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Foot beds: Custom vs SuperFeet - Page 2

post #31 of 42
Quote:
The reason for the question is to see if this commonly accepted belief in the timing of pronation in a ski turn is fundamentally sound. What is the belief based on?
= Gravity, acceleration/ decceleration, and G force developed through out the turn.


Quote:
Does anyone have a better reason for it?
= Laws of physics vs how the body moves through space, having a cage match inside of a ski boot. They both take a beating. It ends up being a draw, and each contestent had to compromise a little.

IMHO

jim
post #32 of 42
Thread Starter 
Thank you all, seriously.
Keep bringin' it!

I'll be well informed when I talk to Jim.


*Why are so many of our boot guys named Jim?
post #33 of 42
Quote:
Originally Posted by RayCantu View Post
I am thinking that pronating, a tri-planer movement (eversion, abduction and plantar flexion) causing the skier to move into a structurally weaker position prior to passing the turn apex (phase of turn where load is near peak) is irrational.

Though I am still open to looking at reasons that might support it.
It's not about the foot being 'weak' or 'strong', that's a foot-centric view of things. And it's certainly not irrational, rather it's about what is necessary biomechanically to ski well.

For example, let's again fuse the subtalar joint (and Chopard's and Lisfranc's joints). The only way to create edge angle now is to incline or hip angulate. If the foot stays absolutely in neutral, the amount of knee angulation available is minimal, if none at all.

The apex of the turn is created by increasing the edge angle to a moment of maximum deflection of the COM.... The most effective way to do this is through angulation (understanding that you can increase edge angle up to a point with inclination). Good angulation involves blending the use of all the lower joints (hip, knee, ankle, STJ, etc) - the ratio of which is decided by the tactical goal, technical preference, motor patterning, and the skier's individual build and gender.

If you accept that you want to use the knee (to some degree) while angulating, then pronation becomes an ipso facto part of the deal.

Whew .
post #34 of 42
I just realized I made a mistake in a previous statement. Pronation is a tri-planer movement of eversion, abduction and dorsi flexion not eversion, abduction and plantar flexion as I incorrectly stated.

I agree with you "It's not about the foot being 'weak' or 'strong'". I am referring to the entire kinetic chain moving into a weaker position.

I do not see how moving the knee out of the line of force between the ski edge and the COM with what you refer to as "knee angulation" is the best way to deal with up to a 3g load.

If the knee is viewed as a hinge joint then it seems that what you refer to as "knee angulation" is more of a rotary movement of the femur at the hip joint and may introduce some torque at the knee which may not be well tolerated by that joint.

Would anyone disagree that the ability to maintain pressure on the head of the 1st metatarsal would be inhibited by pronation?

I guess I don't yet see the ipso facto-ness of the timing of pronation in the ski turn. I realize I am challenging conventional thinking and do appreciate your effort.
post #35 of 42
Ray,

1) The knee is not a hinge joint. Biomechanics 101: Read Kapandji Vol 2 for reference.

2) Also read Witherall, Lemaster, Larson, Joubert re. ski technique.

3) Conventional thinking aside, are you serious with this sh*t or are you pulling my leg?

4) What do you feel when you ski?
post #36 of 42
Having never thought this through before, my observation is that we are not moving into a weaker position when pronating toward apex! It seems to me to be the biomechanically strongest position placing the inside ski edge more directly in line with the forces directed up through the joints? I know I certainly would not want to be supinated at apex or anywhere with a load, and being restrained in neutral would hinder my ability to balance.

This is exactly what I felt when skiing with the non weight bearing system footbeds. I lost any ability to make balance or edge adjustments in my feet/ankles and felt a noticable need to involve the knees more in simple balancing efforts. My arches hurt and my fifth met heads hurt. Oh, and the footbeds were made for me by the inventor himself so I doubt much pilot error.

Personal preference.....maybe?

Would some type of foot dynamics benefit?.....possibly!
post #37 of 42
Quote:
Originally Posted by jdistefa View Post

1) The knee is not a hinge joint. Biomechanics 101: Read Kapandji Vol 2 for reference.
I see that I should not have referred to the knee as a "hinge joint" in an attempt to simplify the point.

