FIFTH GENERATION STANCE RAMP ASSESSMENT DEVICE


Since my first version of the stance ramp assessment device I have made a number of significant improvements. The series of photos below are of the fifth generation device.

The bottom plate or base of the device is approximately 18 inches (46 cm) wide by 16 inches (41 cm) deep (front to back). I intend to make the next version about 22 inches (56 cm) wide by 18 inches (46 cm) deep. Size is not critical so long as the top plate is deep and wide enough for the feet being tested.

Stiffness of the plates is critical. Three quarter inch thick (2 cm) plywood or medium density fiberboard (MDF) are suitable materials. I added 1.5 inch x 1.5 inch wood reinforcing ribs on the sides, middle and rear of the top plate.

The photo below shows the heel end of the device. Two 1/4 inch drive ratchets turn bolts threaded into T-nuts in the top plate that raise the heel end up.

The photo below shows the top plate hinged to the bottom plate with 4 robust hinges.

Four telescoping hard nylon feet are set into the bottom plate to enable the device to be leveled and made stable on the supporting surface. It is important that the device not tilt or rock during testing.

The photo below shows the details of the interface between the top plate on the left and the bottom plate on the right.IMG_3409

I used gasket material purchased from an auto supply to shim the forefoot of my boot boards to decrease the ramp angle so as to obtain the 1.2 degree ramp angle I tested best at.Shim pack

The package contains 4 sheets of gasket material that includes 3 mm and 1.5 mm sheet cork and 2 other materials.Gasket

I cut forefoot shims from the 3 mm cork sheet as shown to the right of the boot board in the photo below.BB w shims

I adhered the shims to the boot board with heavy duty 2-sided tape and feathered the edges with a belt sander.shims installed

I corrected the ramp of my boot boards in 3 stages. Once my optimal ramp angle is confirmed, I will pour a boot board into the base of my ski boot shells in place of the existing boot boards using a material such as Smooth-Cast 385 Mineral Filled Casting Resin. More on this in a future post.

Ramp Angle Appears to User Specific

It is important to stress that although there appears to be a trend to optimal boot board ramp angles for elite skiers in the range 1.5 degrees or less, there is no basis to assume a  ramp angle that is optimal for one skier will be optimal for another skier. Recreational skiers are testing best between 2.0 and 2.5 degrees.

It is also not known at this point whether the initial optimal ramp angle identified with the device will change over time. Based on the impressive results seen so far in the limited number of skiers and racers who were tested and ramp angles adjusted there is no basis to assume that ramp angle is not a critical factor affecting skier balance and ski and edge control. Studies on this issue are urgently needed and long overdue.

It is important that testing for optimal ramp angle be preceded by kinesthetic stance training. This will be the subject of my next post.

9 comments

  1. I guess I was a little wishy washy on one statement; the position of the big toe in relation to the first ray/inside of foot ABSOLUTELY fine tunes the arch height or lack thereof. Like everything else one needs to use wisdom and common sense. A ‘bunion’ which is solidified/calcified in the wrong position can’t just be forced into alignment overnight because the joint is to rigid and that can not only create pain etc. but completely lock up the big toe joint and be worse performance wise than leaving it alone. So my theory on myself was to use the toe spreaders all the time letting the joint which through wear and tear over time (lifetime) is in the wrong position to gradually ‘wear’ back to the right position. I prefer that over an operation because have seen unfortunate individuals get bunion operations… and then too soon after they needed a knee operation or replacement.

    When I personally tried to go too far too soon, I felt the metatarsals lock up (which negates the whole point of having toe spread) but also stress on my navicular joint. What is amazing is how much the correct-er alignment of the big toe changed the position of my knee from being ridiculously bowed out to being much straighter. I’m sure that over time my knee will ‘wear into the original alignment and trust I won’t always have to rely on ‘artificial props’ to align the big toe/knee. Skiing is easier, walking is easier, and pain that was in the knee for 4 decades is mostly non-existant.

    One can find a number of toe spreader sizes online (or possibly in a local store) like a package of 4 about $10. There are different sizes and a friend actually found a a set of 4 with 3 different sizes so buy two packs to have at least two of all 3 sizes. (I’m pretty good a simple math, huh?:) But I use different sizes right now because one big toe is better than the other and I’ll let you guys guess which one!!

  2. I would like to thank Michael for his many thoughtful and perceptive comments and the guest blogs which help to keep me motivated and inquisitive about the many aspects of applying your methods, David. And thanks,Michael, for the can opener. I was wondering the same thing about the toe shim. It seems to go along with the stated objective of having a flat boot board fore/aft and sideways. Is the objective improved neural contact with the bottom of the boot for sensory feedback as well as maximizing pressure on the boot bottom for ski control? The Correct Toes certainly stimulate more nerves in that same area when worn vs. not worn in my shoes. I need to improve toe room in my boots so I am currently removing rivets to gain access to the toe area and then installing removable cuff cant adjusters.

    With boots fitted the old way, constricting circulation and with excessive forefoot pressure and heel pinching to compensate for excessive ramp/delta, and Raynaud’s syndrome, I have suffered some loss of sensation in the toe and heel areas. While I do strengthening/stimulating exercises daily and am always virtually or literally barefoot, any aids to better sensation in the feet and boots are very welcome. Lowering ramp angle was a huge step in that direction as well as removing interference with foot/toe splay and ankle glide path, liner hacks, etc. Thanks to Michael for the big toe spreader idea in the same vein.

    By the way, Dalbello made a “Carvex” model boot with externally adjustable ramp angle a while back. I do not know if that feature is still available in any of their models. I have no idea what the adjustment range was.

