World Cup Racing posts

WINNING BY A FOOT

Numerous studies have attempted to find a correlation between foot size and height. I believe there is a reasonable correlation between foot size and height if stature is considered. Ski racers tend to have moderate body masses. When I worked on racer’s boots, most female racers had a US ladies size 7 foot (US men’s 6). Male racers tended to have a US  8 or 9 foot size. Ski boot makers usually make prototypes in a US men’s size 9 then scale the shell up or down to create other sizes.

Lange recently introduced a size 4 US men’s race shell. Perhaps it is more accurate to state that Lange reintroduced a size 4 race shell.  After I learned how to read the shell mold codes forty years ago, I knew that Lange made size 4 shells. However, they only sold them in softer children’s boots in North America. The XLR Race boot was only sold in Japan. After I got the Canadian distributor to bring in a supply of size 4 XLR Race boots, I was inundated with calls from all over Canada from female racers with small feet who heard that a size 4 XLR was available.

In my experience, I was usually able to estimate the size of a racer’s foot by looking at their stature and height. Here is a list of 6 top World Cup racers in order of height.

Ted Ligety 1.80 m
Lindsey Vonn 1.78 m
Marcel Hirscher 1.73 m
Tina Maze 1.72 m
Mikaela Shiffrin 1.70 m
Anna Fenninger 1.66 m

Based on Lindsey Vonn’s stature, I estimate that she has bigger feet than both Tina Maze and Mikaela Shiffrin who are very close to the same height. Vonn is  close to the height of Ted Ligety. I estimate that she has at least a US ladies Size 8 to 8.5 while Ted Ligety’s foot is in the order of a US men’s 9. Anna Fenninger is 1.66 m and small boned. She probably has small feet, smaller than Shiffrin who probably has a size 7 ladies (6 men’s). Anna Fenninger’s foot will be no bigger than a size 6 ladies (US men’s size 5). Marcel Hirscher at 1.73 m probably has a size 7.5 to 8 US men’s foot.

With a ski that is 65 mm in Minimum Profile Width who has the winning feet? Ted Ligety and Lindsey Vonn.

REVELATIONS FROM THE FIS GS SKI RULING

The controversy that surfaced in 2011 over the FIS decision to increase turn radius on GS skis revealed a lot about what the various authorities in skiing knew and, especially, what they didn’t know, about the mechanics, biomechanics and physics of skiing. Some critics of the ruling took the position that the reduced sidecuts would actually increase the risk of injury. An article in Ski Racing called, Black Diamond: The Deaf Ears Of The FIS, reviewed the various positions on the matter. And while some critics of the FIS ruling had very strong opinions, no one seemed able to put forth a position based on sound principles of science. In what had to be the height of irony, Guenter Hujara, director of the men’s World Cup was reported to have said, The facts are the facts. If you want safety this is a step you have to take.

Since 1977, I have been stressing the importance of the feet in skiing as the transmission path for forces transferred from the skier’s centre of mass to the snow. Knowledge of the forces acting between the soles of the feet and the snow surface is the arbiter of knowledge as a whole in skiing.  At last, a World Cup official was finally talking about taking a step. But my elation was short-lived. Hujara was talking about new regulations for GS skis, not my long hoped for new regulations for ski boots.

Two statements pertaining to injury mechanisms and ski safety were telling; Scientists at the University of Salzburg determined through a subjective study of 63 experts that the main risk factor was the “system ski, binding, plate, boot,” and By their own (FIS) admission, boots are too complex, and plates are, too. I say, ‘wait a moment’. The common denominator in the ski system/skier interface with the potential to cause injury, especially knee injury, is moments of force (torques). To be more specific, an unbalanced inversion moment of force present across the inside edge of the outside ski and the associated joints of the ankle-complex. By association, an unbalanced external (out of the turn) vertical axial moment of force acting on the tibia that tends to rotate it out of the turn against a well-stabilized femur or, worse, a femur that is being rotated into the turn by the powerful hip rotators. Between the tibia and femur lies the knee; a fragile joint with only ligaments holding the two bones in proximity to each other.

Mechanisms of Anterior Cruciate Ligament Injury in World Cup Alpine Skiing  (The American Journal of Sports Medicine, Vol. XX, No. X DOI: 10.1177/0363546511405147), states, under Background,

There is limited insight into the mechanisms of anterior cruciate ligament injuries in alpine skiing, particularly among professional ski racers.