That is an expensive book!

In an attempt to conserve cash, any information you can provide will be appreciated.

What type of joint is the knee?

I still think that moving the knee medially to the line of force created between the ski edge and the COM is not the most effective way to deal with high G load. It seems as if that alignment would shift load away from the skeletal structure and onto the musculature. Am I overlooking something biomechanically?

Quote:
2) Also read Witherall, Lemaster, Larson, Joubert re. ski technique.
Though I have the highest regard for the authors you recommend much of their work was done prior to the higher loads and longer duration of load available with the current ski designs.

Quote:
3) Conventional thinking aside, are you serious with this sh*t or are you pulling my leg?
I am not "pulling your leg", I think the changes in skis are great enough to justify a review of the "conventional thinking".

Quote:
4) What do you feel when you ski?

I feel that pronation introduces unnecessary rotation in the turn, misaligns the kinetic chain which limits the amount of G load that can be resisted and causes the foot to become adaptive and shifts pressure away from the head of the 1st metatarsal and to the arch and rearfoot.

Would you disagree that the ability to maintain pressure on the head of the 1st metatarsal would be inhibited by pronation?
post #38 of 42
Quote:
Originally Posted by RayCantu View Post

I still think that moving the knee medially to the line of force created between the ski edge and the COM is not the most effective way to deal with high G load. It seems as if that alignment would shift load away from the skeletal structure and onto the musculature. Am I overlooking something biomechanically?
I do not have to move my knee laterally to evert my foot?

Quote:
Originally Posted by RayCantu View Post
Though I have the highest regard for the authors you recommend much of their work was done prior to the higher loads and longer duration of load available with the current ski designs.
ski design has changed not physics?

Quote:
Originally Posted by RayCantu View Post
I feel that pronation introduces unnecessary rotation in the turn, misaligns the kinetic chain which limits the amount of G load that can be resisted and causes the foot to become adaptive and shifts pressure away from the head of the 1st metatarsal and to the arch and rearfoot.
Rotation in the turn? Where is the rotation? When the foot everts it does rotate a bit but the rotation is in the opposite direction I believe you are referring to?

It sounds like you are including a multitude of movements into your definition of pronation which are not involved. If you stand and simply rotate your forefoot away from centerline (abduct) the foot/ankle will pronate too without any knee or hip involvement.


Quote:
Originally Posted by RayCantu View Post
Would you disagree that the ability to maintain pressure on the head of the 1st metatarsal would be inhibited by pronation?
Maybe we are confusing pronation with eversion in this conversation.

If the skier demonstrates pronation and a forefoot varus it would be difficult for them to get pressure to the first met head without internal rotation of the femur but if the footbed is made to control the rearfoot and accomandate the forefoot varus yet still allow the arch and midfoot to evert, then the skier will be able to pressure the first met and evert the foot. NO???
post #39 of 42
my 2 $$. Footbed is filling voids resultant fron the foot being held by heel counter of boot and lower leg held by cuff. Foot bed IMO will offer an equal rom to inver/evers not designed to lock foot unless that is the goal. We are controlling kaos of movements(oblique plane,thanks Jack) not trying to eliminate it.

Jim I like the cage match in the boot metaphor. Kind of what my stomach felt like friday morning.
post #40 of 42
Quote:
Originally Posted by bud heishman View Post

ski design has changed not physics?
I agree, the physics have not changed,it's about the skis! The changes allow much higher, as well as more sustained duration of, G load.
The thing that is being overlooked is what is not required by the new ski designs. I am only questioning movement patterns that were developed to create the leverage and forces necessary to turn the old skis.

The question then is:

Are there biomechanically better movement patterns that can be used to replace the movements that are no longer nessasary?


Quote:
Rotation in the turn? Where is the rotation? When the foot everts it does rotate a bit but the rotation is in the opposite direction I believe you are referring to?

It sounds like you are including a multitude of movements into your definition of pronation which are not involved. If you stand and simply rotate your forefoot away from centerline (abduct) the foot/ankle will pronate too without any knee or hip involvement.

