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Ski/boot lateral balance - static vs. dynamic and other thoughts

post #1 of 23
Thread Starter 

I'm really wrestling with the whole concept of how lateral balance in skiing should be tested and what should be considered "in balance".

 

My consternation stems from recently having new custom footbeds built and from the concepts coming from Eric Ward's Shim Balance System.

 

Part of the alignment process during my custom footbed session included some "static" balancing maneuvers while in ski boots.  They tested my balance while lifting one booted leg and standing on the other.  I was told to keep the lifted leg hanging to my side.  Well surprise, surprise I fell over to the side of the lifted leg.  They then proceeded to put varying degrees of cant strips under my stance leg until I could mostly balance well on that leg (ended up at 2 degrees out on the right and 1.5 degrees out on the left).  Then I was given shims to "play" with on slope to see how the canting felt. 

 

So I'm out on the slopes with the cant strips in place and I feel like I'm in an eternal snow plow.  I'm always on my inside edges when straight running.  I removed the strips after a few runs to get back to "normal".  Later at home I tested what the cant strips felt like standing on my wood floor.  With the strips in place I felt exactly what I felt on the mountain - that all the pressure was on the medial side of my soles.

 

So I have to question this process.  The more I thought about it the more it doesn't make any sense to me.  I don't ski with one leg in the air and I don't think that really proves anything about balance.  What I think makes more sense would be the use of a digital pressure pad (or something like that) to determine how well the pressure is being distributed across your boot soles after canting (and also the custom footbed).

 

So I think I read that Eric Ward uses a digital pressure pad, but also espouses his SBS solution - built on the theory of dynamic balance.  Well the whole idea of dynamic balance seems very similar to what I had done already, but without the fancy machine SBS uses.  Maybe that machine makes all the difference though and I hope Eric (Mosh) responds to this post since he didn't respond to my email message.  However, he does present an at-home self-test method which is completely similar to what I have already experienced.  If you do his self-test you can then purchase the appropriate in-boot shims to apply the necessary correction.

 

So I'm now thinking that it would make more sense to test boot canting adjustments by including our skis in the testing.  I'm envisioning a process where a skier stands on a long foam pad while in their skis and a digital level placed on the skis checks whether the ski is sitting flat.  Of course the level would have to be calibrated to the skis and pad without the skier on them first.  Is there any validity to this method?  Does it already exist somewhere at some shop?

post #2 of 23

Noodler,

 

I am sure Bud H. can answer this much better than I can, but canting doesn't have as much to do with lateral balance as it does with edging.  I'm not sure where the skis come into play when measuring degrees of canting.  The soles of the boots are the important item and quite often a very simple device is used to check it, much like a sideways D on each boot with a level.  The skis are an important item when checking for fore/aft alignment, b/c of the delta angle of each binding.

 

RW

post #3 of 23

Canting should be to get the center of your knee over the center of your boot toe.  Then, ski to see if other anatomical problems require a different set up...not common but not impossible.

 

Here's an alignment test...on a very easy slope ski straight on one foot at a time at 45° to the fall line, both left and right of the fall line.  Also ski straight one foot at a time, on one foot as long as possible, then switch feet.  It's best with a helper, really best on video.  If you need to make compensatory body positions to hold a straight line, you need alignment.  Note that cufrf alignment is not real canting regardless of what the label on the boots say.  Cuff alignment aligns the boot cuff to your lower leg.  Important, but not real alignment that gets your knee over your boot toe.

 

For a lateral balance check, ski easy or medium arcs balancing on only the inside edge of your outside ski.

post #4 of 23
Thread Starter 

Thanks, but you know I've been skiing a long time and have been around here for quite some time - so I'm well aware of the differences between in-boot canting (SBS), boot canting, and cuff alignment.

 

The posts so far seem to be separating canting from balance.  So we're going with canting to ride a flat ski on snow (and get the center of knee mass over the second toe) and in-boot canting or custom footbeds to improve balance?

