The invention relates to a bicycle tyre comprising a carcass of particularly
two wires of steel or a similar material having canvas wound onto them, with a
tread of rubber being attached to the canvas.
A soft or a hard type of rubber must be selected as material for
the tread of the tyre. A soft type of rubber has a better grip on a somewhat plane
road, on which one will also often ride, but is less wear resistant.
When the tyre is meant for riding across rough, slanting and irregular
terrains and loose ground, the tyre will be provided with studs for obtaining a
best possible grip of the tyre on the ground. This applies in particular to riding
on loose ground, on irregularities or on riding across a slope and in bends. At
such times, the side studs are loaded laterally.
When the tread is manufactured of a soft type of rubber, on will
obtain a good contact between the tyre and the road when riding across a substantially
plane road. However, the studs will yield stronger and thus be less effective
when riding across loose ground and the like as indicated above. This will also
apply to the studs at the side of the tread, which in particular must perform their
functions on riding across slopes.
Up to now, with the manufacture of bicycle tyres one therefore has
had to compromise in the selection of the type of rubber for the tread.
The object of the invention is to design a bicycle tyre of the type
described above in such a way, that it can optimally perform its functions.
To that end, according to the invention it is provided for, that
the tread is composed of adjacent portions extending in circumferential direction
of the tyre and being of rubber having different properties.
With bicycle tyres meant for riding across rough, slanting and irregular
terrains, the adjacent portions of the tread will in particular be of rubber having
In particular, it will be provided for that the side portions of
the tread are manufactured from a harder type of rubber than the middle portion
of the tread.
When riding across a slope in loose ground, the outer studs will
then optimally perform their functions, since they will not or hardly yield.
For a soft type of rubber, rubber having a hardness of 30 to 60°sha
is considered, and for a harder type of rubber, a hardness of 50 to 80°sha.
Even if the bicycle tyre is not provided with studs, but is meant
for a normal touring bicycle or a racing bicycle, applying the invention can give
According to the invention, the middle portion of the tread can thus
be manufactured from rubber having a low internal friction, and the side portions
from rubber having a high friction between road and tyre.
By manufacturing the middle portion from rubber having a low internal
friction in the way as indicated, the hysteresis causing energy losses and thus
the rolling resistance will be low. By manufacturing the side portions from rubber
having a high friction between road and tyre, one can ride through bends at higher
speeds. The latter is of course particularly important with racing bicycles.
The invention is further explained by means of embodiments, illustrated
in the drawing, in which:
- Fig. 1 shows a diagrammatical cross-section of a bicycle tyre according to
the invention at a given stage of its manufacture;
- Fig. 2 shows a cross-section of the bicycle tyre of Fig. 1, but after it has
undergone the last treatment; and
- Fig. 3 shows a cross-section corresponding to Fig. 2 but of a somewhat modified
embodiment of a bicycle tyre according to the invention.
As shown in Fig. 1, a bicycle tyre is composed of two steel wires
1 across which the canvas is applied, in particular by winding canvas threads onto
the steel wires over an angle in transverse direction. This winding takes place
in a flat state.
The tread 3 is applied onto the canvas 2, said tread according to
the invention being of a soft type of rubber for the middle portion 4 and a hard
type of rubber for the side portions 5. The rubber is then not yet vulcanized and
therefore not retaining its shape.
Subsequently, the entirety is brought into a heated mould so that
the tyre will take up the shape as shown in Fig. 2. In this shape the rubber is
vulcanized, so that it obtains the desired properties. The tread of the tyre is
provided with the studs 6 and 7 in the same way. Therein, the studs 6 will consist
of rubber having a greater hardness than the rubber of the studs 7.
The rubber of the two components of the tread 3 will be chemically
connected to the canvas 2 by vulcanization so that an optimal adherence will be
The bicycle tyre shown in Fig. 3 corresponds substantially to that
of Fig. 2. Only additional reinforcement strips 8 have been applied to protect
the canvas against possible sharp edges of the rim on which the bicycle tyre is
It will be obvious that only some possible embodiments of a bicycle
tyre according to the invention have been illustrated in the drawing and described
above and that many modifications can be made without being beyond the inventive
Thus, obviously the construction of the bicycle tyre can be changed
and for example the rubber of the tread can extend beyond the position of the steel
wires. It is not necessary that the bicycle tyre is provided with studs; it could
have a normal profile for use on common touring bicycles and racing bicycles and
the types of rubber used for the tread can have other specific properties.
All these possibilities will be clear to the expert and will need
no further explanation.