The present invention relates to a bicycle wheel. The invention also relates to a spoke and a hub for a bicycle wheel. Finally, the invention also relates to a method for assembling a bicycle wheel.
For conventional wheels with straight-headed spokes, in the case of a violent impact against uneven or rough ground, the rim deforms elastically and the spokes lose their tension, displacing with respect to the hub and to the rim in the opposite direction to that of tensioning of the spoke. Therefore, it is possible that, following these displacements, the spokes might get stuck in the seats of the hub in an undesired position or even, in the case of seats open at the front end surface of the hub, that the spokes might come out from such seats. In both cases, there is a dangerous situation and a loss of functionality of the wheel. In particular, in the case in which the spoke gets stuck into the seat in an undesired position, the spoke has a useful length that is shorter than the distance between rim and hub; this means that, when the deformed rim goes back into the original configuration, the spoke is subjected to a traction tension that, if greater than the yield point of the spoke, causes it to break.
Accordingly, there remains a need for a wheel that can withstand violent impacts during travel without risking the spoke breaking or coming out from the seat of the hub.
The invention relates to a bicycle wheel comprising a hub adapted to rotate about a rotation axis, a rim, and a plurality of spokes extending between the hub and the rim, at least one of the spokes comprising an elongated body extending along a longitudinal axis and having a first end portion coupled with the hub and a second end portion coupled with the rim, wherein the first end portion of the spoke comprises an abutment surface in contact with a first stop surface of the hub in a tensioning condition of the spoke and a surface substantially opposite the abutment surface and not making contact with the hub, the wheel being characterized in that it comprises locking means of the spoke with respect to the hub adapted to limit a displacement of the abutment surface away from the first stop surface in a detensioning condition of the spoke.
Further characteristics and advantages of the present invention shall become clearer from the following detailed description of some preferred embodiments thereof, made with reference to the attached drawings. In these drawings:
In a preferred embodiment, the aforementioned locking means prevent a displacement of the abutment surface away from the first stop surface in a detensioning condition of the spoke.
Preferably, the aforementioned abutment surface is active, in a tensioning condition of the spoke with the wheel assembled, on the first stop surface to prevent the displacement of the spoke towards the rim.
In a first embodiment of the wheel of the present invention, at least some of the spokes extend from the hub towards the rim in respective planes that contain the rotation axis of the hub. In particular, in a preferred embodiment of the wheel of the present invention, all of the spokes of the wheel extend radially from the hub. In this case the locking means prevent a radial displacement of the spoke towards the center of the hub, i.e., in the opposite direction to the traction direction of the spoke in the tensioning condition of the spoke. However, it is not excluded the case in which just some of the spokes of the wheel extend radially as in, for example, the case of wheels in which the spokes are grouped together on the rim. In this case, the other spokes extend parallel to the radial spoke of the same group or they are inclined with respect to such a radial spoke.
In an alternative embodiment of the wheel of the present invention, at least some of the spokes extend from the hub towards the rim in respective planes that do not contain the rotation axis of the hub. In particular, an embodiment is foreseen in which all of the spokes of the wheel extend from the hub along a direction inclined by a predetermined angle with respect to the radial direction. In this case, the locking means prevent a displacement of the spoke with respect to the hub along such an inclined direction. However, it is not excluded the case in which just some of the spokes of the wheel extend according to such an inclined direction.
In general, the person skilled in the art will recognize that the locking means of the present invention can be used in any type of wheel and with any arrangement of the spokes.
In a particularly preferred embodiment of the wheel of the present invention, the locking means are defined on the elongated body of the spoke and cooperate with a second stop surface of the hub. In this case, preferably, the locking means are made in a single piece with the elongated body of the spoke. In this way the manufacturing costs of the wheel are reduced.
More preferably, the locking means are defined, in the elongated body of the spoke, in a locking portion adjacent to the first end portion of the spoke and such a first end portion of spoke is housed in a respective seat formed in the hub.
In the assembled wheel, the aforementioned locking portion can be arranged outside of the aforementioned seat, in which case the aforementioned second stop surface is an outer surface of the hub, or it can be at least partially housed in the aforementioned seat, in which case the aforementioned second stop surface is an inner surface of such a seat.
