Ski boot modification posts


Since the summer and fall is a time when racers and serious skiers make changes to ski boots, I will describe the strategy I use to assess changes. It is important to make changes in a manner that controls variables and provides a baseline to make one-on-one comparisons against. However, after viewing video provided to me by several followers of my blog that graphically shows the effect on technique of changes made to ski boots over a number of years, it became apparent to me that few, if any, racers or elite skiers have any idea of what a ski boot should ideally feel like and especially how it should affect them in terms of performance.

Without clearly defined end objectives and a sequential process for achieving and confirming successful implementation, skiers and racers can only think in relative terms of better or worse, not optimal.

ASSESSING CHANGES TO SKI BOOTS was originally published on July 11, 2015. The entire post can be viewed at

It should be read in conjunction with BOOT-FITTING 101: THE ESSENTIALS – BOOT BOARDS



Those who went through the 9 exercises in TRANSITIONING THE SR STANCE TO THE SKI BOOT  probably ended up with a number of red flags. Starting with this post, I will go through what I consider to be the essentials of boot-fitting.

While I use the term boot-fitting, I prefer the term boot-modification. Boot-fitting and fit of a ski boot imply a fit of the boot with the foot and leg that results in a degree of dysfunction of the foot. The key to skiing with minimal effort and maximum balance and comfort is a ski boot that creates a functional environment for the foot and leg as opposed to a ski boot that creates an environment that results in a significant degree of dysfunction of the foot and the entire lower limb.

Achieving a functional environment in a ski boot for the foot and leg is about sequence. The fastest route to a ski boot that provides the best functional environment for the foot and leg is a step-by-step process; one that assesses the effect of each essential component in a systematic manner. A minimalist approach makes it easy to assess the effect of changes such as substituting a custom footbed that supports the arch for a baseline flat insole. The gold standard in studies to assess the effect of interventions such as insoles and orthotics is to compare barefoot balance on one limb to balance on the same limb in a specific form of footwear to balance on the same limb in the same form of footwear fit with an insole or orthotic. This protocol enables the effect of a compounding series of interventions to be assessed against a consistent baseline; in this case, barefoot balance on one limb.

Where I Start

At the bottom. By at the bottom, I mean the boot board (aka, the Zeppa).

I prefer to start with a monoplanar boot board. Monoplanar means flat in both the long and transverse axes of the boot board with the plane of the transverse axis parallel to the base plane of the sole of the boot.

Why monoplanar? Because the shape of the boot board can significantly affect foot function and the fact that the shapes of boot boards and materials and construction can and do vary considerably from one boot brand to another and sometimes even among different models in the same brand. The shape of a boot board can also act to compound the shape of custom footbeds and orthotics. A monoplanar boot board establishes a baseline with which to assess the effects of foot function irrespective of the boot brand or model. A monoplanar boot board and a flat insole serve as a baseline reference with which to assess the effect of any changes to that alter the monoplanar surface form of the boot board.

In my opinion, boot boards are one of the weakest components of a ski boot. Boot boards are one of the first things I check when I am considering purchasing or working on new ski boot. In future post, I will discuss a recent study that raised significant issues with boot boards.

What I Look For

Ramp or Zeppa angle is important. But before I even consider this aspect, I check the construction and materials of the boot board. Although I have not conducted an extensive review of boot boards, I consider both the boot boards and the insoles (after heating and pressing them flat) in Head Raptors some of the best I have seen to date.

The photo below shows a boot board from an Atomic boot (upper 2 photos). A boot board from a Head Raptor is shown in the bottom photo.


The 2 photos below are of side and top views of a boot board from a Head Raptor SD. One thing I deem important is continuity across the heads of the metatarsals, especially the head of the first metatarsal (ball of the foot). With the boot board in place, no break in surface continuity should exist between the interface of the boot board and the surface of the boot shell. It is especially important that there is no step at the interface where in the boot board or shell base are at different elevations.


The photo below shows a boot board from a Salomon SX 90 rear entry boot. This type of boot board construction is still found in some recreation boots. I would not consider a ski boot with this type of boot board.


