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Where's your butt?

post #1 of 77
Thread Starter 

Hey all,

 

Something that I've been pondering lately now that there's no snow to test with--in your skiing, where is your butt (or hips) during each phase of the turn relative to the rest of your body, and why? What's the angle, and how far inside or outside of the turn do you keep it?

 

Lastly, are there any dangerous places for your hips to be? E.g. any positions that would encourage or trigger an ACL tear?

post #2 of 77

Walk the path of a normal carved turn on skis. Take note of where your hips are in relation to the foot that you are balancing on. Where are your hips while walking in a normal balanced position? How about if you were to jog/run the same path?

 

That's a good place to start.

post #3 of 77

For efficient skiers, one can use the butt position as a proxy for the center of mass. The lateral angle relative to the feet becomes an approximation of the desired edge angle. The fore/aft relationship to the feet is approximately centered when the skis roll flat, fore above the fall line and aft below the fall line, but the range of movement and timing can vary based on intent (e.g. shooting the feet way ahead to increase ski/snow contact when navigating a gap between bumps, controlling speed in gates).

 

Hips below the knees and behind the heels are contributing factors to ACL injuries.

post #4 of 77

metaphor, good question. I have always been telling my students to point their butt uphill. Not backwards in the direction of the ski tails. That is a trigger for hip rotation, low edge angles and skidding tails (se my video). Depending on what you want to do offcourse but the general rule is to put your hips in a favorable position so that skis are performing as desired and you are in balance. Pointing your butt uphill can sometimes be easier to understand than the words counter and anticipation. Take a look here at my favorite photo montage of how to point your butt uphill:

 

RonLeMaster Tanja.jpg

 

When it comes to the risk of injury I think that the second last frame gives us a pritty good estimate of when and where there is a obvious danger for excessive loding of the knee ligaments and possible ACL injury. Like therusty said, hips below the knees and behind the heels. Its a matter of timing involving rebound and float but not even wc racers get it right all the time.

 

Like noted here before, when pressure is on, your butt and hips need to be aligned so that turn forces and gravity are balanced. That means that during the pressure phase of the turn your hips and butt are way inside the turn and at transition when the skis are flat your hips and butt are aligned over your skis. In Tanjas case in the plane of the sum of the forces her hips and butt are aligned over her feet during the pressure phase and behind her feet during the transition and float.

post #5 of 77
Thread Starter 

Thanks guys :) Great ideas... your "butt" is really just an easy pointer to direct your hips. a lot of people have a concept of where their butt is! tdk, great montage.

post #6 of 77


 

Quote:
Originally Posted by tdk6 View Post

metaphor, good question. I have always been telling my students to point their butt uphill. Not backwards in the direction of the ski tails. That is a trigger for hip rotation, low edge angles and skidding tails (se my video). Depending on what you want to do offcourse but the general rule is to put your hips in a favorable position so that skis are performing as desired and you are in balance. Pointing your butt uphill can sometimes be easier to understand than the words counter and anticipation. Take a look here at my favorite photo montage of how to point your butt uphill:

 

RonLeMaster Tanja.jpg

 

When it comes to the risk of injury I think that the second last frame gives us a pritty good estimate of when and where there is a obvious danger for excessive loding of the knee ligaments and possible ACL injury. Like therusty said, hips below the knees and behind the heels. Its a matter of timing involving rebound and float but not even wc racers get it right all the time.

 

Like noted here before, when pressure is on, your butt and hips need to be aligned so that turn forces and gravity are balanced. That means that during the pressure phase of the turn your hips and butt are way inside the turn and at transition when the skis are flat your hips and butt are aligned over your skis. In Tanjas case in the plane of the sum of the forces her hips and butt are aligned over her feet during the pressure phase and behind her feet during the transition and float.


I like to think, not in every occasion, to sit on a race motorbike...Look how they move their butt inward, into the turn (of course that's to help them turning the bike) and their shoulders...
 

post #7 of 77
Quote:
Originally Posted by Nobody View Post


I like to think, not in every occasion, to sit on a race motorbike...Look how they move their butt inward, into the turn (of course that's to help them turning the bike) and their shoulders...
 



