GB2618645A

GB2618645A - Bicycle aerodynamic chainset cover

Info

Publication number: GB2618645A
Application number: GB2302131.4A
Authority: GB
Inventors: James Butcher Clinton
Original assignee: Ez Gains Ltd
Current assignee: Ez Gains Ltd
Priority date: 2022-02-15
Filing date: 2023-02-15
Publication date: 2023-11-15
Also published as: GB202302131D0; GB202201970D0

Abstract

A bicycle chainring/crankarm fairing 100 comprises a single skin composite fairing incorporating an inner domed portion 102 and an outer planar portion 104, wherein at least the outer planar portion 104 is used to secure the fairing to a chainring; and there is an aperture 106 for the crank arm. The fairing may be secured to the chainring by double sided adhesive tape. Also claimed is a method of manufacturing a bicycle chainring/crankarm fairing, comprising laying dry carbon fibre layers and/or glass cloth layers into a composite or aluminium mould; introducing an exothermic curing polymer resin, preferably epoxy resin, to the layers; curing the layers until solidified; and demoulding the solidified layers and trimming to required dimensions.

Description

Bicycle Aerodynamic Chainset Cover

Field of Invention

The present invention relates to a bicycle aerodynamic chainring/crankarm cover, and in particular to a bicycle aerodynamic chainring/crankarm cover being attached to a chainring to enhance the aerodynamic performance of the bicycle. The invention also relates to a process for manufacture of a bicycle aerodynamic chainring/crankarm cover.

Background

The bicycle chainring and crankarm are a source of aerodynamic drag. UCI (Union Cyclist International) Rules permit rotational items, and this allows fitment of a cover to this area to improve the aerodynamic performance. Aero Chainsets are costly and require a mechanical component to transfer load from the pedal to the chain.

Existing aerodynamic chainsets are metallic and structural, resulting in a very expensive component due to the need ensure the torque from the pedal is transferred to the chain without introducing any off-axis shear failure.

Aerodynamic blending of the crankarm and the chainring results in a performance gain. The current solution is to use a large quantity of tape to act as an aerodynamic "cover" this often needs replacement and cannot be reused. Normal tape also commonly leaves a residue when removed to change a chainring, chainset or crank. The present invention shows an aerodynamic advantage in wind tunnel testing at Silverstone sports engineering hub.

The present invention seeks to ameliorate the above problems without compromising the structural integrity of the chainring/crankarm, and without the cost and other disadvantages mentioned above for installation and longevity.

Summary of the Invention

Aspects and embodiments of the present invention are set out in the appended claims.

These and other aspects and embodiments of the invention are also described herein.

According to one aspect disclosed herein, there is provided a bicycle chainring/crankarm fairing comprising of a single skin composite fairing incorporating an inner domed portion and an outer planar portion, wherein: at least the outer planar portion is used to secure the fairing to the chainring; and at least one area is cut out as an aperture for the crank arm.

Preferably, the fairing comprises means for fastening the fairing to a bicycle chainring. -2 -

Preferably, the means for fastening is affixed to a chainring side of the fairing.

According to another aspect disclosed herein, there is provided a bicycle chainset fairing comprising: an inner domed portion; an outer planar portion; at least one aperture for a crankarm of the bicycle chainset; and means for fastening the fairing to a chainring of a bicycle chainset, wherein: the means for fastening is affixed to a chainring side of the fairing; and the means for fastening is arranged to secure the fairing to the chainring by the outer planar portion.

Preferably, the inner domed portion and the outer planar portion are comprised of a single skin composite.

Preferably, the means for fastening is affixed to the outer planar portion on the chainring side of the fairing.

Preferably, the fairing comprises a recess, preferably an annular recess, on the chainring side of the fairing, preferably on the chainring side of the outer planar portion, arranged to accommodate the means for fastening the fairing to a chainring.

Preferably, the means for fastening is double-sided adhesive tape. Preferably, the inner domed portion comprises a flat top.

Preferably, the domed portion comprises a sloped part between the flat top of the domed portion and the outer planar portion.

Preferably, the gradient of the sloped part of the domed portion is shallower opposite the aperture than adjacent the aperture.

