method, will result in a successful climb. The subject is further muddled by another major issue, organic diversity between climbers: weight, height, finger strength, finger size, body tension, ape index, hip turnout flexibility, and a vast number of other factors.

One perspective of "forcing" a move is creating a choice for the climber. The choice will affect the climber's relative chances of success on the climb through what I see as a reward/punishment system. Successfully choosing the correct sequence will reward the climber with better body position, a better hold, or an opportunity to move to the next choice; choosing the wrong sequence will punish the climber with a poor body position, a bad hold, and often either necessitate retreating and making the choice again, or result in a failure. I'll talk more about the choice-reward system in climbing in a different post.



To illustrate one perspective of "forcing" a move, here's a simple graph. The line of probability reflects the point at which a climber should be able to climb a route. The colors indicate a routesetter's relative ability to force a move. As a climber's raw ability increases, their ability (and number of options) on a route increases. Thus, the green area on the graph is a point where a routesetter may find it easier to get the climber to do the intended sequence. A red area on the graph indicates that a routesetter might find it very frustrating to try and get a climber to do the intended sequence.



As a way of understanding this concept, here's a simple example. Joe, a V3 climber, arrives at the crux of a boulder problem at his absolute physical limit. Matched on a crimp rail with high feet, he must lock off and make what is, for him, a big right hand move to a slot. He barely makes it, and then is able to move his left hand to a good jug hold slightly higher. Exhausted, he completes the sequence and goes on his weary way. Tim, a V10 climber, wanders up to the problem and quickly climbs into the same move. His better lockoff strength and higher body tension allows him to move all the way directly to the jug. He finishes, drops off and moves on.

In this example, one difference between the two climbers was Tim's greater reach due to being a stronger climber. Another way of looking at the example is that Tim's climbing ability and experience offered him a wider variety of choices. He had the ability to reach the bigger hold, but still could have chosen to do the intended sequence. His ability and instincts were more developed than Joe's.



One critical element of this example is this: the red area must represent not the ability to do ONE move, but the relative difficulty of all possible choices that the climber could make that would result in a successful rock climb. In other words, if Tim finds the lockoff to the jug just as hard as Joe finds the 2-move sequence, the routesetter has done an effective job forcing the sequence. (Not that V3 will feel hard for Tim - but as long as it feels V3 to both of them, the routesetter has still succeeded.)

Therefore, from this perspective, forcing a sequence can be looked at as: a) limiting the number of choices that a climber can make from any given point in the route, regardless of organic discrepancies between climbers, and b) ensuring that the reward/punishment system involved in those choices will cause a successful attempt to have the same number of rewards (rest points, good body positions, etc.) and a failed attempt to be a result of the same potential wrong choices (i.e. a short climber should not run into five potential stopper moves when a tall climber runs into two.)

Looking again at the graph, you could use the gradient as a vague gauge of how consistent, or "classic" it is. If a move on a moderate climb lands in the red area for a climber, and they still do the intended sequence, the move was pretty well set. If they do a different sequence, that's okay too - as long as it feels consistent to them. Routes where climbers of different grades do the same sequence naturally are often considered classic. When I say naturally, I mean when they are not intentionally trying to skip moves and make the route harder than it is.

This is, based on my limited understanding of the science of routesetting, the most meager introduction to forcing a move that I could pare into words. Further posts will get more specific.