Yes, the bicers do it too. Their problem thou is that they cannot flex through the transition. They are forced to vault over. This is a serious limitation when they have to turn quickly back and forth.

post #8 of 77

 

Quote:
where is your butt (or hips) during each phase of the turn relative to the rest of your body, and why? What's the angle, and how far inside or outside of the turn do you keep it?

The only place this can be defined is during the instant the skis are released from the snow between the end of one turn and the beginning of the next turn.  The hips are directly over the feet then.  During the turn the hips must be inside the feet, but the extent of that is totally dependent of the skier's use of angulation, the desired edge angle, the speed of the skier, and the radius of the turn.  The skiers center of gravity is above the hips, about in the area of the upper abdomen.  For a turn of a given radius and speed the center of gravity will always be on the same line from the feet.  On the same radius and speed of turn, if the skier has more angulation for more edge angle the hips will be more inside.  If the skier has more inclination the hips will be less inside.

 

Where is the COG in each phase of the turn?  Again, depends on skiing style.  An effective carver will have the edge angle increasing all the way through the turn to handle the increasing forces, and the hips must drop farther inside to achieve these angles (no, not forcing the hips in & down, but allowing them to drop).  A skidder with flat skis on the snow won't, can't, ski this way.  A really, really, really good skier making GS or bigger turns may incline in the first part of the turn keeping the skis on less of an angle for speed, then make a sharp change to angulation for edge angle to carve through a gate at the end of a turn.

post #9 of 77

Regarding how much hip angulation is used I think the determining factor is whether you want to edgelock or not. Early in the turn edgelock is usually not desired (at least in racing), and therefore more inclination is used. Later in the turn when the direction is ok and edgelock is desired the hip must be further inside the turn. I made the following picture to illustrate this.

 

Assuming for simplicity that all weight is on the outer ski, is it clear that in the left picture the gravity/acceleration/normal force will drive the ski up in the snow and cause a skid, whereas in the right picture the force will push the ski down in the snow. If the forcevector is outside the leg inclination edgelock is achieved.

Edgelocked vs not edgelocked.jpg

post #10 of 77

Jamt, good graphics. I however do not quite agree with you regarding the edge lock early in the turn. I find it very important to lock my edges early in the turn. That is not always possible but that is more a question of skill than tactics. If I compare myself and other averidge masters in GS to young good FIS skiers on a race course, we run at same races, the FIS racers ski with higher edge angles and they carve edge locked more. Sometimes every inch of the course. And they are much much faster. We are more upright like you left picture. The young racers like the one to the right. One thing is clear though. They all incline a lot. They have such high edge angles that they cannot level their shoulders without seriously countering and braking at the waist. They do not do that however. They drop their inside shoulder. And they do not need to angulate a lot at the top of the turn. They get away with inclination without skidding. In SL its the same. Although they here skidd more of the top part of the turn. However, they are in the air most of the time when they do this.

 

The big challange is to keep your skis locked in a carve. On a race course its 100 times harder than it is while free skiing because you dont know where exactly your ski tips end up when passing the gate 10cm away, 12m further down the slope at 40kmh. And in GS you need to ski further away from the gate in order to let your body pass arround the gate.

post #11 of 77
Quote:
Originally Posted by tdk6 View Post

Jamt, good graphics. I however do not quite agree with you regarding the edge lock early in the turn. I find it very important to lock my edges early in the turn. That is not always possible but that is more a question of skill than tactics. If I compare myself and other averidge masters in GS to young good FIS skiers on a race course, we run at same races, the FIS racers ski with higher edge angles and they carve edge locked more. Sometimes every inch of the course. And they are much much faster. We are more upright like you left picture. The young racers like the one to the right. One thing is clear though. They all incline a lot. They have such high edge angles that they cannot level their shoulders without seriously countering and braking at the waist. They do not do that however. They drop their inside shoulder. And they do not need to angulate a lot at the top of the turn. They get away with inclination without skidding. In SL its the same. Although they here skidd more of the top part of the turn. However, they are in the air most of the time when they do this.

 

The big challange is to keep your skis locked in a carve. On a race course its 100 times harder than it is while free skiing because you dont know where exactly your ski tips end up when passing the gate 10cm away, 12m further down the slope at 40kmh. And in GS you need to ski further away from the gate in order to let your body pass arround the gate.