Preferably, the sloped part comprises a formation adjacent the aperture, the formation comprising at least one channel arranged to guide airflow around the domed portion.

Preferably, the formation comprises at least one channel on either side of the aperture.

Preferably, the at least one channel is arranged between an upper lip and a lower lip of the formation.

Preferably, the domed portion comprises a hollow interior to accommodate a bicycle crankarm.

Preferably, the aperture is formed as a cut out from the domed portion. -3 -

Preferably, the outer planar portion provides a flange for fastening the fairing to a bicycle chainring.

Preferably, the flange locates onto the geometry of the chainring.

According to another aspect disclosed herein, there is provided a bicycle comprising a chainring/crankarm fairing as aforementioned, the fairing being secured around the diameter to a chainring of the bicycle using double-sided adhesive tape.

According to another aspect disclosed herein. there is provided a kit of parts comprising: a bicycle chainring/crankarm fairing; and a length of self-adhesive tape.

Preferably, the fairing is as aforementioned.

According to another aspect disclosed herein, there is provided a method of manufacturing bicycle wheel cover a bicycle chainring/crankarm fairing, the method comprising: placement of a composite fabric into a mould; and moulding the composite fabric using a resin infusion process laying dry carbon fibre layers and/or glass cloth layers into a composite or aluminium mould; introducing an exothermic curing polymer resin, preferably epoxy resin, to the layers; curing the layers until solidified; and demoulding the solidified layers and trimming to required dimensions.

Preferably, the method further comprises vacuum bagging the mould before introducing the resin, preferably wherein the resin is introduced to the vacuum bag through an inlet port and associated hose, clamp and flow media.

Preferably, the curing comprises curing under ambient conditions, preferably room temperature, until solidified.

Preferably, the curing comprises curing at a temperature of approximately 50 degrees Celsius for approximately 6 hours.

According to another aspect described herein, there is provided a bicycle chainring/crankarm cover comprising: a single skin composite fairing adapted over the top of a chainset.

According to another aspect described herein, there is provided a kit of parts comprising of the chainring/crankarm cover and a length of self-adhesive tape. According to another aspect described herein, there is provided a method of manufacturing a bicycle chainring/crankarm cover using the method of resin infusion.

According to another aspect described herein, there is provided a bicycle chainring/crankarm fairing comprising of a single skin composite fairing incorporating an inner domed portion -4 -and an outer planar portion, wherein: at least the outer planar portion is used to secure the fairing to the chainring; and at least one area is cut out as an aperture for the crank arm.

According to another aspect described herein, there is provided a bicycle chainring/crankarm fairing secured around the diameter using double-sided adhesive tape.

According to another aspect described herein, there is provided a kit of parts comprising: a bicycle chainring/crankarm fairing; and a length of self-adhesive tape.

According to another aspect described herein, there is provided a method of manufacturing a bicycle chainring/crankarm fairing comprising: placement of a composite fabric into a mould; and moulding the composite fabric using a resin infusion process.

According to another aspect described herein, there is provided a bicycling chainring/crankarm cover comprising: a single composite cover adapted to cover the crank arm and blend it to the chainring, wherein: affixed to the chainring side of the cover is a method of fastening. The chainring side of the cover is the side arranged to contact the chainring to fasten the cover to the chainring.

Preferably the method of fastening is an adhesive tape.

Preferably the outer face of the cover is domed.

Preferably the cover has a cut out to allow the crankarm to pass through.

Preferably the cover has a flange to permit fitting of adhesive tape.

Preferably the cover has a flange which locates onto the geometry of the chainring.

According to another aspect described herein, there is provided a method of manufacturing bicycle aerodynamic chainring/crankarm cover comprising: Laying of dry carbon fabric into a mould tool, the mould comprising of a composite and/or metallic material, vacuum bagging the material and curing it, cutting the moulded part to conform to the Table of Dimensions set out below.

Preferably the mould is formed of a composite or aluminium material.

Preferably the method is a method of manufacturing a bicycle chainring/crankarm cover as previously described.

Features, integers, or characteristics described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the -5 -features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments.

As used herein, the term "domed" or "doming" or related terms preferably connote a dome shaped structure. These terms include a structure with a rounded or hemi-spherical type shape. These terms also include conical or funnel shaped structures with a constant gradient. These terms also include flat-topped dome-shaped or cone-shaped structures. The term "domed" is interchangeable with the term "conical".

