Adjustable brake control for a bicycle

The brake lever system includes a cable attachment fitting which rides within an open slot of a brake lever body which tilts away from the departure point of the brake cable as a brake lever body is pivoted away from a brake lever housing. A threaded screw or rod carried within the open slot can be adjusted to raise or lower the height of a rectangular or other block which rides without turning within the open slot and which forms an adjustable lower limit below which the cable attachment fitting cannot travel. When activated, the cable attachment fitting moves in the direction of the point of pivot and the mechanical advantage is increased to the limit permitted by the metal block within the open slot. This produces a rapid closure of the brakes during the first extent of brake engagement, and a much less rapid closure as the brake lever body is displaced from the brake lever housing. The brake lever system of the present invention can be adjusted during the riding operation of the bicycle to adjust for brake pad wear and for changing conditions which might cause the brake cable to expand or contract.

FIELD OF THE INVENTION 
The present invention relates to the field of an improved, adjustable hand 
brake for a bicycle which enables continuous adjustment of the maximum 
mechanical advantage to be applied to a braking system while enabling the 
brakes to return to a maximum open position after the application of 
braking. 
BACKGROUND OF THE INVENTION 
Bicycle brakes include hand brakes mounted to the handle bars of a bicycle. 
The hand brake usually includes a circular mounting portion which 
surrounds the handle bar, and which supports a main housing. The main 
housing usually supports a brake lever pivotally mounted to the main 
housing. The main housing may engage an annular brake cable assembly in a 
manner to allow the brake lever to pull the center brake cable with 
respect to the outer brake cable. 
In most bicycles, the inner brake cable is connected directly to a point on 
the brake lever. In this instance, the angular displacement of the 
pivoting action of the lever translates into a proportional closing of the 
brake shoes against the wheel rim. There may be some trigonometric effect 
since the inner cable is being pivoted away from a support point in the 
brake lever housing. However, since the inner brake cable is supported at 
a constant radius from the pivot point, this effect in a standard system 
is not as pronounced. 
In more specialized systems, there exists the possibility to increase the 
mechanical advantage to be applied to the brake cable. This is 
accomplished by reducing the radial distance between the end of the inner 
brake cable being pulled and the axis of pivot of the brake lever. In one 
known configuration, a series of spacers may selectively removed to enable 
a reduced radius. However, the user cannot adjust the system during the 
riding of the bicycle. This situation is potentially dangerous since the 
brake system of a bicycle becomes more loosely linked over time. The brake 
pads wear, the brake cable and associated hardware can become stretched if 
the brakes are applied too strongly. If any of the brake system changes 
during a ride such that brake lever displacement becomes insufficient to 
engage the brakes, the rider will have lost a portion or all of his 
braking ability. 
Further, the use of removable inserts enables only discrete adjustment. 
Removal of one insert may immediately make the braking system too lax and 
eliminate braking ability, forcing a re-adjustment of the braking system. 
If the braking system becomes too lax, and if the user has the luxury of 
re-adjusting the system, the overall range of pull available to the system 
will still be limited. 
Another system which is known uses a set screw to force a second pivoted 
fitting outward to force the brake cable to be pulled from a radially 
fixed perspective as the brake lever is depressed. This system is not 
adjustable by the rider during operation of the bicycle and requires a 
hexagon wrench since it is a hard adjustment of a set screw which bears 
against a portion of the brake lever. The device cannot be adjusted to 
give a smaller radial distance from the point of cable pull to the point 
of pivot. Thus, adjustability extends from a starting point of minimum 
adjustment to a maximum radius of the cable pull to the point of pivot. 
Further, adjustment to maximum has been shown to lift the point of cable 
pull too far from the point of pivot, and to cause the cable connect 
fitting to interfere with the brake lever housing. 