I dont wnat to put words in people's mouths...but I am pretty sure when Jamt refers to "edge lock" he is using another term for "park and ride".  The term  "edge lock" is somtimes used refering to in "park and ride" the edge angles cannot be adjusted, or feathered...the skier or the edges are just "stuck" or "locked".
 

post #12 of 77

TDK, I agree that early edge lock is essential. The edges should be locked as soon as possible, but what I was trying to say that in todays race courses it is not possible carve cleanly, you have to steer the skis in most turns, and if the skiis are edged too much in that phase they may lock too early with an undesired result.

 

Skidude, I don't think that locked edges and park and ride necessarily are the same. The edges can be locked in very dynamic turns.

post #13 of 77
Quote:
Originally Posted by Jamt View Post

TDK, I agree that early edge lock is essential. The edges should be locked as soon as possible, but what I was trying to say that in todays race courses it is not possible carve cleanly, you have to steer the skis in most turns, and if the skiis are edged too much in that phase they may lock too early with an undesired result.

 

Skidude, I don't think that locked edges and park and ride necessarily are the same. The edges can be locked in very dynamic turns.


Ah yes, sorry just picked up on it....Sweden...Finland.  I will leave you two to it.
 

post #14 of 77
Quote:
Originally Posted by Skidude72 View Post




I dont wnat to put words in people's mouths...but I am pretty sure when Jamt refers to "edge lock" he is using another term for "park and ride".  The term  "edge lock" is somtimes used refering to in "park and ride" the edge angles cannot be adjusted, or feathered...the skier or the edges are just "stuck" or "locked".
 


Locking the edges and carving down a slope at any speed is far from park and ride.

post #15 of 77
Quote:
Originally Posted by Jamt View Post

TDK, I agree that early edge lock is essential. The edges should be locked as soon as possible, but what I was trying to say that in todays race courses it is not possible carve cleanly, you have to steer the skis in most turns, and if the skiis are edged too much in that phase they may lock too early with an undesired result.

 

Skidude, I don't think that locked edges and park and ride necessarily are the same. The edges can be locked in very dynamic turns.


I agree with you that you cannot carve cleanly but not that you cannot carve cleanly "most" of the turns. Depending on the course setter offcourse. When I set courses I try to set them so that most can be carved especially on a flatter part of the course. But the better you become the more you carve cleanly. Looking at the skiers its easy to see that the lower level skiers all skidd their turns even on the flat. They stand upright and they point their butt backwards towards the ski tails. The good skiers lock their edges straight after edge transfer and they offset their body much further inside the turn. Hips almost touching the snow. And they are one gate ahead after 4-5 gates. Look at Tanja in the photo montage. No skidding or steering. Edge to edge carving.

post #16 of 77

Maybe its a bit picky, but even in the clean carve of Tanja there is a slight pivot between frame 1 and frame 2. Very early edge lock though.

The following is a good winning WC example where hardly any of the turns can be carved cleanly. Usually men have a harder time carving cleanly in the WC.

Maybe its a matter of definition also, does pivoting during transition constitue a non-clean carve?

post #17 of 77

Jamt, you are offcourse right. In that video he is not carving arc to arc. But it is a steep part of the track. Do not focus on the steep difficult part of the track. Consentrate on the easy parts. Thats where you are able to develop technique and skill and gain valuable speed and cut time. Its for that part of the track that the skis are optimized. On the steeper parts of the track its more a question of athletisism. Check this video out:

 

 

Note that even if he is airborn and pivots his skis in the air and skidds sideways as he lands he still hooks his edges up early on. ASAP. And many times at the same time he lands. If you look at the above video note that its arc to arc skiing. If you dont see this, and Im not saying that in a ranting manner, then you need to look closer. And remember that this guy is the Nadal of skiing.

