BICYCLE TYRE

Abstract

Bicycle tyre (100) which comprises a pair of bead cores (8), a carcass structure (2) turned around the pair of bead cores (8) and a tread band (4) radially outer to the carcass structure (2); at each bead core (8) being provided: an elastomeric material filler (12) which extends in a radial direction for a first length (HI) starting from the bead core (8), a loop (15) interposed between the carcass structure (2) and the elastomeric material filler (12), turned around the bead core (8) so as to define a first flap (15a) axially outer to the elastomeric material filler (12) and a second flap (15b) axially inner to the elastomeric material filler (12), wherein the first flap (15a) extends in a radial direction for a second length (H2) and the second flap (15b) extends in a radial direction for a third length (H3); preferably, the second (H2) and third (H3) lengths are less than or equal to the first length (H1).

Claims

1-16. (canceled)

17. A bicycle tyre comprising: a pair of bead cores, a carcass structure turned around the pair of bead cores and a tread band radially outer to the carcass structure; wherein each bead core comprises: an elastomeric material filler, extending in a radial direction for a first length (H1) starting from the bead core, and a loop interposed between the carcass structure and the elastomeric material filler, turned around the bead core to define a first flap axially outer to the elastomeric material filler and a second flap axially inner to the elastomeric material filler, wherein the first flap extends in a radial direction for a second length (H2) starting from the bead core, and the second flap extends in a radial direction for a third length (H3) starting from the bead core.

18. The bicycle tyre according to claim 17, wherein the second (H2) and third (H3) lengths are less than or equal to the first length (H1).

19. The bicycle tyre according to claim 17, wherein the first length (H1) is less than a distance (H4) measured in a radial direction between the bead core and the radially outermost portion of the carcass structure.

20. The bicycle tyre according to claim 19, wherein the first length (H1) is between about 20% and about 80% of the distance measured in the radial direction between the bead core and the radially outermost portion of the structure carcass.

21. The bicycle tyre according to claim 18, wherein the second (H2) and third (H3) lengths are at least about 30% of the first length (H1).

22. The bicycle tyre according to claim 17, wherein the loop is placed in direct contact with the elastomeric material filler.

23. The bicycle tyre according to claim 17, wherein the elastomeric material filler is a monolithic insert.

24. The bicycle tyre according to claim 17, wherein the elastomeric material filler has a thickness, measured in an axial direction, greater than or equal to about 0.5 mm.

25. The bicycle tyre according to claim 17, wherein the elastomeric material filler has a thickness, measured in the axial direction, at the portion radially adjacent to the bead core equal to or less than the thickness measured in the axial direction of the bead core measured in the same direction.

26. The bicycle tyre according to claim 17, wherein the loop is made with the same material with which the carcass structure is made.

27. The bicycle tyre according to claim 17, further comprising, at each bead core, an anti-abrasive ribbon-shaped element placed axially outside the carcass structure and turned around the bead core.

28. The bicycle tyre according to claim 17, further comprising a bead core to bead core ply placed radially outside the carcass structure and radially inside the tread band.

29. The bicycle tyre according to claim 17, wherein the carcass structure comprises at least one carcass ply with a plurality of reinforcing cords inclined of a first angle with respect to an equatorial plane.

30. The bicycle tyre according to claim 29, wherein the first angle is ranges from about 30° to about 60°.

31. The bicycle tyre according to claim 29, wherein the carcass ply is turned around the bead cores to produce at least two superimposed layers of carcass ply; the elastomeric material insert and the loop interposed between the two superimposed layers of carcass ply.

32. The bicycle tyre according to claim 31, wherein the carcass ply is turned around the bead cores to produce two layers of carcass ply at two first opposite portions of the tyre and three layers of carcass ply superimposed at a second portion of the tyre, placed between the first two portions; the elastomeric material insert placed in said first two portions of the tyre.

