Bicycle frame, rod assembly and method of assembly

Abstract

A bicycle frame for a bicycle, comprising a stem assembly and a top tube (22) wherein the stem assembly comprises: a handlebar portion (14); a handlebar bar (16) attached or attachable to the handlebar portion (14) and attached or attachable to a steering tube (27) extendable through a head tube portion (18) of the bicycle frame; the bicycle frame further comprises an attachment mechanism for securing the steering tube (27) to the handlebar bar (16), where the attachment mechanism comprises a cover member (50) for at least a portion of the attachment mechanism, the cover member defining a portion of a continuous outer surface of the bicycle frame, a portion of the continuous outer surface is defined by and extends between a handlebar (16) and a top tube (22) of the bicycle frame.

Description

Technical Field

[0001] The preferred embodiment relates to a bicycle, and more particularly to a bicycle frame. The solution of the preferred embodiment relates to a stem assembly of a bicycle frame and a method of assembling the stem assembly of the bicycle frame, the stem assembly for a bicycle handlebar to be mounted thereon. Background Art

[0002] In bicycle components, an adjusting device for adjusting the height of a stem assembly can be provided at the front portion of a bicycle to allow cyclists of different heights or body types to use the bicycle. The stem assembly supports the handlebar of the bicycle, and depending on the desired overall frame size, the adjusting device allows the use of a relatively taller or shorter stem assembly. The stem assembly generally includes a main stem, which may include several components, and the lower end of the main stem is connected to the front fork of the bicycle and the upper end is connected to the handlebar. The number and relative height of the stem components can be selected to meet the requirements of the overall frame size.

[0003] It has been well known that the stem is attached to the bicycle handlebar by a bolt arrangement for manufacturing. However, such an attachment device is vulnerable to variations in the assembly method, and thus, if the bolt is not fully or properly tightened, the handlebar may fall off or be mounted in a crooked fashion, which can be dangerous. Over-tightening the bolt can also cause the stem to break. Such a bolt arrangement of this nature is also unsightly and detracts from the aesthetic quality of the bicycle and the desirability of the bicycle to consumers.

[0004] Therefore, there is a need to provide an attachment device for the stem assembly and the handlebar that allows for consistent assembly and adjustment of the height of the handlebar to provide different bicycle frame sizes. Summary of the Invention

[0005] In one aspect, there is provided a bicycle frame for a bicycle, including a stem assembly and a top tube, wherein the stem assembly includes a handlebar portion and a handlebar stem, the handlebar stem being attached or attachable to the handlebar portion and attached or attachable to a steering tube, the steering tube being capable of extending through a head tube portion of the bicycle frame. The bicycle frame includes an attachment mechanism for fixing the steering tube to the handlebar stem, wherein the attachment mechanism includes a covering member for at least a part of the attachment mechanism, the covering member defining a part of a continuous outer surface of the bicycle frame, the part of the continuous outer surface being defined by the handlebar stem and the top tube of the bicycle frame and extending between the handlebar stem and the top tube.

[0006] The stem assembly may include an adjusting device in the form of a spacer member that can be positioned between the head tube and the handlebar stem to provide a way to select different heights of the handlebar portion relative to the frame for use.

[0007] Although an attachment mechanism is required between the handlebar portion and the steering tube and an interaction with a spacer member, the covering member is advantageous because it allows a streamlined and aerodynamic continuous outer surface of the bicycle frame.

[0008] According to another aspect of the present invention, there is provided a covering member for a bicycle frame of a bicycle, the bicycle frame including an attachment mechanism for fixing a steering tube of the bicycle to a handlebar stem of the bicycle, wherein, in use, the covering member defines a part of the continuous outer surface of the bicycle frame along an upper frame surface of the bicycle frame. The covering member is located between the handlebar stem and the top tube of the bicycle frame.