The main reason I prefer boot boards like the one shown in the photo below is that it is fabricated from dense hard foam. Any contour can be quickly and easily removed with a sharp block hand plane. Ramp angle can also be easily and quickly adjusted with a sharp block plane. I use a belt sander to finish the surface


When the front portion of a board needs to be raised to correct zeppa angle, I use a material like dense gasket cork. The photo below shows boot board from a Head recreational boot with a layer of cork added to the front half to reduce ramp angle.


With the boot board in place in the shells, the insoles from the liners should be placed on top of the boot boards in order to ensure that the foot is sitting at the correct elevation in relation to the shell walls when checking for clearances.  The insoles shown in the photo below are from a Head Raptor.


In terms of resiliency and surface texture, the Head insoles in the above photo are some of the best insoles I have found to date. I heat and press them flat in order to create a baseline insole.

Once a skier or racer has adapted to the baseline fit of a ski boot they can replace a baseline insole in one boot with a custom insole or orthotic and compare it to the  baseline insole in the other boot. If the boot is perceived to be better with the custom insole or orthotic, the baseline insole in the other boot can be swapped. If there is any doubt after a ski-in period, the process is easily reversed.

The protocol I follow is to make one change at a time and always ensure is quickly and easily reversible.



A follower of skimoves posed the following;

“I’m trying to determine my optimal boot shaft angle and ramp angle given my physiology – i.e. what works best for me. I’ve done some of this work on my own by adjusting binding ramp angle (last season). What is interesting is the shaft angle of my newer Head vs. Lange boots”.

As discussed in recent posts, the importance of the cumulative effect of boot board ramp (zeppa) and binding ramp (delta) angles on stance is becoming increasingly recognized. Although binding ramp angle (delta) typically varies widely from one binding to another in recreational bindings, boot board ramp angle seems to be coming into line with functional reality in race boots. Reliable sources in Europe tell me that the boot boot board ramp angle in World Cup boots is in the order of 2.6 degrees. After I eliminated the arch profile in boot boards for a 23.5 Head race boot, I calculated the ramp angle at 2.35 degrees, a far cry from the 5 degrees claimed for the boot boards. I calculated the boot board ramp angle of an Atomic race boot of a local ski pro at a little over 2 degrees. I have also been told that shim kits are available for all race bindings that allow the delta angle to be zeroed.

The default barefoot ramp angle for humans is zero. It has been unequivocally established that anything more than a small amount of ‘drop’ (heel higher than forefoot) in footwear will have a detrimental effect on stance, balance and movement patterns. This especially true for balance on one foot, something that is fundamental to sound ski technique.

Elevating the heel relative to the forefoot will cause the muscles in the back of the lower leg to contract. Over time, these muscles will become chronically shortened. The key muscles affected are the calf muscles; the gastrocnemius and soleus. But the small muscles that stabilize the knee and pelvis are also adversely affected, not a good thing.

If I want to find the optimal boot shaft angle and compare the shaft angle of two or more boots, I start by making the boot boards perfectly flat with the transverse aspect horizontal with the base of the ski. I set the boot board ramp angles for both boots at 2.5 or 2.6 degrees. Since it can take a long time for the body to adapt to even small changes in ramp angle underfoot, the angle is not hypercritical.   I have settled on 2.5 to 2.6 degrees of total ramp (zeppa + delta) as an arbitrary starting point. Although there appears to be a positive effect of a small delta binding angle in SL and GS, I prefer to work with a zero delta angle initially since a positive or negative delta affects the shaft angle of a ski boot.

When moving from one boot model to a different model or to another boot brand, the first thing I do is remove the boot boards and calculate the ramp angles with the top surface monplanar. If the boot boards are not flat, I plane or grind them flat. If a new boot is to be be compared to a current boot with a boot board angle of 2.5 to 2.6 degrees, I modify the boot board of the new boot so it has the same angle as the current boot.

Next, I compare the shells and the angles of the spine at the back of the shaft of each boot. Even if the angles of the spines of the boot shells appear similar, there is no guarantee that what I call the static preload shank angle (more on this in a future post) will be the same.

