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Title:
BICYCLE HAVING A SINGLE, HOLLOW PRIMARY TUBE
Document Type and Number:
WIPO Patent Application WO/2008/056204
Kind Code:
A1
Abstract:
A bicycle frame (12) has a plurality of tubes (14, 16, 18, 20, 22, 24, 26, 28) , at least one of which is a single, hollow tube of composite material, wherein tubular "ports" (30, 32, 44, 51, 58) extend through the hollow tube. The ends of the ports are bonded to the walls of the hollow tube. The ports improve the stiffness, strength, aerodynamics and comfort of the bicycle frame component .

Inventors:
DAVIS, Stephen J. (18 Hansel Road, Newtown, PA, 18940, US)
GAZZARA, Roberto (Via Fiume, 4/C, Mestre, I-30171, IT)
Application Number:
IB2006/054151
Publication Date:
May 15, 2008
Filing Date:
November 07, 2006
Export Citation:
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Assignee:
PRINCE SPORTS, INC. (One Advantage Court, Bordentown, NJ, 08505, US)
DAVIS, Stephen J. (18 Hansel Road, Newtown, PA, 18940, US)
GAZZARA, Roberto (Via Fiume, 4/C, Mestre, I-30171, IT)
International Classes:
B62K19/16; B29C70/68; B62K3/02; B62K19/10
Domestic Patent References:
WO2003076176A22003-09-18
Foreign References:
US4850607A1989-07-25
FR2699882A11994-07-01
FR877814A1943-01-04
US5072961A1991-12-17
US2330560A1943-09-28
Attorney, Agent or Firm:
ZANOLI, Enrico et al. (Via Melchiorre Gioia 64, Milano, I-20125, IT)
Download PDF:
Claims:

CLAIMS

1. A bicycle frame comprising a plurality of tube members, wherein at least one said tube member is fabricated of a relatively rigid material with limited flexibility; wherein the at least one tube member is a single hollow tube having at least one pair of aligned holes extending through opposite wall portions of said tube; and wherein the at least one tube member further comprises a hollow port associated with each pair of holes, which port extends through its respective pair of holes, each said port comprising opposite ends and a peripheral wall; and wherein said opposite ends are bonded to said handle tube.

2. The system as set forth in claim 1, wherein the tube and each port are made of composite material.

3. The system set forth in claim 1, wherein the tube is made of metal and the port is made of a composite material.

4. The system set forth in claim 1, wherein the ports are made of metal.

5. A bicycle frame as defined in claim 1, wherein said at least one tube member is formed of a ported tube construction.

6. The system as set forth in claim 1, wherein the tube member is a front fork.

7. The system as set forth in claim 1, wherein the tube member is a handlebar.

8. The system as set forth in claim 1, wherein the tube member is a seat post.

9. The system as set forth in claim 1, wherein said tube member has a longitudinal axis, and wherein said at least one port is at least generally oval in shape, to form a pair of arches, with the long dimension of the oval axially oriented.

10. A bicycle frame member for producing geometric shapes and improving the flexibility and strength and other characteristics of the system comprising, in combination: a tube member fabricated of a single tube of multiple plies of carbon filaments held together with an epoxy binder, the filaments of each ply being parallel to one another, the tube member having a long generally hollow tubular configuration;

at least one pair of aligned holes extending through opposing sides; and a hollow port extending through each said pair, wherein said port has a peripheral wall and opposite ends, and wherein said opposite ends are bonded to said handle tube.

11. A method of forming a bicycle frame member comprising the steps of:

(a) forming a hollow prepreg single tube of uncured composite material;

(b) forming at least one pair of aligned holes through opposed walls of said tube;

(c) inserting a pair of inflatable bladders, each having opposite ends, through said prepreg tube, wherein said bladders are side-by-side and wherein the opposite ends of said bladders extend out of said prepreg tube;

(d) inserting a hollow tubular plug through each pair of aligned holes, wherein each said plug includes opposite ends and extends between said bladders;

(e) placing said prepreg tube into a closed mold having the shape of at least said handle; and

(f) heating said mold, while inflating said bladders, so that said prepreg tube assumes the shape of the mold and cures, and such that the opposite ends of said plug bond to said prepreg tube during molding.

12. The method as recited in claim 11, wherein said at least one plug is uncured composite material, comprising further the step, prior to step (f), of inserting a mold pin through each said plug, so that each said plug assumes the shape of said pin during molding and curing.

