BRAKE SHOE FOR BICYCLE

Abstract: Brake shoes (13a, 13b) are of an embedded type to be mounted to brake arms (12a, 12b) of a brake equipment (1) which act on both side surfaces (5a) of a rim (5), and are provided with a securing pin (15) and a shoe body (18). The securing pin (15) is formed of aluminum to be connectable to the brake arms (12a, 12b). The shoe body (18) comprises a holder plate (16) fixed to the tip end of the securing pin (15) and a friction pad (17) of an elastic material, in which the holder plate (16) is embedded and which makes contact with the rim (5). The shoe body (18) has a mass of 28.0 grams or more, and the holder plate (16) is greater in mass than the friction pad (17). A mass ratio of the shoe body (18) to the securing pin (15) is equal to or more than 10.

Description: TECHNICAL FIELD The present invention relates to a bicycle brake shoe, particularly, an embedded type which is to be attached to a brake arm of a brake device which acts upon a bicycle wheel rim. BACKGROUND ART A bicycle capable of running off-road, which is, for example, called a mountain bike or all-terrain bike (ATB), is generally equipped with a cantilever type brake device for obtaining a strong deceleration force. The cantilever type brake device comes into contact with both sides of a bicycle wheel rim and thereby acts upon them, and is equipped with a pair of brake arms and a pair of brake shoes. An end of each brake arm is freely pivotally supported by a front fork or a seat stay, and the other end is hung on a brake wire. In addition, the brake shoes are oppositely placed along both sides of the bicycle wheel rim in the middle of the brake arm. Of the brake shoes, an embedded type has: a fixing pin which can be connected to the brake arm; and a shoe main body which is fixed on the fixing pin. The shoe main body includes a mainly synthetic resin-made friction pad, in which a holder plate that is fixed on a tip of the fixing pin is embedded. Such a construction is known from JP-62-170393. In such a cantilever type bicycle brake device, the brake arms are allowed to pivot in the closing directions by pulling brake wires with a brake lever, so that the brake shoes are brought into contact with the rim to press it, thus achieving deceleration. In such a bicycle brake device, in the case where the wheel rim gets wet because of running under rainy weather or under wet conditions such as on mud roads, noises may be made when the brake shoes are in contact with the wheel rim to press it during deceleration. The noises can roughly be divided into high sound components which sound "Kiiii!" and low sound components which sound "Biiii!" , and they all grate upon riders' ears. Accordingly, bicycle brake devices are necessary which suppress noises even if the wheel rim gets wet. An object of the present invention is to suppress noises during deceleration. DISCLOSURE OF THE INVENTION A bicycle brake shoe, according to a first embodiment of the present invention, is an embedded type brake shoe to be attached to a brake arm of a brake device which acts upon a bicycle wheel rim, the bicycle brake shoe including a fixing pin and a shoe main body, wherein the fixing pin is made of aluminum and can be connected to the brake arm, and the shoe main body has: a holder plate fixed on a tip of the fixing pin; an elastomer-made friction pad in which the holder plate is embedded and which comes into contact with the wheel rim and thereby acts upon the wheel rim; and a mass of 28.0 g or larger. As to this bicycle brake shoe, when the brake arm pivots, the brake shoe connected to the brake arm comes into contact with the wheel rim to press it, thereby effecting deceleration. On this occasion, in the case where the mass of the shoe main body is less than 28.0 g, the use of the aluminum-made fixing pin is liable to cause loud noises. However, it is difficult for noises to occur in the first embodiment of the present invention, because the mass of the shoe main body is 28.0 g or larger. A bicycle brake shoe, according to a second embodiment of the present invention, has the same features as the first embodiment, but in the second embodiment the holder plate has a larger mass than the friction pad. Therefore, also in the second embodiment, it is difficult for noises to occur. A bicycle brake shoe, according to a third embodiment of the present invention, has the same features as the first or second embodiment, but in the third embodiment the mass ratio of the shoe main body to the fixing pin is 10 or larger. Therefore, in the third embodiment, it is difficult for noises to occur. A bicycle brake shoe, according to a fourth embodiment of the present invention, is an embedded type brake shoe to be attached to a brake arm of a brake device which acts upon a bicycle wheel rim, the bicycle brake shoe including a fixing pin and a shoe main body, wherein the fixing pin can be connected to the brake arm, and the shoe main body has: a holder plate fixed on a tip of the fixing pin; an elastomer-made friction pad in which the holder plate is embedded and which comes into contact with the wheel rim and thereby acts upon the wheel