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Which foot to pull back? - Page 4

post #91 of 167

Balance

Quote:
Originally Posted by justanotherskipro View Post
Wow! I've never been accused of trying to be perfect. Nothing could be further from the truth though. What I have written here is pretty common stuff that has been around for a very long time. Refining your balancing skills allows you to be more centered more often. Those who can do so all of the time put forth the effort to become that good. Give them their due instead of assuming that something cannot be done because you cannot do it.
Quote:
Originally Posted by Ron White View Post
jhcooley,
I couldn't disagree more, balanced skiing is fluid, exciting skiing. Are you able to swich from carving around a turn, to stepping at any point in the turn you want? Are you able to go from terminal velosity long carved turns to short turns at any time? Able to ski any pitch and snow condition effectivally? If not, there is a big balance issue. Once you can get balanced and keep balanced, skiing gets totally fluid, exciting and dynamic.

Lessons that don't force the student to find balance on skis lead to boring, static skiing. Most recreational skiers are so out of balance they can hardly do any effective movements, only try to make corrective movements. Most ski instructors are in better balance, but few understand how to balance on a ever varing pitch or incline as their skis pass the fall line, leaving them out of balance to make the next turn. The sooner they regnigize it, the sooner they can be on the path to balanced skiing (with some coaching). Hopefully some day you will understand what I'm talking about.

RW
Sigh. I am sorry I have been too rigid in my concept of "balance." I have a technical background, and so I believe that completely balanced forces lead to either
a) no motion at all, or
b) motion at a constant speed in a straight line

Imbalanced forces, on the other hand, lead to acceleration, where "acceleration" is anything that is not a constant speed in a straight line. Imbalanced forces are required in order to gain speed, to lose speed, to turn. As skiers, we create and control (perhaps imperfectly) that imbalance. What we, as skiers, regard as "balance" is actually effective, efficient control of imbalance. Difficulties arise when the magnitude of the imbalance becomes too great relative to the available forces, or when a movement executed to control or alter the state of imbalance is out of proportion to the actual requirement.

I stand by my statement: A graceful, elegant, powerful skier is actually managing imbalance beautifully rather than rigidly maintaining balance.

JASP, I don't think I accused you of trying to be perfect, although this very discussion suggests that we are all trying to achieve some sort of "perfection," at least in our own minds. What you say regarding being more centered more often is absolutely true, but I don't think I've ever seen any skier, including D-team members, who are centered by some absolute standard 100% of the time. Instead, they use forces, movement and, yes, imbalance, to adjust and adapt as necessary and to ski to a very high standard indeed.

RW, in my defense, I've been told by some people who should know that my skiing is, shall we say, decent. Nonetheless, I will confess to rarely being satisfied with it. I'll always find things I don't do very well.

I will also contend that the tasks you suggest require effective creation and control of unbalanced forces so that the skier moves most effectively. This does require balance, in some sense, but not the balance of a perfectly balanced cinder block.

In skiing, when we speak of balance, we tend to think of the location of the CoM relative to the base of support (BoS). At any instant in time, there is some optimal relationship between these two. Further, there are some locations of the CoM relative to the BoS that are nearly always grossly ineffective. My concept of balance in skiing is to move toward the optimal relationship between CoM and BoS. Since it's constantly changing, I will constantly be seeking that optimum, but it's unlikely I'll manage to stay exactly there. Fortunately, there's enough compliance in the system so that being reasonably close will generally serve quite well.

Deb Armstrong once posted in EpicSki (May 25, 2006):
Quote:
Skiing is so athletic, alive, spontaneous, reactive, calculated…all at he same time. However I ski with guests who insist on stopping when they get out of balance because the “made a mistake”. What I love about skiing the bumps, crud or whatever is the moment of being out of balance and working to bring my body back into balance while continuing the run. Inspirational skiing is not always perfect or in balance at every moment yet that skier maintains the ability to bring it all back together on the fly.
JASP himself responded:
Quote:
It reminds me of a good musician vs. a great musician.
The good musicians can play a piece but a really great musician makes it their own by bending the rules a little.
To get back to the original point of this thread, the correct observation by RW that corrective moves would not be necessary if we just stayed centered or "in balance" all the time does not mean that we should not discuss optimal ways of correcting imbalance. To that end, methods and foci proposed by both JASP and RicB are effective with different people in different circumstances. I must admit that I don't understand Mr. Blake's concept of pushing the feet forward and then repositioning the CM over the feet, but that's just me.
post #92 of 167
jhcooley,