Maybe we are confusing pronation with eversion in this conversation.
The movement of Pronation is best described as a Tri-Plane movement. Eversion is the movement in the Frontal Plane and is combined with Dorsi-flexion the movement in the Sagatial Plane and Abduction the movement in the Transverse Plane.

The rotation, I am describing, is the result when the movement of abduction takes place while maintaining a closed kinetic chain. If the foot is 'stuck' to the floor then abduction moves the midline of the body in the opposite direction. (rotates in the direction of the turn)
Quote:
If the skier demonstrates pronation and a forefoot varus it would be difficult for them to get pressure to the first met head without internal rotation of the femur but if the footbed is made to control the rearfoot and accomandate the forefoot varus yet still allow the arch and midfoot to evert, then the skier will be able to pressure the first met and evert the foot. NO???
I believe that internal rotation of the femur restricts the ability to get pressure to the first met head. The moment you unlock the midtarsal and subtalar joints, you lose energy transmission to the medial column/1st ray. That would result in shifting the skiers weight rearward as well as creating rotation in the direction of the turn.
post #41 of 42
Ray - FWIW, see my responses in the boot fitter shop talk area.
post #42 of 42
Thread Starter 
Quote:
Originally Posted by starthaus View Post
What is the difference in the different colour foot beds, and who do those foot beds serve best?

There are now 6 different color Superfeet that you may encounter at a ski shop.

That being said, of those 6 colors, there are only 3 different shapes of Superfeet that would effect the feel or fit inside the boot.

The Green top is the Basic Superfeet shape that has been around for years. This device fits well into higher volume boots with skiers that have a medium height arch. This is the least expensive of the 6.

The Blue top works better with lower height arches, and where boot volume is an issue. They are priced the same as the Green.

The Red Hot and Pink Hot are new for this year they share the same shape under support as the Orange and Berry. All of these fit the same to the foot and boot. They are best suited for the average sized arch, and because the width profile is slightly narrower then the Green, they drop in nicely to narrower lower volume boots. The Red Hot and Hot Pink, have Outlast material on the top cover for added warmth, as well as reflective material under the toes for added warmth. Based on the Outlast and the new toe material these cost more then the basic models.

Being phased out of the ski offering are the Orange and Berry. They will be targeted at the shoe market in the future, however they are the exact same shape as Red Hot and Hot Pink, so the fit and function the same. They do not have the Outlast top, and do not have the reflective material under the toes. They are priced in between the basic and the Outlast models.

A good fitter will know by asssessing some simple parameters of your foot, like arch height and shape, arch flexibility, heel stance, ROM, boot choice, and budget, which Superfeet Trim to Fit is right for you.

All this info is moot if the footbed is not properly sized to your Arch/foot. And in terms of function, all of these devices are designed to sit on a level bootboard. The single biggest mistake I see is bootfitters forgetting to make the boot board "neutral" to interface properly with any footbed.

IMO All of these devices work OK with average feet, they can stabilize and improve the long term fit for many skiers. They hit a big chunk of the skier population well. They are most always an improvement over the stock insole the manufacturers supply. They can also be mildly adjusted to accomodate exceptions to the sweet spot of the skiing public. In most cases where specific foot aligment issues are identified, the skier would be better served seeing a bootfitter that has the eyes and the hand skills to produce a custom footbed that solves the identified problem.

I have a good friend that describes the relationship between a Trim to Fit and a Custom footbed like this: " Footbeds are like a cover charge to a men's club. To get into the good fit club you have to pay the minimum cover charge ($35.00 for trim to Fit ) however if you want the really good stuff you need to pay to go into the VIP room ( $185 for a Custom footbed) "

One other point to bring up is that trim to fit and the Superfeet brand have become one in the same in the mind of the consumer. They are the market leader in the USA. There are many other legitimate brands of off the shelf or semi customizable products on the market, like Down Unders, Conformable, Zapz, etc. Some shops offer a selection some just one type or brand.

jim
I have been skiing in both of my pairs of boots, one with Green Super feet from my old boots, and one with the hot pink. There is a noticeable difference in the warmth of the hot pink.

Not that it matters, just sayin'
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