CA2357598C - Aerodynamic bicycle frame - Google Patents
Aerodynamic bicycle frame Download PDFInfo
- Publication number
- CA2357598C CA2357598C CA002357598A CA2357598A CA2357598C CA 2357598 C CA2357598 C CA 2357598C CA 002357598 A CA002357598 A CA 002357598A CA 2357598 A CA2357598 A CA 2357598A CA 2357598 C CA2357598 C CA 2357598C
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- CA
- Canada
- Prior art keywords
- tube
- bicycle frame
- frame according
- tubes
- aerodynamic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62K—CYCLES; CYCLE FRAMES; CYCLE STEERING DEVICES; RIDER-OPERATED TERMINAL CONTROLS SPECIALLY ADAPTED FOR CYCLES; CYCLE AXLE SUSPENSIONS; CYCLE SIDE-CARS, FORECARS, OR THE LIKE
- B62K19/00—Cycle frames
- B62K19/02—Cycle frames characterised by material or cross-section of frame members
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62K—CYCLES; CYCLE FRAMES; CYCLE STEERING DEVICES; RIDER-OPERATED TERMINAL CONTROLS SPECIALLY ADAPTED FOR CYCLES; CYCLE AXLE SUSPENSIONS; CYCLE SIDE-CARS, FORECARS, OR THE LIKE
- B62K19/00—Cycle frames
- B62K19/02—Cycle frames characterised by material or cross-section of frame members
- B62K19/04—Cycle frames characterised by material or cross-section of frame members the material being wholly or mainly metallic, e.g. of high elasticity
- B62K19/06—Cycle frames characterised by material or cross-section of frame members the material being wholly or mainly metallic, e.g. of high elasticity tubular
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62K—CYCLES; CYCLE FRAMES; CYCLE STEERING DEVICES; RIDER-OPERATED TERMINAL CONTROLS SPECIALLY ADAPTED FOR CYCLES; CYCLE AXLE SUSPENSIONS; CYCLE SIDE-CARS, FORECARS, OR THE LIKE
- B62K3/00—Bicycles
- B62K3/02—Frames
- B62K3/04—Frames having a substantially horizontal top bar
Abstract
An arrangement of a bicycle frame wherein the seat tube below the seat post-seat tube junction, and down to the down tube-seat tube junction, is greatly curved so as to follow the curvature of the rear wheel.
Description
TITLE OF THE INVENTION
AERODYNAMIC BICYCLE FRAME
FIELD OF THE INVENTION
The invention relates to a bicycle frame comprising a partially curved seat S tube, which has a constant width at the trailing edge when viewed from the rear, and which covers a substantial portion of the front and upper portion of the rear wheel, for the purpose of aerodynamically shielding the rear wheel.
In conjunction with this, the invention also incorporates an improved rear brake area that integrates the seat stays into the frame in such a manner to improve the aerodynamics of this area and includes a brake plate to which the rear brake is attached prior to its mounting to the frame. This plate permits attachment of the brake to the frame without compromising the aerodynamics, stiffness, or strength of the frame. The present invention further improves the aerodynamics by integrating the rear wheel with the frame through rearward facing adjustable dropouts that allow proper wheel to seat tube spacing, and a recessed concave trailing edge to the lower curved seat tube. Finally, the invention enhances the stability of the bike by moving the center of pressure rearward.
AERODYNAMIC BICYCLE FRAME
FIELD OF THE INVENTION
The invention relates to a bicycle frame comprising a partially curved seat S tube, which has a constant width at the trailing edge when viewed from the rear, and which covers a substantial portion of the front and upper portion of the rear wheel, for the purpose of aerodynamically shielding the rear wheel.
In conjunction with this, the invention also incorporates an improved rear brake area that integrates the seat stays into the frame in such a manner to improve the aerodynamics of this area and includes a brake plate to which the rear brake is attached prior to its mounting to the frame. This plate permits attachment of the brake to the frame without compromising the aerodynamics, stiffness, or strength of the frame. The present invention further improves the aerodynamics by integrating the rear wheel with the frame through rearward facing adjustable dropouts that allow proper wheel to seat tube spacing, and a recessed concave trailing edge to the lower curved seat tube. Finally, the invention enhances the stability of the bike by moving the center of pressure rearward.