rim; and a mass at least 10 times that of the fixing pin. Therefore, also in the fourth embodiment, it is difficult for noises to occur. A bicycle brake shoe, according to a fifth embodiment of the present invention, is an embedded type brake shoe to be attached to a brake arm of a brake device which acts upon a bicycle wheel rim, the bicycle brake shoe including a fixing pin and a shoe main body, wherein the fixing pin is made of iron and can be connected to the brake arm, and the shoe main body has: a holder plate fixed on a tip of the fixing pin; an elastomer-made friction pad in which the holder plate is embedded and which comes into contact with the wheel rim and thereby acts upon the wheel rim; and a mass at least 4 times that of the fixing pin. Therefore, also in the fifth embodiment, it is difficult for noises to occur. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a front part of a bicycle to which an embodiment of the present invention is applied. FIG. 2 is a front view of a brake device. FIG. 3 is a side view of the brake device. FIG. 4 is a side view of a brake shoe. FIG. 5 is a plan of the brake shoe. FIG. 6 is a VI-VI section of FIG. 4. FIG. 7 is a plan of a brake shoe used in experiments. BEST MODE FOR CARRYING OUT THE INVENTION In FIG. 1, a cantilever type brake device 1 to which an embodiment of the present invention is applied is, for example, used for a front wheel and freely pivotally supported in the middle of a front fork 4 of a frame 3. The brake device 1 comes into contact with and press both sides 5a of a rim 5 of a front wheel 2, thereby effecting deceleration. As shown in FIGS. 2 and 3, the brake device 1 is connected to: an end part of a brake wire 10 extending from a brake lever 7 installed on a handle 6; and an end part of a wire 11 connected to a middle part of the brake wire 10. The brake device 1 has: brake arms 12a and 12b of which the tip parts are connected to the wires 10 and 11 respectively; and brake shoes 13a and 13b which are adjustably and oppositely installed in the respective middles of the brake arms 12a and 12b. Respective base end parts of the brake arms 12a and 12b are freely pivotally supported by the front fork 4, and springs (not drawn) to orient the brake arms 12a and 12b in the respective opening directions are attached to pivots 14a and 14b. Thus, the brake arms 12a and 12b are usually oriented in the opening directions (to the brake release position), but they are made to pivot in the closing directions around the pivots 14a and 14b as the respective centers by pulling the brake wires 10 and 11 by operating the brake lever 7, so that the deceleration is effected. The brake shoes 13a and 13b have structures which are oppositely arranged along both sides 5a of the rim 5 and have mirror-symmetrical relation to each other. The brake shoe 13a is hereinafter explained. As shown in FIGS. 3 to 6, the brake shoe 13a includes: an aluminum- or iron-made fixing pin 15 which can be connected to the brake arm 12a; and a shoe main body 18. The shoe main body 18 has: a holder plate 16 which is fixed on a tip of the fixing pin 15; and a friction pad 17, for example, made of synthetic rubber, in which the holder plate 16 is embedded and which comes into contact with the rim 5 and thereby acts upon it. The holder plate 16 is, for example, made of aluminum or iron. Water-cutting concaves 19 are formed at three positions on a rim contact face of the friction pad 17. In the case where the fixing pin 15 is, for example, made of aluminum, the mass of the holder plate is, for example, 16.2 g, the mass of the friction pad 17 is, for example, 13.8 g, the mass of the fixing pin 15 is, for example, 2.9 g, their total mass being accordingly 32.9 g, and the mass of the shoe main body 18 is, for example, 30 g. In addition, in the case where the fixing pin 15 is made of iron, the mass of the holder plate 16a is, for example, 27.4 g, the mass of the friction pad 17 is, for example, 10.4 g, the mass of the fixing pin 15 is, for example, 9.3 g, their total mass being accordingly 47.1 g, and the mass of the shoe main body is, for example, 37.8 g. In the brake device 1 having such features, if a rider operates the brake lever 7, the brake wires 10 and 11 are respectively pulled, the brake arms 12a and 12b pivot in the respective closing directions, the contact faces of the friction pads 17 and 17 are brought into contact with the sides 5a of the rim 5 to press them, whereby the deceleration is effected. In addition, if the brake lever 7 is released, the brake wires 10 and 11 are loosened, the springs impel the brake arms 12a and 12b to pivot in the respective opening directions, and tips of the friction pads 17 and 17 of the brake shoes 13a and 13b part from the sides 5a of the rim 5, whereby the brake is released. (Examples): In order to prevent noises of such brake shoes, various experiments were carried out under the following conditions. First, as to a brake shoe having an iron-made fixing pin, a product No. 1 which was a conventional product was used, and the mass of the product was changed by, as shown in FIG. 7, adhering weights 20 having various masses