 

I've always found the "travese on the uphill ski" exercises kind of odd for testing balance and alignment - no one really skis that way so is it really a reliable indicator?  I can make javelin turns on either ski all day long (that's where the lifted ski is crossed over the stance ski), but if I hang the lifted ski off to the side then my balance is still shifted to that side.  I'd like to see a video of someone doing these exercises to really see what their body position looks like while doing them.

 

I guess I'm feeling like what was done for me didn't really do what it was supposed to do because the method used to determine the amount of boot canting doesn't make sense (at least to me).

post #5 of 23

Have you called Mosh? That's probably where to start.

post #6 of 23

 

Quote:
Originally Posted by Noodler View Post

 

I've always found the "travese on the uphill ski" exercises kind of odd for testing balance and alignment - no one really skis that way so is it really a reliable indicator? 

Seems a reasonable indicator for where the outer limit of your balance envelope is. Whether or not you actually ski there is a different issue, no?

Quote:

 I can make javelin turns on either ski all day long (that's where the lifted ski is crossed over the stance ski), but if I hang the lifted ski off to the side then my balance is still shifted to that side.  

Unless you have hip motion range to put the stance hip on the other side of the stance boot from teh lifted ski, and keep it there with your upper body stacked on top of it?


Edited by comprex - 3/10/2009 at 03:10 pm
post #7 of 23
Thread Starter 

 

Quote:
Originally Posted by comprex View Post

 

Unless you have hip motion range to put the stance hip on the other side of the stance boot from teh lifted ski, and keep it there with your upper body stacked on top of it?

 

I see - so with the leg lifted I should be expecting that my hip should move across the stance ski further so that the CoM is over the stance ski - makes sense.  When I did that in the shop (boots on only) that's when they slid the cant strips under my boot - and then of course I was able to easily balance on one foot, but once I re-assume a normal stance I feel like the cant strips are overly pressuring the inside edges. 

 

I guess you can color me still confused about what we should really be after.  I think getting the center of knee mass aligned is relatively straight forward - and getting the ski to ride flat should be also.  It's the balance issue (dynamic or static) where I'm having a tough time recognizing the validity of the testing procedures and the evaluation of the results.

post #8 of 23

Hi Noodler,

 

Your right on target with your evaluation that balance and alignment are to a degree separate issues. It is very possible to do that balance test successfully with vast amounts of canting on either side of your foot. To prove it to myself I just experimented here with 2 magazines stacked under my boot, probably around 10+ degrees of cant, and was easily able to balance with the magazines under either side of my foot. Get yourself aligned properly so that you can ride a flat ski, then focus on your lateral balance skills extensively and you'll be good.

 

Rick

www.YourSkiCoach.com


Edited by Rick - 3/10/2009 at 04:12 pm
post #9 of 23

Noodler,

 

The on snow drills SoftSnow gave are excellent.  Being flat on the snow is a rough guide, but ultimately what matters is how well you can initiate your turns, rolling from one set of edges to the other.  If you have been skiing a long time, then you will also have the ability to adjust your balance with gross body movements, and not even realize you are doing it.  You will stay in balance, but someone watching you may spot that you're using certain movements to compensate.  Sometimes it can be as subtle as the lifted ski will cross over the other ski in the air.

 

When you do one leg traverses on the downhill ski, note if your knee tends to dive in, even when you hip angulate a bit.  If so, the knee needs to move out.  It should be possible, but just a little bit more difficult to traverse on the LTE of the uphill ski.  If its too easy to traverse on the uphill edge, then perhaps knee needs to move in.

 

Try traversing across the hill balanced on the uphill ski, make sure your weight is fore, not aft.  While holding the downhill ski in the air, tip it towards its LTE(down the hill).  If this causes your uphill ski to roll over nicely onto the downhill edge and starts to turn, then great.  If it falls over too quickly, then your uphill knee needs to move out.  If it tends to rail straight then your uphill knee needs to move in.

 

Make sense?