2 BACKGROUND OF THE INVENTION
Prior art seat tubes are either straight or only have a recessed curved section and, as such, do not fully shield the rear wheel. Additionally, prior art seat tubes with a curved section cut iryto a predominantly straight seat tube (as shown in figure 1 (a) and 'I (b)) do not have a trailing edge with a constant width as viewed from the rear (see figure 2): the middle is wider, and the top and bottom narrower.
As well, the prior art seat tube does not extend much over the upper portion of the rear wheel. Further, it is the upper portion of the rear wheel where aerodynamic shielding is the most useful. By not covering as much of the upper portion of the rear wheel, current bicycle frames do not achieve optimal aerodynamic shielding in this area.
Conventional bicycle frames, as illustrated for example 1n Fig. 12 generally have a one-piece straight seat tube. Bicycle frames with a one-piece seat tube having a curved portion are also known in the art, as 111ustrated for example in United States patents No. 5,957,473 to Lawwill and No. 4,900,050 to Bishop et al.
If has been found advantageous to establish an aerodynamic shielding on the rear wheel of a bicycle, especially on the upper portion. Attempts to achieve this goal have been made by constructing bicycle .frames with a straight seat tube having a recessed curved section. Unfortunately, this design does not allow for a full shielding of the upper porkion of the rear wheel.
Trimble in United States patent Nos. Re. 33,295; 4,941,674; and 4,982,975 discloses a bicycle frame made of comp4site material. The frame 2a comprises a seat tube having a curved section which is cut into a one-piece straight seat tube. ~ Such seat tubs is also illustrated in Figs. 1(a) and 1(b). The resulted design of the bicycle frame according to Trimble is that of a traditional 'double diamond" frame, which has two open triangles with a common side. Typically, the curved section of such designs of seat tube does not allow for a full coverage of the upper portion of the rear wheel and thus an optimal aerodynamic shi8lding is not achieved.
Therefore, there remains a need fnr a bicycle frame allowing for a maaomum aerodynamic shielding and reduced aerodynamic drag. There is also a need for an aerodynamic frame having a brake which is temovably attached therefrom without reducing the aerodynamic efficiency of the frame, or its strength or stiffness.
Indeed, in frames with recessed curved cutouts it becomes very difficult to attach a brake of conventional design because access to the rear of the brake is required to affix it. A large gap must therefore be left around the back of the brake for access to attach and tighten the brake to the frame. This large gap reduces the aerodynamic efficiency of the frame. In outer designs, access holes are provided in the frame for attachment of the brake thereto. This n3sults in adding weight as well as costs, and the stiffness and structural Integrity of the frame are reduced.
SUMMARY OF THE INVENTION
t3y using a seat tube of constant width at the trailing edge of the curved section, greater aerodynamic efficiency is achieved through more effective aero-dynamic shielding. As well, by employing a larger curve in the seat tube, a greater 2b portion of the rearwheel is aerodynamically shielded. This includes the upper portion of the rear wheel, where the greatest aerodynamic benefits are achieved.
It is an object of the present invention to provide a bicycle frame allowing for an optional aerodynamic shielding on the upper portion of the rear wheel.
It is also an object of the invention to provide an aerodynamic bicycle frame allowing for a reduced aerodynamic drag.
It is yet another object ofthe invention to provide an aerodynamic bicycle frame which integrates a brake, without reducing the aerodynamic efficiency of the frame.
In accordance with the invention, there is provided a bicycle frame comprising a bicycle frame comprising: a first tube; a second tube extending transversely from an upper region of the first tube, in a direction; a third tube extending transversely and downwardly from a lower region of the first tube, and towards the same direction as the second tube; and a two-part tube joining the respective ends of the second and third tubes, the two-part tube having a straight upper part and a curved lower part, the straight upper part being substantially verkical and the curved lower part being curved longitudinally towards the first tube such as to confomn to the curvature of a bicycle wheel.
In accordance with a preferred embodiment, the two-part tube can be aerodynamic shaped and its upper part can be adapted to receive therein a post member.
