Technical field

The present invention relates to a road racing bike frame. The present invention also relates to a road racing bike comprising such a frame.

Road racing bikes, also referred to as (road) racing bicycles, may travel at average speeds as high as about 40-55 km/h, with top speeds as high as about 80-90 km/h. It is therefore a wish that road racing bikes have good aerodynamics. of the invention

It is an object of the present invention to provide an improved road racing bike frame, which in particular has improved aerodynamics.

These and other objects are achieved by the present invention as defined in the appended independent claim(s). Embodiments are set forth in the appended dependent claims.

Brief of the

The present invention will now be described in more detail, with reference to the appended drawings showing currently preferred embodiments of the invention.

Fig. 1 is a partial side view of a road racing bike frame with winglets according to one or more embodiments of the present invention.

Fig. 2 is partial front view of the road racing bike frame of fig. 1 .

Fig. 3 is side view illustrating e.g. exemplary size of the winglets.

Fig. 4 is a partial side view of the road racing bike frame of fig. 1 without the winglets.

Fig. 5 is partial front view of the road racing bike frame of fig. 1 without the winglets.

Fig. 6 illustrates an airfoil of the winglet. Fig. 7 illustrates top views of the headtube with and without winglets as well as air pressure.

Fig. 8 is a top view illustrating wakes with the winglets.

Fig. 9 is a top view illustrating wakes without the winglets.

Fig. 10 illustrate a road racing bike frame with winglets according to another embodiment of the present invention.

Fig. 11 is a side view of a road racing bike according to an aspect of the present invention.

Detailed description of the invention

Figs. 1-2 illustrate a road racing bike frame 10 according to one or more embodiments of the present invention. The road racing bike frame 10 could also be referred to as (road) racing bicycle frame 10. It should be noted that the present frame 10 also could be used on the track or for time trial.

The road racing bike frame 10 may comprise a top tube 12, a down tube 14, and a head element 16 connected to or merging with the top tube 12 and the down tube 14. The head element 16 may for example be a head tube. The road racing bike frame 10 may also comprise a front fork 18 (see fig. 11 ), with left and right fork blades.

According to the present invention, the road racing bike frame 10 further comprises a first (left) winglet 20a arranged on a left outer side (as seen in/relative to the forward riding direction 34) of the road racing bike frame 10, and a corresponding a second (right) winglet 20b arranged on a right outer side of the road racing bike frame 10. The first and second winglets 20a-b could also be referred to as air deflectors. The first and second winglets 20a-b improve the aerodynamics of the road racing bike frame 10, which will be discussed/explained further hereinbelow.

In figs. 1 -2, the first winglet 20a is arranged on a left outer side (surface) 22a of the head element 16, and the second winglet 20b is arranged on a right outer side (surface) 22b of the head element 16. With this position of the winglets 20a-b, they do not enter in interference with the bike or rider while being used, while they do improve the aerodynamics of the road racing bike frame 10. Being arranged at the head element 16 (or on the front fork 18 as indicated in fig. 11 ), the winglets 20a-b could be referred to as front winglets 20a-b.

The winglets 20a-b may for example be made of polymer or metal/alloy or composites material.

With further reference to fig. 6, each of the first winglet 20a and the second winglet 20b preferably has the shape of an airfoil 24. This shape may improve the airflow around the head element 16. An airfoil (or aerofoil) like airfoil 24 may generally be defined as a body designed to provide a desired reaction force when in motion relative to the surrounding air. The first and second winglets 20a-b in general, and the airfoils 24 in particular, may be substantially vertically arranged. The latter can be seen in the top view of fig. 7. That is, the cross section of the winglets 20a-b as seen from above may be airfoil-shaped. The airfoil 24 may have a camber value between 0 and 10%, a maximum camber position between 0 and 90%, and a thickness T between 1 and 40 % of the chord length L of the airfoil 24. Furthermore, concave sides of the airfoils 24 may face the head element 16 (whereas convex sides of the airfoils 24 are facing away from the head element 16), as also seen in the top view of fig. 7.

The aerodynamic improvement by means of the winglets 20a-b/airfoil 24 has been proved by CFD (Computational Fluid Dynamics) analysis. The CFD analysis shows how the winglets 20a-b reduce the turbulent area behind the head element 16 obtaining a smaller drag force (i.e. wind resistance). Fig. 7 shows a section in the middle of the head element/tube 16, with the winglets 20a-b (top) and without winglets (bottom). With the winglets 20a-b, one can see in fig. 7 that the turbulent area behind the head element 16 is smaller than without the winglets. Furthermore in figs. 8-9, it can be seen that the wake 26 behind the head tube 16 is smaller when there are winglets 20a- b (fig. 8) compared to without the winglets (fig. 9). Also the wake 28 behind the seat post is bigger when there are no winglets. The overall results of the CFD analysis are presented in Table 1 :

Table 1

Cd = Coefficient of Drag, A = Frontal Area exposed to wind flow, CdA = Normalized Coefficient of Drag (= coefficient of drag multiplied by frontal area), Fd = Drag force, and Power = Drag Power. The test result are at 45 km/h bike speed.