A quick check of how the structure of the shell of the new boot is affecting the functional configuration of the foot and leg compared to the current boot, is to put the current boot on one foot then put the new boot shell with the liner from the current boot on the other foot. If a significant difference is perceived, the source is the new shell.

At this point, it may be apparent that there is a difference in the shank angles of the left and right legs when comparing the current boot to the new boot. But whether one boot is better than the other or even if one boot eanables the optimal static preload shank angle would not be known. I will explain how I identify this angle in my next post. For now, study this recent video of Lindsey Vonn starting off by skiing in what appears to be a strange ski stance. In fact, the exercise Vonn is doing is a familiar routine to me, one that I do before I start skiing –

Why is Vonn skiing this way? What is she trying to do?

Also, check out this screen shot of Anna Fenninger. Note her compact, forward in the hips stance.


Finally, watch this video in which Brandon Dyksterhouse compares Shiffrin and Fenninger – Shiffrin GS Analysis –

What do Vonn and Fenninger have in common? Why?



“A problem with stronger sports people is that they can ‘fake’ the outcome. But when it comes to free form, fluid skiing… the real deal is still missing (for me).” – Whistler Ski Pro, Matt

Since last fall, I have been working with Matt. His situation is not uncommon. It is one thing to look like a good skier. It is another matter entirely to be able spread your wings and fly like a bird in free form, fluid skiing. A small number of skiers can ski at this elite level in boots right out of the box, with little or no modification. These are the skiers that rise to the top. Based on my experience, I estimate that this elite skier group makes up less than 0.5% of the skier population. But these are the skiers those such as Matt are chasing but never getting any closer to, no matter how hard they work at their skiing. Matt’s problem isn’t a lack of talent, fitness or athletic ability. Matt’s feet are simply out of specification for most performance ski boots.

The reason I started this blog is to provide serious skiers like Matt with information that would help them realize their full potential. About a year ago, I started working with a small number of serious skiers and racers in different parts of the world, mostly by email. Since that time, I have learned a lot more than I previously knew about how equipment, especially the ski boot, can affect a skier. More important, I have learned a lot more about the process with which to correct and reverse these effects so skiers whose progress has stalled, can reach a higher level.


On October 11, 2015, I received the following message from Matt:

“Hi David, I have been following your posts and discussion with interest. I’m a ski coach, I work 10-11 months of the year on snow. Summer in Australia and Winter in Whistler. I have a lot of questions for you. To keep it short, will you be in Whistler this season? And secondly, are you available for any amount of time to briefly discuss boot fit/make an assessment of me on/ off skis. I would be happy to pay any amount of money for your services.”

On October 22, 2015, Matt wrote:

“Thank you for your comments, it makes sense to read. Now my next question is…. Through the season could I look at creating the perfect boot and liner with you. Whilst I make do with my vacuum fit in the mean time, I’d like to invest and do this properly as I understand the critical importance of this.”

On October 26, 2015, Matt wrote:

“I appreciate all of your advice on the matters. In my years of skiing I’ve yet to have a boot where I’ve felt as if it’s the correct fit. Whether that be adverse effect in my feet or the outcome to my connection to the ski and snow!”

Matt knew that something was preventing him from realizing his potential.

I replied, “Once you have found a product you can work with, the process is not difficult.”

Feet First

The first thing I did was ask Matt to send me photos of his feet taken from top, sides and rear. Matt is solid and athletic. His problem is his feet, not in terms of their function, but in their inability to function within the constraints of pretty every performance ski boot.

In the photos below, Matt’s big toes are angled inward and twisted outward. His forefoot is also wider than performance boot shells, which are narrower than recreational boots. A big clue to Matt’s issues are the prominent heel spurs on both feet and the inflamed area outlined on the shank of his left foot. It was almost certain that his prominent inside ankle bones were in hard contact with the inside of the shells of his boots.