13. The method of claim 11, wherein said aligned holes are formed by separating fibers in said prepreg material.

14. A bicycle frame as defined in claim 1, wherein said portion includes said rear stay.

15. A bicycle frame as defined in claim 1, wherein said portion includes said chain stay.

16. A bicycle frame as defined claim 1, wherein the tube member having said portion comprises a metal tube for a portion of its length.

17. A bicycle frame as defined in claim 11, wherein said ports vary in size.

18. A bicycle frame as defined in claim 1, wherein the ports have an axis therethrough, and wherein the axes of said ports are spaced apart from one another by at least two distances.

19. A bicycle frame as defined in claim 1, wherein said ports have an axis therethrough, and wherein at least two of said ports have different, horizontal axial orientations.

Description:

BICYCLE HAVING A SINGLE, HOLLOW PRIMARY TUBE

A A A A A

BACKGROUND OF THE INVENTION

The present invention relates to an improved structure for a bicycle frame including the top tube, down tube, seat stays, chain stays as well as the front wheel supports (forks), handlebars, and seat post. In particular, the present invention is a bicycle frame component where the component is formed of a single, hollow tube having at least one, and preferably a series, of "ports" that extend through the hollow tube. The ports provide specific performance advantages. Each port has a peripheral wall that extends between opposed holes in the hollow component tube. The opposite ends of each port are bonded to the tube. The wall forming the port, which extends between opposite sides of the tube, preferably is shaped to act as opposing arches which provide additional strength, stiffness, comfort, and aerodynamic benefits.

The weight of a performance bicycle is a critical feature in determining performance. The lighter the weight, the quicker the bike will accelerate, the easier to sustain high speeds, the easier to climb uphill grades as well as being easier to maneuver. Therefore, the lightest materials and designs are used to achieve these performance goals. The most popular high performance material for modern bicycle design is carbon fiber reinforced epoxy resin (CFE) because it has the highest strength to weight ratio of any realistically affordable material. As a result, CFE can produce a very light weight bicycle frame with excellent rigidity as well as provide an aesthetically pleasing shape.

However, there are inherent problems and challenges with carbon fiber based materials used for bicycle structures. A bicycle frame made from carbon fiber composite can be susceptible to catastrophic failure resulting from excessive compressive forces which cause buckling of the thin walled tubes. A composite tubular part in a bicycle frame is subjected to a multitude of stress conditions. There are bending loads in a multitude of directions. There are torsional loads. There are impact loads and vibrational loads. There can be any combination of these loads resulting in a complex stress state.

In addition to light weight and strength, a tailored stiffness of the bicycle frame is highly preferred. This is because it is not always the stiffest frame that is preferred, but a frame that is tuned, where different portions are stiff and others are more resilient, allowing more deflection. For example, sometimes a bicycle frame can be too rigid and have a "dead" feel to a rider. Other frames can be very flexible and have a "springy" feel. There are a multitude of factors such as weight, rigidity, resilience, torsional stiffness and vibration damping among others that contribute to a desirable frame. To date, modifying these characteristics of a traditional composite bicycle frame has been limited to changing the cross sectional dimensions of the tubular parts or selecting different materials or fiber angles.

For example, if more bending stiffness is desired in one direction than another, the cross section of the tubular part can be designed to provide that stiffness. For example, an oval shaped cross section will have much more stiffness in one direction than another. This can have a very desirable effect, for example, in the down tube of the bicycle frame or in the front forks. However, the major disadvantage of an oval shaped cross section is the susceptibility to buckling of the thin wall section along the wide portion of the cross section due to bending in this direction or due to torsional loads which can also wrinkle or buckle this broad thin wall area.

Another desirable feature in a bicycle is aerodynamics. An aerodynamic bicycle frame which has a reduced frontal area to the direction of travel is possible with composite materials, but comes with compromises. Carbon fiber composites offer the designer more options in terms of frame shape in order to reduce aerodynamic drag. For example, the frame tubes or front forks or handle bars can be made thinner to have less frontal area and therefore having less aerodynamic drag. However, this all comes with a price, because the thinner beam is less rigid and weaker because the cross section is reduced. Therefore, to achieve improved aerodynamic performance one must be willing to accept the compromise of reduced stiffness and strength.

