GB2210832A

GB2210832A - Adjustable steering for cycles

Info

Publication number: GB2210832A
Application number: GB8723828A
Authority: GB
Inventors: Ernest Trevor Jones
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-10-10
Filing date: 1987-10-10
Publication date: 1989-06-21
Anticipated expiration: 2007-10-10
Also published as: GB2210832B; GB8723828D0

Abstract

The handling characteristics of a cycle or similar vehicle can be varied by constructing the steering head so that the angle of inclination of the steering axis can be altered. This is facilitated for example by providing a spherical bearing at the top of the steering head and a threaded adjuster 5 at the bottom, so that the fork/head assembly 8 can be adjustably pivoted about the spherical bearing. This also means that the offset of the wheel axis from an imaginary extension of the steering axis downwards, is also adjustable. <IMAGE>

Description

WHEELED VEHICLE STEERING - MUTABLE STEERING GEOMETRY This invention relates to the mechanics of steering bicycles and other vehicles which are steered by means of road wheels.

Several factors influence the steering characteristics of wheeled vehicles. In the case of bicycles and single-tracked wheeled vehicles these factors may also affect balance.

One important factor is the angle at which the steering axis of the steering column is placed when the vehicle is viewed from the side with the steered wheel in the straight-ahead position. A second, and related, factor is the amount of offset provided. The term offset is used to describe a measure of the distance, usually forwards, from a line coincident with the steering axis to a parallel line drawn through the rotation centre of the wheel.

In the case of bicycles the near universal adoption of the diamond frame has resulted in the selection of steering column, or fork, angles (known sometimes as the 'head angle') and offsets from a quite small range.

The steering axis, or head, angle is invariably less than 900, measured from horizontal to the rear, and in normal practice is placed within the sector 65 -75 . The amount of offset is dependent upon the head angle and wheel diameter. It is usually such as to provide a small amount of trail, i.e. the degree to which the steering axis extended to the ground falls ahead of a point on the ground directly below the centre of rotation of the wheel. Conventionally, the head angle and the offset of the steering axis are determined at the time of manufacture and, along with the consequential effects upon the steering and balancing properties of the vehicle, remain a constant feature thereafter.

According to the present invention there is provision for a bicycle or other single-track wheeled vehicle or any vehicle steered by road wheels to have an arrangement of the bearings on the static frame and on the attached moveable steering column which enables the steering axis to be adjustable so that the angle of the steering axis and or the amount of offset of that axis and or the angle of the steering column may be changed either singly or in combination as an intrinsic feature.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a side view of the bicycle.

Figure 2 shows the points of attachment of the steering column to the upper and lower parts of the static frame and details of the bearing mechanism.

Figure 3 is a perspective view from the rear quarter showing the frame structures.

The steering column or fork is attached to the frame at points 4 and 5, as shown in Figures 1 and 2. The column as a whole may swing from its attachment at 4 by the employment of a spherical bearing 6. The arc of swing is confined to the longitudinal plane and restricted in its extent by the attachment of the column to the lower frame 5, as shown in Figures 1 and 2.

A spherical bearing 7 is also employed to attach the column to the lower frame as shown in Figure 2. This bearing is mounted in such a manner as to control two movements: (a) the angular movement of the steering column in an arc which has its radius origin at bearing 6, and (b) an angular movement, in the same plane, of the steering axis relative to the steering column structure 8.

There are thus two possibilities of adjustment at the lower bearing 7.

The first provides for a change to the angle of the steering column and by the same action a change to the steering axis, and the second provides for a change to the offset of the steering axis relative to the angle of the steering column. Such changes may be made independently or in combination.

A change to the steering column angle would change the angle of the steering axis and would necessarily affect the amount of trail. The amount of trail, within certain limits, may however be restored by an adjustment of the second movement, which alters the angle of the steering axis relative to the angle of the steering column, or new and different values may be obtained. On the other hand, the second movement could be used to change the amount by which the steering axis is offset and thus give rise to different values of trail for a particular steering column angle.

Figure 2 illustrates in detail the mounting of the upper and lower bearings. As may be seen, the outer ring 9 of the upper bearing is housed in the upper head of the static frame 4. The inner bearing ring 6 is attached to the steering column by means of a shaft at the top of the column. Figure 2 also shows that the lower spherical bearing 7 is a rod end, i.e. the bearing is housed in a forging provided with a threaded rod.

This rod is employed by means of locknuts to secure the bearing to the lower head on the static frame 5 and thereby effect and control angular movement of the steering column 8. The inner bearing ring 7 is housed with a sliding fit on a shaft 10 attached to the steering column. This shaft is so mounted that it may be moved forwards or backwards on and within the steering column using a screw adjustment. This allows changes to be made to the position of the steering axis in relation to the steering column.

Claims

1A bicycle or other single-track wheeled vehicle or any vehicle steered by road wheels equipped with an arrangement of the bearings on the static part of the frame and on the attached moveable steering column which enables the axis of the steering to be adjustable so that the angle of the steering column and or the angle of the steering axis and the amount of offset of that axis may be changed, either singly or in combination, as an intrinsic feature.

2 A wheeled vehicle as claimed in Claim 1 wherein spherical bearings are employed as a means of attachment of the steering column to the static frame.

3 A wheeled vehicle as claimed in Claim 1 wherein the tilting capacity of spherical bearings is employed as a means of effecting changes to the angle of the steering column and or the angle of the steering axis and the amount of offset of that axis as an intrinsic feature.

4 A wheeled vehicle as claimed in Claim 1 wherein the mountings on the static frame and on the moveable steering column are so constructed as to provide for a bearing or bearings to be tilted as a means of changing the angle of the steering column and or the steering axis and the amount of offset of that axis as an intrinsic feature.

5 A wheeled vehicle as claimed in Claims 1, 3 and 4 wherein as an intrinsic feature the upper bearing and or its housing provides for the adjustment of the angular inclination of the steering column and or the steering axis and its amount of offset and wherein as an intrinsic feature the lower bearing and or its housing provides the radius origin of the arcs of rotation of change to the angle of the steering column and or the steering axis and the amount of offset of that axis.

6 A bicycle substantially as described herein with reference to Figures 1, 2 and 3 of the accompanying drawings and written descriptive references.