The term "Crankarm" when used with reference to a Bicycle Aerodynamic Chainset cover refers to the arm extending from the centre of rotation of the chainring to the pedal.

The term "Chainring" when used with reference to a Bicycle Aerodynamic chainring/crankarm cover refers to the rotating disc which transfers force from the crankarm through to the chain.

The term "Chainset" when used with reference to a Bicycle Aerodynamic chainring/crankarm cover refers to the assembly of the chainring and crankarm which rotate as a single structural unit to transfer force from the pedal to the chain.

Any apparatus feature as described herein may also be provided as a method feature, and vice versa. As used herein, means plus function features may be expressed alternatively in terms of their corresponding structure.

Any feature in one aspect of the invention may be applied to other aspects of the invention, in any appropriate combination. In particular, method aspects may be applied to apparatus aspects, and vice versa. Furthermore, any, some and/or all features in one aspect can be applied to any, some and/or all features in any other aspect, in any appropriate combination.

It should also be appreciated that particular combinations of the various features described and defined in any aspects of the invention can be implemented and/or supplied and/or used independently.

The invention extends to methods, system and apparatus substantially as herein described and/or as illustrated with reference to the accompanying figures.

One or more aspects will now be described, by way of example only and with reference to the accompanying drawings having like-reference numerals, in which: -6 -Figures 1 to 3 are views of the Bicycle Aerodynamic chainring/crankarm cover according to one embodiment; and Figures 4 to 9 are views of other embodiments of the bicycle aerodynamic chainring/crankarm cover with varying dimensions.

Detailed description

The Bicycle Aerodynamic chainring/crankarm cover disclosed herein comprises of one main part. This main part is secured to the chainring.

Figures 1 to 3 show a cover for covering the chain side of a bicycle chainset. This comprises of the features of a circular outer edge, a domed fairing and an aperture for the crank arm to pass through. The outer edge is sized to fit the rim of the chainring. The degree of doming is intended to cover the crank arm and still fit the rim of the chainring.

The size of the aperture depends on the size of the crankarm. The inventor has carefully chosen the dimensions of this to ensure fitment. (Shown below in the Table of Dimensions and described with reference to Figures 4 to 9.) Chainring/crankarm cover The cover 100 is formed as a single, unitary piece, having a generally circular shape with diameter D. The cover 100 acts as a fairing to improve the aerodynamic performance of a bicycle chainset. The cover 100 comprises a domed inner portion 102 and a planer outer portion 104. The domed inner portion 102 comprises a flat top having a plane parallel to the planar outer portion. Inside the domed portion is hollow space to accommodate a crankarm, and the connection of the crankarm to the chainring, when the cover 100 is attached to a chainset. The planar outer portion 104 is provided as a flange (in this example, an annular flange) to enable fastening of the cover to a chainring. As the cover 100 is formed a single piece, the planer outer portion 104 extends continuously from the domed inner portion 102.

The cover 100 comprises an aperture 106. In this example, the aperture is provided as a cut-out from the domed inner portion 102 only. In other examples, the aperture 106 may be provided as a cut-out from both the domed inner portion 102 and the planar outer portion 104. The aperture 106 is arranged to accommodate a bicycle crankarm when the chainring cover 100 is fitted to a chainring.

A crankarm axis or crankarm plane (indicated by arrows A in Figure 3) can be defined as running along a diameter of the chainring cover 100 through the centre of the cover 100 and through the centre of aperture 106, bisecting the width of the aperture. 7 -

The cover 100, and in particular the domed inner portion 102 of the chainring cover 100, is symmetrical either side of the crankarm axis or crankarm plane. In other words, the domed inner portion 102 falls away to form the planar outer portion 104 in the same way on either side of the crankarm axis or crankarm plane. Conversely, the cover 100, and in particular the domed inner portion 102 of the cover 100, is asymmetrical either side of an axis or plane (indicated by line D in Figure 3) perpendicular to the crankarm axis or crankarm plane.