Another desirable feature for a bicycle is comfort. Comfort can be broken down into two categories: large deflection and small deflection. Large deflection occurs when riding off road on rough terrain. There are a number of active suspension systems in bicycles today which use a

variety of mechanical devices such as springs and shock absorbers, but these are heavy. Small deflections can be attributed to either vibrations transmitting from the surface conditions, or deflection of the bike due to pedaling, climbing or other rider induced loads. Riding on a rough road can transmit undesirable vibrations known as "road buzz" to the rider which cause discomfort. Many experienced riders describe a preferred feel of a bicycle, which is a combination of the rigidity and resilience of the bicycle structural components, e.g. frame, forks, handlebars and seat post as well as their ability to damp vibrations.

The evolution of the modern bicycle over the past twenty years has focused mainly on light weight. For this reason, there have been numerous designs incorporating carbon fiber composites for bicycle frames and components. Some of the original designs utilized the traditional double triangle shaped frame by replacing the metal tubes with composite tubes, such as shown in U.S. Pat. No. 4,657,795 by Foret. With this design, only the tubular parts such as the top tube or the down tube are replaced with lighter weight composite tubes. The metal joints, also known as lugs, remain unchanged and therefore the benefits of the composites are limited.

Bicycle frame design improved by integrating single composite tubes with light weight composite lugs such as with U.S. Pat. No. 5,116,071 by Calfee. With this design, the lugs are more firmly attached to the tubes in a seamless manner to improve the rigidity and strength of the frame. Another alternative of composite bicycle frame design is the joining of precured composite tubes and lugs is shown in U.S. Pat. Nos. 5,624,519 and 6,270,104 to Nelson et. al. These patents describe manufacturing the single composite tubes and lugs separately, then joining together in a bonding operation.

Another alternative bicycle frame design is known as the monocoque design as shown in U.S. Pat. No. 4,850,607 by Trimble. Here the entire frame is molded as a one piece unit in an attempt to reduce weight by eliminating the redundant overlapping of material using tubes and lugs. It also provides an attractive aerodynamic shape. However, with this design using a large single tube, the area of the thin wall is even greater, and therefore the susceptibility of buckling is even greater also.

It is desired that other components of the bicycle structure have the same features and benefits of the bicycle frame, namely light weight, stiffness, strength, aerodynamics and greater comfort.

The front forks are a major element in the bicycle structure because they connect to the front wheel and steer the bicycle. Therefore stiffness and strength are critical. The front forks also contribute considerable aerodynamic drag because of the large frontal area exposed to the direction of travel.

The initial prior art describes composite bicycle forks as being constructed of a single tube, with the primary goals being light weight and greater strength. U.S. Pat. No. 4,828,285 to Foret describes a composite fork with an internal foam core molded as a one piece unit. This compression molding technique using a foam core to consolidate the plies limited the achievement of super light weight.

U.S. Pat. Nos. 5,692,764 and 5,944,932 to Klein describe a composite bicycle fork with an improved stiffness to weight ratio as well as improved strength. This process produces a more efficient fork because it is without a core material and thus lighter in weight. However, there is no mention of improved aerodynamics or improved comfort.

U.S. Pat. No. 6,655,707 to Buckmiller, et. al., describes a composite fork produced by a filament winding method. This is a technique to automate the production process and to use continuous fibers in an attempt to improve the product quality.

U.S. Pat. No. 6,669,218 to Sinyard, et.al., describes a composite front fork with an intermediate portion in each fork leg which defines a cavity into which an elastomeric damping material is positioned. The main purpose of this design is to provide vibration damping to enhance comfort.

No aerodynamic benefit is achieved.

U.S. Pat. Application No. 10/366,760 to Cobb describes a bicycle fork where each fork leg portion is comprised of two legs arranged generally parallel to each other and with a certain distance in between. Each fork leg has an airfoil shaped cross section, and they are separate legs yet fixed to each other using connectors at various locations. Although two legs are used, they are not integrated together. The main purpose of Cobb is to guide the airflow away from the wheel,

but not through the fork.

It is critical that the bicycle fork be very strong in order to support the weight of the rider, and also to withstand the combination of loads imposed by riding conditions. A bicycle fork which fails in a catastrophic manner can result is serious injury to the rider. Although many of the aforementioned designs claim greater strength, it may not always be true on a consistent basis, because the molding procedure for composite tubular parts is labor intensive, and if there are portions which result in thin wall thicknesses, buckling failures can occur.

The handlebars are another part of the bicycle structure that are exposed to the direction of travel, and therefore should be designed with aerodynamics in mind. In addition and similar to the forks, the handlebars must withstand a multitude of loads without failing. U.S. Pat. No. 5,557,982 to

Klein describes a light weight composite bicycle handlebar which has improved stiffness to weight and strength to weight ratios. There is no mention of aerodynamics or comfort features, and the handlebar is produced using a single composite tube.

