Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Background of the Invention
Field of the Invention The present invention
refers to a rock climbing shoe, and more particularly to an
insole incorporated into said shoe.
Description of the Prior Art: It is well known that,
in order to improve the purchase and to facilitate the step of
a climber during ascent in rocks, and especially during ascents
of difficult, steep grades, it is necessary and customary to
impart to the soles of the rock climbing shoes a flexibility irelative to a forward portion that includes the toe, and a
stiffness relative to a rear portion that includes the heel.
~t the present time, in order to satisfy such a need,
incorporated into the sole of a rock climbing shoe is a thin ` ~ ;
metal plate which generally extends longitudinally over a short
distance inside the sole itself.
However, the use of a thin metal plate presents some
disadvantages, either from a technical point of view or from an -economic point of view. In fact, taking into account the
repeated and also considerable flexion forces to which a sole
is subjected during a climb, the different degree of deform-
ability of the thin metal plate and of the material (leather,
rubber, plastic and the like) that constitute the sole is such
that, after a short time, it is possible to verify the existence `~
of deformations in the sole, humps that cancel out the desired ;~
comfort characteristics, to the point that it becomes necessary
to change the shoe. Moreover, in many cases, it has been
verified that the thin plate was directly causing ruptures in ~ ;
the sole, creating dangerous conditions for the climber. In
other cases, which are no less frequent, it was possible to
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ascertain that, following long periods of non-use, the thin
metal plate had conferred an accentuated concaveness to the sole
which rendered the shoe completely unusable. To overcome such
disadvantages, steps have been taken to increase the~ thickness
of the material constituting ~he sole, but such an increase is
reflected in an increase in weight for the entire shoe up to the
point that it is no longer acceptable for ascents of some given
difficulty. Other disadvantages associated with the use of a
thin metal plate inside of a sole consist in the tediousness and
the difficulty of incorporating such a plate and of the ensuing
difficulty of applying the sole that is thus equipped to the
footwear.
The problem that is the basis of this invention is that
of making available a rock climbing shoe that is equipped with
an insole having structural and functional characteristics such
as to overcome the disadvantages cited above and referring to -
known technology.
Summary of the Invention
In accordance with the invention, this problem is
resolved in that said insole is formed of a single piece of ~ ; ~
synthetic plastic material and has at least one portion, includ- ~ ;
ing the toe and part of the sole of the foot, that has a linearly
variable thickness in the longitudinal direction, with respect ;~
to the insole itself, so that said insole displays a differen-
tiated flexibility in said longitudinal direction with a maximum
of flexibility relative to said toe.
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My invention includes an insole for use in a rock climb- `
ing shoe, said insole being formed o~ synthetic plastic material
and having a heeI por-tion and a front portion, with said heel por-
tion being of sufficient thickness to be substantially rigid in
use, and said fron~ portion underl~ing the toes and a portion of
the ball of a weaxer's foot in use, said front portion being tap-
ered in thickness and decreasing in the longitudinal direction to-
ward the toes to provide substantially greater flexibility of the
front portion than said heel portion while distributing stress
throughout its length.
My invention also includes such an insole having a con- `
stant thickness in each of its transverse sections, or being an-
atomicallv shaped.
My invention also includes such an insole having a first
portion extending from the heel for a predetermined distance and
having a constant thickness in the longitudinal direction with
respect to the insole itself, and a second portion extending in
prolongation of said first portion and having, in the longitudinal
direction, a linearly decreasing thickness down to a minimum value
relative to the toes of said insole, and wherein the synthetic
plastic material is constituted by a mixture of polyamides, par-
ticularly the mixture known under the name of APIFLEX 1026.
My invention also includes an insole having one or more
of the above characteristics and formed of a unitary piece of ~ ~ ~
synthetic plastic material. `-` ` `
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Description of the Drawîng
Eurther characteristics and advantayes of the inven-
tion will be better understood from the following description
of a preferred form of embodiment of an insole for a rock climb-
iny shoe that is in accordance with the invention, description
yiven in the followiny with reference to the attached sketch
wherein said insole is represented, in the single figure, in
lonyitudinal cross section.
Description of the Preferred Embodiment
With reference to the above-mentioned figure, repre-
sented overall by 1 is an insole for rock climbing shoes formed
of a single piece by means of techniques that are known per se,
using plastic materials, for example injection techniques (at
pressures of 210-215 Kg/cm2 and temperatures of 160-190 C)
using a mixture of polyamides, preferably a polyamide mixture ~ ;
known commèrcially under the name APIFLEX 1026. Said insole 1 -
includes a first portion 2 that extends from the heel up to a
distance of about 10.5 cm from the toe, which portion 2 has a
constant thickness in the longitudinal direction. Subsequent
to numerous tests, it was possible to establish that the
optimum thickness for this portion is 7mm for the material used.
A second portion 3 that extends in prolongation of section 2 ~;~
in order to include the toe of insole 1 has, in the longitudinal ";
direction with respect to said sole, a thickness that decreases
linearly up to attaining a minimum value relative to the toe. ~ -
Following all of the numerous tests mentioned above, it was ;
always possible to establish that the optimum thickness for said
toe is lmm for the material used.
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A further dimensional characteristic of insole 1 of
this invention is constituted by the fact that said insole has
a constant thickness in each transverse section. Advantageously,
insole 1 is given an anatomical shape.
The nature of the material, method of molding, but
above all the dimensional characteristics presented for insole 1
confer upon it a differentiated flexibility in the longitudinal
direction, with a maximum of flexibility relative to the toe
and a maximum of rigidity in portion 2 that includes the heel.
Thanks to such characteristics, it has been possible to establish
by repeated climbs of notable difficulty how a rock climbing
shoe equipped with an insole of the type described above could
provide noteworthy qualities of "purchase" at minimum lean-out `
(angle) to the rocky wall and how it facilitates the step of the
climber with, consequently, less fatigue. ~`
Added to these qualities, not to be found in rock
climbing shoes incoxporating insoles of earlier technology, are
the advantages of resistance, wear and non-deformability over
time, whether subsequent to intensive use or whether subsequent
20 to extensive non-use. ;
I conclude, sticking to the concept of imparting to
an insole of plastic material a differeniated flexibility in
the longitudinal direction by means of a thickness gradient in ~ `
the longitudinal direction of the insole itself, the values
reported further above being capable of varying as a function
of the dimensions of the insole and as a function of the
intrinsic characteristics of the synthetic plastic material used. ~ -
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