Description

DESCRIPTION OF THE FIGURES AND OF PREFERRED EMBODIMENTS

[0103] Further features and advantages of the tyre of the present invention will become clearer from the following detailed description of some preferred embodiments thereof, made with reference to the attached drawings. In such drawings:

[0104] FIG. 1 schematically shows a perspective section of an embodiment of the bicycles tyre in accordance with the present invention;

[0105] FIG. 1A shows an enlargement of a detail of FIG. 1; and

[0106] FIGS. 2-8 show possible constructive schemes representative of alternative embodiments of the tyre of the invention.

[0107] In FIG. 1, reference numeral 100 wholly indicates a bicycles tyre according to the present invention. The tyre is intended to be mounted on the wheels of a bicycle, in particular on the wheels of an electric bicycle or on the wheels of an off-road bicycle.

[0108] The tyre 100 comprises a rotation axis O and an equatorial plane X perpendicular to the rotation axis O. Also defined are a circumferential direction arranged according to the direction of rotation of the tyre 100 and an axial direction perpendicular to the equatorial plane X and/or parallel to the rotation axis O.

[0109] The tyre 100 of FIG. 1 comprises a carcass structure 2 comprising a crown portion 2a preferably symmetrically arranged with respect to the equatorial plane X and opposite lateral portions 2b arranged on axially opposite sides with respect to the crown portion 2a.

[0110] In radially outer position to the carcass structure 2 a tread band 4 is provided, by means of which the contact of the tyre 100 with the road surface takes place.

[0111] The tread band 4 comprises a central portion 5 and two lateral portions 6 (or sidewalls 6) arranged on axially opposite sides with respect to the central portion 5.

[0112] The central portion 5 can comprise (like in the example illustrated in FIG. 1) a plurality of blocks 7.

[0113] In the embodiment illustrated in FIG. 1, the carcass structure 2 comprises a single carcass ply 3, but there are other embodiments (like for example those schematized in FIGS. 4, 7 and 8) in which the carcass structure 2 comprises two carcass plies indicated with 3, 3a in FIGS. 4, 7 and 8.

[0114] What is described below with reference to the carcass ply illustrated in the drawings applies both to the single carcass ply 3 of the tyre and to each carcass ply 3, 3a of a tyre having plural plies, unless explicitly stated otherwise.

[0115] The carcass ply 3 is turned around respective annular anchoring structures 8, called “bead cores”.

[0116] The carcass ply 3 is turned around the bead cores 8 so as to produce many layers of carcass ply 3 radially juxtaposed over one another.

[0117] In the embodiment illustrated in FIG. 1 and schematized in FIGS. 2 and 5, the carcass ply 3 is turned around the bead cores 8 so that two layers of carcass ply 3 are arranged at two opposite first portions 9 of the tyre that are preferably at least partially juxtaposed at the sidewalls 6 of the tread band. The carcass ply 3 also has three juxtaposed layers of ply at a second portion 10 axially arranged between the first two portions 9 and preferably at least partially coinciding with the crown 2a.

[0118] The carcass ply 3 has two end edges 11 that define two separation areas between the portion with three juxtaposed layers of ply and the two portions of two juxtaposed layers of ply of the carcass ply 3.

[0119] In an alternative embodiment illustrated in FIGS. 3 and 6 the carcass ply 3 is turned around the bead cores 8 so that two layers of carcass ply 3 are arranged at two opposite first portions 9 of the tyre that are preferably at least partially juxtaposed at the sidewalls 6 of the tread band. The carcass ply 3 has a single layer of play at a second portion 10 axially arranged between the first two portions 9 and preferably at least partially coinciding with the crown 2a.

[0120] The carcass ply 3 has two end edges 11 that define two separation areas between the portion with a single layer of ply and the two portions of two juxtaposed layers of ply of the carcass ply 3.

[0121] In a further alternative embodiment illustrated in FIGS. 4 and 7 there are two carcass plies 3, 3a wherein each carcass ply 3, 3a is turned around the bead cores 8 so that two layers of ply of each carcass ply 3, 3a are arranged at two opposite first portions 9 of the tyre that are preferably at least partially juxtaposed at the sidewalls 6 of the tread band. The two carcass plies 3, 3a have a single layer of ply each at a second portion 10 axially arranged between the first two portions 9 and preferably at least partially coinciding with the crown 2a.

