GB2359350A

GB2359350A - Cycle brakes

Info

Publication number: GB2359350A
Application number: GB0003587A
Authority: GB
Inventors: Michael James Poyzer
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-02-17
Filing date: 2000-02-17
Publication date: 2001-08-22
Anticipated expiration: 2020-02-17
Also published as: GB2359350B; GB0003587D0

Abstract

A single brake lever (10) is mounted on a cycle handlebar (11) for rotation about a first axis (14) and has a grooved pulley (15) pivoted about a second axis (16). A single brake inner cable (17) is looped around the pulley (15) and extends through separate outer casings (18, 19) to operate two brake mechanisms, which may be on the same or different wheels, and one brake mechanism may be a disc brake (Fig.3) and the other mechanism may be a cantilever-type brake (Fig.4).

Description

1 2359350 CYCLE BRAKE

Field of the Invention

This invention is concerned with the provision of brakes on cycles and particu larly, but not exclusively, with the provision of brakes on pedal cycles, for instance bicy cles, tandems and tricycles. The invention provides both a cycle incorporating a novel braking system and a kit for modifying the brakes of an existing bicycle to this novel braking system.

Background to the Invention

Bicycles are conventionally provided with brakes for both their front and rear wheels. These brakes can be of various designs including cantilever type rim brakes in which a brake mechanism pushes a pair of brake blocks against opposite sides of a wheel rim, and disc brakes in which a disc pad is pushed by a brake mechanism against a brake disc secured to the wheel about its axis of rotation. Each brake mechanism is conventionally operated by a Bowden type cable operated by a handlebar mounted brake lever. In order to optimise safe deceleration of the bicycle, the cyclist is required to exercise skill in selecting the sequencing with which the two brake levers are applied and particularly in controlling the force with which the front and rear brakes are applied with two hands which are usually of differing strength. It is an object of this invention to provide a cycle with brakes which reduce the skill required to achieve safe deceleration.

When it is desirable for a bicycle to have particularly strong brakes, for instance in the case of mountain bicycles and bicycles for downhill racing, it has hitherto been necessary to incur the considerable cost of installing hydraulically actuated disc brakes. It is alternatively an object of this invention to provide a cycle with strong brakes without the need of installing any hydraulic system.

Summary of the Invention

According to one aspect of the invention a cycle is provided with two wheel braking devices and has a single brake lever arranged to operate both wheel braking devices. In this manner both wheel braking devices can be operated by a single hand on the single brake lever thereby co-ordinating operation of both braking devices and re leasing the cyclist's other hand for another function. Both of the wheel braking devices may be arranged to operate either on the same road wheel or on different road wheels. In the case where both wheel braking devices operate on the same wheel, it is possible to use both rim and disc brakes on the same wheel, thereby increasing braking performance to equate with an hydraulic brake but without the cost and complexity of installing an hydraulically operated disc brake; with this configuration the cycle can of course be provided with a first single brake lever at one end of the handlebars to operate dual brakes on the front wheel, and with a second single brake lever at the opposite end of the handlebars to operate single or dual brakes on the rear wheel.

The two wheel braking devices are preferably operable by a single brake cable which passes around a pulley carried by the brake lever. In this manner the single brake cable applies an equal force to both wheel braking devices without requiring any coordination by the cyclist. This brake lever is preferably mounted from a handlebar of the cycle for rotary movement about a first axis, and the pulley is mounted from the brake lever for rotary movement about a second axis spaced from the first axis. The first and second axes may be substantially parallel whereby a first portion of the single brake cable will engage the pulley at a position further away from the first axis than a second portion of the cable, the first portion of the cable being connected to operate a cantilever brake mechanism and the second portion of the cable being connected to operate a disk brake mechanism. In this manner the relatively greater movement required to operate the cantilever brake mechanism can be matched to the greater travel of the first portion of the brake cable.

The brake lever may be arranged to apply the same operating force to each braking device. In this event, each braking device may have a disengagement spring and the ratings of these springs are chosen to control the sequential operation of the braking devices.

