Bicycle steerer tube with variant stiffness
A bicycle steerer tube is adapted to reside in a plane of travel of the bicycle. A thickness at a point on the wall of the steerer tube body in a lower section thereof varies as a function of the cross-sectional angle of the point to the plane of travel, with the wall thickness being at a maximum in the plane of travel. An inner wall of the lower section may be elliptical, with a minor axis aligned with the plane of travel and a major axis orthogonal to the plane of travel.
1. A steerer tube for a bicycle, the steerer tube comprising:
an elongate hollow body arranged around a steering axis located in a vertical plane of travel of the bicycle,
the body having upper and lower sections, a segment of the upper section adapted to be joined to a bicycle handlebar, a segment of the lower section adapted to be joined to a crown of a front wheel fork of the bicycle, the lower section joined to the upper section, and outer surfaces of the upper and lower sections of the body being circular in cross section, and
the body formed by a wall, a thickness of the wall at any point in the lower section of the body varying as a function of the cross-sectional angle of the point relative to the plane of travel, the wall thickness being at a maximum in the plane of travel of the bicycle.
2. The steerer tube of claim 1 , wherein an outer diameter of the lower section of the body is greater than an outer diameter of the upper section of the body.
3. The steerer tube of claim 2 , wherein the lower section of the body has first and second portions, the first portion adjoining the upper section of the body, an outer diameter of the first portion of the lower section being greater than an outer diameter of the upper section and less than an outer diameter of the second portion of the lower section.
4. The steerer tube of claim 3 , wherein the outer diameter of the first portion of the lower section gradually tapers from the second portion of the lower section to the upper section of the body.
5. The steerer tube of claim 4 , wherein an inner surface of the upper section forms an ellipse in cross section, a major diameter of the ellipse formed to be perpendicular to the plane of travel, a minor diameter of the ellipse formed to be in the plane of travel of the bicycle.
6. The steerer tube of claim 4 , wherein an inner surface of the upper section is circular in cross section.
7. The steerer tube of claim 6 , wherein the inner and outer surfaces of the upper section are substantially circularly cylindrical and the outer surface of the second portion of the lower section is substantially circularly cylindrical.
8. The steerer tube of claim 6 , wherein a ratio of an inner diameter of the upper section of the body to an outer diameter of the upper section of the body is within the range of 0.75 to 0.95, inclusive.
9. The steerer tube of claim 1 , wherein an outer diameter of the lower section of the body is substantially the same as an outer diameter of the upper section of the body.
10. The steerer tube of claim 1 , wherein an inner surface of the upper section is circular in cross section.
11. The steerer tube of claim 10 , wherein the inner and outer surfaces of the upper section are substantially circularly cylindrical and the outer surface of the lower section is substantially circularly cylindrical.
12. The steerer tube of claim 10 , wherein a ratio of an inner diameter of the upper section of the body to an outer diameter of the upper section of the body is within the range of 0.75 to 0.95, inclusive.
13. The steerer tube of claim 1 , wherein the segment of the lower section of the body is formed as one piece with the crown of the front wheel fork.
14. The steerer tube of claim 1 , wherein the body is formed from a material selected from the group consisting of steel, carbon fiber reinforced composite, aluminum, titanium and magnesium.
15. The steerer tube of claim 1 , wherein the wall thickness is at a minimum in a plane containing the steering axis and orthogonal to the plane of travel of the bicycle.
16. The steerer tube of claim 15 , wherein an outer diameter of the lower section of the body is greater than an outer diameter of the upper section of the body.
17. The steerer tube of claim 16 , wherein the lower section of the body has first and second portions, the first portion adjoining the upper section of the body, an outer diameter of the first portion of the lower section being greater than an outer diameter of the upper section and less than an outer diameter of the second portion of the lower section.
18. The steerer tube of claim 17 , wherein the outer diameter of the first portion of the lower section gradually tapers from the second portion of the lower section of the body to the upper section of the body.
19. The steerer tube of claim 18 , wherein an inner surface of the upper section forms an ellipse in cross section, a major diameter of the ellipse formed to be perpendicular to the plane of travel, a minor diameter of the ellipse formed to be in the plane of travel of the bicycle.