The bicycle frame according to the invention may comprise a first set of tubes extending from the two-part tube at a junction between the upper and the lower ~C
parts. The first set of tubes are attached at their other ends to dropout means located at the center of the wheel. in addition, the frame may also comprise a second set of tubes extending from a lower end of the two-part tube and attached at their other ends to dropout means located at the center of the wheel. Preferably, the second set of tubes may be attached at a junction between the upper and the lower parts.
In accordance with a preferred embodiment, the lower part can be curved in both horizontal and Vertical planes in arderto conform to the curvature ofthe bicycle wheel.
A prefer-ed embodiment of the bicycle frame can include brake means which is removably attached to the two-part tube at a junction between the upper and the lower parts. More preferably, the brake means can include a brake mounted to a plate.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other advantages of the invention will become apparent upon reading the following detailed description and upon referring to the drawings In which:
FIGURE 1 (a ~ b) is a side view of a prior art aerodynamic bicycle frames;
FIGURE 2 is a rear view of the seat tube of a prior art aerodynamic bicycle frame;
FIGURE 3 is a rear view of the seat tube of the aerodynamic bicycle frame according to the invention;
FIGURE 4 is a cross section of the lower section df the seat tube of the aerodynamic bicycle frame according to the invention;
Prior art seat tubes are either straight or only have a recessed curved section and, as such, do not fully shield the rear wheel. Additionally, prior art seat tubes with a curved section cut iryto a predominantly straight seat tube (as shown in figure 1 (a) and 'I (b)) do not have a trailing edge with a constant width as viewed from the rear (see figure 2): the middle is wider, and the top and bottom narrower.
As well, the prior art seat tube does not extend much over the upper portion of the rear wheel. Further, it is the upper portion of the rear wheel where aerodynamic shielding is the most useful. By not covering as much of the upper portion of the rear wheel, current bicycle frames do not achieve optimal aerodynamic shielding in this area.
Conventional bicycle frames, as illustrated for example 1n Fig. 12 generally have a one-piece straight seat tube. Bicycle frames with a one-piece seat tube having a curved portion are also known in the art, as 111ustrated for example in United States patents No. 5,957,473 to Lawwill and No. 4,900,050 to Bishop et al.
If has been found advantageous to establish an aerodynamic shielding on the rear wheel of a bicycle, especially on the upper portion. Attempts to achieve this goal have been made by constructing bicycle .frames with a straight seat tube having a recessed curved section. Unfortunately, this design does not allow for a full shielding of the upper porkion of the rear wheel.
Trimble in United States patent Nos. Re. 33,295; 4,941,674; and 4,982,975 discloses a bicycle frame made of comp4site material. The frame 2a comprises a seat tube having a curved section which is cut into a one-piece straight seat tube. ~ Such seat tubs is also illustrated in Figs. 1(a) and 1(b). The resulted design of the bicycle frame according to Trimble is that of a traditional 'double diamond" frame, which has two open triangles with a common side. Typically, the curved section of such designs of seat tube does not allow for a full coverage of the upper portion of the rear wheel and thus an optimal aerodynamic shi8lding is not achieved.
Therefore, there remains a need fnr a bicycle frame allowing for a maaomum aerodynamic shielding and reduced aerodynamic drag. There is also a need for an aerodynamic frame having a brake which is temovably attached therefrom without reducing the aerodynamic efficiency of the frame, or its strength or stiffness.
Indeed, in frames with recessed curved cutouts it becomes very difficult to attach a brake of conventional design because access to the rear of the brake is required to affix it. A large gap must therefore be left around the back of the brake for access to attach and tighten the brake to the frame. This large gap reduces the aerodynamic efficiency of the frame. In outer designs, access holes are provided in the frame for attachment of the brake thereto. This n3sults in adding weight as well as costs, and the stiffness and structural Integrity of the frame are reduced.
SUMMARY OF THE INVENTION
t3y using a seat tube of constant width at the trailing edge of the curved section, greater aerodynamic efficiency is achieved through more effective aero-dynamic shielding. As well, by employing a larger curve in the seat tube, a greater 2b portion of the rearwheel is aerodynamically shielded. This includes the upper portion of the rear wheel, where the greatest aerodynamic benefits are achieved.
It is an object of the present invention to provide a bicycle frame allowing for an optional aerodynamic shielding on the upper portion of the rear wheel.