The braking devices are preferably arranged to be actuated by respective brake mechanisms operable by the brake lever, and the mechanical advantage of each brake mechanisms is selected to provide a desired braking ratio between the braking devices.

According to another aspect of the invention a brake modification kit for a cycle comprises a single brake lever carrying a pulley, and a single brake cable which will en- gage the pulley and is provided at its ends with connectors for respective braking mechanisms. In this manner an existing bicycle can be readily converted so that a single brake lever will operate two wheel braking systems. This brake lever is preferably ar ranged for mounting to a cycle handlebar for rotary movement about a first axis, and the pulley is mounted from the brake lever for rotary movement about a second axis spaced from the first axis.

Brief Description of the Drawings

The accompanying drawings are diagrams illustrating one embodiment of the invention, as applied to a bicycle, by way of example only.

Figure 1 is a plan view of a single brake lever mounted adjacent the right hand end of the handlebars of a bicycle, the single brake lever being shown in its inoperative position; Figure 2 is the same as Figure 1 but shows the single brake lever in its operative position; Figure 3 is a side elevation of the front cycle fork of a bicycle together with as sociated disc brake and disc brake mechanism, the wheel being omitted for the sake of clarity, and Figure 4 is a transverse vertical section through the upper portion of a wheel rim and associated cantilever brake mechanism, the fittings to the bicycle being omitted for clarity.

Detailed Description of the Illustrated Embodiment

With reference to Figures 1 and 2, a single brake lever 10 is mounted adjacent to one end of a handlebar 11 for use in steering the front wheel of a bicycle in the usual manner. A brake mounting bracket 12 is secured to the handlebar by the usual clamp ing bolt 13. The single brake lever 10 is mounted from the brake mounting bracket 12 by a pivot 14 which defines a first axis.

A pulley 15 is mounted from the single brake lever 10 by a pivot 16 which de fines a second axis that is spaced further from the handlebar 11 than the first axis 14.

A single brake inner cable 17 is received in the grooved periphery of the pulley as shown and extends through separate outer casings 18 and 19 having their ends secured by respective threaded fixtures 20 and 21 to the outer end of the brake mounting bracket 12. In this manner, the outer casings 18 and 19 and the single brake inner cable 17 define two Bowden cables which lead to two wheel braking devices car ried by the bicycle.

With reference to Figure 2 it will be noted that, on pulling the single brake lever towards the handlebar 11, the pulley 15 is moved to the right along an arc struck about the first axis defined by pivot 14. This movement causes the single brake inner cable 17 to be drawn through both of the outer casings 18 and 19 to operate the re spective wheel braking devices. It will be noted that the pivots 14 and 16 are substan tially parallel whereby the operation of the single brake lever 10 will pull the portion of the inner cable passing through outer casing 18 a greater distance than the portion of the inner cable passing through the outer casing 19. This feature is particularly useful when the single brake lever 10 is used to operate wheel braking devices requiring dif fering amounts of travel. It is known that a disc brake mechanism, such as that shown in Figure 3, requires less travel than a cantilever brake mechanism such as that shown in Figure 4. For this reason, the portion of the inner cable 17 extending through the outer casing 19 is connected to operate the disc brake shown in Figure 3, whilst the portion of the brake inner cable 17 passing through the outer casing 18 is used to op erate the 'V' type cantilever brake shown in Figure 4.

The operation of the single brake lever 10, as illustrated in Figures 1 and 2, will be dependent on the rating of the return springs used in the respective braking devices.