[0009] In another aspect, there is provided a bicycle including a bicycle frame according to any of the previous aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] For a better understanding of the preferred embodiments, reference will now be made to the accompanying drawings, which illustrate preferred non - limiting embodiments by way of example only, in which:

[0011] Figure 1 is a perspective view of a rod system of a bicycle, which forms part of a bicycle frame according to an embodiment of the present invention;

[0012] Figure 2 is Figure 1 an exploded view of a part of the rod system in [reference numeral], showing details of a spacer member of the rod system;

[0013] Figure 3 is a perspective view seen from the underside to show in more detail the Figure 1 handlebar stem of the rod system in [reference numeral];

[0014] Figure 4 is Figure 3 a cross - sectional view of the handlebar stem in [reference numeral], showing the relative dimensions and positions with respect to the steering tube of the bicycle when assembled;

[0015] Figure 5 is Figure 1 a side view of a part of the rod system in [reference numeral], showing in more detail the position of a cover of the rod system, but a part of the cover itself is cut away;

[0016] Figure 6 is a perspective view of the handlebar stem seen from the rear side;

[0017] Figure 7 is Figure 6 a perspective view of the covering member in [reference numeral] seen from the front side;

[0018] Figure 8Isometric view of a bracket forming part of a stem system;

[0019] Figure 9 Is Figure 8 Isometric view of an alternative bracket to the bracket shown;

[0020] Figure 10 Is Figure 8 And Figure 9 Isometric view of another alternative bracket to the bracket shown;

[0021] Figure 11 Is an exploded view of a cover member and a portion of the main stem of the handlebar together with screws for attachment;

[0022] Figure 12 Is with Figure 2 Isometric view of the head tube of a stem system with an alternative spacer member to the spacer member shown in

[0023] Figure 13 To show the position when the spacer member is in situ on the head tube of a bicycle; and Detailed Description

[0024] For the purposes of the following description, references to "front" and "rear" of the bicycle are intended as directional references relative to the normal direction of travel of the bicycle in use.

[0025] Referring to Figures 1 to 5 , the stem assembly (generally designated 10) of the bicycle includes a handlebar portion 14, a handlebar stem 16, a head tube portion 18, and forks 20, with the handlebar portion 14 mounted on the handlebar stem 16. The head tube portion 18 defines an upper peripheral surface that defines a ledge 18a. The top tube 22 and the down tube 24 of the bicycle frame extend rearwardly and downwardly respectively from the head tube portion 18 of the stem system. The top tube 22 extends rearwardly from the base of the handlebar stem 16. The steering tube 27 extends through the head tube portion 18, projects through an opening adjacent to the ledge 18a at the top of the head tube portion 18, and extends from the forks 20 to the lower end of the handlebar stem 16. In this example, the handlebar stem 16 is a V-shaped portion that supports the handlebar portion 14. A head tube bearing 26 at the upper end of the head tube portion 18 supports the steering tube 27 for rotation relative to the head tube portion 18. As best seen in Figure 3 , the handlebar stem 16 (viewed from the underside) is a generally hollow tube or casing that has an internal structure in the form of a stem cylinder 17 that receives the upper portion of the steering tube 27 when the stem system is assembled.

[0026] The stem assembly 10 includes a stem attachment system for connecting the handlebar stem 16 to the fork 20 via the steering tube 27. The stem attachment system 12 includes a head tube bearing 26, a compression ring 28, a spacer member 30, and an extension 31 of the stem cylinder 17 of the handlebar stem 16. A screw ( Figures 1 to 5 not shown in the figure) is introduced into an opening 21 in the handlebar stem 16 to allow the handlebar stem 16 to be tightened to the steering tube 27. The stem attachment system further includes a cover member 50, which will be described in further detail below.

[0027] As Figure 2 and Figure 3 most clearly shown in the figure, the extension 31 (also referred to as a nut clamp) projects from the rear side of the cylinder 17 of the handlebar stem 16 and is received within a nut support bracket 32 ( Figure 1 not shown in the figure), which forms part of the stem attachment system 12. The nut support bracket 32 is in the form of a U-shape, defining an internal volume 34 between its left and right sides to receive the extension 31.