Another example is U.S. Pat. Application No. 10/261,531 to Whiting and Hulick which describes a one piece composite handlebar made from a single tube.

Both of the aforementioned composite handlebar designs are also susceptible to thin walled buckling failures because they are designed with continuous hollow composite tubes.

The seat post is another critical part of the bicycle frame system because it bears the weight of the rider as well as the circumferential stress of clamping to the frame. U.S. Pat. No. 6,213,488 to

Filice, et.al, describes a light weight high strength bicycle seat post comprised of a metal tube with an internal composite tube. In this example the the wall thickness is increased to because of the concentric tubes to provide a thicker and stronger wall design at the expense of greater weight.

U.S. Pat. No. 6,848,701 to Sinyard, et.al., describes a composite seat post with a cavity into which an elastomeric material is inserted to damp vibrations. Similar to U.S. Pat. No. 6,669,218, this is primarily a comfort technology and has no strength or aerodynamic benefit.

There exists a continuing need for an improved bicycle frame design. In this regard, the present invention substantially fulfills this need.

SUMMARY OF THE INVENTION

The present invention is a bicycle frame system where at least one component is formed of a single, hollow tube having at least one, and preferably a series, of "ports" that extend through the hollow tube. The ports provide specific performance advantages. Each port has a peripheral wall that extends between opposed holes in the hollow tube. The opposite ends of each port are bonded to the handle tube. The wall forming the port, which extends between opposite sides of the tube, preferably is shaped to act as opposing arches which provide additional strength, stiffness, comfort, and aerodynamic benefits.

The bicycle frame system according to the present invention substantially departs from the conventional concepts and designs of the prior art and in doing so provides an apparatus primarily developed for the purpose of maintaining light weight while providing tailored stiffness, improved resilience, improved strength, improved aerodynamics as well as improved appearance. This combination of benefits is unique in bicycle frame design.

In view of the foregoing commonality inherent in the known types of bicycle frames of known designs and configurations now present in the prior art, the present invention provides an improved bicycle frame system.

There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject matter of the claims attached.

In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of descriptions and should not be regarded as limiting.

As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.

The present invention provides a new and improved bicycle frame system which may be easily and efficiently manufactured.

The present invention provides a new and improved bicycle frame system which is of durable and reliable construction.

The present invention provides a new and improved bicycle frame system which is susceptible of a low cost of manufacture with regard to both materials and labor.

The present invention further provides a bicycle frame system that can provide specific stiffness and resiliency combinations to various locations of the frame.

The present invention provides an improved bicycle frame system that has superior strength and fatigue resistance.

The present invention provides an improved bicycle frame system that has improved aerodynamics.

The present invention provides an improved bicycle frame system that can improve the vibration damping characteristics of the frame.

The present invention provides an improved bicycle frame system that has a unique look and improved aesthetics.

Lastly, the present invention provides a new and improved bicycle frame system made with a single tube design, where apertures, i.e., "ports," that extend through opposed holes in the component tube act, and preferably are shaped as double opposing arches to provide a means of adjusting the stiffness, resiliency, strength, comfort, and aerodynamics of the implement.

For a better understanding of the invention and its advantages, reference should be made to the accompanying drawings and descriptive matter in which there are illustrated preferred

embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a side view of a bicycle constructed in accordance with an embodiment of the present invention;

Figure 2 is a front view of a portion of an alternate bicycle frame;

Figure 3 is a side view of another embodiment of a bicycle;

Figure 4 is a front view of a seat post constructed in accordance with an embodiment of the present invention;

Figure 5 is a front view of a portion of a prepreg tube during formation of the component tube.

Figure 6 is an isometric view of the prepreg tube of Fig. 5 during a subsequent step in forming the component tube.

Fig. 7 is a front view of the prepreg tube of Fig. 6 during a subsequent step in forming the component tube,

Fig. 8 is a sectional view of the prepreg tube of Fig. 7, taken in the direction of arrows 8-8 of Fig.

7.

Fig. 9 is a side view of the prepreg tube of Fig. 7 during a subsequent step in the formation of the component tube.

Fig. 10 is an enlarged, isometric view of a portion of the component tube after molding.

Figure 11 is a sectional view of a portion of the component tube, taken in the direction of arrows

11 - 11 in Figure 10.

