AU2007100444A4

AU2007100444A4 - Improvements to bicycles

Info

Publication number: AU2007100444A4
Application number: AU2007100444A
Authority: AU
Inventors: Lewis James Mathiske
Original assignee: MATHISKE LEWIS
Current assignee: MATHISKE LEWIS
Priority date: 2007-05-29
Filing date: 2007-05-29
Publication date: 2007-08-23
Anticipated expiration: 2015-05-29
Also published as: AU2007100444B4

Description

29/05 2007 10:42 FAX 001161755943980 John R G Gardner 444 IP AUSTRALIA [a03 LEWIS JAMES MATHISKE

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR AN INNOVATION PATENT IMPROVEMENTS TO BICYCLES The following statement is a full description of this invention, including the best method of performing it know to me:- COMS ID No: SBMI-07559282 Received by IP Australia: Time 11:06 Date 2007-05-29 29/05 2007 10:42 FAX 001161755943980 John R G Gardner 444 IP AUSTRALIA 004 Co 2

O

C' IMPROVEMENTS TO BICYCLES Technical Field This invention relates to improvements to bicycles and in particular to an improved frame for bicycles. The present invention also relates to an improved head tube for a bicycle.

Background Art Many different designs of bicycle frames are currently available however when O required for competition purposes such as in bicycles for time trials, track or road races, Sbicycle frames are required to fit within certain parameters in accordance with international regulations. In particular bicycle frames are required to be made up of 0 elements which fit within a template of a triangular form. Bicycle frames which have been developed to improve the performance characteristics of bicycles but which do not fit within this template are limited in their use particularly in competitive use. Whilst some developments in frames which fit within the template have been made, those frames do not provide optimum performance. For example excessive wind resistance tends to occur between the tyre on the front wheel of the bicycle and the down tube of the frame due to the substantial space between the down tube and tyre.

Bicycle frames have been further improved by constructing them of lightweight materials for example reinforced plastics such as carbon fibre reinforced plastics. Whilst these frame do provide improved performance because of the reduction in overall weight of the bicycle, the frames that are available still tend to provide excessive wind resistance.

Summary of the Invention The present invention aims to provide an improved bicycle frame and a bicycle incorporating an improved frame. The present invention in particular aims to provide a bicycle frame which has improved aerodynamic characteristics. The present invention in a further aspect aims to provide an improved head tube for a bicycle and in particular to a head tube which has improved aerodynamic characteristics. Other objects and advantages of the invention will become apparent from the following description.

The present invention thus provides in a preferred aspect a bicycle frame comprising a head tube and bottom bracket and a down tube or bar extending between said head tube and bottom bracket, said down tube or bar having a leading end, and wherein an intermediate portion of said leading end of said down tube or bar has a COMS ID No: SBMI-07559282 Received by IP Australia: Time 11:06 Date 2007-05-29 29/05 2007 10:42 FAX 001161755943980 Jobn R G Gardner 444 IP AUSTRALIA 0 3 concave curve centered substantially on the axis of rotation of a front wheel mountable to said bicycle frame and wherein said leading end portion in use is located adjacent to the periphery of said front wheel.

The term "wheel" as used throughout the specification and claims includes the tyre of the wheel.

Typically the concave curved leading end portion is positioned relatively close to the tyre of the front wheel but not such that the front wheel or tyre carried thereby will o strike the down tube. Preferably the concave curved leading end portion is spaced in use a radial distance of a minimum of approximately 1 Omm from the tyre on the front wheel.

10 This allows for normal deflection of the front forks in use without the front wheel or tyre O of the front wheel striking the down tube.

Preferably the leading end of the down tube also includes a first convex portion extending from the head tube of the bicycle fi-ame to the concave portion. Preferably the leading end of the down tube also includes a second convex portion extending from the concave portion to the bottom bracket of the bicycle frame. Thus the down tube at least on its leading end and in side view is in the form of a continuous wave or curve suitably of sinusoidal form between the head tube and the bottom bracket of the frame being initially convex, then concave and subsequently convex.