[0028] The extension 31 takes the form of two rearwardly extending flanges separated by a gap. Each flange of the extension 31 is provided with two through holes 36 (shown and labeled on only one flange), which are aligned with the through holes on the other flange. Then when the extension 31 is received within the internal volume 34 of the bracket 32, each hole 36 is aligned with a corresponding one of a pair of holes 38 on each side of the nut support bracket 32. The aligned pairs of holes 36 and 38 receive side screws (not shown), which allow the nut support bracket 32 to be fixed to the stem cylinder 17. The nut support bracket 32 supports a captive nut 42 for receiving an attachment screw 44, which allows the cover member 50 to be affixed to the bracket 32.

[0029] The cover member 50 is provided with screw mounting features 70 on its rearward facing side, which are recessed into the rear wall. The cover member 50 can be made of carbon fiber. The screw mounting features receive the attachment screw 44, which then cooperates with the captive nut 42 on the nut support bracket 32 to hold the cover member 50 in place on the stem attachment assembly. The cover member 50 provides a cover for the stem attachment system in the intersection or engagement area between the handlebar stem 16 and the nut support bracket 32.

[0030] As in Figure 1As best seen in , when assembling the stem system, the spacer member 30 of the stem attachment system abuts against the lower end of the handlebar stem 16. The spacer member 30 is typically made of plastic, and its main purpose is to provide the required separation distance between the head tube portion 18 and the handlebar stem 16 such that the handlebar portion 14 attached to the handlebar stem 16 assumes the correct vertical position relative to the head tube portion 18.

[0031] The spacer member 30 is located on top of the compression ring 28, which in turn rests on the head tube bearing 26. When all parts are fixed together using the compression screw, the compression screw, the tether nut 42, and the compression ring 28 load the head tube bearing 26 in a compressive manner. When assembling and in the case of screwing these parts together by introducing the screw into the opening 21, the handlebar stem 16 presses against the spacer member 30, which in turn presses against the head tube bearing 26 and the compression ring 28 and onto the head tube portion 18, such that the spacer member 30 is "trapped" in place within the attachment assembly, between the handlebar portion 16 and the head tube portion 18.

[0032] As best seen in Figure 2 As best seen in , the spacer member 30 includes an outer peripheral edge 60 that defines the height of the spacer member. A main opening 62 in the spacer member 60 allows the steering tube 27 to pass through and be received therein such that the lower surface of the spacer member 30 rests on the platform 18a of the head tube portion 18. A cutout or recess 64 is provided in the body of the spacer member 30 to remove some plastic material, substantially for the purpose of reducing the weight of the component, but without affecting the overall height of the component and thus without affecting the spacing between the head tube portion 18 and the handlebar stem 16. A main recess of the spacer member 30 is provided with a pin 66 that faces the rear of the spacer member 30, and this pin serves as an alignment feature, as will be described in further detail below. The alignment pin 66 mates with an opening 69 in the floor of the cover member 50.

[0033] Figure 4 Shows how the steering tube 27 is received within the cylinder 17 of the handlebar stem 16, where there is a clearance between the inner surface of the cylinder 17 and the outer surface of the steering tube 27, but a relatively smaller clearance G1 between the sides of the cylinder 17 compared to the clearance G2 at the front of the steering tube 27. When the side screws are inserted through the paired holes 36, 38, the compression of the flange of the extension 31 serves to compress the cylinder 17 around the steering tube 27.

[0034] In Figure 5 the side view of , the position of the spacer member 30 can be seen. Generally, the edge of the spacer member 30 can have a height of approximately 20 mm, but can vary depending on the overall size and nature of the bicycle frame. From Figure 5It can be understood that the main opening of the spacer member 30 for receiving the steering tube 27 is positioned towards the front of the spacer member 30 and thus towards the front of the bicycle, while the extension 31 and the nut support bracket 32 are vertically aligned above the rear of the spacer member 30. The top tube 22 has a forward-facing inclined surface against which the rear side of the spacer member 30 abuts (identified as surface 30a in Figure 5 ).