Turning to fig. 3, wherein each of the first winglet 20a and the second winglet 20b may have a size substantially corresponding to the head element 16 as seen from the side. Specifically, the height and the width of each winglet 20a-b could be within the two dimensions of a box 30 which overlaps the height and the width of the head tube 16 of about 20 mm. As also seen in fig. 3 (as well as in fig. 1 ), each of the first and second winglets 20a-b may have the shape of a trapezium as seen from the side of the road racing bike frame 10, which trapezium has substantially parallel top and bottom sides 30a-b, a front side 32a leaning backwards relative to the forward riding direction 34 of the road racing bike frame, and a rear side 32b leaning more backwards than the front side 32a.

Furthermore, wherein the first winglet 20a may be arranged at a first recessed portion 36a on the left outer side 22a of the head element 16, and the second winglet 20b may be arranged at a second recessed portion 36b on the right outer side 22a of the head element, see further figs. 4-5. By this, it is further assured that the winglets 20a-b do not enter in interference with the bike or rider while being used. Furthermore, the recessed portions 36a-b may decrease the frontal area (of the head element 16) exposed to wind flow. With same coefficient of drag, the normalized coefficient will be lower and drag is reduced. The depth of the first and second recessed portions 36a-b may increase in the forward direction of the road racing bike frame 10, and the depth at the front of the first and second recessed portions 36a-b may as well increase in a downward direction of the road racing bike frame 10, as appreciated in particular from fig. 4. Furthermore, the first recessed portion 36a may comprise a first protrusion 38a to which the first winglet 20a is mounted, wherein the second recessed portion 36b comprises a second protrusion 38b to which the second winglet 20b is mounted. The winglets 20a-b are preferably attached/mounted by standard lateral screws, but the utilization of snap fit, magnets, or adhesives is also feasible. To this end, the road racing bike frame 10 may have threaded inserts dedicated for the winglets 20a-b, in particular on the protrusions 38a-b. Preferably the first and second protrusions 38a-b are elongated in the forward/rearward direction of the road racing bike frame, to be aerodynamically efficient.

It is conceivable that the winglets 20a-b need not be attached/mounted to road racing bike frame 10 by use of protrusions 38a-b. The winglets 20a-b may alternatively be integrally formed with the road racing bike frame 10. By integrally formed it is herein meant that the winglets 20a-b may be connected to the road racing bike frame 10 so as to form a single unit. The winglets 20a- b may be integrally formed by e.g. welding together the winglets 20a-b to the road racing bike frame 10 should the winglets 20a-b and the road racing bike frame 10 be made of a material suitable for welding. Alternatively, the winglets 20a-b may be integrally formed with the road racing bike frame 10 by, already in a fabrication process of the road racing bike frame 10, introducing the winglets 20a-b in the very same fabrication process. Such a fabrication process may involve for instance a moulding process of the road racing bike frame 10. It may in this context be noted that the fabrication process of the road racing bike frame 10 may vary depending on the material thereof. For certain materials it is conceivable that the winglets 20a-b may be glued/adhered onto the road racing bike frame 10 so as to be integrally formed thereto. Thus, there is provided a convenient fabrication process of the road racing bike frame 10.

By the winglets 20a-b being integrally formed with the road racing bike frame 10 so as to form a single unit there are provided several advantages. An advantage is that there need not be provided separate protrusions 38a-b in order for the winglets 20a-b to be connected to the road racing bike frame 10. The protrusions 38a-b are associated with a weight. Also, there is no need for separate attachment means such as lateral screws or magnets, which are associated with a respective weight as well. By integrally forming the winglets 20a-b with the road racing bike frame 10 the weight of the road racing bike frame 10 may be comparably low. This is especially true compared to had the winglets 20a-b been attached/mounted to the road racing bike frame 10 via the protrusions 38a-b and/or by separate attachment means such as lateral screws or magnets.