[0122] The two carcass plies 3, 3a have two end edges 11 that define two respective separation areas between the portion with a single layer of ply and the two portions of two juxtaposed layers of ply of each carcass ply 3, 3a.

[0123] According to this embodiment, the carcass structure 3 has four layers of carcass ply (two for each carcass ply 3, 3a) juxtaposed at the two opposite first portions 9 of the tyre and two layers of carcass ply (one for each carcass ply 3, 3a) juxtaposed at the second portion 10 of the tyre.

[0124] In an alternative embodiment illustrated in FIG. 8, there are two carcass plies 3, 3a wherein each carcass ply 3, 3a is turned around the bead cores 8 so that two layers of ply of each carcass ply 3, 3a are arranged at two opposite first portions 9 of the tyre that are preferably at least partially overlapped at the sidewalls 6 of the tread band.

[0125] The two carcass plies 3, 3a have a triple layer of ply each at a second portion 10 axially arranged between the first two portions 9 and preferably at least partially coinciding with the crown 2a. The two carcass plies 3, 3a have two end edges 11 that define two respective separation areas between the portion with juxtaposed triple layers of ply and the two portions of two juxtaposed layers of ply of each carcass ply 3, 3a.

[0126] According to this embodiment, the carcass structure 3 has four layers of carcass ply (two for each carcass ply 3, 3a) juxtaposed at the two opposite first portions 9 of the tyre and six layers of carcass ply (three for each carcass ply 3, 3a) juxtaposed at the second portion 10 of the tyre.

[0127] The bead cores 8 are preferably made of textile fibers with high elastic modulus, like for example aramid fibers (common name of aromatic polyamide fibers), or metal wires, like for example steel.

[0128] In radially outer and adjacent position to each bead core 8 there is an elastomeric material filler 12 preferably monolithic. The elastomeric material filler 12 extends from a radially outer surface of the bead core 8. As illustrated in FIG. 1, the elastomeric material filler 12 is not present radially inside the bead core 8, in other words it only extends in a radially outer direction from the radially outer surface 8a of the bead core 8.

[0129] The elastomeric material filler 12 is axially interposed between the layers of carcass ply 3, as illustrated in the attached figures. The elastomeric material filler 12 is axially arranged between the carcass plies 3 preferably in radially inner position with respect to the two end edges 11 of the carcass ply 3, so that each elastomeric material filler is respectively arranged at the two portions of two juxtaposed layers of ply of the carcass ply 3.

[0130] The area of the tyre 100 comprising the bead core 8 and the elastomeric material filler 12 forms the so-called “bead”, intended for anchoring, through elastically forced fitting, the tyre 100 on a corresponding mounting rim 101 (partially illustrated in FIG. 1).

[0131] As illustrated in the attached figures, at each bead core 8 and in particular in axially outer position to the carcass structure 2, it is possible to apply an anti-abrasive ribbon-shaped element 13. Such an anti-abrasive ribbon-shaped element 13 is interposed between the carcass ply 3 and the rim 101 of the wheel when the tyre 100 is mounted on such a rim 101. The anti-abrasive ribbon-shaped element 13 has the function of ensuring grip and friction with the rim 101 of the wheel, avoiding possible damage due to the abrasion following rubbing of the carcass ply 3 with the rim 101.

[0132] Instead of the anti-abrasive ribbon-shaped element 13 it is possible to use a single reinforcing cord deposited possibly after adhesion treatment.

[0133] With reference to FIGS. 1, 2, 3 and 4, a bead core to bead core ply 14 is illustrated that can optionally be present in the tyre 100.

[0134] The bead core to bead core ply 14 is associated with the carcass structure 2 in radially outer position and preferably extends from one bead core 8 to the other bead core 8 without being turned around the bead cores. Alternatively, the bead core to bead core ply 14 extends only at the crown 2a of the carcass structure 2.

[0135] The bead core to bead core ply 14 is arranged radially inside the tread band 4. The function of the bead core to bead core ply 14 is to prevent possible punctures of the tyre 100.