Irrespective of the specific position of the locking portion with respect to the hub in the configuration with the wheel assembled, the aforementioned locking means are preferably defined by at least one cross section of the aforementioned locking portion having, along at least one predetermined transversal direction, an extension greater than that of at least one cross section of the first end portion of spoke. The variation in cross section of the spoke between locking portion and first end portion of the spoke can in practice be made by simply providing, in the locking portion of the elongated body of the spoke, a conical side surface, or a surface inclined with respect to the longitudinal axis of the spoke, or a step.
Preferably, the aforementioned at least one cross section of the aforementioned locking portion has, along a direction perpendicular to the aforementioned predetermined transversal direction, an extension shorter than that of the aforementioned at least one cross section of the first end portion of spoke.
In a different embodiment of the spoke that can be used in the wheel of the present invention, the aforementioned locking means are defined by an element that projects from a side of the elongated body of the spoke.
The seat of the hub and the spoke are preferably shaped so that by rotating the spoke with respect to the seat, in the assembly step of the wheel, about a rotation axis passing through a free end of the first end portion of the spoke, the locking means abut on the aforementioned second stop surface.
What is described above is applicable both to a straight-headed spoke, i.e., a spoke in which the aforementioned first end portion extends entirely along the longitudinal axis of the spoke, and to a curved-headed spoke, i.e., a spoke in which the aforementioned first end portion extends along a direction inclined with respect to the longitudinal axis of the spoke. Both in the case of a straight-headed spoke or of a curved-headed spoke, the aforementioned rotation preferably occurs in a plane substantially perpendicular to a median plane of the wheel, however, it is also contemplated the possibility of a rotation in a different plane, for example, in a plane inclined or substantially parallel to such a median plane of the wheel.
From what has been stated above it can be seen how the locking means do not block the aforementioned rotation of the spoke with respect to the hub, which is an essential movement in the assembly step of the wheel. Such a rotation occurs in a plane that intercepts the rim and terminates when the end of the spoke for coupling with the rim is at the rim. Since in the configuration with the wheel assembled the end for coupling with the rim is locked on the rim, any rotation of the spoke with respect to the hub is technically impossible, therefore the spoke cannot become disengaged from the hub.
In a preferred embodiment of the wheel of the present invention, the hub comprises an annular central portion and a plurality of spoke attachment portions projecting radially from the aforementioned central portion and each seat is formed on a respective spoke attachment portion of the hub.
Preferably, each seat comprises a first opening for the insertion of the first end portion of the spoke in the assembly step of the wheel and a second opening for the passage of the spoke from the hub to the rim in the configuration with the wheel assembled, the first and second openings being in communication with each other through a slit having at least one dimension smaller than that of the first opening.
More preferably, the first opening and the slit are formed on a front end surface of each spoke attachment portion and each seat for housing spokes comprises, in an axially inner position with respect to the slit and between the first opening and the second opening, a housing cavity of the first end portion of spoke having a first inner side surface portion adapted to act in abutment on the first end portion of spoke to prevent the displacement of the spoke along a direction parallel to the rotation axis of the hub and a second inner side surface portion adapted to act in abutment on the first end portion of the spoke to prevent the displacement of the spoke towards the rim. In such a case a reasonable limited displacement is such as not to allow the end portion to come over the inner side surface portion of the seat.
Even more preferably, the aforementioned cavity comprises a first cavity portion adjacent to the first opening and a second cavity portion having a dimension smaller than that of the first cavity portion and defined on the opposite side to the first opening with respect to the first cavity portion. In this case, the aforementioned first inner side surface portion is defined in the first cavity portion and the aforementioned second inner side surface portion is defined at the interface between the first cavity portion and the second cavity portion.
The aforementioned cavity extends radially in the respective spoke attachment portion preferably along a direction inclined by a predetermined angle with respect to the rotation axis of the hub, such an angle being the camber angle of the wheel.
In an alternative embodiment of the wheel of the present invention, the locking means are not defined in the elongated body of the spoke but are associated with the body of the hub and cooperate with a free end surface of the first end portion of the spoke. Such an embodiment is particularly advantageous since it allows the technical advantages of the present invention to be achieved with the most common types of spokes on the market, without needing to modify such spokes. The spoke can, for example, be a common straight-headed cylindrical spoke.
Preferably, the locking means in this case comprise a retaining ring housed in a throat formed on a front end surface of the hub and projecting from the throat so as to define an abutment surface for the free end surface of the first end portion of the spoke. Such a preferred embodiment of the wheel of the present invention can easily be obtained by making slight modifications to the most common types of hubs on the market.