The domed portion 102 of the cover 100 comprises a part 108, 110 that slopes away to the boundary of the domed inner portion and the planar outer portion 102. Opposite the aperture 106 (i.e., on the left-hand side of line D in Figure 3), the sloping of the domed portion is formed as a continuous slope 108 from the flat top of the domed portion to outer planar portion, the sloping having a relatively shallow gradient. In some embodiments, the sloping of the domed portion adjacent the aperture 106 may also by formed as a continuous slope from the flat top of the domed portion to outer planar portion with a similarly shallow gradient.

In other embodiments, however, such as those shown in the drawings, the sloping of the domed portion adjacent the aperture 106 may have a steeper gradient than the sloping opposite the aperture. In the pictured embodiment, the sloped part of the domed portion adjacent the aperture comprises a formation 110 for guiding air flow around the domed portion. The formation is arranged between the flat top of the domed portion and the outer planar portion. The formation comprises two parts, one arranged on either side of the aperture 106. Each part of the formation comprises an upper lip 112 and a lower lip 114 forming therebetween a channel 116. The channel 116 acts to guide air flow around the domed portion 102 of the cover 100.

In use, when the cover 100 is attached to a bicycle, a bicycle crankarm is inserted through the aperture 106 and the cover 100 is attached by its planar outer portion 104 to a chainring.

As the bicycle moves through the air, during at least part of one rotation of the crankarm the crankarm will tend to direct incoming air along the length of the crankarm towards the cover 100. The formation 110 acts to guide the incoming air along the channels 116 either side of the aperture 106 and around the domed portion 102 of the cover 100. This may increase reduce the aerodynamic drag associated with the crankarm and chainring by providing a more aerodynamically efficient path for air around the chainring via the channel 116.

Fitting the cover The cover 100 comprises a recess (not shown) on the underside of the planar outer portion 104. The recess is approximately 1.5 mm deep and has an annular shape so that it follows -8 -the underside (i.e., the chainring side) of the planar portion 104. The recess is for accommodating a means for fastening the cover to a chainring. The means for attaching the cover to the chaining may comprise an adhesive, preferably a length (or ring) of double-sided adhesive tape arranged to fit within the recess and secure the cover 100 to a chainring. The tape is preferably approximately 1.5 mm thick, meaning that when the tape is fitted within the recess in the underside of the cover 100, the cover will provide a substantially flush surface for fastening the cover to the chainring.

Attaching the cover 100 directly to the chainring is advantageous because it provides a more secure fitting of the cover to the chainring which may provide improved aerodynamic performance, for example as compared to a cover fastened to the crankarm where there might be a gap between the cover and the chainring.

Dimensions The inventors have carefully chosen the dimensions of the chainring cover 100 to ensure fitment. Figures 4 to 9 show embodiments of the cover 100 with varying dimensions chosen to fit a wide range of crankarms and chainrings.

Figures 4 to 9 show, for each embodiment, four dimensions which are varied to ensure fitment of the cover 100 to a wide range of available crankarms and chainrings. These dimensions are as follows: * Total diameter: this dimension refers to the diameter of the entire cover 100, and this dimension can be varied to suit chainrings of different sizes * Flat top diameter: this dimension refers to the diameter of the flat top part of the domed portion, excluding the sloped part of the domed portion, and this dimension can be varied to suit chainrings of different sizes * Depth: this dimension refers to the distance from the top of the flat top of the domed portion to the bottom of the planar portion, and this dimension can be varied to change the amount of space within the interior of the domed portion to accommodate crankarms of different sizes * Aperture width: this dimension refers to the width of the opening in the cover, and this dimension can be varied to accommodate crankarms of different widths Each of Figures 4 to 9 show three views of the various embodiments. One view (labelled (a) in each Figure) is a perspective view of the cover, another view (labelled (b) in each Figure) is a plan view of the cover, and another view (labelled (c) in each Figure) is a view of a -9 -section of the cover along the line A-A, as shown in the plan view. All dimensions shown are in millimetres (mm).

In Figure 4, the total diameter is 208 mm, the flat top diameter is 40 mm, the depth is 19 mm, and the aperture width ranges from a minimum of 37 mm to a maximum of 52 mm. This embodiment of the cover is for used for chainrings having a size of 54 teeth. This embodiment might be used on track bikes and time trial (TT) bikes.