[0136] FIGS. 5, 6, 7 and 8 show tyres structures without the bead core to bead core ply 14.

[0137] At each bead core 8 and in a position axially interposed between the elastomeric material filler 12 and the carcass ply 3 there is a loop 15 turned around the bead core 8. The loop 15 defines a first flap 15a and a second flap 15b, respectively axially outer and axially inner with respect to the elastomeric material filler 12, which extend radially away from the bead core 8.

[0138] The function of the loop 15 is to hold together in a substantially integral manner the elastomeric material filler 12 and the bead core 8. As shown in FIG. 1 and schematically represented in FIGS. 2 to 7, the flaps 15a, 15b of the loop are in direct contact with the elastomeric material filler 12.

[0139] Both the loop 15 and the elastomeric material filler 12 extend circumferentially along the entire extension of the tyre 100.

[0140] As shown in the enlargement of FIG. 1A, the elastomeric material filler 12 extends in a radial direction for a length H1 starting from the bead core 8. The first length H1 is less than the distance H4 (illustrated in FIG. 1) measured in the radial direction that separates the bead core 8 from the radially outermost portion of the crown 2a of the carcass structure 2, in other words the elastomeric material filler 12 engages less than half of the carcass structure 2. In the preferred embodiment of the invention, the first length H1 is between about 20% and about 80%, including extreme values, of the distance H4, preferably is between about 30% and about 70%, including extreme values, of the distance H4, even more preferably it is about 50% of the distance H4.

[0141] In absolute terms, the first length H1 is comprised between about 10 millimeters and about 50 millimeters extremes included, more preferably comprised between about 20 millimeters and about 40 millimeters extremes included, even more preferably comprised between about 30 millimeters and about 35 millimeters extremes included.

[0142] The elastomeric material able to be used as elastomeric material filler 12 according to the present invention can have the following mechanical properties (static and dynamic):

[0143] Ultimate tensile strength equal to or greater than 10 MPa, preferably comprised between about 15 MPa and about 40 MPa extremes included.

[0144] Elongation at break equal to or greater than about 120% preferably equal to or greater than about 150%, even more preferably comprised between about 200% and about 800% extremes included, even more preferably comprised between about 300% and about 800% extremes included.

[0145] Dynamic elastic modulus E′ (23° C.-10 Hz) equal to or greater than about 2 MPa, preferably comprised between about 3 MPa and about 35 MPa extremes included.

[0146] Dynamic elastic modulus E′ (70° C.-10 Hz) equal to or greater than about 2 MPa preferably comprised between about 2.2 Mpa and about 25 Mpa extremes included.

[0147] Hereinafter an example is indicated of elastomeric material for elastomeric material filler 12 and of preparation of the elastomeric material filler 12 (the amounts of the various components are indicated in phr—Parts per Hundred Rubber).

[0148] All of the components, with the exception of sulfur, accelerant (TBBS) and retardant (PVI), were mixed in an internal mixer (Pomini model PL 1,6) for about 5 minutes (1st step). As soon as the temperature has reached 145±5° C., the elastomeric composition was discharged. The sulfur, the accelerant (TBBS) and the retardant (PVI) were added and the mixing was carried out in an open roller mixer (2nd step).

TABLE-US-00001 Elastomeric material 12 1st step IR 100.00 CB 5.00 Stearic acid 2.00 Zinc oxide 8.00 Tackifying resin 2.00 Oil 3.00 Silica 40.00 Supported silane 6.00 2nd step TBBS 1.50 PVI 0.30 Vulcanizer 5.30 IR: high cis-1,4-polyisoprene synthetic rubber, SKI-3, Lee Rubber. CB: Carbon black, N375, Cabot. Stearic acid: Sogis. Zinc oxide: Zincol Ossidi. Tackifying resin: Octylphenol resin, SP1068, Si Group. Oil: MES (Mild Extraction Solvate), ENI SPA. Silica: Zeosil ® 1165 - Solvay. Supported silane: 50% bis[3-(triethoxysilyl)propyl]tetrasulfide on 50% carbon black, Evonik-Degussa. TBBS: N-tert-butyl-2-benzothiazylsulfenamide, Vulkacit ® NZ/EGC, Lanxess; PVI: cyclohexyl-thiophthalimide, Santogard PVI, Flexsys Vulcanizer: Sulfur, Redball Superfine, International Sulphur Inc.