In a second aspect thereof, the invention relates to a spoke for a bicycle wheel, comprising an elongated body extending along a longitudinal axis and having a first end portion for coupling with a bicycle hub and a second end portion for coupling with a bicycle rim, wherein the first end portion of the spoke comprises an abutment surface adapted to act in contact with a stop surface of the hub in a tensioning condition of the spoke with the wheel assembled, the spoke being characterized in that it comprises locking means of the spoke with respect to the hub adapted to limit a displacement of the aforementioned abutment surface away from the aforementioned stop surface in a detensioning condition of the spoke with the wheel assembled.
Preferably said locking means prevent a displacement of the aforementioned abutment surface away from the aforementioned stop surface in a detensioning condition of the spoke with the wheel assembled.
Preferably, the aforementioned spoke has, individually or in combination, all of the structural and functional features discussed above with reference to the spokes of the wheel of the present invention.
In particular, preferably, the aforementioned abutment surface is adapted to act, in a tensioning condition of the spoke with the wheel assembled, against the aforementioned stop surface of the hub to prevent the displacement of the spoke towards the rim of the wheel.
Preferably, the locking means are defined on a side surface of a locking portion of the elongated body of the spoke, such a locking portion being adjacent to the first end portion of the spoke.
In particular, the locking means are preferably defined by at least one cross section of the aforementioned locking portion having, along at least one predetermined transversal direction, an extension greater than that of at least one cross section of the first end portion of the spoke.
Even more preferably, the aforementioned at least one cross section of the aforementioned locking portion has an extension, along a direction perpendicular to the aforementioned predetermined transversal direction, shorter than that of the aforementioned at least one cross section of the first end portion of the spoke.
Alternatively, the locking means can be defined by an element projecting from a side of the elongated body of the spoke.
As already stated above, the spoke can be a straight-headed spoke, in which case the aforementioned first end portion extends along the longitudinal axis of the spoke, or a curved-headed spoke, in which case the aforementioned first end portion extends along a direction inclined with respect to the longitudinal axis of the spoke.
In a third aspect thereof, the invention relates to a hub for a bicycle wheel, comprising a body having at least one seat for housing a respective end portion of spoke comprising a first stop surface adapted to act in contact with an abutment surface of a respective end portion of spoke in a tensioning condition of the spoke with the wheel assembled, wherein, on the opposite side to the first stop surface, the hub body is not intended to come into contact with the end portion of spoke, the hub being characterized in that it comprises locking means of the spoke with respect to the hub adapted to limit a displacement of the aforementioned abutment surface away from the aforementioned stop surface in a detensioning condition of the spoke with the wheel assembled.
Preferably, said locking means prevent a displacement of the aforementioned abutment surface away from the aforementioned stop surface in a detensioning condition of the spoke with the wheel assembled.
Preferably, the aforementioned hub has, individually or in combination, all of the structural and functional features discussed above with reference to the hub of the wheel of the present invention.
In particular, preferably, the aforementioned first stop surface is adapted to act, in a tensioning condition of the spoke with the wheel assembled, against the abutment surface of the spoke to prevent the displacement of the spoke in the direction of the rim of the wheel.
Preferably, the locking means are positioned in the hub body in a radially outer position with respect to the aforementioned first stop surface.
In a first embodiment of the hub, the locking means are defined on an inner side surface of each seat.
In this case, preferably, the side surface defines, in at least one first cross section of the seat, an area having, along at least one predetermined transversal direction, an extension greater than that of an area defined by the same surface in a second cross section closer to the stop surface.
More preferably, the area defined by the side surface in the at least one first cross section of the seat has an extension, along a direction perpendicular to the aforementioned predetermined transversal direction, shorter than that of the aforementioned at least one adjacent second cross section of the seat.
In a preferred embodiment of the hub, the hub body is substantially tubular and comprises an annular central portion and, at least one of the opposite end portions thereof, a plurality of spoke attachment portions projecting radially from the aforementioned central portion, wherein the at least one seat is formed on a spoke attachment portion.
In a specific embodiment of the wheel of the present invention, each seat is formed on a respective spoke attachment portion. Preferably, the wheel is in this case a front wheel for a bicycle with V-brakes.