My US Patent No.  5,459,949 published on or about November 29, 1994, goes into great detail about the importance of positioning the foot within in the ski boot and especially positioning the ball of the foot in relation to the inside edge of the outside ski of a turn so as to facilitate the setting up of moments of force (torques) into the turn with which to oppose externally generated torques out of the turn and the avoidance of mechanical relationships that result in unbalanced torques, It can be debated whether the presence of an unbalanced external vertical axial moment of force causes or contributes to an injury. But there is no debate that an unbalanced external vertical axial moment of force is a predisposing factor to injury.

 

Here are some excerpts from the subject patent that discuss moments of force acting about the inside edge of the ski with my notes and emphasis (bold) added. Due to the relatively short moment arm, aligning applied and ground (snow) reaction forces in opposition to each other or even creating an alignment where the applied force is on the inside turn aspect of the inside edge of the outside ski is not, in itself, sufficient to engage the external forces that drive a ski into a turn. It is merely a prerequisite. The factors that multiply moments of force once an over-centre mechanism is initiated are much complex than a simple misalignment of opposing applied and snow reaction forces.

SOLE ADJUSTMENT

While the adjustment of medial forefoot counter 2201 enables the foot 2001 of the user to be correctly aligned on rigid base 2100 yet another problem has arisen. The alignment of the head of the first metatarsal of the foot 2001 of the user has been altered in relation to the appliance affixed to the sole of the footwear, in this instance, a snow ski, in comparison with the alignment of the appliance in relation to the head of the first metatarsal as shown in FIG. 63.

Alignment of the center of the head of the first metatarsal is an important factor influencing physiological mechanisms which balance pronation/supination moments acting transversely across inside edge of appliances such as snow skis. The contact point of such an appliance with the surface on which it is acting can act as a fulcrum and, in so acting, establish a moment arm pivot in situations where the ground reaction force and the force applied by the user are not acting linearly in opposition to each other. In monopedal stance (pronated) the weight of the body acts substantially through the center of the head of the first metatarsal.

It is important, in activities such as snow skiing, that means be provided to allow the center of the head of the first metatarsal to be positioned so that the force applied by the user can be aligned in opposition to the ground reaction force when the snow ski is placed on its inside edge. If opposing ground reaction and applied forces can not be aligned, a moment arm will be created with the effect that the force applied by the user will tend to rotate the foot in the direction of either supination or pronation.

The location of the inside edge of (the outside ski) a snow ski tends to favour a supination moment arm since the ski edge generally lies medial of the center of the head of the second metatarsal. If the force applied by the user is sufficient in the presence of a moment arm to rotate the foot in the direction of either supination or pronation, the long axis of the tibia will also be caused to rotate through an intrinsic mechanism within the tarsus of the foot.

The means to adjust the transverse position of the foot in relation to the inside edge of a snow ski while maintaining the means to independently adjust the position of the foot on the longitudinal axis of the sole of the footwear is important and advantageous to the user and is thus an object of the present invention. FIG. 70 shows substantially the same view as FIG. 69 except that the ground reaction force FR and the force applied by the user F are shown substantially as they would be when the user is in monopedal stance (pronated) with the foot correctly positioned in relation to the inside edge of a snow ski affixed to sole 2101.

FIG. 71 shows substantially the same view as FIG. 70 except that the snow ski shown affixed to sole 2101 is wider on its medial aspect in comparison to the snow ski affixed to sole 2101 as shown in FIG. 70. The position of the inside edge of the snow ski in relation to force F applied by the user is such that the ground reaction force FR and the force F applied by the user are not acting linearly in opposition to each other. The transverse offset between the ground reaction force FR and the force F applied by the user creates a moment arm MA which acts lateral of the ski edge with the result that force F applied by the user acting on the moment arm MA will tend to rotate the foot in the direction of supination when the ski is placed on its inside edge.

Fig 70-72

FIG. 72 shows substantially the same view as FIG. 71 except that sole 2101 has been shifted laterally in relation to rigid base 2100 so that the ground reaction force FR and the force F applied by the user are now acting linearly in opposition to each other with the result that the moment arm MA as shown in FIG. 71 facilitates a countering muscularly generated torque from internal rotation of the leg at the pelvis.