Quote:
Sigh. I am sorry I have been too rigid in my concept of "balance." I have a technical background, and so I believe that completely balanced forces lead to either
a) no motion at all, or
b) motion at a constant speed in a straight line
I understand what your concept of balance is, and maybe I should refer to a "balanced skier" as a skier who can use dynamic balancing movements. A novice skier once told me as a lesson began that "I can ski just fine, I just can't stop or turn". It requires much less dynamic balancing movements to ski streight than it does to balance against the forces generated when turning and also encountering an ever increasing pitch as the skis are turned away from the fall line. The for/aft balancing movements are much easier for people to grasp than the lateral balancing issues that are encountered in skiing, combined with the external forces generated while changing direction. It is those 2 factors that gets skiers out of balance. Once skiers can understand the relationship and balancing movements needed to effectivally manage these two factors, they can ski in dynamic balance, and believe me, it's fun to do and fun to watch.

RW

Quote:
but not the balance of a perfectly balanced cinder block.
cinder blocks can't ski or balance unless they stop moving
post #93 of 167
Sorry folks,

There should be no difference in any instructor notion of balance. That there is, identifies a huge problem with ski instruction.....
post #94 of 167
Quote:
There should be no difference in any instructor notion of balance. That there is, identifies a huge problem with ski instruction.....
Maybe not with instruction in general, but with how some instructors teach.

RW
post #95 of 167
JH if you searched further you would see that your definition of balance is similar to mine. Which is why I do not use it very often. Centered, balancing movements, and dynamic balancing are phrases I use all the time. All of them imply a slightly unbalanced state which is necessary for linear and non linear movement, although angular momentum comes to mind as an exception to your definition.
That should not detract from the idea of centered skiing though. In fact,it fits quite well with the quote you used. To expand on the analogy of a great musician, they are bending some of the timing and such but they still remain within the framework of the piece as it was written. Ya gotta know the rules quite well before you know where there is room to bend those rules. Which is why I want to share my version of an absolute standard for this idea. Being balanced and able to access and apply any of the three skills at any point in a turn. Balancing within a zone verses a specific point in space.

Thats about as close as we can come to a Newtonian law of ski motion.
post #96 of 167
Quote:
Originally Posted by justanotherskipro View Post
To expand on the analogy of a great musician, they are bending some of the timing and such but they still remain within the framework of the piece as it was written. Ya gotta know the rules quite well before you know where there is room to bend those rules. Which is why I want to share my version of an absolute standard for this idea. Being balanced and able to access and apply any of the three skills at any point in a turn. Balancing within a zone verses a specific point in space.

Thats about as close as we can come to a Newtonian law of ski motion.
I think we've been down that road before,and I continue to disagree with the bolding. I understand the intent of it, but many folks can pivot, edge and manage pressure all from the back seat. Bode even makes a living at it.

In fact, so long as the vector sum of all forces that might pull me over lies within my base of support, I can apply any of the three skills. So as a "definition" I have to say it misses the mark.

What I really believe people teach when they go down this route is the idea that *being centered* enables the *most efficient application* of the skills. This is closer to a definition, in the sense that the most efficient application of the skills can occur when you are centered.

What I am trying to do here is show that the physical notion of balance does not need to change to accomodate what we do when we are skiing. IMO, the desire to reuse this very specifically defined word in novel ways breeds trouble. Only confusion results when people start to bend definitions to suit their needs.
post #97 of 167
E, I'm glad you brought Bode Miller into this discussion. I would be quick to point out that he has spent a lifetime learning the "rules". When he doesn't finish a race (which is quite often), it's usually because he bent one of those rule too much. I also would offer the idea that a race course is a perfect example of the framework I mentioned earlier. To finish you need to "balance" the riskier maneuvers and tactics with safer maneuvers and tactics.


