What is “Edging”?

Mike King

AKA Habacomike
Instructor
Joined
Nov 13, 2015
Posts
2,307
Location
Louisville CO/Aspen Snowmass
Personally I’m rarely if ever coaching or teaching “pressure”.
About the only thing you hear in junior race coaching is an emphasis on “pressure at the top of the turn”. That magical stage of late transition/early turning where the skier benefits from actively moving to the new ski.

That said, I like to coach movements not outcomes. The movements that contribute to the “perfect” turn are, as Razie described in an earlier post, that combination of ankle flexion (eversion included) hips, upper body, and muscular engagement that most efficiently engages a ski at the “right” time.
And the “right” time is almost always in the fall line.

When the critical elements are in place, “pressure” becomes a result of the above.

Teaching “pressure” as a movement, IMO, produces compromised outcomes. Yes, the passive skier can become more aggressive , and appear to make improvements. But the skier who works to improve all of the pieces, will be ahead in the long run.
Coach a young developing racer to add more “pressure” to the ski in the turn, and you will likely get more rotation and more skidding. Yes, while free skiing, the modern shaped ski will “reward” the skier with positive feelings of engagement and rebound, but in the course they will almost always be slower with a higher DNF percentage.

I’m always impressed watching the slo-mo of a top World Cup slalom skier in the course. Total reliance on stance and establishing high edge angles before engaging. Very little skidding, and efficient use of the muscles.
Who knows what most PSIA folk teach. There’s lots of beliefs, and we do not believe in final forms. But if you were in PSIA Rocky Mountain, you would be very unlikely to hear one of our examiners ever talk about adding pressure to the skis. Our Ed staff believes that you rarely, if ever, push the skis. We look to manipulate pressure, not create it. We look to alter the timing of pressure, moving it higher in the turn by moving with the skis, establish early edge, and reducing the pressure that otherwise would occur later in the turn.
 

JESinstr

Lvl 3 1973
Skier
Joined
May 4, 2017
Posts
595
Who knows what most PSIA folk teach. There’s lots of beliefs, and we do not believe in final forms. But if you were in PSIA Rocky Mountain, you would be very unlikely to hear one of our examiners ever talk about adding pressure to the skis. Our Ed staff believes that you rarely, if ever, push the skis. We look to manipulate pressure, not create it. We look to alter the timing of pressure, moving it higher in the turn by moving with the skis, establish early edge, and reducing the pressure that otherwise would occur later in the turn.
Mike, While I wholeheartedly agree with what you, @Average Joe and some others have stated in terms of edging pressure and bending the ski, I continue to be bothered by how the discussion of pressure seems to be "locked" into a single silo of conventional Gravity based understanding.

In this and other recent threads, I have seen lots of "talk" on managing pressure. Yet, I can't recall the term Centripetal Force being discussed/explained. Why is that? THIS IS THE FORCE THAT BENDS THE SKIS! This is the force that the skis are designed to create. Is it that hard for skiers to get their heads around the concept? It may be. To complicate the issue, many skier's physiological relationship with the inward push of Centripetal force is masked by the more prominently perceived outward pull of the "Centrifugal" aspects of the turning force

Skiers need to seek out and embrace the inward turning force using the edging and balance management skills that you and others profess.

Unfortunately, many of the visuals that have been used to support positions on proper pressure management are not Centripetally based. The Lever diagram in the dorsiflexion thread comes to mind.

And here's another.
Take the great "Bending the Ski" video you posted by Gellie . Look how he demos the correct point he is trying to make! He is physically pushing the middle of the ski with his arms because that is the only way to bend the ski under the circumstances. That is not, in reality what happens, just the opposite. Yet this is the visual that non informed skiers take away. So one should not wonder why so many adopt a "Pushing" mentality.


1590071884799.png


Thanks in advance for indulging me.
 
Last edited:

Mike King

AKA Habacomike
Instructor
Joined
Nov 13, 2015
Posts
2,307
Location
Louisville CO/Aspen Snowmass
@JESinstr, I know you love your physics, but the general public, and even most ski instructors, do not. Many people would not understand centrifugal force, let alone that it is a fictional force. So while it may be useful to delve into physics of skiing for some, many of our guests, and our colleagues, do not have the background or interest in doing so.