[0035] A covering member 50 is provided to improve the aesthetic appearance of the stem attachment system, to protect the stem attachment portion in the intersection area between the handlebar stem 16 and the steering tube 27, and to contribute to the aerodynamic benefits of the bicycle. As best seen in Figure 2 , the covering member 50 takes the form of a housing and is a three-walled component that, together with the top and bottom plates of the covering member 50, defines an internal volume with an open front side. The three walls of the covering member 50 include a left side wall and a right side wall and a rear-facing wall 50a that, when in place, abuts the inclined front surface 30a of the top tube 22.

[0036] At the front of the component, the open side of the covering member allows the extension 31 of the head tube portion 18, together with the nut support bracket 32, to be received into the internal volume of the covering member 50.

[0037] As best seen in Figure 5 , when the covering member 50 is in place on the stem attachment assembly, the bottom plate of the covering member 50 abuts the upper surface of the spacer member 30. Thus, the continuous outer surface on the upper side of the frame is defined by the upper surfaces of the handlebar stem 16 and the top tube 22 together with the upper surface of the covering member 50. This continuous outer surface provides advantageous aerodynamic characteristics for the bicycle. It should be understood that any discontinuity along the surface of the frame may adversely affect the aerodynamic performance of the bicycle. Thus, the covering member 50 enables a smooth and continuous transition between the handlebar stem 16 and the top tube 22 to achieve aerodynamic performance while allowing height adjustment of the stem assembly by using the spacer member 30.

[0038] It should be understood that a covering member 50 of a unique size is required for each handlebar height, since a spacer member 30 of a different height is required for each handlebar height.

[0039] From Figure 5 the construction in and the height of the spacer member 30 in this embodiment, it will be understood that the screw mounting features 70, 44 for the covering member 50 are not always well positioned to receive screws. In such cases, alternative attachment means may be preferred.

[0040] During the assembly of the rod attachment assembly, the cover member 50 is brought into position, and the opening 69 in the base plate of the cover member 50 is located on the locating pin 66 of the spacer member 30. In this way, the cover member 50 can be correctly positioned on the spacer member 30 where it is located. In the case where the cover member 50 is fixed to the nut support bracket 32, and in the case where the nut support bracket 32 is fixed to the steering tube 27 via the extension 31, the cover member 50 is firmly assembled to the head tube assembly. When in position, the cover member 50 is arranged such that the rod attachment portion is protected by the cover member 50 on the rear side of the rod assembly, and such that the cover member 50 provides an aerodynamic surface at the intersection between the top tube 22 and the handlebar stem 16 on the rear side of the bicycle frame. In other words, the top surface of the cover member 50 provides a cover for the gap that inevitably occurs by itself when the handlebar stem 16 is spaced from the top tube 22. By providing the cover member 50, a neat and streamlined finish is achieved at the intersection between the top tube 22 and the handlebar stem 16, regardless of the spacing determined by the spacer member 30 between these two parts. The main screw is received through the opening 21 in the handlebar stem 16 to be received in the steering tube 27.

[0041] Figure 6 and Figure 7 illustrates different embodiments where there are improvements to the cover member 50 and the handlebar stem 16, where alternative positioning means are provided to enable the cover member 50 to be correctly positioned on the handlebar stem 16. Here, the positioning means takes the form of two screws 80 that are screwed into the forward-facing surface of the top plate of the cover member 50. These screws 80 engage with a corresponding pair of screw bosses 82 on the rear side of the handlebar stem 16. The attachment means for attaching the cover member 50 to the handlebar stem 16 is the same as previously described, where the U-shaped nut support bracket 32 is mounted to the cover member 50 via the tether nut 42 for receiving the screw 72 ( Figure 6 and Figure 7 the screw is not shown in).