It is also an object of the invention to provide an aerodynamic bicycle frame allowing for a reduced aerodynamic drag.
It is yet another object ofthe invention to provide an aerodynamic bicycle frame which integrates a brake, without reducing the aerodynamic efficiency of the frame.
In accordance with the invention, there is provided a bicycle frame comprising a bicycle frame comprising: a first tube; a second tube extending transversely from an upper region of the first tube, in a direction; a third tube extending transversely and downwardly from a lower region of the first tube, and towards the same direction as the second tube; and a two-part tube joining the respective ends of the second and third tubes, the two-part tube having a straight upper part and a curved lower part, the straight upper part being substantially verkical and the curved lower part being curved longitudinally towards the first tube such as to confomn to the curvature of a bicycle wheel.
In accordance with a preferred embodiment, the two-part tube can be aerodynamic shaped and its upper part can be adapted to receive therein a post member.
The bicycle frame according to the invention may comprise a first set of tubes extending from the two-part tube at a junction between the upper and the lower ~C
parts. The first set of tubes are attached at their other ends to dropout means located at the center of the wheel. in addition, the frame may also comprise a second set of tubes extending from a lower end of the two-part tube and attached at their other ends to dropout means located at the center of the wheel. Preferably, the second set of tubes may be attached at a junction between the upper and the lower parts.
In accordance with a preferred embodiment, the lower part can be curved in both horizontal and Vertical planes in arderto conform to the curvature ofthe bicycle wheel.
A prefer-ed embodiment of the bicycle frame can include brake means which is removably attached to the two-part tube at a junction between the upper and the lower parts. More preferably, the brake means can include a brake mounted to a plate.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other advantages of the invention will become apparent upon reading the following detailed description and upon referring to the drawings In which:
FIGURE 1 (a ~ b) is a side view of a prior art aerodynamic bicycle frames;
FIGURE 2 is a rear view of the seat tube of a prior art aerodynamic bicycle frame;
FIGURE 3 is a rear view of the seat tube of the aerodynamic bicycle frame according to the invention;
FIGURE 4 is a cross section of the lower section df the seat tube of the aerodynamic bicycle frame according to the invention;
3 FIGURE 5 is a side view of the aerodynamic bicycle frame according to the invention, showing the seat post - seat stay junction;
FIGURES 6 and 7 are opposite side views of the aerodynamic bicycle frame according to the invention;
FIGURE 8 is a front view of the aerodynamic bicycle frame according to the invention;
FIGURE 9 is a rear view of the aerodynamic bicycle frame according to invention;
FIGURE 10 is a top view of the aerodynamic bicyde frame according to invention;
FIGURE 11 is a bottom view of the aerodynamic bicycle frame according to invention;
FIGURE 12 is a side view of a prior art bicycle showing the various parts of the whale bicycle; and FIGURE 13 is partial side view of the bicyde according to the invention, showing the dose proximity of the tire to the trailing edge of the lower curved portion of the seat tube.
While the invention will be described in conjunction with illustrated embodiments, it will be understood that it is not intended to limit the invention to such embodiments. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be inGuded urithin the spirit and scope of the invention as defined by the appended claims.
FIGURES 6 and 7 are opposite side views of the aerodynamic bicycle frame according to the invention;
FIGURE 8 is a front view of the aerodynamic bicycle frame according to the invention;
FIGURE 9 is a rear view of the aerodynamic bicycle frame according to invention;
FIGURE 10 is a top view of the aerodynamic bicyde frame according to invention;
FIGURE 11 is a bottom view of the aerodynamic bicycle frame according to invention;
FIGURE 12 is a side view of a prior art bicycle showing the various parts of the whale bicycle; and FIGURE 13 is partial side view of the bicyde according to the invention, showing the dose proximity of the tire to the trailing edge of the lower curved portion of the seat tube.
While the invention will be described in conjunction with illustrated embodiments, it will be understood that it is not intended to limit the invention to such embodiments. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be inGuded urithin the spirit and scope of the invention as defined by the appended claims.
4 DETAILED DESCRIPTION aF THE PREFERRED EMBODIMENTS
In the following description, similar features in the drawings have been given similar reference numerals.