Figure 12 is isometric cut away view of a portion of the component tube.

Figure 13 is an isometric cut away view of a portion of a down tube 40.

Figure 14 is a cross sectional view of the down tube in Figure 3 taken along the lines 14-14.

Figure 15 is a cross sectional view of the down tube in Figure 3 taken along the lines 15-15.

Figure 16 is a cross section of the down tube in Figure 3 taken along the lines 16-16.

Figure 17 shows an example of how multiple ports could be oriented in a four bladder construction.

Figure 18 is a cross sectional view along the lines 18-18 of Figure 17.

Figures 19A-D show various shapes of ports.

The same reference numerals refer to the same parts throughout the various Figures.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 illustrates a bicycle, which is referred to generally by the reference numeral 10. The bicycle 10 includes a frame 12 which is comprised of a top tube 14, a down tube 16, a seat tube 18, a rear stay 20, and a chain stay 22.

The bicycle frame further includes front forks 24, handlebars 26, and a seat post 28. Figure 1 shows one preferred embodiment wherein each of the tubular parts contains openings, formed by "ports" 30, oriented 90 degrees to the direction of travel. The exception is with the handlebar 26 which has the ports oriented in line to the direction of travel, and are not visible in Figure 1. Another handlebar design such as the straight bars used for recreational bikes and mountain bikes will also benefit with ports oriented in this manner.

As described below, each of the component tubular parts is formed of a single tube where a plurality of "ports" are formed in the hollow tube. The ports extend between opposing faces of the tube. Each aperture is preferably oval in shape, with the long axis of the oval in line with the central axis of each tube. Each port includes a peripheral wall that extends between the opposing faces of the tube, whose ends are bonded to the tube.

Figure 1 shows the ports 30 oriented primarily for passive suspension purposes, with the axis of the ports generally horizontal and 90 degrees to the forward direction of travel of the bicycle. Ports oriented in this manner provide the means to achieve more flexibility from each of the tubular members. Thus, the front fork 24 has ports 30 oriented primarily for passive suspension purposes, with the axis of the ports generally horizontal and 90 degrees to the direction of travel. The size and spacing of the ports 30 can vary according to the dimensions of the legs of the fork. Figure 2 shows an alternative embodiment, in which the ports 32 are oriented primarily for aerodynamic purposes, with the axis of the ports generally horizontal and parallel to the direction of travel. The handlebar 26, front forks 24, and down tube 16 are the components of the bicycle

structure with the greatest frontal area and would therefore reduce the aerodynamic drag the most with ports oriented in this manner. Typically the width of the fork legs 24 are reduced for aerodynamic purposes. With the ported double tube construction, the width of the fork can be greater and still maintain aerodynamic while improving the stiffness and strength requirements.

In Figure 4, the ports of the seat post assembly with seat post 28 are oriented for aerodynamic purposes. The ported tube design also can provide some passive suspension since the seat post can be somewhat flexible due to the ports. In addition, the peripheral port wall assists in resisting the clamping stress of securing the post to the bicycle frame.

In Figure 2, the ports 32 for the handlebar 26 are oriented for aerodynamic purposes. This is only one example of the many different types of handlebars used on bicycles. This particular example is a utility type handlebar, but there are many different designs and shapes, all of which can benefit from ported tube members.

Figure 3 is a side view of a bicycle 10 with both ports 30 oriented horizontal and perpendicular to the direction of travel and ports 32 oriented parallel to the direction of travel.

The component tube is preferably made from a long fiber reinforced prepreg type material.

Traditional lightweight composite structures have been made by preparing an intermediate material known as a prepreg which will be used to mold the final structure.

A prepreg is formed by embedding the fibers, such as carbon, glass, and others, in resin. This is typically done using a prepreg machine, which applies the non-cured resin over the fibers so they are all wetted out. The resin is at an "B Stage" meaning that only heat and pressure are required to complete the cross linking and harden and cure the resin. Thermoset resins like epoxy are popular because they are available in liquid form at room temperature, which facilitates the embedding process.

A thermoset is created by a chemical reaction of two components, forming a material in a nonreversible process. Usually, the two components are available in liquid form, and after mixing together, will remain a liquid for a period of time before the crosslinking process begins. It is during this "B Stage" that the prepreg process happens, where the resin coats the fibers. Common

thermoset materials are epoxy, polyester, vinyl, phenolic, polyimide, and others.