As an aside, there is a well known instructor from Aspen who was the head of the ski school at Highlands, Snowmass, and a former demo team member. He used to teach at Taos, and gave periodic off snow clinics on skiing. One day, his topic was the physics of skiing. He was about 5 or 10 minutes into his lecture when it became apparent to him that there was a loss of connection with his audience. He asked if everyone was following along and if there were any questions or comments. The reply? "We are physicists from Los Alamos..."

Back on topic, does the ski bend because of centripetal force? Or is it because there has been a steering angle introduced and it is the effect of inertia? Does it really matter?

As far as the levers in the other thread go, the diagrams presented were ones that others picked up off of the internet, I presume. It doesn't matter if they are relating to gravity or some other force -- the mechanics are the same. And I don't know how else Tom could have made the point about the amount of bend in the ski on hard snow -- and trying to use an analogy to centripetal force in that video would have lost a very large part of the audience.

Just to be clear, Tom does not talk about centrifugal force, he talks about gravity and centripetal force, and makes the point that gravity is a minor part of the equation -- the force to be managed and used is centripetal force.

Mike
 
Last edited:

Dakine

Out on the slopes
Skier
Joined
Dec 21, 2015
Posts
663
Location
Tip of the Mitt
"Just to be clear, Tom does not talk about centrifugal force, he talks about gravity and centripetal force, and makes the point that gravity is a minor part of the equation -- the force to be managed and used is centripetal force."

Actually it is the resultant vector of the two accellerations that has to be managed.
At low speeds it is all gravity and at high speeds the vector becomes dominated by centripetal accelleration.
F = M x A ......
 

Mike King

AKA Habacomike
Instructor
Joined
Nov 13, 2015
Posts
2,307
Location
Louisville CO/Aspen Snowmass
"Just to be clear, Tom does not talk about centrifugal force, he talks about gravity and centripetal force, and makes the point that gravity is a minor part of the equation -- the force to be managed and used is centripetal force."

Actually it is the resultant vector of the two accellerations that has to be managed.
At low speeds it is all gravity and at high speeds the vector becomes dominated by centripetal accelleration.
F = M x A ......
Sure, but gravity is a relatively weak force compared to the centripetal force with medium radius turn and relatively slow velocity:

Fc = m v2 / r
 

François Pugh

Making fresh tracks
Skier
Joined
Nov 17, 2015
Posts
3,346
Location
Great White North (Eastern side currently)
In this and other recent threads, I have seen lots of "talk" on managing pressure. Yet, I can't recall the term Centripetal Force being discussed/explained. Why is that?
It's because most people have a very poor grasp of physics, and a little knowledge is a dangerous thing.

Which force is "real" (as real as gravity) and which is fictional depends on the frame of reference being used.

Best to avoid it all-together, unless you are dealing with someone who understands Newtonian physics, nothing to do with advanced theoretical physics, or something you need a degree in physics for, just your basic high school (at least it used to be taught in high school) physics.

BTW the forces have equal weight ( ogwink ) when v^2/r is equal to g. At a speed of ~18 mph in a turn of 7 m radius they are roughly equal, or at ~28 mph in a 15 m turn.
 
Last edited:

JESinstr

Lvl 3 1973
Skier
Joined
May 4, 2017
Posts
595
Just to be clear, Tom does not talk about centrifugal force, he talks about gravity and centripetal force, and makes the point that gravity is a minor part of the equation -- the force to be managed and used is centripetal force.

Mike

Actually it is the resultant vector of the two accellerations that has to be managed.
At low speeds it is all gravity and at high speeds the vector becomes dominated by centripetal accelleration.
F = M x A ......
You are correct and this is exactly what I am trying to address when it come to teaching low end to plateaued skiers.

Sure, but gravity is a relatively weak force compared to the centripetal force with medium radius turn and relatively slow velocity:

Fc = m v2 / r
What kind of answer is that Mike?
Gravity for balance is where the skier begins their learning journey and therefore uses movement patterns relative to that force opening up the door for a life of pushing the ski. Why blow it off as insignificant or is it that in you world, you only deal with advanced tactics?

I agree, don't talk Centrifugal as I believe it is just one's mass trying to return to a straight line path and another reason to push the ski.

And just to be clear, I don't teach physics to my students but I would think that an instructor should have basic knowledge on how the thing they are trying to teach works.
 

geepers

Out on the slopes
Skier
Joined
May 12, 2018
Posts
1,465
Location
Australia
A few years back (before I started doing CSIA courses) they used a skills focused approach with 5 key skills:

Foundation Skills:
  • Stance and balance
  • Timing and co-ordination
Steering Skills:
  • Pivoting
  • Edging
  • Pressure control
These days it's more of a functional focus with the 4 Tech References. These don't include the word "edging" but they do include the word "grip".