Consequently, the portion of the single brake cable 17 connected to the brake with the weaker return spring will be the first to be drawn through its outer casing 18 or 19, the pulley 15 rotating to accommodate this differential movement. The brake inner cable 17 will continue to move against the weaker return spring until such time as the associ ated brake pad engages the brake surface. At this point, further movement of the sin gle brake lever 10 will move the other portion of the inner brake cable 17 against the greater force exerted by the second return spring until the brake pad of the second braking device becomes engaged. In this manner, the operation of the single brake lever 10 applies the appropriate tensile force to both portions of the single brake cable 17, the resultant force on the respective wheel braking devices being dependent upon the settings of their return springs. If both return springs are of the same rating, both braking mechanisms will be operated at substantially the same time with an equal force being applied to each thereby giving balanced braking. On the other hand, if the return springs are of different rating, the braking device with the lower rated return spring will engage first until the force exerted by the single brake lever overcomes the higher rating of the second wheel braking device. Accordingly, this arrangement enables twowheeled braking devices to be operated by the single brake lever 10 in a consistent and balanced manner.

The two-wheeled braking devices could either be operative on the same cycle wheel, or on different cycle wheels. The latter feature is particularly useful where the cyclist is only able to use one hand for operating the cycle brakes.

On the other hand, the single brake lever 10 can be used to operate two differ- ent braking devices on the same vehicle wheel, for instance the disc brake shown in Figure 3 and the 'Y' type cantilever rim brake shown in Figure 4. This combination of brakes provids wheel braking which can be of comparable capacity to a hydraulic disc brake without the cost and weight burdens of installing a hydraulic system.

Figure 3 shows a typical disc brake applied to the front fork 22 of a bicycle. The disc braking device comprises a slotted brake disc 23 having mounting holes 24 for attachment to the unshown front wheel of which the axle is received in the usual way in the slotted end 25 of the fork 22. As shown, the portion of the inner brake cable 17 that extends through the outer cable 19 operates a lever 26 to actuate the disc brake mechanism 27 which is arranged to push an unshown brake pad against the brake disc 23, release of the pad being effected by an unshown release spring in well-known manner.

In Figure 4 opposite sides of a wheel rim 28 are braked by a pair of brake blocks 29, 30 which are mounted in the usual manner from levers 31 and 32 for rota- tion towards the cycle wheel about pivots 33 and 34 by the operation of the portion of the inner brake cable 17 that extends through the outer casing 18. Release of the brake blocks 29, 30 is effected by an unshown release spring in the usual manner.

Claims

1. A cycle provided with two wheel braking devices and having a single brake lever arranged to operate both wheel braking devices.

2. A cycle, according to Claim 1, in which both of the wheel braking devices are arranged to operate on the same road wheel.

3. A cycle, according to Claim 1, in which each of the wheel braking devices is arranged to operate on different road wheels.

4. A cycle, according to any preceding claim, in which the two wheel braking devices are operable by a single brake cable which passes around a pulley carried by the brakelever.

5. A cycle, according to Claim 4, in which the brake lever is mounted from a handlebar of the cycle for rotary movement about a first axis, and the pulley is mounted from the brake lever for rotary movement about a second axis spaced from the first axis.

6. A cycle, according to Claim 5, in which the first and second axes are substan tiaily parallel whereby a first portion of the single brake cable engages the pulley at a position further away from the first axis than a second portion of the cable, the first portion of the cable being connected to operate a cantilever brake mechanism and the second portion of the cable being connected to operate a disk brake mechanism.

7. A cycle, according to any preceding claim, in which the brake lever is ar ranged to apply the same operating force to each braking device.

8. A cycle, according to Claim 7, in which each braking device has a disengage ment spring and the ratings of these springs are chosen to control the sequential opera tion of the braking devices.

9. A cycle, according to any preceding claim, in which the braking devices are arranged to be actuated by respective brake mechanisms operable by the brake lever, and the mechanical advantage of each brake mechanisms is selected to provide a de sired braking ratio between the braking devices.

10. A cycle substantially as described herein with reference to the accompanying drawings.

11. A brake modification kit for a cycle comprising a single brake lever carrying a pulley, and a single brake cable which will engage the pulley and is provided at its ends with connectors for respective braking mechanisms.

12. A brake modification kit, according to Claim 11, in which the brake lever is arranged for mounting to a cycle handlebar for rotary movement about a first axis, and the pulley is mounted from the brake lever for rotary movement about a second axis spaced from the first axis.

13. A brake modification kit substantially as described herein with reference to the accompanying drawings.