Another advantage is that by integrally forming the winglets 20a-b there is provided a convenient and strong attachment between the winglets 20a-b and the road racing bike frame 10. Since such an attachment between the winglets 20a-b need no separate attachment means in the form of e.g. lateral screws or magnets, said attachment need little to none maintenance. It may in this context be noted that separate attachment means such as lateral screws or magnets may deteriorate structurally over time, hence necessitating maintenance over time alternatively need to be replaced. Also, the protrusions 38a-b, and any threaded inserts arranged thereon, may need maintenance which may also deteriorate over time. Also, it may in this context be noted that any such parts may affect the aerodynamics of the road racing bike frame 10. Thus, the omission of such parts may be advantageous in terms of weight and aerodynamics of the road racing bike frame 10. Even further, the attachment between the integrally formed winglets 20a-b and the road racing bike frame 10 may be designed to be substantially flush with a surface of the road racing bike frame 10 and a respective winglet 20a-b. Thus, an aerodynamically efficient attachment may be provided between the integrally formed winglets 20a-b and the road racing bike frame 10.

It is also implied that a perimeter, or at least a major portion thereof, of a respective winglet 20a-b may abut the road racing bike frame 10 and thereby prevent air, water or e.g. an object such as a leaf, a pebble, or dirt from entering into the respective winglet 20a-b through a gap between said respective winglet 20a-b and the road racing bike frame 10. To this end, the aerodynamics of the road racing bike frame may be improved even further. Another advantage is that the integrated winglets 20a-b may provide an improved torsional stiffness of the road racing bike frame 10. Thus, the road racing bike frame 10 may be structurally sound and aerodynamical ly efficient.

It may in this context be noted that whenever there is a reference to the winglets 20a-b having certain geometrical properties, arrangements on the road racing bike frame 10 or dimensions etc. this is typically equally applicable to the case where the winglets 20a-b are integrally formed with the road racing bike frame 10.

Furthermore, the first winglet 20a may have has a first inwardly angled upper portion 40a, an intermediate portion 40a’, and a first inwardly angled lower portion 40a”. Correspondingly, the second winglet 20 may have a second inwardly angled upper portion 40b, an intermediate portion 40b’, and a second inwardly angled lower portion 40b”. Specifically, the inwardly angled portions may (each) be angled in relation to the respective intermediate portion e.g. by 10-30 degrees, be angled inwards towards the head element 16 (or the respective fork blade), extend along the complete width of the winglets 20a-b, and/or have a height corresponding to 10-25% of the total height of each winglet 20a-b. By the inwardly angled portions, any vortexes at the top and bottom tips of the winglets 20a-b, which vortexes may create unwanted drag, are reduced or eliminated. Preferably the first winglet 20a is mounted to the first protrusion 38a at the intermediate portion 40a’, and the second winglet 20a is mounted to the second protrusion 38b at the intermediate portion 40b’.

Furthermore, (the intermediate portion 40a’ of) the first winglet 20a could have a first inwards ridge 42a on each side of the first protrusion 38a as seen in the upward/downward direction of the road racing bike frame 10, which first inwards ridges 42a are elongated in the forward/rearward direction of the road racing bike frame 10. Likewise, (the intermediate portion 40b’ of) the second winglet 20b could have an elongated second inwards ridge 42b on each side of the second protrusion 38a. The inwards ridges 42a-b serve to keep the air flow straight, and to avoid having a rotating flow at the trailing edge 32b of each winglet 20a-b which would generate a bigger wake.

Fig. 10 illustrates a road racing bike frame 10’ with winglets 20a’ and 20b’ according to another embodiment of the present invention. Here the winglets 20a’ and 20b’ have a triangular shape as seen from the side, which triangular shape points (generally) backwards in relation to the forward riding direction.

Finally fig. 11 illustrates a road racing bike 100 according to an aspect of the present invention. The road racing bike 100 could also be referred to as (road) racing bicycle 100. It should be noted that the bike/bicycle 100 also can be used on the track or for time trial.

The road racing bike 100 comprising the present road racing bike frame 10 (or 10’) with the winglets 20a-b (or 20a’ and 20b’). The road racing bike 100 may further comprise - among other things - two wheels 102a-b in tandem, the front fork 18, handlebars 104 for steering, a seat post 106, a saddle (not shown), and pedals (not shown) for propelling the road racing bike. The road racing bike 100 will typically not be electrically assisted. The road racing bike frame 10 may further comprise a seat tube 108, seat stays 110, and chain stays 112.

As discussed above, the winglets 20a-b may be arranged one on each side of the head tube 16. Alternatively or in addition, the first winglet may be arranged on a left outer side of the left fork blade of the front fork 18, wherein the second winglet is arranged on a right outer side of the right fork blade of the front fork 18, as indicated by 114 in fig. 11. Here, each winglet may have a similar dimension to the side view of the fork blade.

The person skilled in the art realizes that the present invention by no means is limited to the embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.