I guess the paragraph you puled that you pulled the quote from would make more sense if I had used a comma instead of a period between the words turn and balancing. I think we're saying the same thing differently.
post #98 of 167
Here is how I look at it.

Most ski instructors work from the base of support up the kinetic chain and try to balance and move the center of mass via the kinetic chain. This is all fine and dandy on groomers but it still produces a center of mass that follows the feet. With this approach, once the base of support starts bouncing all over the place because of terrain and snow differences the center of mass flow is completely disrupted and the skier is in trouble.

I like to think of letting the center of mass flow freely and use the kinetic chain to coordinate where I want the skis to flow without interfering with the center of mass flow. With this approach the center of mass is always allowed to flow freely and the feet and base of support can bounce all over the place. Dynamic balance is never upset unless the kinetic chain cannot keep up.
post #99 of 167
Quote:
Originally Posted by Pierre View Post
Most ski instructors work from the base of support up the kinetic chain and try to balance and move the center of mass via the kinetic chain. This is all fine and dandy on groomers but it still produces a center of mass that follows the feet. With this approach, once the base of support starts bouncing all over the place because of terrain and snow differences the center of mass flow is completely disrupted and the skier is in trouble.
Can you give us an example of the terrain you are thinking of that causes the BoS to bounce all over the place?
post #100 of 167
Well said Pierre. A lot of good things happen once we recognize momentum.
post #101 of 167
Thousand steps drills come to mind because the core is moving and the legs/feet are doing exactly what Pierre suggests. Some would argue the movement of the feet is the motive force but once in motion is it?
post #102 of 167
Quote:
Originally Posted by Max_501 View Post
Can you give us an example of the terrain you are thinking of that causes the BoS to bounce all over the place?
Stumps, rocks refrozen crud, breakable crust and logs to name a few Max.
post #103 of 167
Quote:
Originally Posted by Pierre View Post
Stumps, rocks refrozen crud, breakable crust and logs to name a few Max.
Thanks Pierre. Now I know what you are talking about.

BTW, from your description above it sounds as though you are releasing the turn without doing anything under the CoM. That's a notion I don't understand.
post #104 of 167
Quote:
Originally Posted by Max_501 View Post
BTW, from your description above it sounds as though you are releasing the turn without doing anything under the CoM. That's a notion I don't understand.
That's a notion you came up with all on your own.
post #105 of 167
Quote:
Originally Posted by jhcooley
Imbalanced forces, on the other hand, lead to acceleration, where "acceleration" is anything that is not a constant speed in a straight line. Imbalanced forces are required in order to gain speed, to lose speed, to turn. As skiers, we create and control (perhaps imperfectly) that imbalance. What we, as skiers, regard as "balance" is actually effective, efficient control of imbalance. Difficulties arise when the magnitude of the imbalance becomes too great relative to the available forces, or when a movement executed to control or alter the state of imbalance is out of proportion to the actual requirement.
Nicely worded jhcooley. This is exactly how I see it too.

The unending debate over a precise definition for "Balance" in relation to skiing is not surprising.

Developing a meaningful definition that correctly applies to all scenarios and works from all perspectives is amazingly complex. In order to simplify our own pronouncements we often cherry-pick mechanical concepts that support our personal perspective while ignoring mechanical concepts that undermine it.


---
Controlling the motion of a Kinda-Falling, Kinda-Sliding object is all about actively managing that object's state of constant imbalance.

The predictive precision with which we manage our state of imbalance in this moment directly impacts our ability to efficiently implement subsequent predictive adjustments. It's not about being precisely in-balance all the time; it's about being as close as possible to the state of imbalance that will most directly morph our body into a position appropriate for the next moment.

Another way to say it is ... our current state of imbalance causes changes to our overall body-position which then falls into a new state over the next moment. That new state is *not* one of Balance in that new location but rather a new state of imbalance - one that will again lead into another re-morphing into yet another imbalanced body position appropriate for yet another future moment ... and so on.