In a different embodiment of the wheel of the present invention, at least one spoke attachment portion comprises at least two seats. Such seats are preferably formed on opposite sides of the spoke attachment portion. Preferably, the wheel is in this case a rear wheel for a bicycle with V-brakes, and in this case the spoke attachment portions with two seats are provided on the side of the hub in which the sprocket assembly is mounted, or a front or rear wheel for a bicycle with disc brakes, and in this case the spoke attachment portions with two seats are provided on both sides of the hub, with twice the number of spokes on the side of the hub in which the disc, in the case of the front wheel, or the sprocket assembly, in the case of the rear wheel, is mounted.
Preferably, each seat comprises a first opening for the insertion of the end portion of the spoke in the assembly step of the wheel and a second opening for the passage of the spoke from the hub to the rim in the configuration with the wheel assembled, the first and second openings being in communication with each other through a slit having at least one dimension smaller than that of the first opening.
More preferably, the first opening and the slit are formed on a front end surface of the spoke attachment portion and the slit communicates with a housing cavity of the first end portion of spoke formed in the spoke attachment portion between the first opening and the second opening, the housing cavity of the end portion of spoke having a first inner side surface portion active in abutment on the end portion of spoke to prevent the displacement of the spoke along a direction parallel to the rotation axis of the hub and a second inner side surface portion active in abutment on the end portion of the spoke to prevent the displacement of the spoke towards the rim.
Even more preferably, the aforementioned cavity comprises a first cavity portion adjacent to the first opening and a second cavity portion having a size smaller than that of the first cavity portion and defined on the opposite side to the first opening with respect to the first cavity portion. In this case, the aforementioned first inner side surface portion is defined in the first cavity portion and the second inner side surface portion is defined at the interface between the first cavity portion and the second cavity portion.
The aforementioned cavity extends radially in the respective spoke attachment portion preferably along a direction inclined by a predetermined angle with respect to the rotation axis of the hub, such an angle being the camber angle of the wheel.
In an alternative embodiment of the hub, the locking means are associated with the hub body and preferably comprise a retaining ring housed in a throat formed on a front end surface of the substantially tubular hub body projecting from the throat so as to define an abutment surface for a free end surface of the end portion of the spoke.
In a fourth aspect thereof, the invention relates to a method for assembling a bicycle wheel, comprising the steps of:
wherein the step of associating a first free end portion of each spoke with a hub comprises the steps of:
The aforementioned method can be carried out for the assembly of the wheel of the present invention.
The aforementioned rotation preferably takes place in a plane substantially perpendicular to a median plane of the wheel, for example to mount straight-headed spokes in seats formed on the front end surface of the hub or curved-headed spokes in seats defined by through holes having an opening on the front end surface of the hub.
In a specific embodiment for the assembly of a wheel having, on a free end portion of the hub, a number of spokes which is twice that of the opposite free end portion of the hub, the step of associating a first free end portion of the spoke with the hub comprises the steps of:
Advantageously, in this way it is possible to mount all of the spokes on the hub through the aforementioned rotation.
In
The wheel 1 comprises a rim 2, a hub 3, and a plurality of spokes 5, each of which has an end portion 10 for coupling with the hub 3 and an end portion 15 for coupling with the rim 2.
The spokes 5 extend from the hub 3 towards the rim 2 in respective planes that contain the rotation axis M of the hub 3 and, in particular, along radial directions with respect to the hub 3.
The coupling between spoke 5 and rim 2 is carried out according to methods known in the field, for example through a nipple 20 (
The coupling area between the hub 3 and the spokes 5 is illustrated in detail in
The spokes 5 of the wheel of
In particular, these are straight-headed spokes, i.e., spokes in which the head 30 extends coaxially to the elongated body 6 of the spoke along the longitudinal axis X.
The head 30 comprises an abutment surface 31 that, in the tensioning condition of the spoke, is in contact with an inner surface 53 (
The head 30 also comprises a surface 32 opposite the abutment surface 31; such a surface does not make contact with any surface of the hub.
The head 30 is preferably conical and is joined to the central portion 35 through a neck 40. As can clearly be seen in
In the embodiment described above the neck 40 has a cross section equal to the cross section 41 at each point and it is possible to identify a theoretical line of discontinuity 48 (
Each spoke 5 also comprises a theoretical demarcation line 49 between the neck 40 and the head 30.