Whilst I'm sure there's plenty of CSIA instructors who would be familiar with either the skills or Tech Ref approach you don't have to go too far to find instructors (typically those who have been around a while) unfamiliar with Tech Refs and others (typically slightly newer ones) unfamiliar with the skills based approach. And unless a individual is well versed in CSIA speak it would probably be difficult to know which approach was being used in a lesson.

The CSIA also have a booklet entitled "Science and Skiing" which covers the basics of skiing physics and uses terms like BoS, COM, forces, gravity, GRF, edge angle, angulation, grip, yada yada. It doesn't mention platform angle which is a concept I found extremely useful in helping understand how angulation leads to grip.
 

geepers

Out on the slopes
Skier
Joined
May 12, 2018
Posts
1,465
Location
Australia
Thinking about if you could ski on the moon at 1/6 G....?
Yep, changing the environment can do interesting things to the outcomes.

IIRC the guy who wrote the X-Plane flight simulator posted that he'd spent a few hours virtual flying on Mars. One issue was attempting landings with a 400 mph TAS! (Mars atmosphere is only 1% of Earth so 40 mph IAS === 400 mph TAS).

In the case of skiing in 1/6 gravity.... and here I'm guessing so one of the real physics guys may like to confirm or contradict... acceleration down the fall line would be much slower, the mass of the skier is unchanged so the same centripetal force would be required to carve a turn for a given radius and speed. Since our gravity vector would be substantially reduced but the centripetal vector would be the same as earth we'd need to incline further to balance those forces. I suspect that the same platform angle <90 degrees would apply although it would be more sensitive to angulation.

In the vertical...flex to release would probably rule. There's less gravity holding us on the surface so any force directing an upward movement of the CoM is likely to result in lots of up. Better be super fast to absorb in the bumps for the same reason.:)
 

Mike King

AKA Habacomike
Instructor
Joined
Nov 13, 2015
Posts
2,307
Location
Louisville CO/Aspen Snowmass
What kind of answer is that Mike?
Gravity for balance is where the skier begins their learning journey and therefore uses movement patterns relative to that force opening up the door for a life of pushing the ski. Why blow it off as insignificant or is it that in you world, you only deal with advanced tactics?

And just to be clear, I don't teach physics to my students but I would think that an instructor should have basic knowledge on how the thing they are trying to teach works.
I just love that equation. It is so informative. There's the V squared term, so force isn't linear with speed. There's m in the numerator, so my force is probably twice yours (at least that's were pandemic expansion is taking me). And then there's the r in the denominator, meaning the tighter you go, the greater the force, and it is nonlinear. It explains a lot.

I often teach low to mid intermediates, and I use the two forces that the skier experiences, gravity and centrifugal force, to help them understand the forces they experience in a turn and that they are balancing against.

Mike
 
Thread Starter
TS
Average Joe

Average Joe

Getting off the lift
Skier
Joined
Jul 5, 2017
Posts
313
Some even describe this as "a combination of inclination and angulation" as if we put the skis on edge with the hips and compensate with the shoulders..
So - what is edging? Any combination of foot tipping, inclination of COM and angulation that allows you to create edge angles.
I think that foot tipping, or ankle eversion/inversion, is a critical part of the equation that is commonly missing.

Inclination and angulation, alone or combined, don’t engage the edge without it.

One example of this is a perfectly executed sustained pivot slip on a steep groomer: plenty of inclination, a bit of angulation, and zero edge engagement. The skier that perfectly executes this drill successfully relaxes/ everts/inverts their ankles and maintains a direction of travel down the fall line.

High level racers in a steep, tightly set GS course will sometimes “stivot”, a redirect of their mass/skis into their preferred line before engaging their edges. In slo-mo video we can see quite a bit of inclination and angulation developing as the stivot progresses, well before the ankles and edges are engaged.
 
Last edited:

LiquidFeet

lurking
Instructor
Joined
Nov 12, 2015
Posts
3,321
Location
New England
....
Inclination and angulation, alone or combined, don’t engage the edge without it.
....
High level racers in a steep, tightly set GS course will sometimes “stivot”, a redirect of their mass/skis into their preferred line before engaging their edges. In slo-mo video we can see quite a bit of inclination and angulation developing as the stivot progresses, well before the ankles and edges are engaged.
I am a ski instructor, not a race coach. I can do a beginner's version of a stivot, and a not so bad pivot slip. I've got a question.

