Cantilever brake device

A brake link for a cantilever device includes a basal end structured for rotatably supporting the brake link on a bicycle, an intermediate section structured for supporting a brake shoe, and a distal end. An anchor member is structured for attaching a cable thereto, and the distal end of the brake link is structured for detachably and nonrotatably engaging the anchor member.

BACKGROUND OF THE INVENTION 
The present invention is directed to cantilever bicycle brake devices. 
Bicycles capable of off-road travel, such as MTBs (mountain bikes) are 
equipped with cantilever brake devices in order to provide strong braking 
force. Cantilever brake devices straddle both sides of the bicycle rim to 
provide braking action, and are generally equipped with a pair of left and 
right brake links and brake shoes attached to the brake links. The brake 
links are rotatably supported in cantilever fashion on the front and rear 
forks, and their top ends are connected to cable components which are 
split into two at their distal ends. 
Cable component connection designs include the straddle cable design and 
the unit link design. In the straddle cable design, a straddle cable is 
linked through a metal hanger to the distal end of the inner cable, whose 
basal end is engaged by the brake lever, and both ends of the straddle 
cable are detachably linked to the brake links. With the straddle cable 
design, the brakes are adjusted by adjusting the inner cable attachment 
position using the metal hanger. The difficulty entailed in adjusting the 
attachment position has gradually led to the adoption of the unit link 
design. 
In the unit link design, the distal end of the inner cable is screwed 
directly to the distal end of one of the brake links. A branch cable, 
termed a unit link, is connected at some point along the inner cable, and 
the distal end of this branch cable is detachably engaged by the other 
brake link. However, since the unit link design involves screwing one of 
the brake links to the distal end of the inner cable, when the unit link 
is disengaged from the other brake link, it sometimes happens that the 
first brake link does not open sufficiently towards the brake release 
position if the inner cable is not made sufficiently slack. When this 
happens, sufficient space between the wheel and the brake shoes is not 
maintained, and the wheel may come into contact with the brake shoes, 
making it difficult to remove. 
To overcome this problem, one known design provides an anchor member 
secured to the distal end of the inner cable, wherein the anchor member is 
detachably engaged at the distal end of one of the brake links. The anchor 
member principally comprises a screw with a hexagonal hole and a 
cylindrical nut. A through hole which extends in the diametrical direction 
is made in the nut, and the inner cable is inserted through this through 
hole. The inner cable is pressed against the interior of the nut by the 
screw in order to secure the inner cable to the anchor member. 
With the conventional cantilever brake device described above, when the 
wheel is to be removed from the fork, the unit link and the anchor member 
are disengaged from the two brake links. This allows the two brake links 
to be opened towards the brake release position, ensuring that there is 
sufficient space between the wheel and the break shoes to allow the wheel 
to be removed with ease. However, during brake adjustment, a wrench, 
screwdriver, or other tool must be used on the screw and nut while the 
anchor member is engaged by the brake link, and the length of the inner 
cable must be adjusted using these tools while manipulating the brake link 
and the inner cable. Thus, brake adjustment is difficult to perform alone, 
and is a fairly complicated operation. 
SUMMARY OF THE INVENTION 
The present invention is directed to a cantilever brake device for a 
bicycle which facilitates adjustment of the brake by one person. In one 
embodiment of the present invention, a brake link for a cantilever brake 
arm apparatus includes a basal end structured for rotatably supporting the 
brake link on a bicycle, an intermediate section structured for supporting 
a brake shoe, and a distal end. An anchor member is structured for 
attaching a cable thereto, and the distal end of the brake link is 
structured for detachably and nonrotatably engaging the anchor member. In 
a more specific embodiment, the anchor member includes a first screw 
member and a second screw member. The first screw member and the second 
screw member are structured for fixing the cable to the anchor member when 
the first screw member and second screw member are screwed together. The 
first screw member may comprise a bolt having a head section and a shaft 
section, wherein the distal end of the brake link includes a convex 
section for nonrotatably receiving the head section of the bolt therein. 
The inventive brake link may be incorporated in a complete cantilever brake 
device. In this case the device includes a cable having a first end 
connected to a brake lever and first and second second ends. The anchor 
member of the brake link described above may be connected to the first 
second end of the cable. A second brake link includes a basal end 
structured for rotatably supporting the second brake link on the bicycle, 
an intermediate section structured for supporting a brake shoe, and a 
distal end for detachably engaging the second second end of the cable. 
Each brake link includes a biasing means for biasing the brake link 
laterally outwardly.

