Land vehicles – Wheeled – Occupant propelled type
Reexamination Certificate
2001-08-01
2003-10-14
Morris, Lesley D. (Department: 3611)
Land vehicles
Wheeled
Occupant propelled type
Reexamination Certificate
active
06631915
ABSTRACT:
STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT
(Not Applicable)
REFERENCE TO A “MICROFICHE APPENDIX”
(Not Applicable)
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates generally to suspension components on a vehicle having a single front wheel, and more particularly to a bicycle front fork travel limiter.
2. Description of the Related Art
Conventional bicycles have a frame component to which the front wheel is mounted. This component is the fork, which has legs that are positioned on opposite sides of the wheel. The wheel's axle mounts to or near the lower ends of each of the fork's legs and the radially extending portion of the wheel is interposed between the legs.
The legs of the fork extend upwardly from the wheel's axle to a crown, which rigidly connects the upper ends of the fork together just above the peripheral tread surface of the tire on the wheel. A cylindrical steering tube is rigidly mounted to the upper surface of the crown, extending approximately vertically through a cylindrical passage at the front of the bicycle's frame. The cylindrical passage's axis is coincident with the steering tube's axis, and the cylindrical passage thereby functions as a bearing to support the steering tube and permit it to rotate about the axis of the steering tube. There are normally ball bearings to reduce the friction at the interface of the steering tube with the cylindrical passage.
The steering tube is mounted to the steering stem, which is the structure to which the handlebars attach. Therefore, when the handlebars are pivoted about the axis of the steering tube, the fork and the wheel's axle, and therefore the wheel, rotate.
On some conventional bicycles, especially those designed for off-road use, there are shock-absorbing structures built into the bicycle's frame. The shock-absorbing structure of the front wheel is ordinarily built into the fork. The most common example is a telescoping structure in which each of the fork's legs is divided into two telescopically engaging members. In such a telescoping structure, each leg comprises an upper leg member having an outer, cylindrical surface extending downwardly from the crown into a lower leg member having an internal cylindrical surface. Typically the telescoping arrangement contains coils, elastomeric materials, compressed gas or other mechanical means for biasing the leg members away from one another and for damping the spring action of the fork, just as in shock absorbers for other vehicles. It is important for the purposes of negotiating the ruts and bumps of rough terrain for a bicycle to have shock-absorbing capability, particularly at its front wheel.
All things being equal, the longer the relative movement between the upper member of the suspension fork and its lower member, the greater its capability to absorb shocks. However, the size of the front wheel of the bicycle affects the lower limit of the movement, or travel, of the upper member part of the fork. Increasing the travel of the lower member necessitates extending the upper member of the fork upward, and thereby necessitates an increase in the height of the front of the bicycle to accommodate this extension. This extension of the fork and corresponding increase in ride height results in two well-known problems.
The first problem occurs because, for mechanical reasons, the steering tube of most bicycles is tilted backward from true vertical, placing the wheel's axle slightly forward of the steering tube. As the fork is extended upward to allow for greater travel, the angle between the fork and the plane of the ground must become more acute to accommodate the size restrictions discussed above. This results in less precise steering, a larger turning radius and other disadvantages that are well known in the art.
The second problem is that the greater the height of the front of the bicycle, the greater the difficulty a rider has maintaining optimum position and weight distribution when climbing a hill.
In addition to these two problems related to the increase in height of the front of the bicycle inherent in suspension forks, there is another problem related to the telescopic movement of the fork. During vigorous pedaling, as during climbing and sprinting, a bicycle rider must stabilize himself with the handlebars while rapidly shifting his position from side to side relative to the bicycle. At such times the same range of travel of the suspension fork that is advantageous in absorbing shocks becomes disadvantageous insofar as it absorbs energy that would otherwise be transmitted to the drive wheel. A temporary decrease in the front fork's travel range would help a rider in such a situation. In other situations, such as making banking turns over smooth terrain, a rider would benefit from a temporary increase in the fork's resistance to movement and a decrease in its range of movement.
Various devices have been created to address the problems cited above. Some of these consist of fork “lock-out” mechanisms that substantially increase the fork's resistance to movement under compression, either by mechanically preloading the spring or by severely restricting the transit of a gas or fluid damping media. These devices solve one problem, that of undesired movement of the fork in certain situations. Typically, however, they maintain the fork at the upper limit of its extension, exacerbating the problems caused by increased height of the front of the bicycle.
One type of lock-out allows the fork to be “frozen” or arrested in a partially compressed position by completely closing off the orifices which permit the flow of damping fluid in the shock-absorbing mechanism. Rather than simply altering the fork's range and threshold of movement to better suit a given situation, this device less ideally eliminates all suspension action in the front end of the bicycle.
Further disadvantages to lock-out devices include difficulty of engagement due to the position of the device on the bicycle and, where they involve hydraulic valving, the cost of manufacture.
Therefore, the need exists for a mechanism that when actuated limits the extension of the front fork and thereby lowers the height of the bicycle's front end while increasing the threshold of movement of the fork by effectively preloading its spring. Such a device would allow the rider to improve the front-end geometry of the bicycle for climbing and steering at speed. At the same time, the device would reduce “bob” or unwanted fork movement in such situations while still retaining a degree of front-end suspension for negotiating roughness in the terrain.
SUMMARY OF THE INVENTION
The invention is a bicycle fork travel limiter mounted to a bicycle frame. The frame includes a front wheel fork having first and second legs extending around opposite sides of a front wheel. Each of the legs has an upper leg member moveably connected to a corresponding lower leg member. Each of the lower leg members is movable relative to its corresponding upper leg member in a compression direction and an opposite, rebound direction through an original fork stroke.
With reference to
FIG. 1
, the travel limiter comprises a first link, such as the member
11
, connected to at least one of the upper leg members, and a second link, such as the cable
26
, connected to at least one of the lower leg members. Actuable means, such as the travel limiter
10
, is connected to the first and second links for, when the actuatable means is unactuated, permitting movement of the lower leg members relative to the upper leg members in the compression and rebound directions through the fork stroke; and, when the means is actuated, permitting movement of the lower leg members relative to the upper leg members in a first of said directions through the fork stroke and limiting movement of the lower leg members relative to the upper leg members in a second of said directions.
REFERENCES:
patent: 4807860 (1989-02-01), Simons
patent: 5301969 (1994-04-01),
Eko Sport, Inc.
Foster Jason H.
Kremblas, Foster Phillips & Pollick
Morris Lesley D.
Royal, Jr. Paul
LandOfFree
Bicycle fork travel limiter does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Bicycle fork travel limiter, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Bicycle fork travel limiter will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3166196