While a skier doing pivot slips straight down the fall line can tip the ankles without doing much else and get the skis to cause left-right travel down the hill, ankle-tipping alone isn't how a stivot is converted from a sideways skid to a forward carve, is it? Can your racer's ankles withstand the sudden increase in pressure that ankle-tipping can encounter at the peak of a high speed stivot?
 

Bendzeekneez

Booting up
Skier
Joined
Oct 24, 2019
Posts
19
Location
North
A few years back (before I started doing CSIA courses) they used a skills focused approach with 5 key skills:

Foundation Skills:
  • Stance and balance
  • Timing and co-ordination
Steering Skills:
  • Pivoting
  • Edging
  • Pressure control
These days it's more of a functional focus with the 4 Tech References. These don't include the word "edging" but they do include the word "grip".

Whilst I'm sure there's plenty of CSIA instructors who would be familiar with either the skills or Tech Ref approach you don't have to go too far to find instructors (typically those who have been around a while) unfamiliar with Tech Refs and others (typically slightly newer ones) unfamiliar with the skills based approach. And unless a individual is well versed in CSIA speak it would probably be difficult to know which approach was being used in a lesson.

The CSIA also have a booklet entitled "Science and Skiing" which covers the basics of skiing physics and uses terms like BoS, COM, forces, gravity, GRF, edge angle, angulation, grip, yada yada. It doesn't mention platform angle which is a concept I found extremely useful in helping understand how angulation leads to grip.

Grip and Edging are two completely different things. In my understanding.

Grip is a result and in my opinion a result of good steering skills as you listed, Edging, Pressure, Pivot (I would argue Timing and Coordination and S&B have to play a role as well) and I would disagree that the Technical Reference is more functional focus, it's just more outcome focused.

In my opinion the goal of the ski teacher it to work out simply is what "action" creates the grip for the client. I can create more grip adding angulation and I don't necessarily require angulation for grip depending on speed/turnshape/conditions. I can also create grip through methods that may not be technically sound in traditional ski teaching, however they create "grip".

The CSIA has just tuned in to say we think Angulation is the best way to create grip. How do you angulate? Well utilizing the body, adding new motor patterns...essentially teaching "Edging" from the skill system that you listed before.

But perhaps that client is not ready for "edging" because of a stance issue, if I correct the stance grip will increase as the skier is more comfortable on the outside ski. Therefore I can create grip for that client without talking about edges.

In the end its the 'action' that leads to the outcome, be it "tip the foot more at the start of the arc" or "move the hip inside" etc whatever the teachers and student decide the cue needs to be for them (internal/external/drills/brushes/corridor/thought etc) that will in turn create (relative to the student) higher edge angles and/or better and earlier balance on the outside ski.

It may not be a traditional "edging" move..I can provide more grip if I am balanced to the outside ski earlier in the arc. That's 'timing and coordination" or "pressure control" and 'Grip' as an outcome is relative to the skill level of the student.

This way I feel the CSIA hasn't pigeon-holed teachers to only teach "Edging" and think that that is good enough. Rather give an outcome "Grip" and explore moves, actions, skills or whatever you wanna call them to create that outcome with the client. It allows for much clearer understanding "I want to have more grip on the steep groomed slope" how we get there is up to the student and teacher with the teacher leading the experience, and utilizing actions/skills/drills etc. that actively and directly get the client closer to the outcome.

My point simply though is that the CSIA haven't changed what edging is. It's simply tipping the ski over, we just don't think it's the end goal. We don't call it grip. The two are not necessarily synonymous.

Thanks.
 
Last edited:

karlo

Out on the slopes
Skier
Joined
May 11, 2017
Posts
2,594
Location
NJ
One day, his topic was the physics of skiing. He was about 5 or 10 minutes into his lecture when it became apparent to him that there was a loss of connection with his audience. He asked if everyone was following along and if there were any questions or comments. The reply? "We are physicists from Los Alamos..."
That would be like a video editor watching at a movie, too distracted by all the mistakes to appreciate the story.
 

SkiSpeed

Getting on the lift
Skier
Joined
Aug 17, 2017
Posts
131
Location
VT
Posting a training video from Petra Vlhova; watch her feet, especially during the stubbie flush training set at the end.

 

Members online

Top