DETAILED DESCRIPTION OF THE EMBODIMENTS 
A cantilever brake device 1 pertaining to one embodiment of the present 
invention, for example, a device for front wheel use, is illustrated in 
FIGS. 1 and 2. The brake device 1 is rotatably supported on the front fork 
4 of the frame 3. The front fork 4 comprises, for example, an air/oil 
system or elastomer system suspension fork capable of absorbing shock from 
the pavement. The front fork 4 is equipped with a pair of left and right 
suspension members 4a, mounting members 4b for mounting the pair of 
suspension members 4a, and a stabilizer 4c for reinforcing the suspension 
members 4a. The stabilizer 4c is essentially of an inverted U-shape which 
splits into two arms. Its bottom ends are affixed at points midway down 
the suspension members 4a, and the top end is equipped with a cable stay 
4d that retains the outer casing. 
A pair of left and right pedestals 8a and 8b are disposed at the bottom 
ends of the stabilizer 4c. As shown in FIG. 5, stepped mounting pins 9a 
and 9b (only 9a is shown) project forward from the pedestals 8a and 8b. 
Three engagement holes 15a, 15b, and 15c are made on each pedestal 8a and 
8b, and they are disposed on a circle which is centered on the mounting 
pin 9a (9b) in order to engage a coil spring (described later) which is 
provided to the brake device 1. 
As shown in FIG. 2 and FIG. 3, the distal end of the inner cable 10, whose 
basal end is linked to a brake lever 7 provided to the handlebar 6, and 
the distal end of a branch cable (termed a unit link), which is linked to 
the inner cable 10 at some point, are linked to the brake device 1. An 
anchor fitting 14 is screwed onto the distal end of the inner cable 10. 
The branch cable 11 is provided with a branch fitting 11a which is movably 
disposed midway down the inner cable 10, a cable 11b whose basal end is 
secured to the branch fitting 11a by staking, and a cylindrical engagement 
fitting secured to the distal end of the cable 11b by staking. 
The brake device 1 is equipped with a pair of left and right brake links 
12a and 12b whose distal ends are detachably linked to the inner cable 10 
and the branch cable 11, respectively, and with brake shoes 13a and 13b 
which are mounted facing each other in an adjustable manner midway down 
the brake links 12a and 12b. Braking action is provided by bringing brake 
shoes 13a and 13b into contact with the side surfaces 5a of the rim 5 of 
the wheel 2. 
As shown in FIG. 2 and FIG. 3, the brake links 12a and 12b have 
plate-shaped link bodies 20a and 20b which bend outward at the top and 
which have been lightened at the back surfaces. The basal ends of the link 
bodies 20a and 20b are provided with rotatably supported members 16a and 
16b which are rotatably supported on the mounting pins 9a and 9b which 
project from the pedestals 8a and 8b. The midsections are provided with 
shoe mounting members 17a and 17b for mounting the brake shoes 13a and 
13b. The distal end of the link body 20a is equipped with a first 
engagement member 18a which detachably engages the anchor fitting 14, and 
the distal end of the link body 20b is equipped with a second engagement 
member 18b which detachably engages the engagement fitting 11c. 
In the following discussion, description of components that are identical 
for the left and right brake links 12a and 12b will be described only for 
the left side (the right side in FIG. 2). 
As shown in FIG. 4, the rotatably supported member 16a is provided with a 
cylindrical bushing 21a that fits over the mounting pin 9a which has been 
staked to the basal end of the link body 20a, and with a bottomed 
cylindrical spring cover 22a that is mounted around the outside surface of 
the bushing 21a. A cylindrical gap 23a is formed between the spring cover 
22a and the bushing 21a. Gap 23a houses a coil spring 25a that energizes 
the brake link 12a towards the brake release position. As shown in FIG. 5, 
the back end 26a of the coil spring 25a is engaged by one of the 
engagement holes 15a, 15b, and 15c that have been made in the pedestal 8a. 
By varying the engagement position among the engagement holes 15a, 15b, or 
15c, it is possible to adjust the strength of the force towards the brake 
release position between three different levels. The front end of the coil 
spring (not shown) is engaged by the bottom of the spring cover 22a. The 
engagement position of the front end of the coil spring 25a on the brake 
link side 12a can be moved in the circumferential direction of the 
mounting pin by means of a spring adjustment screw 27 which screws into 
the outside wall of the spring cover 22a. 
