The human foot is a masterpiece of engineering and a work of art.

                                                                                                                  Leonardo da Vinci

Despite what da Vinci said, skiers seem to have an inherent distrust in the structural capacity and integrity of the human foot.

In skiing demonstrations with ski boot prototypes based on the Birdcage it didn’t matter how hard I tried to explain to testers how the dorsal loading system worked and how little force was needed to secure their foot, it didn’t stop them from attempting to crush their foot by tightening down the dorsal plate until their noses bled. They were so conditioned by the persistent, ‘the tighter the boot, the better the ski control’ message that they just didn’t want to believe how little force it takes to activate the auto stiffening mechanism of the longitudinal arch (FIT VS. FUNCTION) and retain the foot in solid contact with the base of the boot.

In order to try and convince testers how little force was required to make their foot dynamically rigid one of our team members had a device we called the Logan Chassis designed and fabricated. The photo below is of the Logan Chassis aka The Convincer.

If it’s not obvious from the photo  the Logan Chassis was very heavy. The components were milled from solid blocks of aluminum. The heel counter and a few other components are missing. But the photo should give you a good enough idea. This thing was a tank. This device was not intended for skiing. It was a pre-ski boot skiing test conditioner.

To demonstrate how little force it takes to make the foot so rigid it is like steel I would get the test subject to put their foot in the Logan Chassis. Then I would try to get them to adjust the knob on the screw to the point where it applied firm but gentle pressure on the dorsum of their foot making sure there was no discomfort. Then I would ask them to stand up and lift the foot in Logan Chassis off the floor and tell me what they felt. They were shocked. Hell, I was shocked when I tried this.

The Logan Chassis feels incredibly light and the foot feels glued to the base with no sensation of pressure or discomfort. It defies logic. But I doubt I would have to convince da Vinci.

The truth is whatever people are willing to believe.

The problem is that most skiers have been convinced to believe that tight is not just right, tight is might.


  1. Yes, David, the frustration level was/is pretty high . I was hoping to improve my chances of success by building up a 4 buckle overlap boot this year but the challenges have been significant. What I have going for me is that this/your method is a new challenge and I am a life-long student. Often, the frustration is in not having the experience to know what is involved and what could happen when making a change and attempting to apply non-conventional methods of boot fitting without having the guidance of a nearby bootfitter with a truly open minded attitude. My ex-bootfitter used to say “NO RULES” for bootfitting but, when presented with your method all I heard was a litany of rules. It seems that most of the better ones get something(s) right, often accidentally, but, totally miss others.

    I cannot imagine how frustrating it must be for you that your work and discoveries have gone relatively unrecognised by the skiing public and the industry despite being the most well researched, documented, and explained (both in this blog and in your patents). Bootfitters, coaches, instructors, designers and manufacturers should be “foaming” at the mouth over this stuff! There is more than one book’s worth of material here and the recognition you deserve. As you have said, a lot of ski “engineering” is trial and error without the knowledge and research work backing it up. You have the PROOF sorely lacking in the work of others.

    I do believe Holdener is still with Head boots.but, not sure. Anna Sven Larsson and Alice Robinson (who?) are also coming up fast behind Shiffrin. I hope Holdener was not too discouraged by her loss(0.07 sec), she looked devastated at the end.

    Tweaking on with regards,

    1. First off Hoeldner is still in Head boots. But I think it ptobable her ramp angle has been reduced. Robinson is in Dalbello boots. I have gotten word from insiders that Dalbello and one or two other boot makers are experimenting with engineered boot boards. Dalbello funded a study by Italian engineers in 2004 that found unacceptable instability in boot bases that would significantly impact skier balance at 1.6 Gs which is well within the recreational range. World Cup racers experience sustained loads of up to 5Gs with transient peaks much higher. I identified boot base instability as an issue by 1980 and started bonding structural boot boards to the base of Lange boots.

      With regard to frustration, it is not so much a case of me being frustrated but more a case of being disillusioned and disappointed by those whose sole interest in skiing is to get a piece of the action. Serious mistakes were made very early in the development of the injected plastic ski boot. But instead of performing basic research to validate or invalidate concepts such as immobilizing the foot or supporting the arch marketing stories were created along with circus side show demonstrations intended to convince people that their feet are not designed to support their weight and footbeds are essential to provide a foundation. The marketing story created a lucrative market for footbeds. So everyone doubled down on it. Whether the theory even made sense (it didn’t) was irrelevant.

      But the worst thing the ski industry did that may have sealed their fate was ignoring the criticism of the internatonal experts who contributed to the chapter on the ski boot in the medical text book, The Shoe in Sport. Professor Martin Pfieffer of the Department of Sports Science at the University of Salzburg (ground zero in the ski industry) summed it up succinctly when he stated: These medical requirements with respect to sports should not be construed as criticism of the (ski) boot industry. It is hoped they are a contribution to the development of a ski boot designed along anatomical principles. This goal has not yet been achieved.

      ………………has not yet been achieved.
      ………………has not yet been achieved.
      ………………has not yet been achieved.
      ………………has not yet been achieved.

      1. David, please cease and desist from banging your head against the wall !!!

        I for one do not need convincing. As I struggle with bootfitting, I can’t help but think there must be a better way, a better design, for achieving forefoot hold down.

        Dalbello had a Carvex boot model years ago which had adjustable ramp angle built in. I believe they are still family owned and may have more flexibility for trying “new” ideas than the big corps.