In Figure 5, the total diameter is 192 mm, the flat top diameter is 98 mm, the depth is 23 mm, and the aperture width ranges from a minimum of 37 mm to a maximum of 52 mm. In Figure 6, the total diameter is also 192 mm, and the aperture width also ranges from a minimum of 37 mm to a maximum of 52 mm. However, in Figure 6 the flat top diameter is mm, and the depth is 19 mm, so in this embodiment the domed portion is smaller and shallower than in the embodiment of Figure 5. The embodiments of the cover shown in Figures 5 and 6 are used for chainrings having a size of 53 teeth and might be used on Shimarno cranks.

In Figure 7, the total diameter is 186 mm, and the depth is 19 mm. The aperture width ranges from a minimum of 37 mm to a maximum of 52 mm.

In Figure 8, the total diameter is 184 mm, the flat top diameter is 98 mm, the depth is 23 mm, and the aperture width ranges from a minimum of 37 mm to a maximum of 52 mm.

In Figure 9, the total diameter is 182 mm, the depth is 23 mm, and the aperture width ranges 20 from a minimum of 37 mm to a maximum of 52 mm. This embodiment of the cover can be used for chainrings having a size of 50 to 53 teeth.

The embodiments having a larger depth (e.g., 23 mm, as in Figures 5, 8 and 9) are used for crankarms that sit further from the face of the chainring, or to provide space to accommodate a power meter which may be attached on the crankarm where the crankarm joins to the chainring.

In other embodiments not shown in the Figures, the cover 100 may have the following dimensions: * A total diameter of 176 mm, which can be used with chainrings with a size of 50 to 52 teeth and might be used on Shimarno crankarms * A total diameter of 204 mm, which can be used with chainrings with a size of 54 teeth, and optionally with a depth of 23 mm or more to accommodate a power meter on the face of the crankarm -10 -Although the embodiments described above all have crankarm apertures with a width of 37 mm to 52 mm, in other examples the cover may comprise a crankarm aperture of a different size. For example, any of the covers described above may be provided in two variants: one with a crankarm aperture with a width of 40mm and another with a crankarm aperture with a width of 50mm. These various embodiments ensure that the cover can accommodate crankarms with a variety of widths, while minimising the gap between the crankarm and the cover when a crankarm is inserted through the aperture in use.

In all embodiments, the extent of the planar outer portion may be adjusted to suit the chainring. Preferably, the cover is sized to extend to the edge of the chainring (in order to improve aerodynamic performance over the entire area of a chainring), while at the same time minimising the size of the domed portion (to reduce drag). This is achieved by providing an embodiment of the cover 100 with a domed inner portion 102 and aperture 106 just large enough to accommodate a crankarm, and with a planar outer portion 104 that extends to the edge of the chainring. In some embodiments, the planar outer portion extends approximately 8 mm from the domed portion. In other embodiments, the planar outer portion extends approximately 14 mm from the domed portion.

The above dimensions for the Bicycle Aerodynamic chainring/crankarm cover are summarised in the following table.

Table of Dimensions

Embodiment Overall Diameter Flat Top Diameter Depth Aperture width V1 (Figure 4) a 208 40 19 37 (or 40) b 52 (or 50) V2 (Figure 5) a 192 98 23 37 (or 40) b 52 (or 50) V3 (Figure 6) a 192 40 19 37 (or 40) b 52 (or 50) V4 (Figure 7) a 186 19 37 (or 40) b 52 (or 50) V5 (Figure 8) a 184 98 23 37 (or 40) b 52 (or 50) V6 (Figure 9) a 182 - 23 37 (or 40) b 52 (or 50) The inventors have found that these sizes permit the cover to be fitted to a wide range of chainsets.

Manufacturing method Below is a process for manufacture of the aerodynamic chainring/crankarm cover 100. This process uses resin infusion.

A composite or aluminium mould is required.

Firstly, layers of dry carbon fibre and/or glass cloth are laid into the mould.

Next the mould is vacuum bagged to seal the cloth in.

Next an exothermic curing mixed polymer resin, preferably epoxy, is introduced to the vacuum bag through an inlet port and associated hose, clamp and flow media.

Next the part is allowed to cure under ambient conditions (room temperature) until solidified.

