GB2476120A

GB2476120A - Bicycle rear suspension with selectable rising or falling rate.

Info

Publication number: GB2476120A
Application number: GB0921813A
Authority: GB
Inventors: Paul Simon Mackie
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-12-14
Filing date: 2009-12-14
Publication date: 2011-06-15
Also published as: GB0921813D0

Abstract

A bicycle suspension system comprises a linkage arrangement which can easily be converted by the rider whilst the bicycle is stationary to provide either a rising rate or falling rate suspension system. A pivot 12 of a rocker link 11 is detachable from a bicycle frame 1 where it provides a falling leverage ratio acting upon a damper 6, and re-attachable at a secondary pivot location 10 to provide a rising leverage ratio acting upon the damper 6. The linkage is thereby reconfigured between rising rate and falling rate suspension leverage. The operation may be carried out using basic tools or an integral quick release clamp system.

Description

Swappable Rising Rate and Falling Rate Bicycle Rear Suspension Linkage

Description

This invention relates to a bicycle rear suspension linkage configuration which allows for swapping between a rising rate and falling rate leverage acting upon the shock absorber (aka!damper!).

There are a multitude of different bicycle (mainly mountain bike) rear suspension configurations. These linkages control the axle path movement (aka !travel!) of the rear wheel under rider induced compression or dump absorption. The force of the wheel movement is transferred into a damper which controls the compression and rebound movement of the rear wheel and dissipates kinetic energy. The damper consists of a spring (either conventional wound metal or gas filled chamber) and a rebound circuit.

In a basLc bicycle rear suspension arrangement the rear wheel is attached to a swingarm which in turn is connected to the front triangle of the frame by means of a pivot. As the swingarm pivots through the suspension motion the damper resists this movement. A linkage is often incorporated between the swingarm and the damper to!drive! the compression of the damper when subjected to rear wheel movement. This linkage often consists of rocker arms which imparts a leverage to modify the amount of force transferred to the damper.

For a given amount of wheel axle movement, the damper will compress a certain amount -this is often referred to as the leverage ratio (wheel axle movement: damper compression movement). In a linear suspension system the wheel movement would be directly proportional to the damper compression movement throughout the full travel motion. Typically however, the leverage ratio of a given bicycle suspension configuration varies through the suspension movement.

The varyLng leverage ratio can either be termed!rising rate' or!falling rate!. Conventionally, rising rate implies that the spring rate of the damper increases through the suspension movement, i.e. the spring will provide increasingly more resistance through the suspension movement compared to a linear spring resistance (stress vs. strain relationship). The rising spring rate is caused because the suspension linkage imparts progressively less leverage upon the damper through the suspension movement. Conversely, a falling rate implies that the spring rate provides less resistance through the suspension movement compared to a linear spring resistance, i.e. the suspension linkage leverage increases through the movement meaning that the incremental wheel movement will increase over the travel range compared to a decrease in incremental damper compression movement.

Typically, a bicycle rear suspension linkage arrangement will either be a !rising rate! or!falling rate! configuration. A rising rate suspension design gLves different ride characteristics opposed to a falling rate arrangement. These different ride characteristics are desirable to the bicycle rider for a given situation and terrain.

The present invention here proposes to have a linkage configuration which can be easily swapped by the bicycle rider between a rising rate and falling rate leverage ratio system by means of relocating the pivot location of a rocker arm in the linkage arrangement.

There are currently designs which allow for the suspension linkage to be adjusted to provide different amounts of suspension travel and frame geometry adjustment, but not to change the suspension linkage from a rising rate to a falling rate, or vice versa.

Figure 1 shows an example of a typical rising rate bicycle rear suspension arrangement. Note: Fully compressed suspension position of linkage shown in dashed line type.

1 -Bicycle frame front triangle.

2 -Swingarm pivot (connection the swing arm to the front triangle) 3 -Swingarm.

4 -Strut.

-Rocker linkage.

6 -Rocker linkage pivot.

7 -Damper.

8 -Damper mount.

9 -Wheel axle (original position) -Suspension travel (aka axle path').

11 -Wheel axle (end travel position) 12 -Suspension travel movement.

13 -Damper compression movement.

Figure 2 shows an example of a typical falling rate bicycle rear suspension arrangement. Note: Fully compressed suspension position of linkage shown in dashed line type.

1 -Bicycle frame front triangle.

2 -Swingarm pivot (connecting the swing arm to the front triangle) 3 -Swingarm.

4 -Strut.

-Rocker linkage.

6 -Rocker linkage pivot.

7 -Damper.

8 -Damper mount.

9 -Wheel axle (original position) -Suspension travel (aka axle path').

11 -Wheel axle (end travel position) 12 -Suspension travel movement.

13 -Damper compression movement.

Figure 3 shows typical stress vs. strain relationships for rising and falling rate suspension arrangements against a linear relationship.

1 -Rising rate (i.e. damper resistance increases through suspension movement due to decreasing suspension linkage leverage ratio) 2 -Falling rate i.e. damper resistance decreases through suspension movement due to increasing suspension linkage leverage ratio) Figure 4 shows typical examples of how the leverage ratio (wheel movement: damper movement) can vary through a suspension movement for a rising rate system and a falling rate system.

1 -Rising rate (i.e. damper resistance increases through suspension movement due to decreasing suspension linkage leverage ratio) 2 -Falling rate (i.e. damper resistance increases through suspension movement due to decreasing suspension linkage leverage ratio) An example of the invention will now be described by referring to the accompanying drawing: Figure 5 shows how the rocker linkage is relocated to swap between a rising rate (Position A) and falling rate (Position B) suspension system.

1 -Bicycle frame front triangle.

2 -Swingarm pivot.

3 -Swingarm.

4 -Rear wheel axle.

-Strut.

6 -Damper.

7 -Damper mount.

S -Switching movement of rocker linkage between rising rate and falling rate suspension system.

9 -Rocker linkage in Position A: Rising rate.

-Rocker linkage pivot Position A: Rising rate.

11 -Rocker linkage in Position B: Falling rate.

12 -Rocker linkage pivot Position B: Falling rate.

The switching of the rocker linkage pivot between positions A and B is intended to be undertaken by the rider using common tools or an integral clamping system (aka!quick release! skewer). The switching of the rocker linkage position cannot be undertaken whilst the bicycle is being ridden.

It should be noted that the linkage arrangement shown here is indicative for the purposes of explaining the patented idea of a bicycle rear suspension linkage that can be easily swapped between a rising rate and falling rate system. Linkage arrangements may vary in configuration and dimensions, yet the principle of a linkage which can be swapped between rising and falling rates is what is applied for here.

Claims

Claims 1) A bicycle rear suspension linkage arrangement which can be switched to provide a rising rate or falling rate leverage acting upon the damper.
2) Current bicycle rear suspension systems offer linkage adjustment predominantly for suspension travel, geometry adjustment and modified leverage ratio, but do not swap between a rising rate and falling rate actuation.
3) The pLvot location of a rocker link is changed by the rider whilst the bicycle Ls stationary using basic tools or an integral mechanical clamp system to provide either a rising or falling suspension rate giving diametrically opposed suspension ride characteristics.