The more actively and rapidly we are morphing, the more imbalance we need to rapidly assume the next necessary position (assuming the next necessary position is not where our existing momentum would otherwise carry us).

.ma
post #106 of 167
On the issue of Pulling The Feet Back... I think we *do* pull our feet back (essentially) in each turn whether we recognize it or not. I also think it’s provable with simple geometry.


Looking at the relevant geometry we can simplify things to a straight run down a brief 45-degree slope and ignore flexion / extension movements as well as turning considerations for the moment. Consider the Image below (CM=Blue dot, BoS=Red dot)...

Attachment 2577

In the image above our skier travels over flat terrain, down a 45-degree slope and then back onto flat terrain. In order to be in balance at position ‘A’ the skier must have their CM ‘over’ (in a vertical sense) their Base-of-Support. Likewise at position ‘C’.

In order to be in balance at position ‘B’ the skier must have their CM / BoS relationship in the position shown - essentially along a line perpendicular to the slope (due to the down-slope acceleration they are experiencing). The skier at position ‘B’ must maintain this CM / BoS relationship until the slope angle changes again at the bottom of the hill.

The question is: How does this skier change their CM / BoS relationship to accommodate the necessary relationship changes from ‘A’ to ‘B’ and on to ‘C’?

---
The idea that we move our CM forward in relation to our feet is attractive because we perceive that we’re moving our upper body forward of our feet (as well as laterally) at the start of each new turn (the ‘Diagonal Move’). This CM-Forward concept is depicted in figure ‘A’ below.

Attachment 2578

In figure ‘A’ the skier tries to rotate forward from their feet - but this isn’t mechanically realistic for a freely-sliding skier.

In order to actively drive our CM forward (leaving our feet where they are) we’d need to push back against something stable under our feet. In the real world of skiing we have very little friction underfoot so any attempt to drive our feet backward against the snow will actually result in our feet being driven back (in relation to our overall Mass).

The concept of pulling our BoS (feet) Backward is depicted in figure ‘B’.

In figure ‘B’ the skier rotates about the CM - a much more realistic scenario for a freely-sliding skier.

An action like dorsiflexion tries to rotate our skis in the F/A plane about an axis within our ankle. This ankle rotation drives our ski-tails downward against a firm surface. If we’re not moving then Static Friction may be enough to keep our skis right where they are and the torque created will be strong enough to cause our upper body to be driven forward.

But if our skis are sliding forward over a low friction surface our large upper-body Mass will resist being driven forward while our freely-sliding feet will easily slow their forward progress instead - causing us to rotate about our CM.


Looking at the typical ski turn we have essentially the same situation. A long radius turn going from traverse to traverse on a 45-degree slope is very much like the image above. At either transition our skis are perpendicular to the pull of gravity - just as on the flat slope depicted in the image. At Apex our skis are pointing down a 45-degree slope just as in the image.

Of course, in the image I drew a rapid slope-angle change over a short distance. In a long radius turn the slope-angle underfoot changes more slowly over time - somewhat hiding the progressive Fore/Aft angle-change that our skis undertake from our perception.


Finally, lateral movement at transition also contributes to our F/A position at Apex making some of our active F/A adjustment unnecessary. The shorter the turn, the more easily/efficiently lateral movement converts into our next necessary F/A position.

Consider a stationary skier leaning on their poles 45-degrees sideways (downhill) with their skis across the slope. The skier suddenly pivots their skis from across the slope directly into the fall-line. Since their body was already tipped 45-degrees downhill they needn’t make any F/A adjustments to be in F/A balance - their body is already perpendicular to the slope. In such a case the skier needn’t implement ‘pulling the feet back’ because all necessary re-positioning was created via earlier lateral motion.

.ma
525x525px-LL-vbattach2577.jpg
525x525px-LL-vbattach2578.jpg
post #107 of 167
michaelA, good postings and good picks. The whole consept of pulling the feet back underneath is very strange consept to me. Never thaught about it that way. To me it is completely logical that when we are flexed and unweighted during transition we eather fold over with out upper body to compensate for our butt pointing backwards or we simply accept to be slightly in the back seat. It really does not matter because as we extend into the turn and pressure increases we reposition over our BoS.