Next the part is cured at a temperature of -50 degrees Celsius for 6 hours.

Next the part is demoulded and trimmed to the size show in the dimensions section above.

It will be understood that the invention has been described above purely by way of example, and modifications of detail can be made within the scope of the claims.

Each feature disclosed in the description, and (where appropriate) the claims and drawings may be provided independently or in any appropriate combination.

Reference numerals appearing in the claims are by way of illustration only and shall have no limiting effect on the scope of the claims.

Claims

-12 -Claims 1 A bicycle chainring/crankarm fairing comprising of a single skin composite fairing incorporating an inner domed portion and an outer planar portion, wherein: at least the outer planar portion is used to secure the fairing to the chainring; and at least one area is cut out as an aperture for the crank arm.
2. A fairing according to Claim 1, comprising means for fastening the fairing to a bicycle chainring.
3. A fairing according to Claim 2, wherein the means for fastening is affixed to a chainring side of the fairing.
4 A bicycle chainset fairing comprising: an inner domed portion; an outer planar portion; at least one aperture for a crankarm of the bicycle chainset; and means for fastening the fairing to a chainring of a bicycle chainset, wherein: the means for fastening is affixed to a chainring side of the fairing; and the means for fastening is arranged to secure the fairing to the chainring by the outer planar portion.
5. A fairing according to Claim 4, wherein the inner domed portion and the outer planar portion are comprised of a single skin composite.
6. A fairing according to any of Claims 3 to 5, wherein the means for fastening is affixed to the outer planar portion on the chainring side of the fairing.
7 A fairing according to any of Claims 3 to 6, wherein the fairing comprises a recess, preferably an annular recess, on the chainring side of the fairing, preferably on the chainring side of the outer planar portion, arranged to accommodate the means for fastening the fairing to a chainring.
8. A fairing according to any of Claims 2 to 7, wherein the means for fastening is double-sided adhesive tape.
9. A fairing according to any preceding claim, wherein the inner domed portion comprises a flat top.
10. A fairing according to Claim 9, wherein the domed portion comprises a sloped part between the flat top of the domed portion and the outer planar portion.
11. A fairing according to Claim 10, wherein the gradient of the sloped part of the domed portion is shallower opposite the aperture than adjacent the aperture.
12. A fairing according to Claims 10 or 11, wherein the sloped part comprises a formation adjacent the aperture, the formation comprising at least one channel arranged to guide airflow around the domed portion.
13. A fairing according to Claim 12, wherein the formation comprises at least one channel on either side of the aperture.
14. A fairing according to Claim 12 or 13, wherein the at least one channel is arranged between an upper lip and a lower lip of the formation.
15. A fairing according to any preceding claim, wherein the domed portion comprises a hollow interior to accommodate a bicycle crankarm.
16. A fairing according to any preceding claim, wherein the aperture is formed as a cut out from the domed portion.
17. A fairing according to any preceding claim, wherein the outer planar portion provides a flange for fastening the fairing to a bicycle chainring.
18. A fairing according to Claim 17, wherein the flange locates onto the geometry of the chainring.
19. A bicycle comprising a fairing according to any preceding claim, the fairing being secured to a chainring of the bicycle using double-sided adhesive tape.
20. A kit of parts comprising: a bicycle chainring/crankarm fairing; and a length of self-adhesive tape.
-14 - 21. A kit of part according to Claim 20, wherein the fairing is a fairing according to any of Claims 1 to 19.
22 A method of manufacturing a bicycle chainring/crankarm fairing, the method comprising: laying dry carbon fibre layers and/or glass cloth layers into a composite or aluminium mould; introducing an exothermic curing polymer resin, preferably epoxy resin, to the layers; curing the layers until solidified; and demoulding the solidified layers and trimming to required dimensions.
23. A method according to Claim 22, comprising vacuum bagging the mould before introducing the resin, preferably wherein the resin is introduced to the vacuum bag through an inlet port and associated hose, clamp and flow media.
24. A method according to Claim 22 or 23, wherein the curing comprises curing under ambient conditions, preferably room temperature, until solidified.
25. A method according to any of Claims 22 to 24, wherein the curing further comprises curing at a temperature of approximately 50 degrees Celsius for approximately 6 hours.