The prepreg sheets are cut and stacked according to a specific sequence, paying attention to the fiber orientation of each ply.

Each prepreg layer comprises an epoxy resin combined with unidirectional parallel fibers from the class of fibers including but not limited to carbon fibers, glass fibers, aramid fibers, and boron fibers.

The prepreg is cut into strips at various angles and laid up on a table. The strips are then stacked in an alternating fashion such that the fibers of each layer are different to the adjacent layers. For example, one layer may be +30 degrees, the next layer -30 degrees. If more bending stiffness is desired, a lower angle such as 20 degrees can be used. If more torsional stiffness is desired, a higher angle such as 45 degrees can be used. In addition, 0 degrees can be used for maximum bending stiffness, and 90 degrees can be used to resist impact forces and to maintain the geometric structural shape of the tube.

This layup, which comprises various strips of prepreg material, is then rolled up into a tube.

Referring to Figure 5, according to the preferred embodiment of the invention, a suitable prepreg tube 60 is formed in the manner just described, with the various composite plies oriented at the desired angles. Next, a plurality of openings 62 are formed through opposing walls the tube, generally perpendicular to the axis of the tube. Alternately, e.g., as shown by the ports 32 in

Figure 3, the openings may be offset so that, in the completed frame, the openings will be horizontal. The openings 62 may be stamped through the walls. More preferably, a tool is used to separate the carbon fibers from one another, without cutting the fibers, to form the openings 62.

The openings, at this stage, need not have the final desired shape.

Referring to Figure 6, next a pair of inflatable thin walled polymeric bladders 64, 65, preferably made of nylon, are inserted through the tube 60 such that their facing walls 66, 67 are aligned with the openings 62.

Referring to Figures 7-8, after the bladders 64, 65 have been inserted, a hollow, tubular plug 66 is inserted through each of the holes 62, between the facing walls 66, 67 of the bladders, i.e.,

separating the bladders. The ends of the plugs 66 preferably extend beyond the outer surfaces of the prepreg tube 60, as shown in Fig. 8. The plugs are preferably tubes of prepreg material.

However, if desired the plugs may be made of other materials such as metal or plastic.

Finally, as shown in Figure 9, if the plugs 66 are formed of prepreg material, a mold pin 68 is inserted through each plug 66 to form the internal geometry of the ports. This may occur prior to mold packing, or during the mold packing process.

The tube is then packed into a mold which forms the shape of the bicycle frame component. Air fittings are applied to the interior of the bladders 64 and 65 at the end of the tube 60. The bladders may be closed on the other end of the tube, or connected to other air fittings, or are connected in the shape of a hairpin to form one continuous "U" shaped bladder inside the tube 60.

The mold is then closed over the tube 60 and placed in a heated platen press. For epoxy resins, the temperature is typically around 350 degrees F. While the mold is being heated, the tube 60 is internally pressurized, which compresses the prepreg material and forces the tube 60 to assume the shape of the mold. At the same time, the heat cures the epoxy resin. The bladders also compress the peripheral walls of the plugs 66, so that the inwardly facing surface 70 of each plug 66 conforms to the shape of the mold pin 68 (which is preferably oval). At the same time, the heat and pressure cause the ends of the plug walls to bond to the wall of the prepreg tube 60.

Once cured, the mold is opened in the reverse sequence of packing. The pins 68 are typically removed first, followed by the top portion of the mold. Particular attention is needed if removing the top portion with the pins 68 intact to ensure this is done in a linear fashion. Once the pins 68 have been removed from the component tube, the component can be removed from the bottom portion of the mold.

As shown in Figures 10-11, after molding, the tube 12 is formed of a single, hollow component tube 72, with a plurality of ports 58 extending through the tube 72. The ends of the port walls 74 are bonded to the portions of the handle tube 72 surrounding the ports 58, and the inwardly facing surfaces 76 of the ports 58 extend completely through the component tube 72.

The composite material used is preferably carbon fiber reinforced epoxy because the objective is to

provide reinforcement at the lightest possible weight. Other fibers may be used such as fiberglass, aramid, boron and others. Other thermoset resins may be used such as polyester and vinyl ester.

Thermoplastic resins may also be used such as nylon, ABS, PBT and others.

Figure 12 is an isometric view of the down tube 40 of Figure 3 isolated to one port. In this example, the axis of the port 44 is at an acute angle to the down tube so to be parallel to the direction of travel. This results in an elongated internal wall 46.