Although not as obvious, the front to back cross-section of Matt’s leg, above the ankle bone, appears big in proportion to the length of his foot. The mass of Matt’s calf muscle is also larger lower down on his leg than that of the typical elite skier. This issue is exacerbated by the large heel spurs that prevent Matt’s foot from moving all the way to the rear of the liner and boot shell.

Feet 2.1

Feet 1

Based on Matt’s photos, the most likely source of his problems was that the tongue of the liner of the boot was obstructing the glide path of his ankle joint. The lack of sufficient width was was limiting Matt’s ability to load the heads of his metatarsals, especially the head of the first metatarsal. This was preventing his foot from fully compressing and tensioning the arches. When Matt attempted to flex his ankles by moving forward in the hips, the center of force on tongue pressing on his shank was moving down the shaft of the boot into the glide path of his ankle. I discussed this issue in my posts:




As far back as 1987, the importance of ankle flexion and maintaining the center of force on the shin was recognized by a number of preeminent authorities.

In Kinematics of the Foot in the Ski Boot – Professor  Dr. M. Pfeiffer of the Institute for the Athletic Science at the University of Salzburg, Salzburg, Austria said, “The shaft of the boot should provide the leg with good support, but not with great resistance for about two thirds of the possible arc, i.e., (12 degrees) 20 to 22 degrees. Up to that point, the normal, physiologic function of the ankle should not be impeded. Previous misconceptions concerning its role in absorbing energy must be replaced by the realization that shaft pressure generates impulses affecting the motion patterns of the upper body, which in turn profoundly affect acceleration and balance.”

In Sports Medical Criteria of the Alpine Ski Boot – W Hauser P. Schaff of the Technical Surveillance Association, Munich, West Germany said, “Many alpine skiers have insufficient mobility in their knees and ankle. The range of motion, particularly in the ankles, is much too small”.

In Ski-Specific Injuries and Overload Problems – Orthopedic Design of the Ski Boot –  Dr. med. H.W. Bar, Orthopedics-Sportsmedicine, member of GOTS, Murnau, West Germany said, “Few forms of athletics place as high demands on the footwear used in their performance as alpine skiing. It (the ski boot) functions as a connecting link between the binding and the body and performs a series of difficult complex tasks. (my emphasis added) “The boot must assure freedom of mobility to the toes. This is accomplished by having a large enough inner shoe.

In my next post, I will discuss what’s wrong with ski boots in general.





When Morgan Petitniot, from Font Romeu Ski Resort in Southern France, sent me a video titled ‘Ski Gear Comparison – David MacPhail‘, in which he documented his experiments with different ski boot setups, I was both suitably impressed and flattered. Morgan came across as an athletic individual; one who took skiing very seriously. He was determined not to let anything stop him from reaching the highest possible technical level. And yet, his ski equipment had been doing precisely that. In viewing Morgan’s video, I was both moved and impressed by his dedication and logical approach. Even more impressive is that Morgan realized his equipment was adversely affecting his skiing and impeding his progress. In many ways it was a deja vu experience for me; one that reflected my own journey.

Here are a series of screen shots of title scenes from each of Morgan’s experiments between 2013 and April of 2015.


(Click on images to zoom in)

Morgan, “For the first time in 2013 I saw me skiing (on video). It was the worst day of my skier’s Life ! I saw me totally blocked, tall, with little flexion at the ankle, knee and hips.”

Jan 2013

Morgan, “So I applied what I was understanding on skier’s manifesto.”

Dec 2014 copy


Feb 2015


Mar 16


Mar 28


Mar 2015
April 10


April 17 soma


April 17


April 17 Lange tongue

In my next post I will analyze Morgan’s skiing in his video and describe the events and sequences I look for that indicate problems caused by the ski boot




Morgan Petitniot first contacted me on September 2, 2014 to ask permission to translate my blog posts into French and post them on his own skiing web site. I was happy to accommodate Morgan.