    I would also encourage followers of this blog to read David’s patents which spell out the details of the many ways ski boots do not function properly and why, as well as how they should function and why.

    Thanks again,
    Herb

    1. “I was wondering the same thing about the toe shim. It seems to go along with the stated objective of having a flat boot board fore/aft and sideways. Is the objective improved neural contact with the bottom of the boot for sensory feedback as well as maximizing pressure on the boot bottom for ski control?”

      While I am perceived by some (mostly sellers and promoters of footbeds) as anti-footbed/orthotics, nothing could be further from the truth. What I am is pro-science and especially pro-evidence. I am unequivocally anti-BS. The reason I moved away from interventions that support the arch is that studies are raising serious concerns about these appliances. In my most recent patent I advocate starting all footwear design with a monoplanar, level surface and qualify this by stating that anything introduced between that surface and the plantar aspect of the foot will affect the phyiologic function of the lower limbs and entire body of the user. This does not imply, nor did I state, modifications to the monoplanar surface would have negative effects. So my thinking is algned with Michael’s, that based on my current knowledge, I believe toe shims can be used to tune foot function. Towards this end, I use a 1.5 mm shim under the big toe of my right foot which is still much more compromized than my left foot from years off damage from bad footwear.

      “I would also encourage followers of this blog to read David’s patents which spell out the details of the many ways ski boots do not function properly and why, as well as how they should function and why.”

      You hit the nail on the head. I wrote the patent as both a functional specification for the foot and a guide to creating a functional environment for it. At one point, I started editing the lengthy document with the intent of distilling it down to its essence by removing the legalese and clarifying some aspects. Thanks to your encouragement I intend to resurrect this project and even expand on the content and make the final document available through this blog.

  3. A question about the pieces of cork gasket material; does the ball of the foot rest upon the smaller cut out piece also or does that ‘curve’ rest against the forward aspect of the ball of foot? Thanks in advance:)

    1. You’ve opened up a very large can of worms with that question. In testing ramp angle reponses, I am finding significant problems in boot boards which seem to be all over the map even among different models of the same brand. Some are unstable. Others quite literally rock and not in a good way. They appear to have a high point in the center and rock fore-aft.

      Insofar as my temporary cork shim setup, I want continuity across the MT heads especially under the 1st MT (ball of the foot). There can be (and is) a gap betweem the MT heads and the ends of the toes where they apply pressure. This is where the cork shim is located. The heel can be (and is) a discrete entity. Although there are separate support bases for the heel, MTs and ends of the toes, there is continuity in the plane of support. I am experimenting with good success with thin shims under the end of the big toe.

  4. The last paragraph sums things up very well; without a question, from my experience, it is great to start with a correct ramp angle BUT any little thing can throw off what is then the optimum once one is on snow. What i found this winter was that those that refuse to give up their foot beds seemed to need a higher ramp angle than those without. Unfortunately i didn’t think to test that aspect on the same ramp angle; footbed versus no footbed.

    Interestingly enough a big breakthrough for my boot fitting was toe separators between the big toe and second toe (only because the ones like Correct Toes,between all toes, didn’t fit into my boots). For myself it made my left ski the most functional ever since a knee injury in the ’70s. After the original toe separator helped so much I added 1/8″ more to align my big toe with the first ray better and the increased control of the ski was unbelievable. For another person with severe A-frame for whom I was rearranging the boot cuff, using a toe separator on the more severe side minimized the amount I moved the cuff and didn’t need to re-rivet the other one at all. I think ultimately big toe alignment can effectively replace ‘arch support’ via footbeds.

    In all probability David’s method of identifying ramp angle; using that as the basis for the feet platform and proceeding from there will have only one drawback; either a factor adjusted improperly or one not known (such as the big toe business for me prior to this year skiing and learned from this site and Dr. Splichal) may force one to make small adjustments to Net Ramp once one goes skiing.

  5. David,
    your STANCE RAMP ASSESSMENT DEVICE (what a term) is exactly what I was lookin for! Having a young racer in my family myself and suffering each year again with new ski gear (different ski models, ski length, different heights, plates, boots etc.) and therefor completely different angles. Completely differing conditions on each discipline (SL, GS, SG and free skiing) throughout the last couple of years, each year and each day!

    I will try to get the ramp device ready to check things out and find one base angle setup for the coming training period.

    Whats your opinion, would you prefer to include the angle adjustments in the boot board (as shown in your pictures) or would it be a better idea to adjust the boot lifters?

    Cheers
    chriskapeller from Austria

    1. Hi Chris,

      The first step is to identify the plantar/ski base plane angle that optimizes foot-to-hand tensegrity (see my recent post). Muscle and ski response can be tuned through small variances in the optimal base ramp angle. I will post on my theories on these issues soon.

      Based on my analysis of WC video it appears as if racers like Marcel Hirscher are experimenting with these variances. Since you are in Austria you might try contacting the Christian Doppler Laboratory for Biomechanics in Skiing and/or Erich Muller at the Department of Sport and Sports Science at the University of Salzburg. This should be an obvious field of research. But so far, I have not seen an indication it is being explored.

      An obvious area for innovation is an engineered boot board with ramp angle that can be externally adjusted to allow ramp angle to be changed for piste conditions. A similar technlogy would allow binding toe or heel piece heights to be easily and quickly precisely adjusted. Innovations of this nature would allow muscle and ski response to be tuned for piste/course conditions. Erich Muller commented on the potential to tune muscles in a recent paper. So he must be aware of this.

      Please let me know how the assessment works out for your racer. Any questions or suggestions you might have are welcone and appreciated.

      Best regards from Whistler

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