to an upper part of a shoe main body 18 of the product, thus examining whether noises were made or not. On this occasion, a bicycle was allowed to run on a wet road, and the brake operation was then repeated 15 times on a slope of a dry road to examine the degree of noises. Results are collected in Table 1. As seen in Table 1, it was found that when the iron-made fixing pin was used, noises were small in the case where the mass ratio of the shoe main body to the fixing pin was "4.1", and that as the mass ratio became smaller, noises became larger. Accordingly, it was found that in the case where the fixing pin was made of iron, the mass ratio was preferably 4 or larger. In the case where the fixing pin was made of iron, the mass ratio of 4 or larger is disadvantageous for intending to lighten the weight, because the total mass is no less than about 47.1 g. Thus, experiments were further carried out as to the case where the fixing pin was made of aluminum. In these experiments, the mass of a brake shoe of product No. 2 having an aluminum-made fixing pin was changed by, as shown in FIG. 7, adhering weights 20 having various masses to the brake shoe, thus examining the degree of noises. On this occasion, water was sprayed to the rim, and the brake operation was then repeated 10 times on a slope of a dry road to examine the degree of noises. Results are collected in Table 2, which further shows test results of a brake shoe of product No. 3 according to an embodiment of the present invention. As a result, it was found that if the mass of the shoe main body was larger than 28 g, noises were small, and that if the mass ratio of the shoe main body to the fixing pin was larger than 10.0, noises were small. In addition, it was also found that if the mass of the holder plate was larger than that of the friction pad, noises were small. Furthermore, it was found that in the case where the above-mentioned masses were otherwise smaller or where the relative size of the masses was reversed, noises were large. From these findings, it was found that when the fixing pin was made of aluminum or when the material of the fixing pin was not limited, the mass ratio of the shoe main body to the fixing pin was preferably 10 or larger. In addition, it was found that when the fixing pin was made of aluminum with the intention of lightening its weight, the mass of the shoe main body was preferably 28 g or larger, and that in this case, the mass ratio was more preferably 10 or larger, and the mass of the holder plate was more preferably larger than that of the friction pad. (Modifications): (a) The brake shoe may be furnished on a brake device for a rear wheel instead of a brake device for a front wheel. (b)The brake shoe may be furnished to a caliper type or U-type brake device instead of a cantilever type brake device. INDUSTRIAL APPLICATION The present invention can provide a bicycle brake shoe which only makes small noises and are effective as a brake shoe for mountain bikes and conventional bicycles.

Claims: A bicycle brake shoe (18), being an embedded type brake shoe to be attached to a brake arm (12a, 12b) of a brake device which acts upon a bicycle wheel rim, the bicycle brake shoe (18) comprising: an aluminum-made fixing pin (15) which can be connected to the brake arm; and a shoe main body of 28.0 g or larger in mass, having: a holder plate (16) fixed on a tip of the fixing pin; and an elastomer-made friction pad (17) in which the holder plate (16) is embedded and which comes into contact with the wheel rim and thereby acts upon the wheel rim. A bicycle brake shoe as in claim 1, wherein the holder plate (16) has a larger mass than the friction pad (17). A bicycle brake shoe as in claim 1 or 2, wherein a mass ratio of the shoe main body (18) to the fixing pin (15) is 10 or larger. A bicycle brake shoe (18), being an embedded type brake shoe to be attached to a brake arm (12a, 12b) of a brake device which acts upon a bicycle wheel rim, the bicycle brake shoe comprising: a fixing pin (15) which can be connected to the brake arm (12a, 12b), and a shoe main body having: a holder plate (16) fixed on a tip of the fixing pin (15) an elastomer-made friction pad (17) in which the holder plate (16) is embedded and which comes into contact with the wheel rim and thereby acts upon the wheel rim; and a mass at least 10 times that of the fixing pin (15). A bicycle brake shoe (18), being an embedded type brake shoe to be attached to a brake arm (12a, 12b) of a brake device which acts upon a bicycle wheel rim, the bicycle brake shoe comprising: an iron-made fixing pin (15) which can be connected to the brake arm (12a, 12b) and a shoe main body (18) having: a holder plate (16) fixed on a tip of the fixing pin (15), an elastomer-made friction pad (17) in which the holder plate (16) is embedded and which comes into contact with the wheel rim and thereby acts upon the wheel rim; and a mass at least 4 times that of the fixing pin (15).

Inventors: OHTA KATSUYUKI, TAKIZAWA SHINICHI, OHTA, KATSUYUKI, TAKIZAWA, SHINICHI
Applicants: SHIMANO KK, SHIMANO INC.
Application year: 1995
Main classification: B62L1
IPC codes: B62L1, F16D65