A spring cap 28a which covers the back end of the coil spring 25a is 
rotatably mounted on the back of the spring cover 22a. The spring cap 28a 
is provided with a cylindrical section 30a which fits over the 
large-diameter section of the mounting pin 9a, and with a rotation control 
member 31a of triangular form which projects outward from the peripheral 
surface of the cylindrical section 30a. The bottom of the spring cover 22a 
is provided with a through-hole 32a (FIG. 5) through which the back end 
26a of the coil spring 25a passes, whereby the coil spring 25a may be 
engaged. 
The provision of a spring cap 28a of this design allows the back end 26a of 
the coil spring 25a to be set to any desired position simply by rotating 
the spring cap 28a. Thus, even where the rotation of the brake link 12a is 
restricted, preventing the back end 26a of the coil spring 25a from being 
inserted into desired engagement hole 15a-15c in the natural state, the 
back end 26a can be inserted easily into desired engagement hole 15a-15c 
simply by rotating the spring cap 28a. The spring cap 28a mounting angle 
(orientation of the distal end of the spring cap 28a) changes depending on 
the engagement hole 15a-15c in which the coil spring 25a is engaged, so 
the engagement position of the coil spring 25a, that is, the strength of 
the force towards the brake release position, can be readily determined 
from the orientation of the spring cap 28a. For example, when the coil 
spring 25a is engaged by the engagement hole 15b, the distal end of spring 
cap 28a faces downward. When the coil spring 25a is engaged by the 
engagement hole 15a, the distal end faces diagonally inward. When the coil 
spring is engaged by the engagement hole 15c, the distal end faces 
diagonally outward. Thus, the strength of the force towards the brake 
release position can be readily determined from the orientation of the 
spring cap 28a. 
As shown in FIG. 2 through FIG. 4, the shoe mounting member 17a is provided 
with a shoe mounting bolt 40a which is inserted from the back end of a 
slot 35a made in the central section of the link body 20a, a washer 41a 
which fits over the shoe mounting bolt 40a so as to sandwich the link body 
20a, and a collar 42a. The head 45a of the shoe mounting bolt 40a, which 
is located at the back side of the link body 20a, has a shoe mounting hole 
46a which extends in the lateral direction (perpendicular to the plane of 
the paper in FIG. 4). 
As shown in FIG. 3 and FIG. 4, the brake shoe 13a is provided with a rubber 
shoe body 60a and with a shoe mounting pin 61a which projects outward from 
the approximate center of the shoe body 60a in the lengthwise direction. 
The shoe body 60a is thinner than conventional products and does not 
readily deform during braking. The shoe mounting pin 61a fits through a 
shoe mounting hole 46a provided in the shoe mounting bolt 40a. 
The brake shoe 13a is disposed on the front fork 4 side of the brake link 
12a, so the distance from the front fork 4 is shorter, and the moment 
produced by reaction force from the rim acting on the brake shoe 13a is 
lower. Thus, a decline in breaking force due to torsion of the fork does 
not result even when a suspension fork with relatively low torsional 
rigidity is used. Since the shoe body 60a itself is thin, flexural 
deformation of the shoe body 60a during braking is minimized, in turn 
minimizing the decline in braking force. 
As shown in FIG. 6 through FIG. 8, the first engagement member 118a has a 
convex section 50 comprising a square hole formed at the distal end of the 
link body 20a. The convex section 50 opens laterally outward (as defined 
in FIGS. 2 and 3) towards the brake release position. A cable groove 51, 
through which the inner cable 10 is passed, is formed at the distal end of 
the link body 20a. Cable groove 51 is located further to the inside and 
above the convex section 50. In this embodiment, the side of the cable 
groove 51 from which the cable enters is provided with a mounting hole 53 
for mounting a protective tube 52 in order to prevent the inner cable 10 
from being severed when it is bent. 
The anchor fitting 14 is provided with an anchor bolt 55 which is engaged 
by the convex section 50 in a nonrotatable manner, an anchor nut 56 which 
screws onto the anchor bolt 55, an anchor collar 57 which fits over the 
anchor bolt 55, and a detachment prevention member 58 for preventing the 
anchor fitting 14 from becoming detached from the first engagement member 
18a. In this embodiment, the head 55a of the anchor bolt 55 is square so 
that it may be engaged by the convex section 50 of the first engagement 
member 18a in a nonrotatable manner. The shaft section of the anchor bolt 
55 is double chamfered on the base end, and a cable hole 55c through which 
the inner cable 10 passes is formed in the direction of the diameter. The 
anchor collar 57 is a component which presses the inner cable 10 against 
the cable hole 55c when the anchor nut 56 is tightened in order to anchor 
the inner cable 10 within the anchor fitting 14. 
The detachment prevention member 58 is a component fabricated from a 
synthetic resin, and it fits around the exterior of the anchor collar 57. 