[0042] The opening 69 in the base plate of the cover member 50 may be provided with additional positioning means that may be arranged to allow a single integral part to be manufactured for use with handlebar stems / spacer members having different positioning features.

[0043] Figures 8 to 10 Illustrates various different versions of the nut support brackets 32, 90, 92. Figure 8 Illustrates the nut support bracket 32 in the form of a U previously described. The rear side of the nut support bracket 32 is a flat plate that extends beyond the side boundaries of the bracket 32, as defined by the extension portion 32a of the plate. Figure 9The nut support bracket 90 is shown as an L-shaped part (instead of U-shaped) having two sides, one side for mounting a captive nut 42 for a screw 72 that is screwed into the rear-facing side of the cover member 50, and the (other) side for receiving two side screws (to be received through holes 38), which enables the nut support bracket 90 to be attached to the extension 31 of the rod cylinder 17. Similarly, the rear side of the nut support bracket 32 is a flat plate, but here has a single extension 90a that extends beyond the side boundary of the bracket. Figure 10 is another form of nut support bracket 92, where the bracket is a simplified L-shaped structure.

[0044] Figure 11 is an exploded view of an embodiment, where the internal positioning of the cylinder 17 within the handlebar stem 16 is shown in dashed lines. Side screws 100 for reception through holes 36 are shown here.

[0045] Figure 12 A further modification is shown, where the spacer member 30 has two positioning features 104 in the form of screw bosses on the rear of the edge 60. The recess 64 takes a shape and form that is slightly different from that shown in the previous embodiment. The compression ring 28 and the head tube bearing 26 are Figure 12 not visible.

[0046] Figure 13 is another embodiment, where the spacer member 30 has two screw receiving holes 106 that align with screw bosses 108 on the bottom plate of the cover member for receiving screws 110 from the underside of the spacer member 30. In fact, with respect to the position of the holes 106, Figure 13 the spacer member 30 in Figure 1 is very similar to the spacer member in

[0047] In Figure 13 a screw receiving hole 112 in the steering tube 27 is shown, which receives a main screw 114 provided through an opening 21 in the handlebar stem 16.

[0048] Handlebar drop ends of various different sizes can be incorporated into the intermediate V-shaped rod. In some examples, the handlebar drop ends are incorporated at the factory and cannot be disassembled.

[0049] In the illustrated embodiment, the handlebar stem 16 includes a horizontal crossbar, a V-riser, and an attachment portion of the rod-steering tube. In one embodiment, such features can define an integral part. In another embodiment, such features can include multiple parts.

[0050] It should be understood that various modifications can be made to the described embodiments without departing from the scope of the appended claims.

Claims

1. A bicycle frame for a bicycle, the bicycle frame comprising a stem assembly and a top tube (22), wherein the stem assembly comprises: a handlebar portion (14); a handlebar stem (16) attached or attachable to the handlebar portion (14); and attached or attachable to a steering tube (27) which is extendable through a head tube portion (18) of the bicycle frame; The bicycle frame further comprises an attachment mechanism for fixing the steering tube (27) to the handlebar stem (16), wherein the attachment mechanism comprises a covering member (50) for at least a part of the attachment mechanism, the covering member defining a part of a continuous outer surface of the bicycle frame, the part of the continuous outer surface being defined by the handlebar stem (16) and the top tube (22) of the bicycle frame and extending between the handlebar stem and the top tube.

2. The frame according to claim 1, wherein, the covering member (50) defines an internal volume for receiving a part (31) of the handlebar stem (16), for example, an inner cylinder (17) of the handlebar stem (16).

3. The frame according to claim 1 or claim 2, wherein, the covering member (50) comprises three side walls and an opening for receiving the part (31) of the handlebar stem (16), and a top plate defining the part of the continuous surface on its outer surface.

4. A bicycle comprising a stem assembly according to any one of claims 1 to 3.

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