Features of the bicycle frame according to this invention are illustrated in Figs. 3 through 11 and 13. Referring to Fig. 6, the bicycle frame 9 0 comprises a head tube 20, a top tube 30, a down tube 40 and a seat tube 50. The head tube 20 extends obliquely between its upper end 21 and its lower end 22, and forms an angle of about 0 to 30 degrees with the vertical. In a preferred .embodiment of the invention, this angle is about 20 degrees. The top tube 30 is attached to the upper part 21 of the head tube at its first end 31 and extends substantially horizontaAy therefrom.
The top tube may form an angle of about 0 to 15 degrees with the horizontal and can be sloped either upwardly or downwardly, in a preferred embodiment of the invention, this angle is 0 degree. The down tube 40 is attached at its first end 41 to the lower part of the head tube 22. The down tube extends transversely and downwardiy, toward the same direction as the top tube. The seat tube 50 joins the second end of the top tube 32 and the second end of the down tube 42.
The seat tube 50 of the invention is composed of two pacts: upper part 52 and a lower part 56. The upper part of the seat tube 52, is a substantially stratghttube extending downwardly and substantially vertically from its upper end 51 to its lower end 53. Upper seat tube 52 forms an angle of about 0 to 20 degrees with 'the vertical.
in a preferred embodiment of the invention, this angle is about 5 degrees. The lower part of the seat tube 56 is curved both iong'~tudinaliy and transversely as illustrated in Fig. 4, and extends from its upper end 55 between its lower end 57. The seat tube 50 can be made of two pieces (upper part 62 and lower part 66) welded together or can be made in one piece in the shape according to the invention_ 4a In a preferred embodiment, the two-part seat tube 50 is aero shaped and its interior is adapted to receive therein a seat post 73 (Fig. '13). The seat past 73 may also be aerodynamically shaped and adapted to slide inside the aero shaped upper seat tube 52, matching its interior shape. The terms "aero" and "aerodynamic"
refer to tubes which depart from the traditional tubular shape, but which have an elongated radius in a direction parallel to the direction of travel ofthe bicycle. Such members are generally wing-shape or oval in section. Aftematively, the aero.shaped seat post 73 may not matched the interior of tube 52. The aenxiynamic shape of the seat post reduces the aerodynamic drag of the frame and improves its performance. It should be noted that the two-part seat tube 50 as well as the seat post 73 may also, each separately have any other suitable shape. The cross section of the two parts of the seat tube may also be different.
The upper seat tube 52 of the bicycle frame according to a preferred embodiment of the invention is very close to vertical (as opposed to mostly oblique as in the prior art). Therefore, the seat post 73 and upper seat tube 52 drop substantially vertically towards the wheel from the saddle and the lower curved part 56 thus comes further up and back on the wheel, resulting in a greater coverage of the upper portion ofthe rearwheef and the aerodynamic drag is reduced. In addition, given thefiactthat the seat post and upper seat tube 52 are farther back than on conventional designs, the center of pressure of the bicycle is moved rearward, resulting In better stability.
The lower longitudinally curved part 56 of the seat tube is transversely curved as shown in Fig. 4 and is designed to act as a fairing, and reduces the aerodynamic drag of the rotating rear wheel and tire assembly. Fig. 4 illustrates a cross section of the lower part 56 of the seat tube.
The bicycle frame according to the invention also comprises seat stays TO
which extend from the;unction between upper seat tube 52 and the lower curved part 4b 56. The frame also comprises chain stays 71 which extend from the lower part 57 of the currred lower part 5fi. Seat stays 70 and chain stays 71 meet indirectly at the center of the whe~I, as better explained below.
In a preferred embodiment of the bicycle frame according to the invention, rearward facing horizontal dropout means 7~ is provided at the center of the wheel.
As can be seen for example in Figs. 6 and 7, seat stay 70 and chain stay 71 are each attached thereto. The dropouts~allow the wheel to be adjusted as close as possible to the transverse curved portion of the lower pact of the seat tube 56. This results in an optimal aerodynamic shielding and a reduced aerodynamic drag. The rearward facing horizontal dropouts also allow the user to use different sizes of tires and still optimize the aerodynamic pertormance of the bicycle.
it should be noted thatthe bicycle frame aCCOrding to the invention differs significantly from the traditional "double diamond° frame shape, which generally has two open triangles with a common side. In contrast, the front portion of the bicycle frame of the invention has four sides and incorporates a curved member. The rear portion has only 3 sides and one is a curve. In addition, the seat stays 70 do not intersect at the vertex joining the seat tube 50 and the top tube 32 as in most other firaditional °double diamond" frame designs, but rather at the junction between the upper and lower seat tubes ~2 and 56, This dropped seat stay design improves the aerodynamic performance and stiffness of the frame.