Preferably also the down tube has a substantially aerofoil or wing shaped external configuration in a horizontal cross sectional plane for a substantial proportion of, or for the full extent of its length between the head tube and bottom bracket. Preferably the aerofoil or wing shaped external configuration comprises a symmetrical aerofoil or wing shape. The aerofoil or wing shape may vary in dimensions along the length of the down tube. Thus the transverse width may vary from a minimum at an upper portion of the down tube to a maximum at a lower portion of the down tube. The down tube may vary in width in a front to rear direction along the length of the down tube. Thus the front to rear width may be greater at a lower portion of the down tube as compared to the corresponding width at an upper portion of the down tube.

The bicycle frame also has a seat tube or bar, a top tube or bar, seat stays and chain stays. Preferably the seat tube or bar has a trailing end portion having a concave curvature which is centred on the axis of rotation of a rear wheel mountable to the bicycle frame so that when a rear wheel is mounted to the frame, the trailing end portion of the seat tube is adjacent to the rear tyre of a rear wheel. Most preferably the radial COMS ID No: SBMI-07559282 Received by IP Australia: Time 11:06 Date 2007-05-29 29/05 2007 10:42 FAX 001161755943980 John R G Gardner 444 IP AUSTRALIA t06 4 0 0' distance between the trailing end portion of the seat tube and the tyre of the rear wheel in use is approximately 5 to 6 rnms however this dimension may vary but preferably has a minimum of 4 mm but may be less.

Preferably also the seat tube or bar has an aerofoil or wing shaped external configuration for a substantial proportion of its length or a partial aerofoil or wing shaped external configuration for a substantial proportion of its length in a horizontal cross sectional plane when a bicycle including the frame is on a horizontal surface. Tn a o particularly preferred form the seat tube or bar has the form of a truncated aerofoil or 0 wing at least along the concave trailing end portion. Preferably the truncated aerofoil or o 10 wing shaped portion has a transverse end surface adjacent to the tyre of the rear wheel in 0 use. The end surface may be transversely concave. The aerofoil or wing shaped configuration preferably comprises a symmetrical aerofoil or wing shaped configuration in a horizontal cross sectional plane.

The seat tube or bar may have a substantially constant transverse cross section along a substantial proportion of its length. The front to rear width of the seat tube however suitably varies from the substantial aerofoil or wing shaped form in its upper portion to the truncated aerofoil or wing shaped form in its lower portion.

Preferably the head tube also has a Tross section which reduces wind resistance.

Preferably the head tube is of an aerofoil or wing shaped external configuration in a substantially horizontal cross sectional plane when a bicycle including the frame is in a normal operating attitude on a horizontal surface. Preferably the leading end of the head tube is convexly curved in a direction between the upper and lower end of the head tube.

Preferably the opposite sides of the head tube arc concavely curved from the top to the bottom of the head tube. Thus the head tube has a variable cross section along its length between the top and bottom of the head tube.

The present invention in a further aspect provides a bicycle having a bicycle frame of the above described type.

Brief Description of the Drawings In order that the invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate a preferred embodiment of the invention and wherein Fig. 1 illustrates in side elevation, portion of a bicycle including a bicycle frame according to an embodiment of the invention; COMS ID No: SBMI-07559282 Received by IP Australia: Time 11:06 Date 2007-05-29 29/05 2007 10:42 FAX 001161755943980 John R G Gardner 444 IP AUSTRALIA M]07 o Figs. 2 and 3 are sectional views of the down bar of the bicycle frame along lines A-A and B-B respectively of Fig. 1; Fig. 4 illustrates the head tube of the bicycle frame in front view; Fig. 5 is a sectional view along line C-C of Fig. 4 of the head tube; Figs. 6 and 7 illustrate in views corresponding to Figs. 4 and 5, an alternative head tube; and Fig. 8 illustrates in side view the head tube of the bicycle frame.

O Detailed Description of the Preferred Embodiment Referring to the drawings and firstly to Fig. 1, there is illustrated portion of a o 10 bicycle 10 including a bicycle friame 11 according to an embodiment of the invention, Sthe bicycle 10 further including a front wheel 12 mounted to front forks 13 and a rear wheel 14. The frame 11 includes a head tube 15, a generally horizontal top bar or tube 16 extending from the head tube 15, a down tube or bar 17 extending between the head tube 15 and bottom bracket 18, a seat tube or bar 19, seat stays 20 and chain stays 21.

The frame 11 comprising the above components is typically formed integrally in two opposite identical parts in a plastics moulding process with the parts joined together along a central join line or plane. The plastics may be any reinforced plastics such as carbon fibre reinforced plastics.