 

Make some turns.  The problem with making turns is that you can be not angulating enough, causing more knee angulation and A-framing due to technique more than alignment.  But its the final test.  Listen to what your knee is doing, does it tend to dive in?  Are you making sure to hip angulate?  Do you feel yourself balanced on the inside edge of the outside ski or do you feel like your foot is pushing the base of the ski in a way that wants to push it flat?  If you can get video, look for A framing in both legs on both sides.  But this can also be due to technique, so be aware.

 

Lastly, it should be noted that there are many different things that can cause alignment problems.  The process should start with aligning the boot cuffs, then the foot beds to correct your ankle and foot, then finally canting at the very end to get your knee where it needs to be for clean turn entries.  If any one of those steps is missed or done wrong, then your canting could be more extreme then necessary or perhaps even dead wrong for you.  In a pinch, its better than nothing.  

 

I'm not a fan of in-boot canting.  I think inside the boot should be about ankle neutrality, getting the tripod under your foot established.  Also, fore-aft balance issues.  Canting inside the boot causes your ankle to invert or evert in order to adjust leg alignment.  Could be problematic.  Get your ankle neutral in the boot.  Then adjust leg alignment outside the boot.

 

post #10 of 23
Thread Starter 

Thanks for that reply borntoski - very informative.  I'll make a point of trying those tests and see what I can figure out.

post #11 of 23

Noodler,

 

Where to begin?....  

 

Static balance and dynamic balance are two different animals.  I do not generally check static balance in the shop though I do look at static alignment both fore/aft and laterally.  I believe I can get close in the shop but ultimately we need to test dynamically on the slope and make final adjustments from there.

 

On the lateral and fore/aft alignment, I begin with a foot and ankle assessment to determine how the footbed should be made and posted.  SBS shims obviously post the whole foot the same angle when in fact most people have different needs for hind foot posting or forefoot posting.  While I do occaisionally see a very pronated foot which can benefit from both rear and fore foot posting, for most it is not necessary or at least, not to the same degree.  If the skier does have a forefoot issue where most of the weight is carried on the fifth ray and met head rather than evenly distributed across the whole forefoot, a footbed should address this issue to evenly distribute the pressure across the whole forefoot before we even look at the external canting.  So to reiterate, we begin with placing the foot in a neutral position to bear weight more evenly with a vertical heel cord or sub talor joint (STJ) neutral which ever the boot fitter chooses to use.  It is wise to negate any angle premolded into the zeppa or boot board before inserting the liner and footbed so as not to change the intended angle of the footbed.

 

The next step is to match the cuff angle to the curvature of the lower leg to insure congruency or equadistance between the leg and shell on either side of the leg while standing on the footbed inside the shell.  If there is not enough adjustment or none at all, it may be necessary to add some padding on one side to achieve even pressure.

 

The final lateral alignment step is to adjust the boot sole angle so as to create symetry between right and left legs and place the center of knee mass in the desired location over the boot.  The center seam on the boot is a good starting point but may ultimately vary slightly upon on snow testing and personal preference.

 

SBS in my opinion is not a substitute for external canting but may yield favorable results in some cases where forefoot and hindfoot issues need similar angles to place the foot in neutral.  I have had some resounding successes using SBS shims in combination with external canting.  These same angles can be built into any custom footbed too.

 

hope this helps.

bud

 

 

 

 

post #12 of 23
Thread Starter 

Thanks Bud.  Would you mind elaborating on how the external canting process should work?  This is where I've run into the most trouble (and the main reason I actually initiated the whole process since I'm pretty sure my accident has changed my original alignment)?

 

Also, what about my idea for checking whether or not a ski will run flat with your lateral boot alignment setup (last paragraph of the original post)?

post #13 of 23

What's the Biostance process? I skied with a guy a couple of weeks ago out at Snowbird that was raving about it. Sounded like an in the boot shim type thing adjustment. I always thought that you could post up the footbed- shim etc to achieve the proper alignment until enlightened on the Boot Forum that canting - alignment and footbed adjustments were two separate issues not delivering the same results.