The bicycle frame according to a preferred embodiment of the invention is constructed from custom aluminum extrusions and meets the latest UCI
regulations. It should be noted that any suitable material, such as mefiallic, composite or the like material can be used, Referring to Figs. 6 and 13, the bicycle frame according to a preferred embodiment of the invention is provided with brake means 60, which Is integrated at 4c the junction between the upper seat tube 52 and the seat stays 70. The brake means is constituted of a rear brake of conventional design that is bolted to a small plate 7B, and the plate is subsequently bolted to the rear of the frame. This brake and brake plate design provides the leanest aerodynamic solution by nat requiring a large gap between the tire and frame for access to the brake attachment, and it does not degrade the frame stiffness or strength with access holes or other compromises.
fn addition to the principal invention, the following inventions support the principal invention:
1. The integration of the seat stays with the seat tubs which results in a much cleaner aerodynamic form.
2. The brake plate to which the rear brake must be attached before the plate (with the attached brake) are then bolted to the frame. This design allows us to attach the brake to the frame in its conventional orientation while enhancing the aerodynamics, stiffness, or strength of the area. (see Figure
In the following description, similar features in the drawings have been given similar reference numerals.
Features of the bicycle frame according to this invention are illustrated in Figs. 3 through 11 and 13. Referring to Fig. 6, the bicycle frame 9 0 comprises a head tube 20, a top tube 30, a down tube 40 and a seat tube 50. The head tube 20 extends obliquely between its upper end 21 and its lower end 22, and forms an angle of about 0 to 30 degrees with the vertical. In a preferred .embodiment of the invention, this angle is about 20 degrees. The top tube 30 is attached to the upper part 21 of the head tube at its first end 31 and extends substantially horizontaAy therefrom.
The top tube may form an angle of about 0 to 15 degrees with the horizontal and can be sloped either upwardly or downwardly, in a preferred embodiment of the invention, this angle is 0 degree. The down tube 40 is attached at its first end 41 to the lower part of the head tube 22. The down tube extends transversely and downwardiy, toward the same direction as the top tube. The seat tube 50 joins the second end of the top tube 32 and the second end of the down tube 42.
The seat tube 50 of the invention is composed of two pacts: upper part 52 and a lower part 56. The upper part of the seat tube 52, is a substantially stratghttube extending downwardly and substantially vertically from its upper end 51 to its lower end 53. Upper seat tube 52 forms an angle of about 0 to 20 degrees with 'the vertical.
in a preferred embodiment of the invention, this angle is about 5 degrees. The lower part of the seat tube 56 is curved both iong'~tudinaliy and transversely as illustrated in Fig. 4, and extends from its upper end 55 between its lower end 57. The seat tube 50 can be made of two pieces (upper part 62 and lower part 66) welded together or can be made in one piece in the shape according to the invention_ 4a In a preferred embodiment, the two-part seat tube 50 is aero shaped and its interior is adapted to receive therein a seat post 73 (Fig. '13). The seat past 73 may also be aerodynamically shaped and adapted to slide inside the aero shaped upper seat tube 52, matching its interior shape. The terms "aero" and "aerodynamic"
refer to tubes which depart from the traditional tubular shape, but which have an elongated radius in a direction parallel to the direction of travel ofthe bicycle. Such members are generally wing-shape or oval in section. Aftematively, the aero.shaped seat post 73 may not matched the interior of tube 52. The aenxiynamic shape of the seat post reduces the aerodynamic drag of the frame and improves its performance. It should be noted that the two-part seat tube 50 as well as the seat post 73 may also, each separately have any other suitable shape. The cross section of the two parts of the seat tube may also be different.