Like this:

http://ski.topeverything.com/default...nt&ID=ED+A+01E
post #108 of 167
tdk6,

No doubt a lot of people will look at the diagrams and while the 2-dimensional geometry is unassailable they will still know something’s not quite right in comparison with what they themselves do so successfully.

I posted images of a 45-degree slope to magnify the change in F/A vs. BoS position. On milder slopes this relationship-change still exists but the complexity described in my last two paragraphs above kicks in to hide (even eliminate) the need to actively pull (or hold) our feet back. I think this is where the disconnect will occur. In the 3-D world we have lateral motion converting into F/A motion during a turn.

In virtually every turn we come out of our old turn with at least some lateral momentum - that which is driving crossover. This down-slope-component of our upper body momentum continues to carry our upper body downhill even while our skis travel a bit further across the hill. In effect we’ve created some down-slope rotation of the upper body that we turn into with our skis.

If we successfully predict the exact amount of down-slope CM movement we’ll need for… the given slope, given turn radius, and given speed and we launch ourselves across our skis with exactly that amount; then we end up moving gracefully in F/A balance thru the entire turn.

If we guess incorrectly… speed up more than expected, change our radius, fail to judge snow conditions ahead, or just miss on timing; then some active movement is needed to correct the situation. I think this is 99.99% of all turns in skiing.

---
I’m still trying to develop a clear explanation (without math) to describe the nature of what really happens in rotational transformations between F/A and Lateral balance down a curving path with increasing, then decreasing acceleration… but it quickly turns into a myriad of mutual dependencies.


As to which foot to pull back, I think the best answer (generally) is both. To refine it further though, I think I’d focus on the needs of our particular turn-entry technique. At turn-entry we’re just beginning to accelerate and turn downhill so the more important foot to ‘have back’ is the foot that is supporting most of our weight.

If we start a new turn with weight remaining on our old Outside-Foot then that foot should remain behind our CM. If we choose to step quickly onto our new Outside-foot then that foot must be behind our CM to remain in F/A balance. We can never step primarily onto a foot in front of us and expect to remain in F/A balance.

If our Inside-Foot sneaks forward a lot, that’s probably OK if we’re not using it to support us while it’s out there. If we want to get more use out of that Inside-Ski then it makes sense to pull that foot back to where we can put weight on it without compromising F/A balance.

.ma
post #109 of 167
From my standpoint, it is the difference between proactive and reactive skiing. The proactive skier puts the feet where they need to be not only at any one time, but is anticipating where they need to be next. A reactive skier is trying to get the feet where they should be more as a recovery movement. The reactive skier is doing balancing movements, but a little after the fact where the proactive skier's balancing movements are what moves the CM, and, or keeps it over and between the feet.

In the case of MichaelA's diagram, how many good skiers bother or would even try to change the body position as they ski from the top of one bump, down the back, to the top of another? Would they be better off keeping the body at one position and pressing the tips down as they ski down the back (while extending) and then flexing as the skis follow the terrain to the flatter top of the next bump? The same idea holds true when entering a half pipe from the coping (side).

RW

RW
post #110 of 167
They'd be better off pulling the feet back at transition and holding them back.
post #111 of 167
Mike,
Where to start,
1. I would start with the idea of ignoring turning and pressure control movements (flexing and extending). It's a bad assumption. Warren Miller has a lot of footage of inanimate statues sliding down the hill. Crashing is always the outcome because the statue cannot flex / extend, or turn, or adjust their stance in any way. Which would be my question to you. How in the world would you pull the feet back or move the CoM forward without any change in the body's geometry? It simply can't be done.
2. The USSA and many other national ski federations have commissioned studies by some of the top Kinesiologists in the world. Some of those studies have been published in coaching magazines over the years and I must say none of them are as simple as yours. Which brings up another question for you, If it was so simple why are their studies so complex?
post #112 of 167
Quote:
Originally Posted by Ron White
The proactive skier puts the feet where they need to be not only at any one time, but is anticipating where they need to be next. A reactive skier is trying to get the feet where they should be more as a recovery movement.
And this (I think) is the key concept related to learning to balance while skiing and why so many people take so long to gain the capability to balance properly.