The down tube or bar 17, as shown, has on its leading side adjacent the front wheel 12 an upper convex leading end or edge portion 22 extending from the head tube an intermediate concave leading end or edge portion 23 which is centered on the axis 24 of rotation of the wheel 12 and a further lower convex leading end or edge portion which extends from the concave end or edge portion 23 to the bottom bracket 18. The portions 22, 23 and 25 have a constant radius of curvature. Typically the radius RI of curvature of the edge or end portion 22 is less than the radius R2 of curvature of the concave edge portion 23 which is centred on the axis 14. Typically the radius R3 of curvature of the edge or end portion 25 is greater than the radius R2 of the concave edge portion 23. The leading end or edge of the down tube 17 is thus in side view in the form of a continuous sinusoidal wave between the head tube 15 and bracket 18. The concave end or edge portion 23 is also positioned adjacent to the outer surface of the tyre 26 of the front wheel 12 and being on the same centre as, or coaxial with the wheel 12, is substantially parallel to a portion of the periphery of the tyre 26. Positioning this end or edge portion 23 of the down tube 17 adjacent to the periphery of the tyre 26 reduces the COMS ID No: SBMI-07559282 Received by IP Australia: Time 11:06 Date 2007-05-29 29/05 2007 10:42 FAX 001161755943980 John R G Gardner 444, IP AUSTRALIA Q08 o 6 distance between the tyre 26 and down tube 17 which therefore reduces wind turbulence in this area. Typically the radial distance Rf between the concave end or edge portion 23 and the outer periphery of the tyre 26 is in the region, of 10 to 11 mm. This distance may vary however it is preferred that this distance be not less than Omm so that deflection of the forks 13, wheel 12 and/or tyre 26 in use will not cause the tyre 26 to come into contact with the down tube 17.

The down tube 17 additionally as shown in Figs. 2 and 3 has a symmetrical o aerofoil or wing shaped configuration in a substantially horizontal cross sectional plane Sto further provide a streamlined flow of air between the rear of the wheel 12 and at least the adjacent leading end or edge portion 23 of the down tube 17. The down tube 17 as O is apparent in Fig. 2 typically has a transverse width which tapers towards the bottom bracket 18. In the illustrated embodiment the transverse width of the down tube 17 at the section A-A is approximately 30mm whilst the corresponding dimension at the section B-B is 35 mm. These dimensions however may vary.

The trailing edge 27 of the down tube 17 is substantially linear at an upper portion extending from the head tube 15 but then has a lower concavely curved portion to the bottom bracket 18, the curved portion being substantially parallel to the leading end or edge portion 25. The front to rear width of the down tube 17 may vary along its length. In the illustrated embodiment this width at the section A-A is approximately 75mm whilst the corresponding dimension at the cross section B-B is 77 mm. These dimensions however may vary.

The seat bar or tube 19 has a trailing end or edge 28 which is concavely curved between its junction with the chain stays 21 and seat stays 20 on a radius R4 centred on the axis 29 of rotation of the rear wheel 14 and is thus coaxial with the rear wheel 14. At its upper end adjacent the seat, the seat bar or tube 19 has a symmetrical aerofoil or wing shaped external configuration in a horizontal cross sectional plane. In the curved region between the chain stays 21 and seat stays 20, the seat bar or tube 19 has in a horizontal cross sectional plane, the external configuration of a symmetrical aerofoil or wing which is truncated on its trailing end to form a transverse trailing end surface. The trailing end surface is slightly concave in a transverse direction. Thus the width of the seat bar or tube 19 at the trailing edge 28 is similar to the width of the tyre 30 of the wheel 14.

Further the concavity in the trailing end surface approximates the transverse curve in the tyre 30. There will thus be a smooth transition between the seat bar or tube 19 and tyre COMS ID No: SBMI-07559282 Received by IP Australia: Time 11:06 Date 2007-05-29 29/05 2007 10:42 FAX 001161755943980 John R G Gardner 444i IP AUSTRALIA M09 o 7 C 30 which will reduce air turbulence in this region and allow for a relatively smooth flow of air from the seat bar or tube 19 to the tyro 30. The radial distance Rr between the trailing edge 28 of the seat bar or tube 19 and the leading end of the tyre 29 is typically in the range of 5 to 6mm however this dimension may vary.