The link to US Patent No.  5,459,949 is:

http://patft.uspto.gov/netacgi/nph-Parser Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=5,459,949.PN.&OS=PN/5,459,949&RS=PN/5,459,949

PUTTING THE BOOT TO THE EUROPEANS: A NEW DIRECTION

While waiting for Poborski to return to Whistler in June so I could assemble and tune several pair of race boots for the 1980-81 World Cup season I spent a lot of time thinking about how I could fit the foot differently from the conventional method of supporting the ankle with foam pads inserted between the ankle and the interior boot cuff walls and squeezing the sides of the forefoot together. After discovering that the forefoot of the boot tongue was applying little or no pressure to the instep of most skiers I was trying to find a way to pad the tongue so as to close the gap between the instep of the foot and the forefoot of the shell.

There are three challenges to attempting to pad the tongue of a conventional liner in order to load the instep with the forefoot boot closure. The stiff nature of the plastic and the inability to open the seam of the overlap very much require that the throat of the boot where the cuff transitions into the forefoot be ‘generous’. By ‘generous’ I mean that the instep has to be much higher than the height of the instep of the average skier’s foot in order to facilitate entry. In addition, the point where the forefoot of the boot rolls up into the cuff has to be much farther forward than the same reference in a street shoe. But the biggest challenge is that the shape and form of the typical boot tongue bears little resemblance to the asymmetrical shape of the instep of the human foot where what I refer to as the ‘dorsal ridge’ angles inward towards the ball of the foot from the crown of the midfoot.

In what turned out to be another disastrous experiment with Dave ‘Mur’ Murray I had used 2 mm thick sheet thermofoam to fabricate a custom tongue pad that was inserted into the Lange tongue body in place of the factory foam padding. The custom tongue was laminated from a number of layers of thermofoam heated and shaped to Mur’s shin and forefoot with each layer bonded to the layer below. The final assembly was ground to shape to reflect the corresponding interior shape of the shell. The fit of the final product was perfect. But Mur said the tongues made the flex of his Langes so stiff he could barely ski.

At first I was puzzled. What happened was totally unexpected.  After researching the biomechanics of the tibial talar joint (commonly referred to as the ‘ankle joint’) I found out why the tongue made Mur’s boots stiff. The ankle joint is gliding hinge, not a fixed hinge like the hinge a door swings on. The implications of a gliding hinge in the ankle are that when the ankle dorsiflexes (the shin moves towards the toes) a reference point on the tibia moves closer to a reference point on the top of the foot. When this happens the centre of force of the shin pressing against the boot cuff suddenly drops down the shin. The effect is like someone kicking your feet out from underneath you. Not good.

Once I understood what was happening I decided to try and make a tongue for Pod’s boots that had 2 components, a shin component and a forefoot component. The 2 components would have a gap between them. They would be joined together with a flexible link. This would hopefully allow the 2 components move towards each other without binding and causing the centre of force on the cuff to move downward. Now all I had to do was figure out how to make the new boot-fitting tongue.

…… to be continued.

PUTTING THE BOOT TO THE EUROPEANS: DYNAFIT/LANGE SHOOTOUT

As soon as the 1979-80 World Cup season ended Podborski came to Whistler to test boots for the 1980-81 season. In this session Steve compared the Dynafit World Cup boot he used in the last season to a new Dynafit model and a Lange XLR.

In the photo below Steve and I are on Whistler Mountain where we did the testing in April. Some young potential World Cup stars have joined us. Steve is in the white jacket. I am in the blue vest kneeling down making adjustments to his boots. Steve’s brother, Craig, came along to help out. Craig is standing behind Steve wearing a red vest. If you look closely you will that Steve’s left foot is bare.

Pod Lange 1

Pod Lange 2

Pod Lange 5

We spent two days testing boots.  For the tests I had only made some very basic modifications to the new boots. Based on the results of these tests Steve made the decision to switch to Lange from Dynafit, a bold move since no World Cup Downhill racer had ever won on Lange.

After the tests Steve took a break and made arrangement to get a stock of  Lange parts from the factory so I could make up several pair of race boots when he came back to Whistler in June. Steve had very small feet back then – US Men’s size 6. For these tests we used a pair of boots I had assembled for DeeDee (Diana) Haight. Podborski was also one of the lightest racers in the World Cup Downhill circuit, something that was considered a disadvantage when it can to gliding.

In next post I will show the in-boot technology I invented that enable Pod to ‘Walk on Water’ metaphorically speaking.

……. to be continued.

