The present invention relates to a composite spoke, particularly for
wheels of cycles, motorcycles, and the like.
It is known that the wheels of cycles and motorcycles are usually
provided by means of steel spokes that are tensioned between the hub and the rim
of the wheel.
Steel spokes have the drawback of being relatively heavy and of not
always allowing to obtain a streamlined shape that reduces wind impact.
Attempts to solve the problem by using carbon fibers to manufacture
the spoke have not yielded satisfactory results, since the spokes were found to
be particularly fragile and also caused breakages that produced sharp points that
were particularly dangerous for users; accordingly, these solutions have been abandoned
The aim of the present invention is to solve the above mentioned problem
by providing a composite spoke, particularly for wheels of cycles, motorcycles,
and the like, which is substantially flexible so as to remain intact in case of
breakage without causing potential danger to users.
Within this aim, a particular object of the invention is to provide
a spoke that has a much lower mass than steel spokes and can be obtained with
streamlined contours and with any shape deemed appropriate.
Another object of the present invention is to provide a spoke that
while having a considerably improved structure can be interchangeable with the
spokes currently in use.
Another object of the present invention is to provide a spoke that
by virtue of its particular constructive characteristics is capable of giving the
greatest assurances of reliability and safety in use.
Another object of the present invention is to provide a composite
spoke particularly for wheels of cycles, motorcycles and the like that can be easily
obtained starting from commonly commercially available elements and materials
and is furthermore competitive from a purely economic point of view.
This aim and these and other objects that will become better apparent
hereinafter are achieved by a composite spoke particularly for wheels of cycles,
motorcycles and the like, according to the invention, which comprises an elongated
body that has, at its ends, means for connection respectively to the hub and to
the rim, characterized in that said elongated body is constituted by a single multifilament
yarn made of high-strength, high-tenacity fiber arranged along the length of said
elongated body and incorporated in a flexible matrix of plastic material.
Further characteristics and advantages of the invention will become
better apparent from the description of some preferred but not exclusive embodiments
of a composite spoke, illustrated only by way of non-limitative example in the
accompanying drawings, wherein:
- Figure 1 is a schematic view of a spoke with an eye;
- Figure 2 is a sectional view, taken along the line II-II of Figure 1;
- Figure 3 is an end for connection to the hub;
- Figure 4 is a schematic view of a coupling provided on the composite yarn;
- Figure 5 is a view of the composition of the elongated body;
- Figure 6 is a schematic view of a single spoke;
- Figure 7 is a view of a double spoke.
With reference to the above figures, the composite spoke particularly
for wheels of cycles, motorcycles and the like, generally designated by the reference
numeral 1, comprises an elongated body 2 that has, at its ends, means for connection
respectively to the hub and to the rim of the wheel.
The particular characteristic of the invention is constituted by the
fact that the elongated body 2 is provided by means of a single multifilament yarn
of high-strength fiber, so as to provide a unit that is particularly resistant
to traction, said yarn being made of carbon fibers.
Around the central core 2a, constituted by the carbon fibers, there
is a braided covering sheath 2b obtained with an aramid fiber or the like, which
gives good tenacity so that any impacts or impulsive stresses do not cause breakage.
The fiber part is advantageously incorporated in a plastic matrix
that can be thermoplastic or thermosetting, without altering the concept that the
elongated body 2 must have a certain flexibility.
At its ends, the elongated body 2 is provided with means for connection
to the hub and to the rim that can be of various kinds; thus, for example, it is
possible to provide a metal eye 10 shaped for example like a teardrop, around
which the multifilament yarn is wound so as to incorporate the eye, which can be
connected by means of a tension coupling and the like in order to provide the connections
to the rim or hub.
The eye is surrounded by the multifilament yarn, which is placed inside
a reinforcement 11 made of plastics.
As shown in Figure 3, it is possible to provide a contoured insert
20 that is retained by the multifilament yarn that wraps around it, so as to provide
a contact foot that is arranged in a plastic sheath 21 that enters a recess 24
that can be provided in the hub or in the rim.
It is of course always possible to provide, at the other end of the
elongated body 2, a tension element so as to obtain the typical traction that
has to be applied to the spoke.
Figure 4 illustrates a coupling that can be fitted directly on the
multifilament yarn; in this case, at the end of the multifilament yarn, which
is generally designated by the reference numeral 2, it is possible to overmold
a bush 30 that forms inside it a threaded seat 31 for the connection of a threaded
pivot 32 that acts as a tension element, for example, in combination with the conventional
bush provided on the rims of a cycle or motorcycle.
The above described structure can be used to provide a single spoke,
as shown in Figure 5, or optionally a double spoke, as shown schematically in
Figure 6, in which there is a double coupling to the hub from which two single
spokes 1 for connection to the rim protrude.
The spoke can be fixed to the rim and to the central hub in various
manners, without altering the principle that at least one end must be provided
with screw-type tensioning means for the correct tensioning of the elongated body
2 that constitutes the spoke.
From the above description it is thus evident that the invention achieves
the proposed aim and objects and in particular the fact is stressed that a spoke
is provided which, being obtained by means of a single yarn of carbon fiber, aramid
fiber or the like, is not fragile but is instead particularly flexible and tough,
so that it does not break even in the presence of stresses and in any case does
not create, if any breakage should occur, particularly dangerous rigid sharp points.
The invention thus conceived is susceptible of numerous modifications
and variations, all of which are within the scope of the inventive concept.
All the details may furthermore be replaced with other technically
In practice, the materials employed, so long as they are compatible
with the specific use, as well as the contingent shapes and dimensions, may be
any according to requirements.
Where technical features mentioned in any claim are followed by reference
signs, those reference signs have been included for the sole purpose of increasing
the intelligibility of the claims and accordingly, such reference signs do not
have any limiting effect on the interpretation of each element identified by way
of example by such reference signs.