  2. Hi David ,

    The timing of this post was prescient and amazing. Shortly after reading and for no apparently related reason I had a little epiphany while trying to put a homemade version of your dorsal support system into my boot after putting my foot into the boot, very difficult! I decided to try putting the tongue on my foot and shoving it in, also difficult as the tongue wants to bind and slide back up the leg or out of position. I decided to try using the Intuition Liner fit routine where you put fit aids and extra pads on the foot (over or under socks) with a toe cap (to expand toe space), and then cover everything with a shortened nylon stocking which holds it all in AND provides a smooth slippery surface to enhance the ease of sliding the foot into the liner. I put the tongue on my foot and put the stocking over both and was able to slide my foot into the boot much more easily. I also use a “Boothorn”. The stocking is very stretchy and very thin and does not seem to squish my toes or interfere with anything and you can still adjust the tongue position with the stocking in place.

    The amazing part was lifting my boot up off the floor and instantly noticing how light it felt. The boot felt as if it was a part of my foot, and my foot was not feeling squashed, just comfortably held. Your description of the feeling elicited by the “convincer” slammed home. Now I have a guide to evaluate whether on not my “dorsal fit system” is working. Yahoo!

    Constructing an identical “system” for my other foot was close but, not quite as good. My feet are not perfectly bilaterally symmetrical so, no big surprise. It will require some tweaking. I find having guidelines such as this extremely helpful in achieving the right fit. Thank you!

    Best regards,

    1. Thanks again for your comments.

      The last few years has been an eye opener for me not in a good way. About 2 years ago I started trying to help a racer get a pair of new boots set up. When I set up Lange race boots for her in the late ’70s it was a walk in the park. But this time I could not believe how many liners and shells we went through to try and do something was straight forward 40 years ago. She ended using a stocking to hold the bits and pieces together when she put her foot in the boot. It turned out to be the solution.

      Because I want maximum stability I chose the stiffest race shell I could find when I set up my Head World Cups. I weigh just under 160 lbs. So I am not stressing the boot like heavier skiers. But I am sensitive to uncontrolled deformation. I have a helluva time getting my size 12 foot into the shell. Once it is in, I insert the tongue. Then I could wear them to bed they are so transparent.

      The light feeling is a good confirmation of dorsal loading with inner aspect of the shell. It’s crazy but my skis and boots feel lighter hanging when I ride chair than when they are on the foot rest.

      Once you get both boots tweaked you can never to back to a perfect fit.

      1. Hi David,

        My turn to apologise for not responding sooner to your very kind and encouraging comments. Thank you!

        My elation at having found a forefoot setup which held my foot down with enough security to ski properly was short lived, unfortunately. When I went skiing to test it, the boot and ski together felt heavy and clumsy and the forefoot had loosened considerably. Perhaps the foam is too soft.I had cannibalized an Intuition liner tongue upper with its reinforcing layer and shaped it to be similar to the tongue modeled in “Podborski’s Balancing Act” and “Transitioning From Fit To High Performance Function”, attached it to the tongue forefoot plastic from another boot and used it without heat molding. The foam is much softer than the blue EVA you used so, my next project is to either replace just the foam or the entire forefoot add-on.
        Question: Can you recommend a grade /type/trade name, of the type of plastic backer you use for the EVA foam?

        I have started to review your patent #5,265,350 for more specific ideas regarding where to focus the pressure on the dorsum.
        Question: Is it correct to focus this pressure between the “peak” of the instep and the base of the tibia (at its most anterior limit of travel when weight bearing, I assume) as is suggested by Figure 44A?

        I just watched the women’s World Cup Slalom finals and am struck by the incredible improvement in Wendy Holdener’s form since getting new boots. She smoked everyone in the first run and nearly caught Shiffrin in the second. Her ability to stand taller has improved her quickness and agility markedly. She has been, I believe, more consistent than Vlhova despite not winning… yet. Now she has the tools. It’s all about the boot(s)! And, of course, how they are set up/fitted. Next season will be interesting.

        Best regards,

      2. Hi Herb,

        I feel your frustration. Just when you thought you were there, the foam ‘packed it in’. I have not researched foams for decades because I had large supply which is dwindling as is my enthusiasm for working on ski boots. I identify with the lyrics of Queen’s ‘We are the Champions’: “I’ve paid my dues, Time after time, I’ve served my time, But commited no crime, Now I, Just want to ski, Cause my boots, Are working just fine”.

        The only thing I can suggest is calling foam suppliers and explaining what you are looking for.

        Holdener got new boots? Wow! She must have read my mind. Is she still in Head or? After I criticised Vlhova a few years ago in several posts her skiing went way up. I was tempted a few times to say “WENDY, get your boots set up!” Maybe she heard me thinking out loud. I going watch the SL. Hoeldner has been skiing far below her potential as has the Germans. What happened to German engineering? It seems to be MIA at least in ski racing.

        If racers start applying information on my blog things could get real interesting next season and beyond. World Cup racing is there for the taking.

        Best regards,

  3. I’ve been one of the masses that have always skied with my boots tight. If I wasn’t satisfied with my skiing my reaction was usually to tighten my boots some more. After reading articles on this site a few months ago I started to experiment with various levels of looseness. The results are very positive, especially in the bumps where I now rarely get thrown into the back seat. I also notice that on groomed runs the skis are now able to glide freely waiting for input from me. After a couple months, I’m now skiing with the top two buckles three notches looser than before and I have the power strap loose enough that it only engages under heavy hits. I do still prefer a tighter boot for powder conditions but not as tight as before.

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