PUTTING THE BOOT TO THE EUROPEANS

After the end of the 1979-1980 World Cup season Podborski came to Whistler so I could prepare new ski boots for him for the 1980-1981 World Cup season. It was standard practice with the racers I worked with to make any changes to a new pair boots or to change boot brands or models after the end of the competitive season. This made it easier for the racer to adapt to the changes when training resumed. It was also standard practice to never modify the previous years’ boot. Should problems arise with the new boots and the issues could not be quickly sorted out the racer could revert to their old boots.

Before Pod even came to Whistler I had recommended that he change from the Dynafit boot he had won a Bronze Medal in at the Lake Placid Olympics with to a Lange boot. Despite their success in technical events, no male competitor had ever won a downhill race wearing a Lange ski boot. And at this point no non-European had ever won the grand prix of World Cup racing, the World Cup Downhill title. Pod was naturally apprehensive about changing something that was working for him. But I persisted. He asked me if I could guarantee that he would do better in Lange. I took a deep breath, then confidently said, “Yes”. The pressure was on.

From about 1977 on I had found myself moving farther and farther away from the conventional approach of squeezing the sides of the foot between the walls of the plastic boot shell with padding to ‘support the ankle’. Instead of adding padding to boot liners, as was the common practice, I found myself doing ‘padectomies’; cutting open liners and removing padding. At first, I was doing this to try and make boots more comfortable. As I got more skilled at ‘liner surgery’, I became increasingly better at making ski boots comfortable; something that was a contradiction in terms in those days. As I did, something interesting happened. People started telling me that they were skiing better. This got me thinking that maybe the idea of supporting the foot by creating what amounts to an orthopedic splint with the padding on the insides of the rigid  plastic boot shell was just plain wrong. Soon, I was not just removing padding from within liners, I was cutting away portions of liners and stretching shells to make room for the foot to sit in the shell in its natural, weighted position.

In effect, I was ‘unsupporting the ankle’, the exact opposite of what everyone else was doing.

But as I made more room for the foot a new problem started emerging; the fit of the ski boot was getting increasingly looser to the point where it felt like the foot was floating inside the shell under some conditions; not a good thing.

One day, while riding up Whistler Mountain’s old 2-person Red Chair my outside ski slipped off the foot rest and dropped into space. When the boot with ski attached bottomed-out I felt the instep of my foot jump up inside the boot shell and hit the top of the tongue and inside of the shell. I also felt a sharp twitch at the knee. It seemed as if there were several inches of free or ‘crash-space’ between the top of my foot and the inside of the boot shell. I deliberately let my foot slip off the foot rest and drop into space about 10 more times. The more I did the ‘drop test’ the more it became apparent that the reason my foot felt ‘loose’ in my ski boot was that the tongue portion over top of my instep was putting almost no pressure on my foot.

When I got home after skiing I undid the cuff buckles on my boot, grabbed the shin portion of my tongue and tried pushing it up and down. It was unbelievable. It seemed as if I could move the tongue up and down over my instep about 2 inches. And this was with the forefoot buckles tightly closed. In the coming weeks tried the tongue press test with other skiers with similar results. There had to be a better way to secure the foot to the ski with the boot. But how?

……. to be continued.

MAC MEETS POD: THE MACPOD CONNECTION

By 1979 things were going so well with the BC Ski Team that Glen Wurtele (the coach) asked me to accompany the team to the Pontiac Cup finals and the Spring Series in Quebec.  The Spring Series are especially important for provincial teams because it gives junior racers a chance to compete against National Ski Team and US Ski Team racers. But spring is also a time when warm weather can bring out the worst in ski boots as racers’ feet swell. Because of the importance of these races, most provincial teams brought extra coaches along. But in his typical ‘take the enemy by surprise’ fashion, Wurtele brought a boot technician. Little was he to know that this bold move would set the stage for a successful Canadian assault on the European Juggernaut of World Cup racing, the World Cup Downhill title.

Although I was getting good results with BC Ski Team racers, most of what I was doing, aside from ramp angle, cuff canting and forward lean cuff adjustments, was what I considered band aid boot work. Where the boot allowed, I was starting to do foot alignment. My challenge was that the construction of most boots didn’t allow for significant modification. But in those days any modification was usually an improvement over a stock product.