[0149] The elastomeric material can be characterized by the following parameters

[0150] The static mechanical properties (CA05 load at 50% elongation and CA1 load at 100% elongation) according to the standard UNI 6065 were measured at different elongations (50%, 100%) on samples of the aforementioned elastomeric materials, vulcanized at 170° C. for 10 minutes. The results obtained are given in Table 2.

[0151] The rheometric analysis MDR was carried out using an MDR Monsanto rheometer. The test was carried out at 170° C. for 10 minutes with an oscillation frequency of 1.66 Hz (100 oscillations per minute) and an oscillation amplitude of ±0.5°. The minimum torque (ML) and maximum torque (MH) values were measured.

[0152] The dynamic mechanical properties E′ and Tan delta were measured using an Instron model 1341 dynamic device in traction-compression mode according to the following methods. A test piece of cross-linked material (170° C. for 10 minutes) having a cylindrical shape (length=25 mm; diameter=14 mm), preloaded under compression up to a longitudinal deformation of 25% with respect to the initial length and kept at the predetermined temperature (23° C.), 70° for the entire duration of the test was subjected to a dynamic sinusoidal stress having an amplitude of ±3,5% with respect to the length under pre-load, with a frequency of 10 Hz. The dynamic mechanical properties are expressed in terms of values of dynamic elastic modulus (E′) and Tan delta (loss factor). The Tan delta value was calculated as the ratio between the viscous dynamic modulus (E″) and the elastic dynamic modulus (E′). Thermoplastic behavior was evaluated as the difference deltaE′ between the elastic dynamic modulus values measured at two reference temperatures.

TABLE-US-00002 TABLE 2 Elastomeric material 12 STATIC MECHANICAL PROPERTIES Load at 50% elongation (MPa) 0.8 Load at 100% elongation (MPa) 1.1 Ultimate tensile strength (MPa) 27 Elongation at break (%) 700 Energy (J/cm.sup.3) 52 DYNAMIC MECHANICAL PROPERTIES E′ (23° C. - 10 Hz) (MPa) 3.3 E′ (70° C. - 10 Hz) (MPa) 2.7 Tan delta (23° C.) 0.057 Tan delta (70° C.) 0.027

[0153] The thickness of the elastomeric material filler 12 measured in an axial direction, is less than or equal to the thickness, measured in the same direction, of the bead core. Preferably, the elastomeric material filler 12 has a thickness, measured in an axial direction, greater than about 0.5 millimeters. Preferably, the elastomeric material filler 12 has a thickness, measured in an axial direction, less than about 4 millimeters. Preferably, the elastomeric material filler 12 has a thickness, measured in an axial direction, comprised between about 0.5 millimeters and about 4 millimeters extremes included, more preferably comprised between about 1 millimeter and 3 millimeters extremes included, even more preferably comprised between about 1,5 and 2 millimeters extremes included.

[0154] In the preferred embodiment of the invention, the elastomeric material filler 12 has a constant thickness along the entire extension thereof, whereas in other embodiments of the invention the elastomeric material filler 12 is tapered along the extension thereof in the radial direction, so that the portion of elastomeric material filler 12 radially adjacent to the bead core 8 has a thickness measured in an axial direction greater than the thickness measured in an axial direction of a portion of elastomeric material filler 12 radially distal from the bead core 8.

[0155] In any case, the thickness measured in an axial direction of the elastomeric material filler 12 at the portion radially adjacent to the bead core 8 is equal to or less than the thickness measured in an axial direction of the bead core 8.

[0156] As shown in FIG. 1A, the first flap 15a extends radially away from the bead core 8 for a second length H2. The second flap 15b extends radially away from the bead core 8 for a third length H3, as shown in the enlargement of FIG. 1A.

