Shoe bottoms and shoes

Abstract

When a midfoot portion of a sole is divided by a predetermined sole center line into a medial midfoot region and a lateral midfoot region one on each side in the foot width direction, a rigidity lowering portion, which is provided in the medial midfoot region, is provided and, in such a manner that the bending rigidity of the medial midfoot region around a foot width direction axis becomes smaller than that of the lateral midfoot region, the rigidity lowering portion in the medial midfoot region reduces the bending rigidity of the medial midfoot region due to another factor other than the shape of the medial edge and the shape of the lateral edge of the sole in a planar view.

1 . A shoe bottom comprising a sole,
 wherein when a midfoot portion of the sole is divided by a predetermined sole center line into a medial midfoot region and a lateral midfoot region one on each side in the foot width direction, the sole has a rigidity lowering portion that is provided in the medial midfoot region, and   wherein, in such a manner that the bending rigidity of the medial midfoot region around a foot width direction axis becomes smaller than that of the lateral midfoot region, the rigidity lowering portion in the medial midfoot region reduces the bending rigidity of the medial midfoot region due to another factor other than the shape of a medial edge and the shape of a lateral edge of the sole in a planar view.   
     
     
         2 . The shoe bottom according to  claim 1 , wherein a continuous surface that is continuous in the foot longitudinal direction from a toe side end portion to a heel side end portion of a rearfoot portion of the sole is formed on a ground contact surface of the sole. 
     
     
         3 . The shoe bottom according to  claim 1 , wherein a lateral transverse groove portion that is open on the ground contact surface of the sole and that extends from the lateral edge in the foot width direction is not formed in a range in the foot longitudinal direction where the rigidity lowering portion is provided and in a range in the foot longitudinal direction located on the heel side of the range. 
     
     
         4 . The shoe bottom according to  claim 1 , wherein the rigidity lowering portion is open on the ground contact surface of the sole and serves as a medial transverse groove portion that extends in the foot width direction from the medial edge. 
     
     
         5 . The shoe bottom according to  claim 1 ,
 wherein the sole has either one or both of a midsole and an outer sole, and   wherein a reinforcing member is not attached to the midfoot portion of the sole.   
     
     
         6 . The shoe bottom according to  claim 1 ,
 wherein on the sole,   a plurality of medial transverse groove portions are formed that are open on a ground contact surface of the sole and extend in the foot width direction from the medial edge, and   a longitudinal groove portion is formed that is open on the ground contact surface of the sole, extends in the foot longitudinal direction, and connects with respective end portions of the plurality of medial transverse groove portions in the foot width direction.   
     
     
         7 . The shoe bottom according to  claim 1 ,
 wherein in a planar view of the sole, given that   straight lines along the foot width direction that divide the full length La of the sole in the foot longitudinal direction into 1.5:1.0:1.1 from the toe side to the heel side are defined as lines p and q, respectively,   a straight line along the foot longitudinal direction that divides the full width Lb of the sole into 1.2:1.0 from the medial side to the lateral side in the foot width direction is defined as a line s, which serves as the sole center line,   being viewed from a point O 1 , which is the intersection point of the line p and the line s, a straight line obtained by rotating the line p by 13 degrees around the point O 1  in an outward direction that rotates the toe side outward in the foot width direction, is defined as a line t,   a straight line obtained by rotating the line s by 8 degrees around the point O 1  in the outward direction viewed from the point O 1  is defined as a line u,   being viewed from a point O 2 , which is the intersection point of the line u and the line q, a straight line obtained by rotating the line q by 5 degrees around the point O 2  in the outward direction is defined as a line v,   a region surrounded by the line t, the line u, the line v, and the medial edge is defined as a first region, and   a region formed of the first region is defined as an external torsional resistance expected region,   a rigidity lowering portion is provided in the external torsional resistance expected region.   
     
     
         8 . The shoe bottom according to  claim 1 ,
 wherein in a planar view of the sole, given that   straight lines along the foot width direction that divide the full length La of the sole in the foot longitudinal direction into 1.5:1.0:0.2:0.9 from the toe side to the heel side are defined as lines p, q, and r, respectively,   a straight line along the foot longitudinal direction that divides the full width Lb of the sole into 1.2:1.0 from the medial side to the lateral side in the foot width direction is defined as a line s, which serves as the sole center line,   being viewed from a point O 1 , which is the intersection point of the line p and the line s, a straight line obtained by rotating the line p by 13 degrees around the point O 1  in an outward direction that rotates the toe side outward in the foot width direction, is defined as a line t,   a straight line obtained by rotating the line s by 8 degrees around the point O 1  in the outward direction viewed from the point O 1  is defined as a line u,   being viewed from a point O 2 , which is the intersection point of the line u and the line q, a straight line obtained by rotating the line q by 5 degrees around the point O 2  in the outward direction is defined as a line v,   being viewed from a point P, which is the intersection point of the line r and the line u, a straight line obtained by rotating the line r by 4 degrees around the point P in the outward direction is defined as a line w,   a straight line connecting a point O 5 , which is the intersection point of the medial edge and the line w, and the point O 2  is defined as a line x,   a region surrounded by the line t, the line u, the line v, and the medial edge is defined as a first region,   a region surrounded by the line v, the line x, and the medial edge is defined as a second region, and   a region formed of the first region and the second region is defined as an external torsional resistance expected region,   a rigidity lowering portion is provided in the external torsional resistance expected region.   
     
     
         9 . The shoe bottom according to  claim 1 ,
 wherein in a planar view of the sole, given that   straight lines along the foot width direction that divide the full length La of the sole in the foot longitudinal direction into 1.5:1.0:0.2:0.9 from the toe side to the heel side are defined as lines p, q, and r, respectively,   a straight line along the foot longitudinal direction that divides the full width Lb of the sole into 1.2:1.0 from the medial side to the lateral side in the foot width direction is defined as a line s, which serves as the sole center line,   being viewed from a point O 1 , which is the intersection point of the line p and the line s, a straight line obtained by rotating the line p by 13 degrees around the point O 1  in an outward direction that rotates the toe side outward in the foot width direction, is defined as a line t,   a straight line obtained by rotating the line s by 8 degrees around the point O 1  in the outward direction viewed from the point O 1  is defined as a line u,   being viewed from a point O 2 , which is the intersection point of the line u and the line q, a straight line obtained by rotating the line q by 5 degrees around the point O 2  in the outward direction is defined as a line v,   being viewed from a point P, which is the intersection point of the line r and the line u, a straight line obtained by rotating the line r by 4 degrees around the point P in the outward direction is defined as a line w,   a straight line connecting a point O 5 , which is the intersection point of the medial edge and the line w, and the point O 2  is defined as a line x,   a region surrounded by the line t, the line u, the line v, and the medial edge is defined as a first region,   a region surrounded by the line v, the line x, and the medial edge is defined as a second region,   a region surrounded by the line s, the line u, the line x, and the line w is defined as a third region, and   a region formed of the first region, the second region, and the third region is defined as an external torsional resistance expected region,   a rigidity lowering portion is provided in the external torsional resistance expected region.   
     
     
         10 . The shoe bottom according to  claim 1 , wherein the factor is any one or a combination of two of a recessed portion that is open on the ground contact surface of the sole and the elongation characteristic of a material constituting the sole. 
     
     
         11 . A shoe comprising the shoe bottom according to  claim 1 .