Figure 13 is an isometric view of a cutaway portion of the down tube 40 of Figure 3. In this example, 4 bladder tubes 64a,b,c,d are used to form the structure. The bladder tubes 64a,d are separated from bladder tubes 64 b,c to form port 30, and bladder tubes 64 a,b are separated from bladder tubes 64c,d to form port 32. It is also possible to mold the down tube 40 using two bladder tubes, by changing the position of the tubes as the orientation of the ports change. Each port is molded as discussed previously, by inserting prepreg plugs through opposing holes in the prepreg tube, and between the bladder tubes, and wrapping the prepreg plugs to attach to the walls of the prepreg tube. Pins are inserted to form the internal walls of the ports.. The Figure 13 embodiment includes ports 32 oriented along the tube 40 axis, and ports 30 oriented perpendicular to the tube 40 axis.

With reference to Figure 14, this cross sectional view along the lines 14-14 of Figure 3 of the down tube 40 shows the single tube at a location without a port.

Figure 15 is a cross sectional view of the down tube 40 of Figure 3 along the lines 15-15 of port

32 which is oriented parallel to the direction of travel.

Figure 16 is a cross sectional view of the down tube 40 of Figure 3 along the lines 16-16 of port

30 which is oriented perpendicular to the direction of travel.

Figure 17 is an isometric cutaway view of a component tube structure 50 with four ports located in the same location. This results in an open port 51 that is open on four sides.

In this example, four bladders 64a,b,c,d are used. An internal pin in the shape of an "X" is used to form the interior surface formed by ports 51a,b,c,d as shown in Figure 18. Prepreg material is wrapped around the X shaped pin and attached to the walls of component tube 50. Each bladder

tube is positioned in each quadrant formed between the legs of the pin as shown in Figure 18.

After molding, the X shaped pin is removed.

There can be any number of ports depending on the number of internal bladder tubes used and the number of cutaway portions as well as pins and prepreg plugs.

Figure 19 illustrates some examples of the variety of shapes possible to be used for the ports.

Depending on the performance required of the structure at a particular location, more decorative port shapes can be used.

In this example, the top tube 14, down tube 16, seat tube 19, rear stay 20, and chain stay 22 are molded separately and then glued together, using known techniques. Alternately, these frame members, or some of them, may be molded together, with the bladder members extending continuously through the joined members.

The preferred embodiments of the present invention use single continuous composite tubes into which ports are molded to form apertures in the form of double opposing arches at various locations in the bicycle frame, fork, handlebar, and/or seat post. The basic concept of design and construction can be applied to each of these components because it offers the same advantages, although there exist particularities for each component which will be discussed in more detail separately. For simplicity of discussion, all the above mentioned parts(frame, forks, handlebar, seat post) shall be called "tubular component parts" unless they are mentioned specifically by name.

The single, hollow tubular component part has been the traditional way to design and manufacture composite bicycle frames. This is because originally, the frame components were produced using single hollow metal tubes, so it was natural to replace these tubes with a single hollow composite tube.

It also makes sense from an efficiency viewpoint, that the single hollow tube maximizes properties of bending and twisting, since the material is displaced away from the central axis of the tube to maximize inertial properties. This has been the traditional bicycle structure.

When a single hollow tube has a sufficient wall thickness, for example when weight is not critical,

the design can sufficiently provide adequate stiffness and strength. However, as mentioned previously, when the wall thickness becomes thin relative to the diameter of the tube, the tubular part is susceptible to the wall buckling under the compressive forces which are always present in the bicycle frame.

In accordance with the present invention, conventional single hollow tubes forming the bicycle frame are improved by forming internal ports with cylindrical walls to reinforce the tube internally and resist the deformation of the cross section under loading. This is very effective in improving the susceptibility of the tube to the buckling of the wall under compressive forces.

The invention allows the frame to be custom tuned in terms of its stiffness and resiliency by varying, in addition to the size and shapes of the frame members themselves, the size, number, orientation and spacing of the ports in the various frame members.

Molding in ports, at selected locations results in a double opposing arch construction. What is contributing to the structure, is the "double arch effect" of the ports, which are preferably oval in shape creating two opposing arches which allow the tubular part to deflect, while retaining the cross sectional shape of the tube because of the three dimensional wall structure provided by the port. For example, a ported tubular structure has a combination of exterior walls, which are continuous and form the majority of the structure, and ported walls, which are oriented at an angle to the exterior walls, which provide strut like reinforcement to the tubular structure. The cylindrical walls of the ports prevent the cross section of the tube from collapsing, which significantly improves the strength of the structure.

