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.
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.
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.
The package contains 4 sheets of gasket material that includes 3 mm and 1.5 mm sheet cork and 2 other materials.
I cut forefoot shims from the 3 mm cork sheet as shown to the right of the boot board in the photo below.
I adhered the shims to the boot board with heavy duty 2-sided tape and feathered the edges with a belt sander.
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.