[0157] The second and third length H2, H3 are preferably equal to one another.

[0158] The second and third length H2, H3 are less than or equal to the first length H1. The second and third length H2, H3 are comprised between about 20% and about 80%, including extreme values, of the first length H1, preferably comprised between about 40% and about 60%, including extreme values, of the length H1, even more preferably they are about 50% of the first length H1.

[0159] The carcass ply 3 of the tyre 100 is preferably made of elastomeric material and comprises a plurality of reinforcing cords arranged substantially parallel to one another.

[0160] The reinforcing cords are preferably made of a textile material selected from Nylon, Rayon, PET, PEN, Lyocell, Aramid, or combinations thereof, in one or more pieces, preferably 1 or 2 pieces.

[0161] The reinforcing cords have a diameter preferably comprised between about 0.10 mm and about 0.55 mm, more preferably between about 0.12 mm and about 0.35 mm, extremes included, for example equal to about 0.13 mm.

[0162] The reinforcing cords have a linear density comprised between about 110 dtex and about 1300 dtex, more preferably between about 230 dtex and about 940 dtex, extremes included, for example equal to about 450 dtex.

[0163] Specific examples of textile materials able to be used for the aforementioned reinforcing cords are the following:

[0164] Nylon 930 dtex/1

[0165] Nylon 470 dtex/1

[0166] Nylon 230 dtex/1

[0167] Aramid 470/1

where the number 1 after dtex indicates the number of pieces.

[0168] The reinforcing cords are inclined, with respect to the equatorial plane of the tyre 100, by an angle comprised between about 30° and about 60°, preferably between about 40° and about 50°, extremes included.

[0169] Preferably, the carcass ply 3 has a thread count comprised between about 15 TPI and about 360 TPI, more preferably between about 30 TPI and about 300 TPI, even more preferably between about 60 TPI and about 240 TPI, even more preferably between about 120 TPI and about 200 TPI, extremes included, for example equal to about 60 TPI.

[0170] The tyre 100 illustrated in FIG. 1 does not comprise belt layers arranged in radially outer position with respect to the carcass structure. However, it is possible to provide different embodiments comprising a belt layer or comprising more than one belt layer.

[0171] The loop 15 can be made of the same material from which the carcass ply 3 is made.

[0172] The loop 15 is in any case made from a ply 16 including a plurality of reinforcing cords preferably parallel to one another and inclined, with respect to an equatorial plane, by a second angle. Alternatively, the reinforcing cords of the ply 16 can make a square fabric structure (i.e. having warp reinforcing cords and weft reinforcing cords).

[0173] The reinforcing cords of the loop 15 are preferably made of a textile material selected from Nylon, Rayon, PET, PEN, Lyocell, Aramid, or combinations thereof, in one or more pieces, preferably 1 or 2 pieces.

[0174] The reinforcing cords of the loop 15 have a diameter preferably comprised between about 0.10 mm and about 0.55 mm, more preferably between about 0.12 mm and about 0.35 mm, extremes included, for example equal to about 0.13 mm.

[0175] The reinforcing cords of the loop 15 have a linear density comprised between about 110 dtex and about 1300 dtex, more preferably between about 230 dtex and about 940 dtex, extremes included, for example equal to about 450 dtex.

[0176] Specific examples of textile materials able to be used for the aforementioned reinforcing cords of the loop 15 are the following:

[0177] Nylon 930 dtex/1

[0178] Nylon 470 dtex/1

[0179] Nylon 230 dtex/1

[0180] Aramid 470/1

where the number 1 after dtex indicates the number of pieces.

[0181] The reinforcing cords of the loop 15 are inclined, with respect to the equatorial plane of the tyre 100, by an angle comprised between about 30° and about 60°, preferably between about 40° and about 50°, extremes included.

[0182] Preferably, the ply 16 of the loop 15 has a thread count equal to or greater than the thread count of the carcass plies 3 of the carcass structure 2. Preferably, the ply 16 of the loop 15 has a thread count comprised between about 15 TPI and about 360 TPI, more preferably between about 30 TPI and about 300 TPI, even more preferably between about 60 TPI and about 240 TPI, even more preferably between about 80 TPI and about 200 TPI, extremes included, for example equal to about 120 TPI.