The leading end or edge 31 of the seat bar or tube 19 has in a lower portion a convex curve and is substantially parallel to the trailing edge 28. The leading edge 31 in its upper portion 31' has a convex curve to the seat mount.

O The bar or tube 19 typically has a transverse width which is substantially constant. In the illustrated embodiment the transverse width of the 19 is approximately 30rmm however this dimension may vary.

0 The front to rear width of the seat tube 19 varies along its length from its upper end down to the bottom bracket. In the illustrated embodiment this width at the upper end is approximately 80mm whilst the con-esponding dimension at its intermediate end is 50 mm. These dimensions however may vary.

The head tube 15 as shown in Figs. 4 and 5 is concavely curved as at 31 on opposite sides whilst in a horizontal cross sectional plane as in the section F-F, the head tube 15 has a symmetrical aerofoil or wing shaped external configuration which is maintained between the top and bottom of the head tube 15 (although varying in width).

At its leading end or edge 33, the head tube 15 is convexly curved as at 34 between the top and bottom of the head tube 15 as shown in Fig. 8.

Figs. 6 and 7 show a head tube 15 of similar configuration to that shown in Figs.

4 and 5 but of a different size.

So as to ensure aerodynamic flow of air past the frame 11, a smooth curving transition is provided between the head tube 15 and top tube or bar 16 and down tube or bar 17. A similar smooth transition occurs between the top tube 16 and seat tube 19, the down tube 17 and seat tube 19 and bottom bracket 18 and between the bottom bracket 18 and chain stays 21 and seat tube 19 and seat stays 20. Thus no blunt surfaces are presented to the flow of air past the frame 1i which would cause dirty air and increased wind resistance.

The present invention thus provides a bicycle frame when in use has improved aerodynamic properties compared to conventional bicycles and therefore increased speed potential as required in road or track racing.

COMS ID No: SBMI-07559282 Received by IP Australia: Time 11:06 Date 2007-05-29 29/05 2007 10:42 FAX 001161755943980 John R G Gardner 444 IP AUSTRALIA 610 17- 0 The frame is as referred to preferably moulded from a reinforced plastics however it may be manufactured from other materials such as lightweight aluminium or titanium.

The terms "comprising" or "comprises" as used throughout the specification and claims are taken to specify the presence of the stated features, integers and components referred to but not preclude the presence or addition of one or more other feature/s, integer/s, component/s or group thereof.

o Whilst the above has been given by way of illustrative embodiment of the Sinvention, all such variations and modifications thereto as would be apparent to persons skilled in the art arc deemed to fall within the broad scope and ambit of the invention as o herein defined in the appended claims.

COMS ID No: SBMI-07559282 Received by IP Australia: Time 11:06 Date 2007-05-29

Claims

1. A bicycle frame comprising a head tube and bottom bracket and a down tube or bar extending between said head tube and bottom bracket, said down tube or bar having a leading end, and wherein an intermediate portion of said leading end of said down tube or bar has a concave curve centered substantially on the axis of rotation of a front wheel mountable to said bicycle frame and wherein said leading end portion in use is located o adjacent to the periphery of said front wheel. o 10

2. A bicycle franme as claimed in claim I wherein said leading end of said down I tube includes an upper portion which is convexly curved between said intermediate portion and said head tube.

3. A bicycle frame as claimed in claim 2 or claim 3 wherein said leading end of said down tube includes a lower portion which is convexly curved between said intermediate portion and said bottom bracket.

4. A bicycle frame as claimed in any one of claims I to 3 wherein said down tube has a substantially aerofoil or wing shaped external configuration in a horizontal cross sectional plane for a substantial proportion of,; or for the full extent of its length between said head tube and bottom bracket. A bicycle frame as claimed in any one of claims 1 to 4 wherein said head tube is of an aerofoil or wing shaped configuration in a horizontal cross section, said head tube being ffirther concave on opposite sides and having a convex leading end. Dated this twenty-ninth day of May 2007 LEWIS JAMES MATHISKE By His Patent Attorney JOHN R G GARDNER JOHN R G GARDNER COMS ID No: SBMI-07559282 Received by IP Australia: Time 11:06 Date 2007-05-29