 

Also, there is no pivot in the Tanja photomontage. No no no. Thats as clean as it gets. She is winning wc races. She is skiing very fast on icy hard surface. For sure there is a pivot every now and then but not in that photo. Not one to mention anyway.

post #18 of 77

When I use the term "edge lock", it's meaning precludes dynamic skiing. To me edge lock implies a period of maintaining a consistent edge angle (aka park and ride). I can see how others could view edge lock as the engagement of the edges into a carve and that the edge is "locked" as long as there is no skidding. Whatever.

post #19 of 77

Maybe Edge lock was not a good term to use, what I meant was a state where excessive angulation prevents any type of pivoting. My bad.

 

TDK, I think we agree on the carving turns, its just a matter of terminology. When I said carve cleanly I was meaning edge-to-edge carving, i.e. no pivoting between turns. I fully agree with you however that there is a lot of clearn carving going on in the racetracks, and usually with a variable amount of pivoting between the clean arcs.

 

I do not agree that there is no pivoting in Tanjas picture though. I'm not aguring that there is anything wrong in her technique, but there is pivoting. I'll let the following image with a curve projected on the inner edge at the tail of the skis speak for itself. Not a lot, but its there.

 

Tanja.jpg

post #20 of 77

Jamt, we have the exact same definitions to edge lock and carving. Its just that the way the terms are used is confusing. Thanks for the above pickture. It is indeed interesting to see that there is a glitch in her arc to arc skiing. And you are right. There is a small pivot. I stand corrected. But, do you think it was a pivot on purpose or was it just something that happened as a result of flying over the icy surface with her skis not really on edge as she was kind of floating? It certainly is noting like what Hirscher was dooing in that video you posted.

 

To get back to the original topic, can you give your viewpoints on where the butt is supposed to be? Start with the video you posted of Hirscher.

post #21 of 77

I don't think that Tanjas small pivot is intentional, its more due to the float.

 

My view on the butt position is that before the fall line it should be almost square to the skis and forward (force passing very close to the edge of outer ski, partly due to extension), after the fall line it moves more inside and back due to the counter needed (and also to avoid the gate), but I think it is important also here to avoid too much hip angulation. Too much angulation gives more force on the outer ski, and this produces an arc which is sharper after the fall line, whereas for optimal speed the desire is to have the sharpest part earlier. Less angulation distributes the force more between the skis, and this also gives a natural transition into the next turn.

post #22 of 77
Quote:
Originally Posted by Metaphor_ View Post

Hey all,

 

Something that I've been pondering lately now that there's no snow to test with--in your skiing, where is your butt (or hips) during each phase of the turn relative to the rest of your body, and why? What's the angle, and how far inside or outside of the turn do you keep it?

 

Lastly, are there any dangerous places for your hips to be? E.g. any positions that would encourage or trigger an ACL tear?

 

my axis of balance is in line with my base of support throughout the turns.  This means when the skis are accelerating my axis is moving ahead and inside of my BOS and when my skis are decelerating my axis moves inside and behind my BOS.

 

We need to balance against the forces of the turn and gravity.  It is really quite simple if you can visualize your COM must stay in line with the pull of the combined forces.  As we ski down the hill we accelerate and decelerate with every turn.  The better we balance these forces by knowing when to resist and when to submit the more fluid our descent down the hill.  How far our hips move inside is relative to our balancing needs determined by the magnitude of the forces present, and is a more intuitive than cerebral activity. 
 

Interestingly it would seem the lateral balance (similar to a cycling turn) is easier for people than the fore/aft component.  Because of the terrain, and snow variations the fore/aft balancing is a bit more challenging, certainly more so than cycling.


Edited by bud heishman - 9/16/10 at 9:58pm
post #23 of 77
Quote:
Originally Posted by Jamt View Post

I don't think that Tanjas small pivot is intentional, its more due to the float.

 

My view on the butt position is that before the fall line it should be almost square to the skis and forward (force passing very close to the edge of outer ski, partly due to extension), after the fall line it moves more inside and back due to the counter needed (and also to avoid the gate), but I think it is important also here to avoid too much hip angulation. Too much angulation gives more force on the outer ski, and this produces an arc which is sharper after the fall line, whereas for optimal speed the desire is to have the sharpest part earlier. Less angulation distributes the force more between the skis, and this also gives a natural transition into the next turn.