The size and spacing of the ports can affect tubular part stiffness in a desirable way. These apertures can direct the fiexpoint of the tubular component part toward a desirable location if desired, or stiffen a particular region. The internal ports also increase the torsional stiffness of the tubular component part.

The bicycle frame system of the present invention becomes unique when the ports are molded into the structure. It is not necessary to change the exterior dimensions of the tubular part when molding ports. The size and spacing of each port can vary according to desired performance

parameters. The orientation, or axes of the ports can be in line with the direction of travel, therefore maximizing the aerodynamic benefit. Aerodynamic analysis has shown that a reduction of aerodynamic drag of 20% can be achieved. This is a great benefit to a bicycle rider.

Another option is to form the ports on to a tubular metal portion. In this example, the metal tube replaces the single composite tube, and the process is similar to molding the ports on to the composite prepreg tube, except the metal tube is not flexible like the prepreg material. The process is the same, with the prepreg materials conforming to the metal tube during molding process.

In addition, the ports may be formed using a cylindrical metal plug which can be welded or bonded to the metal tube. This can produce a less expensive structure that can still achieve the performance and aesthetic requirements of the product.

The ported tube construction can also provide more comfort to the rider. As mentioned previously, the stiffness of the tubular part can be optimized to provide greater flexibility if desired. For example on a bicycle frame, the top tube could have ports oriented at 90 degrees to the direction of travel to provide a more flexible tube for enhanced rider comfort. The same could be done for the down tube, or the seat tube, or for the chain stays or seat stays. The front fork is a critical component for determining rider comfort as evidenced by all the suspension technologies available today. A front fork which has ports oriented 90 degrees to the direction of travel has more flexibility and therefore provides greater rider comfort.

Similarly, the same could be done for the handlebar.

Vertical tubular parts such as the seat post and seat tube could also provide greater rider comfort by utilizing ports oriented with horizontal axes to provide improved vertical displacement to absorb shock and vibration.

Another advantage of the invention is vibration damping. Vibrations are damped more effectively with the opposing double arch construction. This is because the movement and displacement of the arches absorbs energy which damps vibrations. As the tubular parts deflect, the shape of the ports can change, allowing a relative movement between the portions of the tube either side of the

port. This movement absorbs energy which damps vibrations.

Finally, there is a very distinguished appearance to a bicycle structure made according to the invention. The ports are very visible, and give the tubular part a very light weight and aerodynamic look, which is important in bicycle marketing. The ports can also be painted a different color, to further enhance the signature look of the technology.

There are unlimited combinations of options when considering a double opposing arch structure.

The ports can vary by shape, size, location, orientation and quantity. The ports can be used to enhance stiffness, resilience, strength, aerodynamics, comfort and aesthetics. For example in a low stress region, the size of the port can be very large in order to maximize aerodynamics and appearance. If more deflection or resilience is desired, the shape of the aperture can be very long and narrow to allow more flexibility. The ports may also use designer shapes to give the product a stronger appeal.

If more vibration damping is desired, the ports can be oriented and shaped at a particular angle, and constructed using fibers such as aramid or liquid crystal polymer. As the port deforms as a result of frame deflection, its return to shape can be controlled with these viscoelastic materials which will increase vibration damping. Another way to increase vibration damping is to insert an elastomeric material inside the port.

A bicycle frame structure according to the invention can be made a multitude of ways. One option is to manufacture the tubular parts separately and later bond the tubular frame parts to lugs. This can be done using external lugs, or produce a seamless integrated part. This can be done using external lugs with the tubular parts inserted into the lug, or use internal lugs which are inserted into the interior of the tubular parts to produce a seamless integrated part. Another option is to mold the entire frame structure in a one step process to produce a monocoque type design.

The front forks can be produced in a similar manner as described with the double opposing arch frame. The size of the ports can vary according to the size of the fork legs. In addition, the orientation and spacing between the ports can vary according to the performance desired.

The handlebars can also be produced in a similar manner as the frame. The size of the ports can

vary according to the size of the handlebar. In addition, the orientation of the ports can vary according to the performance desired. In some cases, it may be preferred to increase the aspect ratio of the ports, creating long ovals to maximize the aerodynamic benefit.

Finally, the seat post can also be produced in a similar manner as the frame. The size, spacing and orientation of the ports can vary according to the size of the post.

With respect to the above description then, it is to be realized that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention. Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.