Anyone who expects to 'feel' their state of balance and make proper adjustments as their felt-state changes is already too late. Only after many miles of experience does the skier begin to *anticipate* their balancing needs and make proactive movements rather than attempting to 'feel' the changing situation and adjust to it.

I know a lot of skiers believe they keep in balance purely by feel - but I suspect their feeling of being in balance is actually a result of having made the right movements earlier.

.ma
post #113 of 167
JASP,

When analyzing a complex situation it's much easier to eliminate unnecessary components and focus on key aspects than to try and incorporate every known component in a Theory-of-Everything.

Eliminating Flex and Extend is a simple and effective way to filter out distractions not strictly relevant to the point being explored.

On your first question...
I've not seen the hollywood entertainment film you refer to about Statues. Still, I'd guess the clips shown were of the best crashes rather than the Statues that successfully navigated the slope. Also, the specific reason a particular Statue falls over may be entirely unrelated to a lack of Flexion and Extension. In any case, it doesn't sound like any sort of controlled experiment and is irrelevant to the concepts described above.

Quote:
Originally Posted by JASP
How in the world would you pull the feet back or move the CoM forward without any change in the body's geometry?
I did specify Dorsiflexion at some point, didn't I? Also, even a Statue will re-orient itself forward (effectively 'pulling it's feet back') if you simply consider the change in CM / BoS position seen from points 'A' to 'B'. For a truely rigid body, the changing slope surface itself (combined with gravity) re-orients the Statue forward.

On your point #2...
I've no idea what studies you are referring to. As I said above a complete analysis of balance is quite complex but the concepts I presented above really are quite simple.

You seem to be categorically objecting to what I posted earlier. Can you be specific about your own mechanical or biomechanical objections?

.ma
post #114 of 167
Sight is a big part of that anticipation, which is why I feel blind skiers are so remarkable. While they have verbal cues provided by a coach, it's all about feel for them. Balancing blindfolded is about as close as I can come to what they do but even then I rely on muscle memory learned as a sighted skier.
post #115 of 167
I've actually tried skiing with my eyes closed on a mild, well groomed slope. Not to difficult (though unnerving). Once I got into even slightly-lumpy terrain I found it very difficult.

As you say, sight is everything when talking about anticipation of upcoming terrain changes. Not so much when executing systematic turns in predictable terrain.

.ma
post #116 of 167
Ya Know...

I wonder if a pair of really long ski poles with skids on them might help a blind skier anticipate terrain changes better...?

If the skier kept the skids on the snow just in front of the ski tips this might provide just enough advance notice of a drop or bump ahead to make appropriate changes to their F/A balance situation.

.ma
post #117 of 167
FYI,
The assumptions you used (eliminating all flexing, extending, and turning) make the model unrealistic. Then you ignored your assumptions by adding dorsiflexion. Changing your parameters halfway through means the original assumptions are not being observed and this makes the conclusion invalid.
On to the biomechanics, We maintain an upright stance (regardless of the activity) by a combination of muscles firing and the joints moving. We do not ski or even stand like a rigid statue. Which is why creating a representative model needs to include all of the movements we make while skiing.
Insofar as the feet being pulled back when a statue goes over the break, it is a combination of gravity pulling down on the object and the tail being the last part of the ski to go over the break. The CoM of the statue falls forward (tip offers no resistance) and the tail acts as a lever pushing the CoM forward as well. The pivot point cannot be up at the CoM, it is down at the snow.
The original question of which foot do I pull back assumes joint movement so I do not see the relevence of a rigid statue on skis. With all due respect I feel your analysis is too simplistic and you need to remain within the parameters you set at the outset. That being said I must I love to read your posts even when I disagree with them...
post #118 of 167
Quote:
Originally Posted by Pierre View Post
Here is how I look at it.
...

