After the initial slope test on November 11, 2015, Matt was convinced of the merits of the extreme modifications made to the liner of his left boot when he compared his skiing performance to his right foot in the boot shell fit with the stock liner and his custom footbed.
The next step in the step-by-step process was to modify the liner for Matt’s right boot shell so it had the same configuration as the liner in his left boot. With the right boot now the reference boot, I took Matt’s left boot to the next level. It is important that the skier or racer I am working with confirms every change as positive or negative and any corrections made prior to moving to the next step. For this reason, I make a change to one boot then use that boot as a reference for changes to the other boot.
One of the first tweaks I made to Matt’s left boot was to remove the padding from the outside of the liner so that there was no padding in either side. The graphic below shows the shape of the foam pad that was inside the inner or medial section of the liner for his left boot. The stitches were cut to gain access to the pad. Once the pad is removed, the liner is restitched. Although it can be restitched by hand with a heavy needle and thread, a shoemaker can perform a more robust repair.
Here is the pad that was surgically removed .
The next tweak I made was to remove the portion of the padding in the in the bend of the left tongue where it turns upward from the instep to the shin. I discussed this issue in my post, TONGUE TIED. With the tongue disconnected from the liner, it is less likely to obstruct the glide path of the ankle in dorsiflexion as the shank moves forward. But I like to ensure that the center of pressure stays at the top of the tongue/shaft where forward movement of the shank can be controlled by the power strap to limit movement of the shank within the shaft of the boot to about 10 to 12 degrees of ankle flexion. Removing the padding in the area of the transition is not difficult. But care should be exercised to avoid knicking and especially cutting into, the plastic tongue body. I cut the stitches on one side, pull the skin back, cut the tongue pad foam with a box cutter and yank the foam out with needle nose pliers. If necessary, any rough edges can be trimmed with sharp scissors. It helps if you have 3 hands to perform this operation.
After the tweaks were made, Matt went back to the ski hill for more testing. Two issues came up that I have underlined in Matt’s text below.
MATT: Notes from today;
-Left boot feels better and no more pressure band.
– Both left and right boots, is there a way I can decrease or prevent the tongue from slipping. The top of the tongue will end up out of line after a few runs.
– I’m very keen to rivet and connect the cuff of the liner to the cuff of the boot as the liner cuff too will experience rotation throughout the day
Skiing felt pretty strong today. I’m getting more and more aware of the front of my foot and getting a lot of data from the snow.
ME: Tongue issue. With your boots on and buckled to the normal tension, grasp the top of the tongue in one boot and see how easily you can pull it up part, way out of the shaft. If there is not much resistance, the instep portion is not applying enough load to your instep. Another possible issue is not quite enough forward lean. I should have some time tomorrow to remove the padding in your other liner and rivet the liners to the shell.
MATT: Excellent. I’ll connect with you tomorrow then! All in all I love the boots.
MATT: Can I cut out the padding on the right foot (outside padding)? So I can have it even for tomorrow?
ME: Sure. You have to peel it away from the skin of the liner then get your hand inside and grab the pad where it attaches behind the Achilles.
MATT: Will I mess up or can I handle this task? I’ll wait it you think I should
ME: Experience helps. But you can probably manage. The trick is to make sure peel pad completely off the liner skin then bunch the pad up, get a firm grip on it and pull on it as close to the rear aspect as possible. Get as much out as you can. I’ll check it tomorrow. Don’t try to rip until you can get a good grip.
With padding removed from the sides of both liners, it usually becomes obvious where the most important area of constraint is lacking; the area between the instep of the foot and the underside of the shell. In the late 1980’s, a husband/wife team of radiologists took some X-rays of the feet of skiers in boots tightly buckled. The X-rays, called Seriograms showed, as much as 2 to 3 cm of free or ‘crash space’ between the top of the boot tongue and the inside of the boot shell that the foot could move upward into. You don’t want to put high pressure on the instep of the foot. But for reasons I will explain in a future post, the foot needs to be dampened against vertical movement caused by perturbations in GRF from undulating terrain that can cause load/unload cycling that perturbs balance and places stress on the knee.
The graphic below on the left shows the top of the left tongue from Matt’s boot. The graphic on the right shows the same tongue with a shim pad outlined in grey. A template is made to the approximate shape of the grey area. Then a shim pad is cut from a piece of dense foam about 2 – 3 mm thick. The stitching is cut on the outside of the tongue and the pad inserted between the top of the tongue foam and the plastic outer skin of the tongue. A good source of foam for this purpose is a thin insole from a running shoe.
The photo below shows some good sources of suitable padding. It is better to start with a thing layer (2-3 mm) then add a second layer if on snow testing finds the fit still lacking.
Since Matt literally lives in his boots 11 months of the year, he wanted the liners positively connected to the shells. This is easy to do with T-nuts. But the locations need to be carefully chosen so as to avoid causing issues with the foot leg especially when putting on the boots. I placed the fixations on either side of the tongue in a seam in the liners. I got Matt to locate the liners in the shells where he wanted them. Then I clamped the liners to the shells, drilled holes through the shell and liner, inserted T-nuts into the liners facing the shell and inserted screws into the T-nuts from the outside of the shell.
As usual, I did the left boot first so that Matt could use it as a reference to compare to the right boot with the unsecured liner.
The rule of thumb is that if you do something, have a process in place to make sure it works. Only the skiers and racers I work with can make that call. I am only the mechanic.
In my next post, I will provide photos and plans for a Stance Ramp and describe how it works in stance training.