[0183] As an example, the carcass ply 3 can have a thread count of about 60 TPI and the ply 16 of the loop 15 can have a thread count of about 120 TPI.

[0184] As shown in FIG. 1, the inclination of the reinforcing cords of the loop 15 is opposite with respect to the inclination of the reinforcing cords of the carcass ply 3 of the carcass structure. As an example, when the reinforcing cords of the carcass ply 3 is 45°, the reinforcing cords of the ply 16 of the loop 15 are substantially perpendicular to the reinforcing cords of the carcass ply 3.

[0185] The anti-abrasive ribbon-shaped element 13 extends radially for a distance H5 (FIG. 1A) less than the second H2 and third distance H3. In other words, the anti-abrasive ribbon-shaped element 13 extends radially for a length shorter than the length of the first 15a and second flap 15b of the loop 15.

[0186] The bead core to bead core ply 14 is a ply comprising reinforcing cords inclined, with respect to an equatorial plane, by a third angle. Such a third angle of inclination of the reinforcing cords of the bead core to bead core ply 14 is between about 30° and about 60°, extremes included, preferably comprised between about 40° and about 50°, extremes included, for example equal to about 45°.

[0187] Alternatively, the reinforcing cords of the bead core to bead core ply 14 can make a square fabric structure (i.e. having warp reinforcing cords and weft reinforcing cords).

[0188] The reinforcing cords of the bead core to bead core ply 14 are made of textile material. The reinforcing cords of the carcass structure and of the bead core to bead core ply are made of the same textile material.

[0189] In preferred embodiments, the bead core to bead core ply 14 has a thread count comprised between about 15 TPI and about 360 TPI, extremes included, preferably between about 30 TPI and about 300 TPI, extremes included, more preferably between about 60 TPI and about 240 TPI, extremes included, even more preferably between about 120 TPI and about 200 TPI, extremes included, for example equal to about 60 TPI.

[0190] In preferred embodiments, the reinforcing cords of the bead core to bead core ply 14 have a diameter comprised between about 0.10 millimeters and about 0.55 millimeters, extremes included, preferably between about 0.12 millimeters and about 0.35 millimeters, extremes included, for example equal to about 0.30 millimeters.

[0191] In preferred embodiments, the reinforcing cords of the bead core to bead core ply 14 have a linear density comprised between about 110 dtex and about 1300 dtex, extremes included, preferably between about 230 dtex and about 940 dtex, extremes included, for example equal to about 450 dtex.

[0192] As shown in FIG. 1, in the case of reinforcing cords of the carcass ply 3 and of the bead core to bead core ply 14 being substantially parallel, the inclination of the reinforcing cords of the bead core to bead core ply 14 is opposite with respect to the inclination of the reinforcing cords of the carcass ply 3 of the carcass structure 2. As an example, when the reinforcing cords of the carcass ply 3 is 45°, the reinforcing cords of the bead core to bead core ply 14 are substantially perpendicular to the reinforcing cords of the carcass ply 3.

[0193] Preferably, the building of the tyre 100 takes place according to processes known by those skilled in the art.

[0194] Some tests were carried out to evaluate the performance of bicycle tyres in accordance with the present invention.

[0195] In particular, three tyres were tested—respectively, a reference tyre (tyre 1), a tyre with filler (tyre 2) and a tyre according to the present invention (tyre 3).

[0196] The three tyres have dimensions of 27.5×2.6 (ETRTO 65-584).

[0197] The three tyres were mounted on respective rims having size 584×21 C. The rigidity of the rims is such that by applying any load to the wheel, the contribution of the rim to the total deformation of the wheel is less than 1%.