 

I had my boots canted back in Dec. using the carpenter squares -center of the knee and I was about 2 degrees in on each leg. The guy doing the work told me when I skied next in the boots I would notice a huge change. Honestly I didn't. I'm very glad I got this work done and when I do the tracking drills I can tell the difference. But as for my skiing it doesn't feel radically different .

 

So from reading Noodler's posts it would appear that you can achieve the holy grain of being flat on your edges but still be somewhat out of balance. Consider the source here as I am endlessly confused regarding this subject, but if his alignment is correct (flat) and there is a balance issue, that becomes a footbed posting issue does it not? If footbed changes are made, will these changes still allow his previous canting work to be representative of his needs?

 

 

post #14 of 23

Quote:

Originally Posted by borntoski683 View Post

 

 I'm not a fan of in-boot canting.  I think inside the boot should be about ankle neutrality, getting the tripod under your foot established.  Also, fore-aft balance issues.  Canting inside the boot causes your ankle to invert or evert in order to adjust leg alignment.  Could be problematic.  Get your ankle neutral in the boot.  Then adjust leg alignment outside the boot.

 

^ Voila :)

 

 

post #15 of 23

Canting assessment is best done on snow - on even terrain, hard snow, and skiing linked turns with symmetry.  Someone with a good eye (video assessment) should help you adjust with shims until you find the sweet spot (edge grip, leverage, engaging & releasing the sidecut, knee mass position, blending and use of all the joints, etc, etc).

 

As Bud has stated many times, static measurements get you in the church, on hill testing puts you in the right pew .

 

The SBS system is a posting shim that will help with dynamic 'canting' feel in some specific cases (i.e. certain foot deformities), but should not be confused with, or used as a substitute for actual canting (boot sole grinding).  Biomechanically they are two very different things and it drives me nuts that they are being perceived as somehow equivalent .

 

Lastly, you cannot balance well on a drifting/unstable platform (i.e. undercanted) and it is difficult to move all the joints inside the arc in a blended and relaxed fashion if you are significantly either under or overcanted.  Overcanted skiers tend to rotate and leave the hip 'outside' the arc, while undercanted skiers tend to a-frame excessively and are limited re. moving the COM well inside the arc. 


Edited by jdistefa - 3/12/2009 at 11:51 pm
post #16 of 23

Noodler,  I wish there were a quick concise answer to your question.  I am unfamiliar with your accident and it's consequences.  Was it a tib/fib break?  If the injury has had negative consequences on your alignment the whole process should be evaluated again.  Beginning with the foot and ankle and working up.  To simply look at one of the parameters independant of the others or try to address external canting before assessing and correcting foot and ankle issues is building the house without a good foundation. 

 

As Jdistefa has said many times, it is important to do the final checks on hill.   When adjusting external cant angle and deciding where to draw the plumb line, we have to consider the skier's goals, their personal preferences for the edge engagement sensations.  The amount of tibia varum will affect where the preferred mark will be for knee over boot sole.  There is no one exact position that is optimal for everyone.

 

The more I experiment with my own alignment the more I learn.  The more acute my sensory development in my feet and lower legs the more aware I become of very small changes in angles.  It is doubtful to me that anyone can hit the nail on the head in the first attempt!  There must be some testing and communication between the boot fitter and the skier to optimize the set up and get as close to the bulls eye as possible. 

post #17 of 23
Thread Starter 

I understand that there's a lot of "art" in this current science, but I'm an engineer and so I naturally am looking for ways to eliminate the art as much as possible and have an easily repeatable process that would get skiers at least to the same starting point - and then perform on slope testing to tweak the setup.

 

My main goals right now are to get my foot/ankle/leg aligned in the boot (for me that means stopping my ankle from crashing into the medial side) and ridiing a flat ski with fairly good knee tracking.  The attempts so far by the "current" boot/stance guy have been lackluster at best.  I have had better results using over-the-counter type footbeds in combination with varus/valgus heel wedges on top of the bootboards (thick side to the inside).  I have no idea if the thickness of the wedges is too much, but this is working much better at getting my ankle off the wall of the boot than the custom footbeds I just had made.