I like to think of letting the center of mass flow freely and use the kinetic chain to coordinate where I want the skis to flow without interfering with the center of mass flow. With this approach the center of mass is always allowed to flow freely and the feet and base of support can bounce all over the place. Dynamic balance is never upset unless the kinetic chain cannot keep up.
Quote:
Originally Posted by Ron White View Post
From my standpoint, it is the difference between proactive and reactive skiing. The proactive skier puts the feet where they need to be not only at any one time, but is anticipating where they need to be next. A reactive skier is trying to get the feet where they should be more as a recovery movement. The reactive skier is doing balancing movements, but a little after the fact where the proactive skier's balancing movements are what moves the CM, and, or keeps it over and between the feet.
Yes. And I believe that this is what Pierre is talking about, from the perspective of a proactive skier. He anticipates what is required to keep the relationship between his CoM and his BoS near some optimum, and moves his BoS as required to allow his CoM to flow easily down the hill. The BoS may "bounce all over the place," but Pierre is directing it.

Of course, the "optimum" relationship may be modified by intent.

Quote:
Originally Posted by Ron White View Post
In the case of MichaelA's diagram, how many good skiers bother or would even try to change the body position as they ski from the top of one bump, down the back, to the top of another? Would they be better off keeping the body at one position and pressing the tips down as they ski down the back (while extending) and then flexing as the skis follow the terrain to the flatter top of the next bump? The same idea holds true when entering a half pipe from the coping (side).

RW
I'm not sure, but I think you're saying the same thing as Pierre (or maybe I'm way off in left field). Allow the CoM to flow and move the BoS to achieve efficiency, effectiveness and intent.

We might note that it is far easier to press the tips down as one skis down the back of a bump if the relationship between the CoM and the BoS does something like what MichealA's admittedly simplified diagram shows - that is, the line from the BoS to the CoM remains roughly perpendicular to the back of the bump. If that line ends up leaning uphill, it's difficult to keep the tips down, and all movements after that are reactive until the relationship between the CoM and the BoS is once again made reasonably effective, one way or another.

And JASP suggests some mechanics that should make it a bit easier to maintain an effective relationship between the BoS and the CoM, if only we allow it, instead of leaning back up the hill as we go over the drop, which is what many skiers do, as we know.

Quote:
The CoM of the statue falls forward (tip offers no resistance) and the tail acts as a lever pushing the CoM forward as well.
JASP, I realize that we don't ski like that, since we aren't statues - but we could allow the phenomenon you describe to give us a little help. A little anticipation here, a little functional tension there, and let gravity do the rest. Stay in the effective zone, but recognize that the zone is not a single point.

And if we get out of the zone, what's the best way to catch up? Sometimes, it really might be a matter of pulling the feet back a little to let the body catch up. But not always. Different turns, different conditions, different circumstances.
post #119 of 167
No hill too fast is a book that was written back in 1985. In it the Marhes propose a variety of exercises to promote a centered stance.
Two ideas they propose are still very relevent some twenty years later.

"The first step in integrating the movements of skiing is to allow the skier to feel a natural stance. Many of the exercises we have shown in this section are designed to help you find your most stable and comfortable body position. This is especially important because every human being has a slightly different natural and balanced body position." (pg. 75)

"By exaggerating forward and backward body positions, moving in and out of balance on the ski, we can feel what is awkward and unnatural and what is comfortable and correct. The modern ski is made in such a way that the skier can find a natural stance centered over the middle of the ski." (pg 58)

This strong focus on moving the core around until we find that Goldylocks zone (the just right place on the skis) is even more important on today's shorter skis because they offer less fore/aft range. Once we establish that zone and learn how to maintain it by projecting the core where it needs to go, the rest is pretty easy.
So while I agree that pulling the feet back is a useful corrective maneuver in some situations, far too many skier rely on it as a default move in every turn they do. If they would just allow their core to keep moving they wouldn't need to use the pull back the feet move very often.
post #120 of 167
BTW, Which move would you guys use to get off a chairlift?
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