Another prior art device is described in U.S. Pat. No. 5,448,927 and 
entitled "Adjustable Leverage Brake Lever" and issued to Wayne R. Lumpkin 
on Sep. 12, 1995. This device enables the pull point of the brake cable to 
be adjusted radially with a threaded bolt to any one of a number of fixed 
radial positions which are adjustable to be closer to or farther from the 
pivot point. The central problem with this device is that it does not 
allow the brake cable to return to a position which would leave the brakes 
in the maximum open position. Thus, where the adjustment is positioned to 
increase the mechanical advantage, it also reduces the range of travel of 
the brake cable from both its maximally extended and maximally retracted 
positions and toward the midpoint of the two extremes. This disenables the 
brakes from assuming the maximum open position and can cause unwanted 
rubbing of the brake shoe on the rim. 
What is therefore needed is a braking system which will allow adjustment 
during riding to insure that the rider has maximum brake control and to 
insure that the rider will always be able to adjust the brakes to insure 
that full braking may be applied before the brake lever is limited in its 
travel by the handle bar. The system should not have significant 
resistance to adjustment of the brake, and should operate as smoothly and 
as effortlessly as possible. 
SUMMARY OF THE INVENTION 
The brake lever system disclosed includes a cable attachment fitting which 
rides within an open slot which tilts away from the departure point of the 
brake cable as a brake lever body is pivoted away from a brake lever 
housing. A threaded screw or rod carried within the open slot can be 
adjusted to raise or lower the height of a rectangular or other block 
which rides without turning within the open slot. The metal block forms an 
adjustable lower limit below which the cable attachment fitting cannot 
travel. The open slot is angled to encourage the cable attachment fitting 
to ride to the top of the open slot when the brake lever body is in the 
maximum brake off position to enable the brake cable to be maximally 
returned to enable the brakes to open to their widest position. When 
activated, the cable attachment fitting 117 moves in the direction of the 
point of pivot and the mechanical advantage is increased to the limit 
permitted by the metal block within the open slot. This produces a rapid 
closure of the brakes during the first extent of brake engagement, and a 
much less rapid closure as the brake lever body is displaced from the 
brake lever housing. The brake lever system of the present invention can 
be adjusted during the riding operation of the bicycle to adjust for brake 
pad wear and for changing conditions which might cause the brake cable to 
expand or contract.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 1, a prior art embodiment of a brake lever system 11 
illustrates a handle body portion 13, having an extended lever portion 15 
and pivotally depending from a brake lever housing 17. The brake lever 
housing 17 is attached to a handle bar section 19 such that the lever 
portion 15 opposes a handle 21. 
A cable 23 is attached to a brake cable fitting 25 which rides within an 
open slot 27 in the handle body portion 13. A series of removable spacers 
29, 31 prevent the brake cable fitting 25 from moving downwardly within 
the open slot 27 as the handle body portion 13 is angularly displaced with 
respect to the brake lever housing 17. The user can remove tiny screws to 
sequentially remove the spacer 29 and perhaps the spacer 31 from within 
the open slot 27. 
Once spacer 29 is removed, for example, the fitting 25 can move further 
toward the axis of pivot of the handle body portion 13 with respect to the 
brake lever housing 17. This pivot point is shown as a pin 33 which joins 
the handle body portion 13 to the brake lever housing 17. Upon activation 
of the brake lever 15, the fitting 25 will move to the bottom of the slot 
27 to give a unit jump to the most mechanically advantaged position. With 
the brake lever system 11 of FIG. 1, the only way to limit the maximum 
mechanical advantage is to re-insert one or both of the spacers 29 and 31 
which requires a tiny screwdriver to re-insert screws holding the spacers 
29 and 31 in place. 
Referring to FIG. 2, a second prior art brake lever system 51 is shown. 
Brake lever system 51 illustrates a handle body portion 53 having an 
extended lever portion 55 and pivotally depending from a brake lever 
housing 57. The brake lever housing 57 is attached to a handle bar section 
59 such that the lever portion 55 opposes a handle 61. 
A cable 63 is attached to a brake cable fitting 65 which is pivotally 
attached to handle body portion 53. The cable fitting 65 also included a 
set off screw 67 which threadably engages the cable fitting 65 and can 
limit the pivot of the cable fitting 65 with the pivotal displacement of 
the handle body portion 53. By forcing the cable fitting 65 away from the 
handle body portion 53, the cable 63 is pulled from a point radially more 
outward from the handle body portion 53. However, the set screw is not 
easy to turn and requires a hex wrench. Further, the head of the screw 
sits close to or within the brake lever housing 57. The forces handled by 
the set off screw 67 are high and therefore it is expected that a manual 
adjustment is difficult to make. The radial pull cannot be lowered, but 
only raised by compression of the set off screw 67. Further, there is a 
jump transition represented by the instant transition from one radial pull 
point to a second radial pull point. 