The upper seat tube 52 of the bicycle frame according to a preferred embodiment of the invention is very close to vertical (as opposed to mostly oblique as in the prior art). Therefore, the seat post 73 and upper seat tube 52 drop substantially vertically towards the wheel from the saddle and the lower curved part 56 thus comes further up and back on the wheel, resulting in a greater coverage of the upper portion ofthe rearwheef and the aerodynamic drag is reduced. In addition, given thefiactthat the seat post and upper seat tube 52 are farther back than on conventional designs, the center of pressure of the bicycle is moved rearward, resulting In better stability.
The lower longitudinally curved part 56 of the seat tube is transversely curved as shown in Fig. 4 and is designed to act as a fairing, and reduces the aerodynamic drag of the rotating rear wheel and tire assembly. Fig. 4 illustrates a cross section of the lower part 56 of the seat tube.
The bicycle frame according to the invention also comprises seat stays TO
which extend from the;unction between upper seat tube 52 and the lower curved part 4b 56. The frame also comprises chain stays 71 which extend from the lower part 57 of the currred lower part 5fi. Seat stays 70 and chain stays 71 meet indirectly at the center of the whe~I, as better explained below.
In a preferred embodiment of the bicycle frame according to the invention, rearward facing horizontal dropout means 7~ is provided at the center of the wheel.
As can be seen for example in Figs. 6 and 7, seat stay 70 and chain stay 71 are each attached thereto. The dropouts~allow the wheel to be adjusted as close as possible to the transverse curved portion of the lower pact of the seat tube 56. This results in an optimal aerodynamic shielding and a reduced aerodynamic drag. The rearward facing horizontal dropouts also allow the user to use different sizes of tires and still optimize the aerodynamic pertormance of the bicycle.
it should be noted thatthe bicycle frame aCCOrding to the invention differs significantly from the traditional "double diamond° frame shape, which generally has two open triangles with a common side. In contrast, the front portion of the bicycle frame of the invention has four sides and incorporates a curved member. The rear portion has only 3 sides and one is a curve. In addition, the seat stays 70 do not intersect at the vertex joining the seat tube 50 and the top tube 32 as in most other firaditional °double diamond" frame designs, but rather at the junction between the upper and lower seat tubes ~2 and 56, This dropped seat stay design improves the aerodynamic performance and stiffness of the frame.
The bicycle frame according to a preferred embodiment of the invention is constructed from custom aluminum extrusions and meets the latest UCI
regulations. It should be noted that any suitable material, such as mefiallic, composite or the like material can be used, Referring to Figs. 6 and 13, the bicycle frame according to a preferred embodiment of the invention is provided with brake means 60, which Is integrated at 4c the junction between the upper seat tube 52 and the seat stays 70. The brake means is constituted of a rear brake of conventional design that is bolted to a small plate 7B, and the plate is subsequently bolted to the rear of the frame. This brake and brake plate design provides the leanest aerodynamic solution by nat requiring a large gap between the tire and frame for access to the brake attachment, and it does not degrade the frame stiffness or strength with access holes or other compromises.
fn addition to the principal invention, the following inventions support the principal invention:
1. The integration of the seat stays with the seat tubs which results in a much cleaner aerodynamic form.
2. The brake plate to which the rear brake must be attached before the plate (with the attached brake) are then bolted to the frame. This design allows us to attach the brake to the frame in its conventional orientation while enhancing the aerodynamics, stiffness, or strength of the area. (see Figure
5).
3. The portion of the seat tube forward of the rear wheel has a trailing edge of constant width which protects the rear wheel by the same amount over its 5 complete length.
4. The long length and high curvature of the lower curved portion of the seat tube protects and covers the forward edge of more of the rear wheel than is possible with prior art designs.
5. The high curvature and long length of the lower curved section of the seat tube results in improved rider comfort compared to prior art designs.
3. The portion of the seat tube forward of the rear wheel has a trailing edge of constant width which protects the rear wheel by the same amount over its 5 complete length.
4. The long length and high curvature of the lower curved portion of the seat tube protects and covers the forward edge of more of the rear wheel than is possible with prior art designs.
5. The high curvature and long length of the lower curved section of the seat tube results in improved rider comfort compared to prior art designs.
6. The use of horizontal dropouts to optimize the tire clearance to the curved seat tube for use with different tire and wheel sizes.