As shown in FIG. 9, detachment prevention member 58 is provided with a 
ring member 60, a pair of rotation preventing members 61 and 61 which 
project upward from the ring member 60 in FIG. 9, and an engagement member 
62 which projects outward from the ring member 60 and which is engaged by 
the distal end of the link body 20a. The ring member 60 fits around the 
outside of the anchor collar 57. When the ring member 60 is fitted around 
the anchor collar 57, the rotation preventing members 61 and 61 contact 
the head 55a of the anchor bolt 55 and prevent the detachment prevention 
member 58 from rotating. The engagement member 62 is provided with a 
projecting member 63 which projects outward from the ring member 60 in a 
tangential direction, a clip member 65, disposed at the distal end of the 
projecting member 63 and provided with a pair of tongue members 66 and 67 
disposed at intervals along its inside edge, and a connecting member 64 
which connects the projecting member 63 and the clip member 65. When the 
detachment prevention member 58 has been fitted around the anchor collar 
57, its engagement member 62 fits over the link body 20a to the rear of 
the cable groove 51 so that the anchor fitting 14 is prevented from 
becoming detached from the first engagement member 18a even when the inner 
cable 10 is not tensed. Since the anchor fitting 14 is detachable from the 
first engagement member 18a, the brake link 12a can be opened reliably 
with being affected by the inner cable 10, even in a unit link design. 
When brake adjustment is to be performed on a brake device 1 constituted in 
this way, the anchor nut 56 of the anchor fitting 14 is loosened, 
releasing the end of the anchored inner cable 10. Holding the brake link 
12a in the proper position, the anchor nut 56 is turned to perform brake 
adjustment. Since the anchor bolt 55 is prevented from turning, it is 
unnecessary to hold the anchor bolt 55 using a tool. Thus, brake 
adjustment can be performed easily by one person, and the gaps between the 
rim and the brake shoes can be appropriately maintained. Of course, where 
the bicycle manufacturer has set the anchor position of the anchor fitting 
14 with respect to the inner cable 10 at the factory, optimal brake 
adjustment can be accomplished subsequently simply by anchoring the anchor 
fitting 14 in this position. 
When the wheel 2 is to be attached or detached, the brake links 12a and 12b 
are held closed while disengaging the anchor fitting 14 from the first 
engagement member 18a of the brake link 12a and disengaging the engagement 
fitting 11c from the second engagement member 18b of the brake link 12b. 
As a result, the two brake links 12a and 12b are energized towards the 
brake release position (laterally outward) by the coil springs 25a and 
25b. The brake shoes 13a and 13b open until the shoe bodies 60a and 60b 
come into contact with the stabilizer 4c. Since the brake line 12a on the 
side to which the inner cable 10 is linked opens reliably, the front wheel 
2 can be attached or detached with ease. 
When installing the brake device on the mounting pins 9a and 9b, the 
rotatably supported members 16a and 16b are mounted onto the mounting pins 
9a and 9b, and the rotation control member 31 is grasped with the fingers 
to position the back ends 26a and 26b of the coil springs 25a and 25b into 
any one of the desired engagement holes 15a-15c. In this state, pushing 
the rotatably supported members 16a and 16b are further back causes the 
back ends 26a and 26b to enter the selected engagement hole 15a-15c. 
Since the brake shoes 13a and 13b are disposed on the front fork 4 side of 
the brake links 12a and 12b in order to maintain strong braking force, the 
back edges of the shoe bodies 60a and 60b come into contact with the 
stabilizer 4c, thereby restricting rotation of the brake links 12a and 12b 
towards the brake release position. However, since the engagement 
positions of the back ends 26a and 26b of the coil springs 25a and 25b can 
be freely changed using the rotation control members 31a and 31b, the ends 
of the coil springs 25a and 25b can be reliably inserted into the desired 
engagement holes 15a-15c even where the rotation of the brake links 12a 
and 12b is restricted. 
While the above is a description of various embodiments of the present 
invention, further modifications may be employed without departing from 
the spirit and scope of the present invention. For example, the present 
invention may be implemented in the rear brake instead of the front brake, 
and the present invention may be implemented in a brake device of straddle 
cable design rather than of unit link design. The method for engaging the 
anchor fitting in a nonrotatable manner is no limited to that shown in the 
embodiment. 
Thus, the scope of the invention should not be limited by the specific 
structures disclosed. Instead, the true scope of the invention should be 
determined by the following claims. Of course, although labeling symbols 
are used in the claims in order to facilitate reference to the figures, 
the present invention is not intended to be limited to the constructions 
in the appended figures by such labeling.