The preferred embodiment of the invention is described beginning at FIG. 3. 
A plan view of a brake lever system 101 illustrates a brake lever housing 
103 which has a lower portion 105 suitable for attachment to a bicycle 
handle bar. There is an adjustment knob 107 extending from a brake lever 
body 109. Brake lever body 109 sits adjacent to an extended brake lever 
111. To the left of the brake lever system 101 is a brake cable 113 
extending into standard threaded inserts 115. 
Referring to FIG. 4, a top view of the brake lever system 101. Shown in 
phantom is a cable attachment fitting 117 having an overall "U" shape. The 
bottom portion of the "U" shape engages the cable 113 end, while the side 
portions of the "U" shape extend toward and outside of the brake lever 
housing. 
Referring to FIG. 5, a side sectional view of the brake lever system 101 is 
shown. The cable 113 terminates in an enlarged portion 119 which enables 
the cable attachment fitting 117 to have axial engagement with the cable 
113. The ends of the "U" shaped cable attachment fitting 117 have 
apertures for engaging cross bar which acts as a cable fitting support 
121. The cross bar extends traversely through an open slot 123 in the 
brake lever body 109. 
A threaded rod or screw 125 extends through the open slot 123 in a 
longitudinal orientation. The threaded screw 125 enters the brake lever 
body 109 from the outside, extends into the slot through its outer end and 
through the slot to the inner end, through the inner end and out of the 
rear side of the brake lever body 109. The tip end of the threaded screw 
125 is secured by a lock washer 127 to insure that the threaded screw 125 
can be axially rotated within the brake lever body 109, but will not be 
axially removable from the brake lever body 109. 
Also shown surrounding the threaded screw 125 is a rectangular metal block 
129. The block 129 lightly engages the inside of the slot 123 and is urged 
upwardly and downwardly in the slot 123 by the turning of the threaded 
bolt 125. The block 129 limits the downward extent of travel of the 117. 
By making the limit variable beneath the cable attachment fitting 117, the 
cable attachment fitting 117 is always free to return to a position which 
returns the brake cable 113 to a position associated with the maximum open 
brake position. 
This differs significantly from the configuration of the 5,448,927 patent 
in which the member which engages the cable attachment fitting is fixed on 
the threaded screw. Fixation on the threaded screw, or any other structure 
on the handle creates a bilateral mechanical advantage. When the cable 
attachment fitting is fixed at its highest position, the minimum 
mechanical advantage is had, along with the maximum open brake on release 
of the brake lever. As the cable attachment fitting is adjusted closer to 
the point of pivot, the mechanical advantage is increased, but a release 
of the lever will not return the brakes to the maximum open position. This 
is because the cable would retain a portion of its displacement in the 
direction of the handle even when the brake lever was fully released. 
The brake lever system 101 captures the benefits of mechanical advantage on 
braking with the advantages of enabling the brake to assume the full open 
position when the brake handle is released. This is achieved because the 
cable fitting support 121 overlies and does not mechanically engage the 
threaded screw 125. In fact, the mechanism shown in FIG. 5 can be 
constructed such that the cable fitting support 121 does not even touch 
the threaded screw 125. In this circumstance, the outer portion of the 
cable fitting support 121 could be sufficiently large to slide against the 
inside surfaces of the slot 123. 
The rectangular metal block 129 may also be sized to gently ride within the 
slot 123, with sufficient contact and clearance that the block 129 may 
have some play within the open slot 123. However, the rectangular block 
129 will definitely contact the lower side of either the cable attachment 
fitting 117 or the cable fitting support 121 when the brake lever system 
101 is engaged, since the rectangular block 129 limits the downward 
displacement of the cable attachment fitting 117. 