 

I am also following up on my idea to achieve a flat ski by measuring the angle of the ski as it hits the surface.  I have a digital angle level mounted on a true bar and a large long foam pad.  I plan on calibrating the level to the skis while resting on the pad (as 0 degrees) and then snapping into the bindings and seeing how my normal neutral stance effects the lateral angle of the skis as they hit the pad.  I have no idea if this will work or have any bearing on the actual on-slope peformance yet, but I'm having fun with it.

 

I wish I had become a biomechanical engineer like my dad wanted me to be in college - I think those skills would have definitely come in handy in my "quest" .

 

 

post #18 of 23

Sorry I have been on full boil mode and just found this.  So it sounds like you have a sense of what SBS is all about.  We make efforts to understand the foot in as dynamic a mode as possible while indoors.  one footed assessments can shine a light on what the foot will be doing inside the shell when the skiing starts. We started this sort of thing many years ago to try to understand the foot movements and muscular responses, through proprioceptive involvement and the interrelatedness of these three parts of the body.  The bones and the muscles and the brain while balancing.  Just like skiing.  

 

When these foot dynamics are understood in this setting you can create incredibly repeatable results with great accuracy.  I find that when you understand the dynamics of balance you can use a simple wedge under the whole foot to create incredible results to the tune of about 97% of the time we get it right the first time.  It takes no time at all to measure someone.  The best part of it all is that the person getting measured actually has a say in the matter.   The skier is like the driver of the car and only the driver knows when the car is working properly.  With normal knee mass measurements it is up to the person measuring to decide what the skier needs.  No opinions from the driver are sought out.  Only after skiing can you comment on what has been done and then it is too late.  you own that grind.    

 

I am sorry I don't have more time to dedicate to this can you ask me more specific questions about what you would like to know.  

post #19 of 23

Mosh,

 

You continue to be a little bit right and a lot wrong. 

post #20 of 23
 Well thanks, 
I tend to be just a bit left of center on many things.  My wife would certainly not agree with your thoughts on my being right, well ever really.  Which begs the question if a man were alone in the woods and said something, and there were no women around to hear him....  would he still be wrong.....?  
post #21 of 23
Noodler, Did you find yourself relearning how to produce a flat ski? Or did you just go out and do the same old things the same old way?
I went with a new bike shoe set up recently that features wedges between the shoes and the cleats. In the past, all of my alignment adjustments were inside the shoe with custom footbeds and such. I was really surprised how this small change feels. Over the next few hundred k the feeling of ackwardness has subsided and overall my average speed is slightly higher (1-2kph). I also don't feel as much lower leg fatugue, or knee stress.

So I guess my point is that change isn't always comfortable at first because we are still using old movements. As those movements change the results will eventually feel more normal...
Edited by justanotherskipro - 8/19/09 at 5:49pm
post #22 of 23
Hi Noodler,

Just a few other thoughts,----I have read through this thread and didn't notice any reference to how knee tracking or a leg length discrepancy effects alignment.  Medically it is estimated that 96% of the adult population, have from 1mm to 10mm LLD and 42% have greater than 10mm, it is always a priority at our facility to determine if the customer has a significant LLD(Doctor diagnosis required here). 

Beyond that issue, If the knee mass moves medially as the ankle/foot goes into increased dorsiflexion the skier may have reasonably good lateral stance when extended and be over edged when compressed. 

I may be wrong but I don't think your idea about the skis on foam with a level on top will tell you much about how your skis are going to react if you have either of these issues---it will only tell you what your stance is in a static position.
Edited by miketsc - 8/20/09 at 12:35pm
post #23 of 23
So true, the bike shoe change was to help my knees track better. Since I had tens of thousands of miles on the old set up, the change just didn't feel right. I had to make myself move differently to make the knees track differently. Sound like Noodler experienced the same thing and chose to go back to his previous set up instead of adjust his technique.
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