Torsion system for an article of footwear
An article of footwear includes a torsion system constructed of a material and configured to allow, in a pre-selected manner, rotation of a forefoot portion of the article of footwear relative to a rearfoot portion of the article of footwear about a longitudinal axis of the article while substantially precluding bending in an intermediate portion thereof.
1. A torsion system for a cycling shoe including a sole with a forefoot area and a rearfoot area, the torsion system including a longitudinal axis and comprising:
a forefoot portion of the torsion system spanning the forefoot area of the sole, the forefoot portion having a generally smooth concave contour along the longitudinal axis;
a rearfoot portion of the torsion system spanning the rearfoot area of the sole; and
an intermediate portion of the torsion system coupling the forefoot portion and the rearfoot portion, and constructed of a material and configured to allow, in a pre-selected manner, rotation of the forefoot portion relative to the rearfoot portion about the longitudinal axis, wherein the intermediate portion includes a rib that projects beyond an adjacent surface of the torsion system, wherein the rib tunes torsionability of the cycling shoe.
2. The torsion system of claim 1 , wherein the forefoot portion and rearfoot portion rotate between about 5-25 degrees relative to each other about the longitudinal axis at 35 Newtons of torsional load.
3. The torsion system of claim 1 , wherein the forefoot portion and rearfoot portion rotate between about 10-20 degrees relative to each other about the longitudinal axis at 35 Newtons of torsional load.
4. The torsion system of claim 1 , wherein the forefoot portion and rearfoot portion rotate about 10 degrees relative to each other about the longitudinal axis at 35 Newtons of torsional load.
5. The torsion system of claim 1 , wherein the intermediate portion defines at least one circumscribed aperture.
6. The torsion system of claim 1 , wherein the rearfoot portion defines at least one aperture.
7. The torsion system of claim 1 , wherein the forefoot portion, the rearfoot portion, and the intermediate portion form a single plate.
8. The torsion system of claim 1 , further comprising an upper.
9. The torsion system of claim 1 , further comprising an outsole.
10. The torsion system of claim 1 , further comprising a cleat attachment system disposed on the forefoot portion.
11. The torsion system of claim 7 , wherein the plate is substantially rigid in a horizontal plane.
12. The torsion system of claim 7 , wherein the plate is between about 1-15 mm thick.
13. The torsion system of claim 7 , wherein the plate is between about 3-10 mm thick.
14. The torsion system of claim 7 , wherein the plate is between about 5-8 mm thick.
15. The torsion system of claim 7 , wherein a thickness of the plate is less in the intermediate portion than in the forefoot and rearfoot portions.
16. The torsion system of claim 7 , wherein a width of the intermediate portion of the plate is narrower than the forefoot and rearfoot portions.
17. The torsion system of claim 7 , wherein the plate comprises nylon.
18. The torsion system of claim 7 , wherein the plate comprises a composite material.
19. The torsion system of claim 7 , wherein the forefoot portion and rearfoot portion comprise material properties different than the intermediate portion.
20. The torsion system of claim 18 , wherein the composite material is graphite.
21. The torsion system of claim 18 , wherein the composite material is fiberglass.