After the Pontiac Cup finals at Mont St Marie the team moved on to Sutton, Quebec for the Spring Series.  The opening race was a GS. The men and women  were running the same course. As usual, DeeDee (Diana) Haight was blowing her competition away. She was even beating a lot of the men when the times were compared. For the first run of the men’s GS I was standing about half way down the course at a position beside some National Team coaches. When an National Team racer in a white downhill suit came zooming past me I was taken by how good this guy was skiing. I knew right then and there he could win World Cup races. I turned to one of the coaches and asked, “Who was that racer that just went down the course?” “Podborski“, the coach replied. I had to meet this Podborski. I asked Wurtele to introduce me. He agreed and gave me a quick introduction during lunch. After the second run of the men’s GS, Pod and I retreated to the base lodge to discuss my ideas on ski boots. I rambled on for what seemed like hours. Most would have thought me possessed or perhaps more than a bit eccentric. But after I finished my spiel Podborski calmly said, “When can I come out to Whistler to work with you?” I replied, “As soon as you can get there”. It was game on.

A few weeks later Pod arrived in Whistler. He was skiing on the Austrian Dynafit boot. In those days, it was the most successful boot on the downhill circuit. But it was bloody awful to work on. The large cuff hinge made altering the cuff cant to align with the racer’s leg, something I considered essential, impossible. During the day Pod and I worked on his Dynafits. At night we listened to his favourite group, Steely Dan……..at concert level volume. Working with Pod was a new experience for me. I likened our working relationship to my favourite race car team, Roger Penske and Mark Donahue where results sprung from a collaboration of the crew chief (Penske) who tuned the race car based on input from the driver (Donahue).

I did the best I could with Pod’s Dynafits. As an exceptionally talented skier with the right foot structure (his foot was US men’s size 6 and what was I referred to as ‘stiff’), he could ski in gum boots and probably be competitive. Still, I wasn’t satisfied that the Dynafit allowed me to make the modifications necessary to enable him ski to his full potential. Pod had an OK 1979-1980 season culminating in a bronze medal run in the downhill at the 1980 Winter Olympics in Lake Placid. Seeing a photo of him airborne with his skis oriented on their outside edges convinced me that he needed to change boots for the next season. Besides, I had a new idea that I wanted to try.

THE LANGE USA CONNECTION

When I started working on Mur’s boots in 1977 I didn’t favour any particular boot brand. Mur was skiing in Langes even though Lange wasn’t in the National Ski Team pool of Official Suppliers. It was an interesting situation. The Crazy Canucks were garnering world wide attention. Mur’s position was that he couldn’t ski in any other boot. So he just skied in Lange’s and that was that. As best I can recall, back then there were maybe 4 boot brands in the pool. When a racer made the National Team they would be assigned to a boot and ski brand from one of the official suppliers. This didn’t work for every racer. If a racer ended up in a boot brand they couldn’t ski in their career could literally go downhill. Sometimes it did. But as the saying goes, “That’s racing!”

Lange USA had a solid racing program in a tech by the name of Alan Trimble. Even though he was assigned to US racers, Trimble was servicing Langes for Mur and a few other Canadians. When I hooked up with Mur he started getting me boxes of parts from the Lange factory in Italy. When Lange USA found out about me they started sending me anything I needed by courier. Ya gotta love those Yanks! The situation with Lange in North America seemed to be unique on the World Cup circuit. For example, the word was that Italian team racers were forbidden from having any alterations made to their boots. They just took them out of the box and went racing. Presumably, other alpine nations had a similar arrangement.

Once I figured out how to build a pair of Lange race boots from parts, I would make templates for each racer. Every pair of boots was different. Even though they looked the same as the ones you could buy at a retail shop, they bore little resemblance in the way they were set up in terms of cuff cant and forward lean. They were also usually expanded in the forefoot and the liners were gutted of padding. I had a stock of liners. So I usually used a liner up to one size larger than the shell size.

Prototype ski boots are typically made to a US men’s size 9 last and then scaled up and down. So a size 5 ladies boot back then was really a scaled down size 9 men’s boot. (Yes, it really is a man’s world ,at least in skiing ladies). Cuffs were canted outward about 3 degrees. Since the angle of the rear spoiler was fixed, the amount of forward lean as represented by the angle of flexion of the ankle joint was determined by the cross-sectional area of the calf muscle. Unless a female racer had a body close to that of man, stock boots were almost unskiable. If you had small feet (many female racers did) you were really in trouble. Trying to set up boots for female racers with small feet was a real challenge. It could take as much as 15 or 20 hours. But when I got the boots right the racers I worked with had a huge advantage over their competition. I didn’t give them anything they didn’t already have. I just enabled them to use what they had. When it comes to ski boots, ski racing is very much an unlevel playing field even today.