Isnt it the opposite way arround... if you want to avoid the gate then you should not project yourself and your butt inside the turn? IMO you do that to balance the turn forces. To avoid hitting the gates in GS/SG/DH you need to arc as far away from them as necessary. In order to fit yourself between the skis tracking in the snow and the gate. Or then you choose to hit the gates with a certain part of your body. Or is this part of why you use angulation?

post #24 of 77
Quote:
Originally Posted by bud heishman View Post

 

my axis of balance is in line with my base of support throughout the turns.  This means when the skis are accelerating my axis is moving ahead and inside of my BOS and when my skis are decelerating my axis moves inside and behind my BOS.

 

We need to balance against the forces of the turn and gravity.  It is really quite simple if you can visualize your COM must stay in line with the pull of the combined forces.  As we ski down the hill we accelerate and decelerate with every turn.  The better we balance these forces by knowing when to resist and when to submit the more fluid our descent down the hill.  How far our hips move inside is relative to our balancing needs determined by the magnitude of the forces present, and is a more intuitive than cerebral activity. 
 

Interestingly it would seem the lateral balance (similar to a cycling turn) is easier for people than the fore/aft component.  Because of the terrain, and snow variations the fore/aft balancing is a bit more challenging, certainly more so than cycling.



I think Metaphor was looking for butt specific information.

post #25 of 77

Tdk and Jamt why do we incline at the top of the turn again?  Why do we angulate more toward the last phase of the turns?  Think you may be missing some important stuff here?

post #26 of 77
Quote:
Originally Posted by Jamt View Post

Regarding how much hip angulation is used I think the determining factor is whether you want to edgelock or not. Early in the turn edgelock is usually not desired (at least in racing), and therefore more inclination is used. Later in the turn when the direction is ok and edgelock is desired the hip must be further inside the turn. I made the following picture to illustrate this.

 

Assuming for simplicity that all weight is on the outer ski, is it clear that in the left picture the gravity/acceleration/normal force will drive the ski up in the snow and cause a skid, whereas in the right picture the force will push the ski down in the snow. If the forcevector is outside the leg inclination edgelock is achieved.

Edgelocked vs not edgelocked.jpg


Like the diagram but not so much the reasoning!

post #27 of 77
Quote:
Originally Posted by tdk6 View Post




Isnt it the opposite way arround... if you want to avoid the gate then you should not project yourself and your butt inside the turn? IMO you do that to balance the turn forces. To avoid hitting the gates in GS/SG/DH you need to arc as far away from them as necessary. In order to fit yourself between the skis tracking in the snow and the gate. Or then you choose to hit the gates with a certain part of your body. Or is this part of why you use angulation?

I simply meant that part of the reason you counter is to be able to ride close to the gate, if you only incline you have to position the skis further from the gate.
 

post #28 of 77
Quote:
Originally Posted by bud heishman View Post

Tdk and Jamt why do we incline at the top of the turn again?  Why do we angulate more toward the last phase of the turns?  Think you may be missing some important stuff here?


You incline becuase of centripetal forces. About angulation in the latter part of the turn I think a better expression is counter. You counter in order to rise again, it does not necessarily mean that you put the hip closer to the ground which is normally associated with angulation.

post #29 of 77
Quote:
Originally Posted by bud heishman View Post




Like the diagram but not so much the reasoning!


What part of the reasoning?

 

The article "inclined to win" by Greg Gurshman is a really interesting article on this subject. (over at youcanski.com)

post #30 of 77
Quote:
Originally Posted by bud heishman View Post

Tdk and Jamt why do we incline at the top of the turn again?  Why do we angulate more toward the last phase of the turns?  Think you may be missing some important stuff here?


Angulation is an interesting thing. It does not always mean a sideways bend at the hip. Knee angulation for instance does not mean that the leg would be bending sideways at the knee. This is the reason that "counter" in combination with a braking at the waist is also called angulation. But it is not sideways bending at the hip. So it looks like the skier is angulating more after apex when he in fact is countering. Right?

 

So, why do we incline at the top of the turn? We need to create edge angles in order to turn. And we need to lower our CoM and project our body inside the turn to resist turn forces as they kick in. Its a living on the edge thing. As we project ourselves inside the turn we literally fall because there are not enough turn forses built up jet.
 

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