Over the coming months, we struck up a friendship and communicated with each other on a regular basis. Morgan was passionate about skiing and motivated to learn to ski at the highest possible level. As I did, he encountered equipment problems that he recognized were impeding his progress. So he started asking why. A big breakthrough came when he,  “…… started to think that probably the soft snow acted under my skis like a platform that permitted me feeling in balance”. At that point, Morgan did what most skiers would do. He purchased tightly fitting boots with a custom insoles. The boots felt good in the ski shop and on perfectly groomed runs. But they were a disaster on more challenging conditions. Morgan started looking for answers outside the ski industry.

He found The Skiers Manifesto. He started applying information from my posts. By April of this year, Morgan was ready to work on his technique and I was ready to help. This is Morgan’s story in his own words, with minimal clarification or comments on my part.


I am Morgan. I am 40. I live in south of France (FONT-ROMEU Ski resort). I love skiing so much that, when we moved my wife and my 2 childrens, to live in Font-Romeu, I started skiing seriously. It was in (2012). I was so involved to ski well that I get a course with a ski instructor. I demand him to explain to me all he knows, even technical aspects, to bring me quickly to a better level.

Problems started immediately. He said to me to ski like him and behind him and reproduce the same movements. I was with a 50/50 (50% groomed, 50% free ride) 180 cm skis with 80mm lift under foot. It was impossible to (for) me to reproduce the movements until, after 2 hours analysing why I was struggling. I took his (the instructor’s) skis (slalom Salomon 9S). And instantly I was able to carve a turn. At this moment, I thought that equipment was a huge key in skiing success. Of course, now I could carve a turn with this type of ski, but to learn skiing it is not a good thing.

But I didn’t know how ski boots should be to me the major factor of improvement. As the believe said: block the ankle, squeeze the forefoot, high flex and tighten shell set up. In the fall I buyed a pair of skiboot, a custom insole and squeeze my foot in all parts. I started to feel more precise. Obviously, such tight that when I was moving one toe all the boot was moving. Precise: OK but efficient? No. I could ski well (feeling) in a perfect snow condition on groomed slopes. I remember that I was saying to me:”Yes I got it” but on the black icy slope, that was a disaster. I started to think that probably the soft snow acted under my skis like a platform that permited me feeling in balance. Today thanks to David’s knowledge shared on his blog I know that I was right. But no one tell me the story.

For the first time in 2013 I saw me skiing (on video). It was the worst day of my skier’s Life ! I saw me totally blocked, tall, with little flexion at the ankle, knee and hips. So I applied that I was understanding on skier’s manifesto.

1/ I disconnected the liner and leave the part that lies on top of the forefoot. I was in Lange Ski boot (ZB 150 WC : 92 mm last). I had to “velcro” the upper aspect of the liner in order to it stay in place.

It increased dramatically my ankle flexion possibilities about 30% but not enough.

RESULTS : was That for the first time I was able to better in holding an arc in icy condition. But not enough.

2/ After reading and understanding the importance of CENTER OF PRESSION (PRESSURE) aligned to the GROUND REACTION FORCE , The importance of the reference shank angle and above all THE PRONATION,  I changed my ski boot. I tried 2 models : head Raptor 130 RS and FISCHER RC4 130. Those boot are very different in geometries, shapes and orientations of the feet.

RESULTS : Much better with Head Raptor to tip the skis on edge but I was feeling blocked at ankle and I could not reached my reference shank angle.


Great with Fischer RC4 because in this boot I can respect the point that david explained to be crucial :

– My soles feet can spread when I am balanced in one foot.

– With a little expansion at the medial aspect of the shell, at the medial ankle bone : My bone can move as I pronate without blocking.

– I can reach my reference shank angle with a minimal contact on the upper part of the tongue

– And with my feet resting on a flat boot sole and a flat stock footbed with all things explained above I can feel the pressure under the ball of my feet.

It was in April 2015. And I remember That I said to me :”Now I can work on technique and improve my skiing”


In my next post, I will detail my analysis of Morgan’s issues using the video he sent me.