In
With reference now again to
The hole 62 is formed in a radially inner position with respect to the slit 52 and communicates, through the slit 52, with an opening 63 formed on the radially outer surface 51 of the spoke attachment portion 60 and adapted to allow the passage of the spoke 5 from the hub 3 to the rim 2 in the configuration with the wheel assembled. The seats 25 are thus open towards the outside in the radial direction of the hub and in the direction of the axis M towards the front end surface of the hub 3.
In the assembly step of the wheel 1, the seats 25 receive the spokes 5 through the holes 62 and slits 52, as shall be better explained later. In particular, the hole 62 is of sufficient size for the passage of the head 30, whereas the slit 52 is of sufficient size for the passage of the neck 40 but not of the head 30.
Each seat 25 comprises a larger cavity 65 at least partially defined by the inner surface 53 matching the head 30 of the spoke 5 and of sufficient size to receive such a head 30, and a smaller cavity 68 having a smaller section than the cavity 65 and of sufficient size to receive the neck 40 of the spoke 5. The larger cavity 65 is thus placed between the hole 62 and the smaller cavity 68 along the radial direction of the hub 3.
Both of the cavities 65 and 68 are axially (with reference to the rotation axis M of the hub) behind the slit 52, so that when a spoke 5 is inserted into the seat 25 and is subjected to traction, a portion of side surface 70 (
The circumferential size of the seat 25 in the area intended to house the neck 40 is slightly greater than that of the neck 40 to make it easier to position the end portion 10 of the spoke 5 in the seat 25, as shall be made clearer hereafter.
Preferably, the smaller cavity 68 is an extension of the slit 52 for which reason the neck 40, which has a rectangular section, is unable to rotate about its own axis X.
The cavities 65 and 68 of each seat 25 extend according to a radial axis Y that in a mounted configuration (
During the assembly step of the wheel 1, illustrated in
Advantageously, the fact that the circumferential size of the seat 25 in the area intended to house the neck 40 is slightly greater than that of the neck 40 allows the insertion of the end portion 10 of the spoke 5 in the seat 25 to be easy even when the end portion 10 is inclined with respect to the median plane of the bicycle by a smaller angle, thus reducing the angle to be traveled during the rotation to complete the positioning of the end portion 10 in the seat 25. In this case, indeed, the neck 40 can easily partially penetrate into the slit 52.
The inner surface of the seat 25 at the smaller cavity 68 and of the stop surface 53 in the interface area between larger cavity 65 and smaller cavity 68 has a shape matching that of the side surface of the neck 40 and of the abutment surface 31 of the spoke 5. In particular, the inner side surface of the seat 25 defines, in at least one first cross section of the seat 25 of the smaller cavity 68, an area having, along at least one predetermined transversal direction, an extension greater than that of an area defined by the same side surface in a second cross section closer to the hole 62 and, along a direction perpendicular to the aforementioned predetermined transversal direction, an extension shorter than that of the aforementioned at least one second cross section.
Due to the relative size of the spoke 6 and of the seat 25, the aforementioned rotation is the only assembly movement that the spoke 6 is allowed to make, and it occurs about a center of rotation A (
What has been described above is just an example embodiment of the invention, many different embodiments being indeed possible. Hereafter, only some of these different embodiments are described, in which elements corresponding to those described above have been indicated with the same reference numerals.
In
The seat 25 is inclined by an angle α with respect to the rotation axis M of the hub and therefore also the surface 61a that defines the step 48 is inclined by the same angle with respect to the axis X of the spoke. The outer surface 51 of the hub, on the other hand, is parallel to the rotation axis M of the hub.
In
The different embodiment of
The assembly of the spoke of
In the assembly step, the head 30 is inserted into the slit 52 in a direction I until it is positioned in the seat 25, then the spoke 5 is rotated according to the arrow R with respect to the median plane P of the wheel until it can be locked onto the rim. The rotation of the spoke occurs in a plane substantially perpendicular to the median plane P of the wheel.
The embodiments of
In the embodiments of
Of course, the person skilled in the art will understand that it is possible to combine the various solutions illustrated and described above, as far as the different ways of embodying the locking means against the displacement of the spoke towards the hub and the configuration of the hub is concerned.
Number | Date | Country | Kind |
---|---|---|---|
MI 2006 A002215 | Nov 2006 | IT | national |