20. The steerer tube of claim 18 , wherein an inner surface of the upper section is circular in cross section.
21. The steerer tube of claim 20 , wherein the inner and outer surfaces of the upper section are substantially circularly cylindrical and the outer surface of the second portion of the lower section is substantially circularly cylindrical.
22. The steerer tube of claim 20 , wherein a ratio of an inner diameter of the upper section of the body to an outer diameter of the upper section of the body is within the range of 0.75 to 0.95, inclusive.
23. The steerer tube of claim 15 , wherein an outer diameter of the lower section of the body is substantially the same as an outer diameter of the upper section of the body.
24. The steerer tube of claim 15 , wherein an inner surface of the upper section is circular in cross section.
25. The steerer tube of claim 24 , wherein the inner surface and an outer surface of the upper section are substantially circularly cylindrical and an outer surface of a portion of the lower section is substantially circularly cylindrical.
26. The steerer tube of claim 24 , wherein a ratio of an inner diameter of the upper section of the body to an outer diameter of the upper section of the body is within the range of 0.75 to 0.95, inclusive.
27. The steerer tube of claim 15 , wherein an outer diameter of the lower section of the body is greater than an outer diameter of the upper section of the body.
28. The steerer tube of claim 27 , wherein the lower section of the body has first and second portions, the first portion adjoining the upper section of the body, an outer diameter of the first portion of the lower section being greater than an outer diameter of the upper section and less than an outer diameter of the second portion of the lower section.
29. The steerer tube of claim 28 , wherein the outer diameter of the first portion of the lower section gradually tapers from the second portion of the lower section of the body to the upper section of the body.
30. The steerer tube of claim 15 , wherein the segment of the lower section of the body is formed as one piece with the crown of the front wheel fork.
31. The steerer tube of claim 15 , wherein the segment of the lower section of the body is joined to the crown of the front wheel fork, the body formed of a material different from the crown of the front wheel fork.
32. The steerer tube of claim 31 , wherein the segment of the lower section of the body is formed as one piece with the crown of the front wheel fork.
33. The steerer tube of claim 15 , wherein the body is formed from a material selected from the group consisting of steel, carbon fiber reinforced composite, aluminum, titanium and magnesium.
34. The steerer tube of claim 15 , wherein an inner surface of the wall within the lower section of the body is formed as an ellipse in cross section, a major diameter of the ellipse formed to be perpendicular to the plane of travel, a minor diameter of the ellipse formed to be in the plane of travel of the bicycle.
35. The steerer tube of claim 34 , wherein outer surfaces of the upper and lower sections of the body are circular in cross section.
36. The steerer tube of claim 35 , wherein an outer diameter of the lower section of the body is greater than an outer diameter of the upper section of the body.
37. The steerer tube of claim 36 , wherein the lower section of the body has first and second portions, the first portion adjoining the upper section of the body, an outer diameter of the first portion of the lower section being greater than an outer diameter of the upper section and less than an outer diameter of the second portion of the lower section.
38. The steerer tube of claim 37 , wherein the outer diameter of the first portion of the lower section gradually tapers from the second portion of the lower section of the body to the upper section of the body.
39. The steerer tube of claim 38 , wherein an inner surface of the upper section forms an ellipse in cross section, a major diameter of the ellipse formed to be perpendicular to the plane of travel, a minor diameter of the ellipse formed to be in the plane of travel of the bicycle.
40. The steerer tube of claim 38 , wherein an inner surface of the upper section is circular in cross section.
41. The steerer tube of claim 40 , wherein the inner and outer surfaces of the upper section are substantially circularly cylindrical and the outer surface of the second portion of the lower section is substantially circularly cylindrical.
42. The steerer tube of claim 40 , wherein a ratio of an inner diameter of the upper section of the body to an outer diameter of the upper section of the body is within the range of 0.75 to 0.95, inclusive.
43. The steerer tube of claim 34 , wherein an outer diameter of the lower section of the body is substantially the same as an outer diameter of the upper section of the body.
44. The steerer tube of claim 34 , wherein an inner surface of the upper section is circular in cross section.
45. The steerer tube of claim 44 , wherein the inner and outer surfaces of the upper section are substantially circularly cylindrical and the outer surface of the second portion of the lower section is substantially circularly cylindrical.