7. A recessed concave area in the rear of the seat tube to further enhance the rear wheel aerodynamics. Seat tube lower cross section is shaped as shown in Figure 4.
8. The design of the seat tube also has the additional advantage of moving the Aerodynamic Center of Pressure to the rear which further enhances stability.
Thus, it is apparent that there has been provided in accordance with the invention an AERODYNAMIC BICYCLE FRAME that fully satisfies the objects, aims and advantages set forth above. While the invention has been described in conjunction with a specific embodiment thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit and broad scope of the invention.
Thus, it is apparent that there has been provided in accordance with the invention an AERODYNAMIC BICYCLE FRAME that fully satisfies the objects, aims and advantages set forth above. While the invention has been described in conjunction with a specific embodiment thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit and broad scope of the invention.
Claims (15)
PROPERTY OF PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A bicycle frame comprising:
a first tube;
a second tube extending transversely from an upper region of said first tube, in a direction;
a third tube extending transversely and downwardly from a lower region of the said first tube, and towards the same direction as said second tube; and a two-part tube joining the respective ends of said second and third tubes, said two-part tube having a straight upper part and a curved lower part, said straight upper part being substantially vertical and said curved lower part being curved longitudinally towards said first tube such as to conform to the curvature of a bicycle wheel.
a first tube;
a second tube extending transversely from an upper region of said first tube, in a direction;
a third tube extending transversely and downwardly from a lower region of the said first tube, and towards the same direction as said second tube; and a two-part tube joining the respective ends of said second and third tubes, said two-part tube having a straight upper part and a curved lower part, said straight upper part being substantially vertical and said curved lower part being curved longitudinally towards said first tube such as to conform to the curvature of a bicycle wheel.
2. The bicycle frame according to claim 1, wherein said two-part tube is aerodynamic shaped and said upper part is adapted to receive therein a post member.
3. The bicycle frame according to claim 2, wherein said two-part tube is aerodynamic shaped and said upper part is adapted to receive therein an aerodynamic shaped post member.
4. The bicycle frame according to claim 1 further comprising a first set of seat stay tubes joined to and extending rearwardly from the said two-part tube and joined to dropouts.
5. The bicycle frame according to claim 4, wherein said first set of tubes is joined to said two-part tube at a junction between said upper and lower parts.
6. The bicycle frame according to claim 1, wherein said upper and lower parts are welded together.
7. The bicycle frame according to claim 1, wherein said upper and lower parts constitute a one piece member.
8. The bicycle frame according to claim 1, wherein said upper part forms an angle of about 0 to 20 degrees with the vertical.
9. The bicycle frame according to claim 8, wherein said angle is about 5 degrees.
10. The bicycle frame according to claim 4 further comprising a chainstay set of tubes extending rearwardly from a lower end of said two-part tube, said chainstay of tubes being attached to said dropout.
11. The bicycle frame according to claim 4 further comprising brake means removably attached to said first set of tubes.
12. The bicycle frame according to claim 1 further comprising brake means removably attached to said two-part tube at a junction between said upper and lower parts.
13. The bicycle frame according to claim 12, wherein said brake means includes a brake mounted to a plate.
14. The bicycle frame according to claim 1, wherein said lower part is transversely curved in both horizontal and vertical planes.
15. The bicycle frame according to claim 4 or 10, wherein said first and second sets of tubes are each a pair of substantially parallel tubes.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002357598A CA2357598C (en) | 2000-09-20 | 2001-09-20 | Aerodynamic bicycle frame |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2,319,985 | 2000-09-20 | ||
| CA002319985A CA2319985A1 (en) | 2000-09-20 | 2000-09-20 | Aerodynamic bicycle frame |
| CA002357598A CA2357598C (en) | 2000-09-20 | 2001-09-20 | Aerodynamic bicycle frame |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2357598A1 CA2357598A1 (en) | 2002-03-20 |
| CA2357598C true CA2357598C (en) | 2005-07-05 |
Family
ID=25682091
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002357598A Expired - Fee Related CA2357598C (en) | 2000-09-20 | 2001-09-20 | Aerodynamic bicycle frame |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2357598C (en) |
-
2001
- 2001-09-20 CA CA002357598A patent/CA2357598C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2357598A1 (en) | 2002-03-20 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |
Effective date: 20190920 |