Initially, the brake lever system 101 will be adjusted to insure that full 
open brake is available when the lever is released, and that the 
rectangular block is low enough that the maximum mechanical advantage is 
obtained and that the brakes are fully engaged at a point before the 
extended brake lever 111 touches handle 131 shown in phantom. As the 
brakes wear, the lever 111 will come closer and closer to the handle 131. 
When this occurs, the rider can simply adjust the threaded screw 125 by 
the knob 107 to reduce the mechanical advantage and insure that the brakes 
are fully engaged before the lever 111 is limited in its travel by the 
handle 131. 
In addition to effects from brake wear, other effects may be present. The 
brake cable 113 may significantly elongate during hot conditions and 
significantly contract in cold conditions. In this event, a simple manual 
adjustment can be made during the riding of the bicycle in order to bring 
the brake lever system 101 back into a preferred operational region. A 
spring 132 surrounds the pivot axis and urges the brake lever body 109 to 
a maximum open brake position. 
The specific operation of the brake lever system is shown in three 
positions with regard to FIGS. 6-8. FIG. 6 illustrates a closeup view of 
the brake lever system 101, as was shown in FIG. 5, but with a schematic 
connection to a brake schematic. The brake cable 113 is connected to a set 
of brake calipers 133. Although the calipers 133 are shown schematically, 
it is understood that modern braking systems can be of several types and 
will typically involve a good deal more detail than is shown in the FIG. 
6. 
At the ends of the brake calipers 133 are a pair of brake pads 135 which 
will engage the rim 137 of a bicycle wheel 139 shown in schematic format. 
As can be seen in FIG. 6, the brake lever body 109 is in a full open brake 
position. This occurs because when the brake lever body 109 is in the 
fully closed position, the open slot 123 is slightly tilted to encourage 
the cable attachment member 117 to be urged toward the upper end of the 
open slot 123. 
As the brake lever body 109 is displaced away from the brake lever housing 
103, the cable fitting support 121 and the cable attachment fitting 117 
begin to be displaced downwardly along the threaded screw 125 and 
downwardly within the open slot 123. As the cable fitting support 121 and 
the cable attachment fitting 117 are displaced closer to the pivot point 
represented by the pinned attachment of the brake lever body 109 to the 
brake lever housing 103 at the connection 141, the mechanical advantage is 
increased. 
As the brake lever body 109 is continued to be displaced with respect to 
the brake lever housing 103, the cable fitting support 121 and the cable 
attachment fitting 117 continue downward until the rectangular block 129 
is engaged by the cable fitting support 121. This limits the maximum 
downward displacement of the cable fitting support 121 and the cable 
attachment fitting 117. The adjustment of the knob 107 to displace the 
rectangular block 129 either toward or away from the point of pivot 
represented by pin or bolted attachment 141 will control the mechanical 
advantage to be achieved. Easy manual adjustment between braking periods 
is enabled. Note in FIG. 8 that the calipers 133 are now fully closed 
about the wheel 139. 
The use of a slot as a transition between the upper position and the lower 
position, enables a smooth transition from one point of mechanical 
advantage to another. Unlike the two pivot points encountered in FIG. 2, 
the system 101 enables a smooth adjustable transition. Because the 
mechanical advantage is changing, note that FIG. 7, the half way 
transition of the brake lever body 109 represents a two-thirds closure of 
the calipers 133 and brake pads 135 against the bicycle wheel 139. The 
remaining closure is accomplished with even greater mechanical advantage 
as shown in FIG. 8. 
While the present invention has been described in terms of a mechanical 
brake lever system for use with a bicycle, one skilled in the art will 
realize that the structure and techniques of the present invention can be 
applied to many appliances. The present invention may be applied in any 
situation where a smooth, adjustable transition is to be made from one 
mechanical advantage to another. 
Although the invention has been derived with reference to particular 
illustrative embodiments thereof, many changes and modifications of the 
invention may become apparent to those skilled in the art without 
departing from the spirit and scope of the invention. Therefore, included 
within the patent warranted hereon are all such changes and modifications 
as may reasonably and properly be included within the scope of this 
contribution to the art.