46. The steerer tube of claim 44 , wherein a ratio of an inner diameter of the upper section of the body to an outer diameter of the upper section of the body is within the range of 0.75 to 0.95, inclusive.
47. The steerer tube of claim 34 , wherein an outer diameter of the lower section of the body is greater than an outer diameter of the upper section of the body.
48. The steerer tube of claim 47 , wherein the lower section of the body has first and second portions, the first portion adjoining the upper section of the body, an outer diameter of the first portion of the lower section being greater than an outer diameter of the upper section and less than an outer diameter of the second portion of the lower section.
49. The steerer tube of claim 48 , wherein the outer diameter of the first portion of the lower section gradually tapers from the second portion of the lower section of the body to the upper section of the body.
50. The steerer tube of claim 34 , wherein the segment of the lower section of the body is formed as one piece with the crown of the front wheel fork.
51. The steerer tube of claim 34 , wherein the segment of the lower section of the body is joined to the crown of the front wheel fork, the body formed of a material different from the crown of the front wheel fork.
52. The steerer tube of claim 51 , wherein the segment of the lower section of the body is formed as one piece with the crown of the front wheel fork.
53. The steerer tube of claim 34 , wherein the body is formed from a material selected from the group consisting of steel, carbon fiber reinforced composite, aluminum, titanium and magnesium.
54. The steerer tube of claim 34 , wherein an inner surface of the upper section is circular in cross section, an inner diameter of the upper section being substantially the same as the minor diameter of the lower section.
55. The steerer tube of claim 34 , wherein the lower section has an axial length, the minor diameter remaining substantially the same along the axial length of the lower section.
56. The steerer tube of claim 34 , wherein the minor diameter decreases as a function of proximity to the upper section of the body.
57. The steerer tube of claim 34 , wherein a ratio of the major diameter to the minor diameter taken at a lower end of the lower section is within the range of 1.05 to 1.3, inclusive.
58. The steerer tube of claim 57 , wherein the ratio is within the range of 1.10 to 1.25, inclusive.
59. The steerer tube of claim 34 , wherein the major diameter of the lower section tapers from the second portion of the lower section to the first portion of the lower section.
60. The steerer tube of claim 34 , wherein a ratio of the major diameter to the minor diameter decreases as a function of proximity to the upper section of the body.
61. A steerer tube for a bicycle, the steerer tube comprising:
an elongate hollow body arranged around a steering axis located in a vertical plane of travel of the bicycle,
the body having upper and lower sections, a segment of the upper section adapted to be joined to a bicycle handlebar, a segment of the lower section adapted to be joined to a crown of a front wheel fork of the bicycle, the lower section joined to the upper section,
and an outer diameter of the lower section of the body is greater than an outer diameter of the upper section of the body, and
the body formed by a wall, a thickness of the wall at any point in the lower section of the body varying as a function of the cross-sectional angle of the point relative to the plane of travel, the wall thickness being at a maximum in the plane of travel of the bicycle.
62. The steerer tube of claim 61 , wherein the lower section of the body has first and second portions, the first portion adjoining the upper section of the body, an outer diameter of the first portion of the lower section being greater than an outer diameter of the upper section and less than an outer diameter of the second portion of the lower section.
63. The steerer tube of claim 62 , wherein the outer diameter of the first portion of the lower section gradually tapers from the second portion of the lower section to the upper section of the body.
64. A steerer tube for a bicycle, the steerer tube comprising:
an elongate hollow body arranged around a steering axis located in a vertical plane of travel of the bicycle,
the body having upper and lower sections, a segment of the upper section adapted to be joined to a bicycle handlebar, a segment of the lower section adapted to be joined to a crown of a front wheel fork of the bicycle, the lower section joined to the upper section, and the segment of the lower section of the body is joined to the crown of the front wheel fork, the body formed of a material different from the crown of the front wheel fork, and
the body formed by a wall, a thickness of the wall at any point in the lower section of the body varying as a function of the cross-sectional angle of the point relative to the plane of travel, the wall thickness being at a maximum in the plane of travel of the bicycle.
65. The steerer tube of claim 64 , wherein the segment of the lower section of the body is formed as one piece with the crown of the front wheel fork.