[0198] The three tyres differ only in the following features: [0199] the tyre with filler has, in addition to the reference tyre, an elastomeric material filler, of the type described having thickness in the axial direction equal to the thickness of the bead core and having extension in the radial direction of about 35 millimeters, at each bead core; [0200] the tyre in accordance with the present invention has, in addition to the filler, a loop, of the type described having reinforcing cords with a thread count double the thread count of the reinforcing cords of the carcass plies and extending up to about half the radial extension of the elastomeric material filler, at each bead core.

[0201] All three of the tyres are provided with identical bead core to bead core ply of the type described, identical carcass structure (of the type represented in FIGS. 1 and 2), identical tread band and identical anti-abrasive ribbon-shaped element.

[0202] In order to carry out rigidity tests of the tyre each wheel (rim and tyre) was mounted on a fixed hub. The tyres were inflated to 2 bar. Each tyre had possible blocks removed from the tread band and the tyre was placed in contact with a flat surface. The wheel was subjected to a fixed vertical load and a longitudinal load, a lateral load and a torsional torque were then applied alternately at the contact area of the tyre with a flat surface. A load cell placed on the hub measured forces and moments transmitted to the wheel. The vertical rigidity was calculated as a ratio between the vertical force applied and the vertical displacement of the wheel. The lateral rigidity was calculated as a ratio between the lateral force applied and the lateral displacement of the wheel. The longitudinal rigidity was calculated as a ratio between the longitudinal force applied and the lateral displacement of the wheel. The torsional rigidity was calculated as a ratio between the torsional torque applied and the rotation of the wheel.

[0203] From comparative rigidity tests of the tyre it emerged that: [0204] the vertical rigidity of the tyre 2 increased by about 6% with respect to the tyre 1 and the vertical rigidity of the tyre 3 increased by about 10% with respect to the tyre 1; [0205] the lateral rigidity of the tyre 2 increased by about 5% with respect to the tyre 1 and lateral rigidity of the tyre 3 increased by about 8% with respect to the tyre 1; [0206] the longitudinal rigidity of the tyre 2 increased by about 6% with respect to the tyre 1 and the longitudinal rigidity of the tyre 3 increased by about 10% with respect to the tyre 1; [0207] the torsional rigidity of the tyre 2 increased by about 8% with respect to the tyre 1 and the torsional rigidity of the tyre 3 increased by about 12% with respect to the tyre 1.

[0208] In order to carry out impact tests against an obstacle, the tyres were inflated to 1.5 bar and each wheel (rim and tyre) had a vertical load of 600 N applied to it. The wheel was made to pass over a fixed obstacle, increasing the speed as 5 km/h increments until the carcass structure broke.

[0209] From comparative impact tests against an obstacle it emerged that: [0210] tyre 1 has breaking speed of the carcass at 20 km/h; [0211] lo tyre 2 has breaking speed of the carcass at 25 km/h; [0212] lo tyre 3 has breaking speed of the carcass at 35 km/h.

[0213] In order to carry out rideability tests, a dual suspension E-MTB bicycle was alternately equipped with the aforementioned tyres of type 1, 2 and 3. The tyres were inflated to about 1.5 bar. The bicycle was ridden by a tester on a route having an alternation of climbs, descents, flats, fast sections, slow sections, gravel, compact ground, corners with lean, corners with counter-gradient and sudden braking.

[0214] The sensations perceived by the tester are summarized in the following table, where the term “rideability” is meant to indicate the ability to maintain the set trajectory, the term “reactivity” is meant to indicate the speed in transferring a drive torque to the ground, the term “sensation of safety” is meant to indicate the progressivity of behavior in cornering. The symbol “+” indicates a slightly improved behavior with respect to a reference given by the bicycle equipped with the tyres of type 1, the symbol “++” indicates a substantially improved behavior with respect to a reference given by the bicycle equipped with the tyres of type 1 and the symbol “+++” indicates a much improved behavior with respect to a reference given by the bicycle equipped with the tyres of type 1.

TABLE-US-00003 Sensation Rideability Reactivity of safety Tyre 2 + ++ + Tyre 3 ++ +++ ++

[0215] The present invention has been described with reference to some preferred embodiments. Different modifications can be brought to the embodiments described above, still remaining within the scope of protection of the invention, defined by the following claims.