Since I started this blog with my first post on May 11, 2013, A Cinderella Story: The ‘Myth’ of the Perfect Fit,  (…ve-perfect-fit/), I have had a number of skiers contact me from various parts of the world, either through my blog via a comment (which I don’t post), through a social media site like FaceBook, Twitter or Linkedin, or through contact information provided by someone they know who knows me. One skier who contacted me privately is Michael Pupko. After he started following my blog, he started trying some of my ideas. Most important, he started giving me valuable feedback. Michael has developed some innovative concepts of his own. He started discussing them with me and asking for my feedback. Over the years I had considered some of his ideas. But never got around to trying them. Michael put them into practice and refined them. We have both learned a lot from our corroboration. He recently posted a large comment. With his permission, I am posting it as a guest post with my comments inserted.



The physics of skiing are secondary to the ability to move within the ski boots. My only contact with David MacPhail has been through this blog and a limited amount of personal emails from which I can guarantee, I don’t have a complete grasp on his ‘alignment concepts’ of ski equipment but am 100% convinced of their validity because applying my limited understanding to what I have discovered myself over the past 20 years has changed what I do with equipment radically for the better. The latest discovery before being given the link to this blog (I can’t even take credit for finding it myself!) was to leave my boots unbuckled to the point where I hit the cuff just before my ankles range of motion is zeroed out so should I happen to need it, my binding would release before my ankle. Upon reading this blog I found someone who knew the why and methods of doing this properly, so I’m grateful to not have to reinvent the whole wheel, just try to build on it and make it better and above all, understand methods already proven by Podborski, etc.

Sometime around 2005 I ‘discovered’ a new method of adjusting footwear and orthotics that is better than any current method THAT I”M AWARE OF (which doesn’t mean there isn’t a better method). Finally after 1000s $ and many rejections I now have a patent on the method because I was finally able to convince the necessary parties that the vertical relationship of the heel to forefoot is different than the lateral (canting wedges) relationship. Since over 99% of humans that have access to fancy footwear walk anatomically incorrectly, the vertical relationship, called toe drop by some, remains a critical aspect of fitting not just ski boots but all footwear for me, guess what? I am now skiing without footbeds/orthotics for the first time in 2 decades with better results than with because what I learned from this blog enabled me to remove the original interference in the arch that was the limiting factor in not only my ski boots, but also other footwear.

In spite of a pile of fancy orthotic blanks and the equipment to create orthotics it will take a strong argument from any one to convince me to make them a pair because MacPhail’s methods are better than what I was doing. So obviously his methods is based upon a more solid ‘principle’ than my methods.

My theory on Ligety’s last season is so silly I never dared to mention it last year; I say it boiled down to his broken hand / wrist. When one is competing at any level, in any sport, anything that can cause one to hold back just a touch will change the standings dramatically.

COMMENT: I agree

We’ll see as the season progresses how far ‘back’ he is, obviously. Nothing could stop Ted though in Beaver Creek last season because his mental strength overcame whatever other issues seemed to be there last seasons. He ‘rose to the occasion!’ Bottom line is that Ligety and Shiffrin are both better aligned for their best disciplines than any other current racer and while they are dialled in them, either they don’t know or their equipment techs won’t allow them to transfer it over to the disciplines. Something we’ll never be able to prove now is that if Bode had MacPhail as his boot-fitter I feel he would have left Stenmark’s records in the dust. As dominant as Ligety has been in GS, he still has a little bit of catch-up when it comes to Stenmark who skied on brands of equipment that no other racer has won consistently on!

COMMENT: I agree

MacPhail’s theory that removing the inner liner of the ski boot keeps one’s feet warmer doesn’t make much sense. I did that and with an extra pair of liners in a pair of used boots I had bought and I’ve never gone back.

COMMENT: I think Michael means he tried his boots with minimal liner and found it works. Racers I worked with like Podborski, skied in shells with no liner except for the portion of the liner that was screwed in the shaft of the boot. They never had cold feet. This is not something I recommend without careful experimentation.

My boots are a joke, I laugh every time I go skiing because I have so much more fun. I challenge any critics to simply apply these ideas to your equipment and then if you want to argue fine. But I’d first ask for MacPhail’s help in what went wrong because my experience has been that my problems were in a mistake that I made.