NL1043311B1 - Bicycle rear suspension - Google Patents

Abstract

A bicycle rear wheel suspension system 100, whereby the rear wheel 300 is pivotably coupled to the frame 200 by a multi-bar linkage, allowing pivoting of the rear wheel around an instant center of rotation. The multi-bar linkage comprises a chain stay 101, pivotably coupled at the front to the frame and pivotably coupled at the rear to rear bar 102 which is pivotably coupled at the rear by the rear wheel axle 503 to the rear wheel. The rear bar is pivotably coupled at the front to first rocker arm 103 which is pivotably coupled to the frame. The first rocker arm is pivotably coupled to second rocker arm 104 which is pivotably coupled to lever 105 which is pivotably coupled to the frame. The second rocker arm is pivotably coupled to shock absorber 400 which is pivotably coupled to the frame.

Description

BICYCLE REAR SUSPENSION

TECHNICAL FIELD The invention relates to bicycle rear suspension systems. More particularly, the disclosed embodiments relate to bicycles having a rear suspension system comprising a multi-bar linkage.

BACKGROUND A bicycle rear suspension system allows the rear wheel of a bicycle to follow the terrain and, if designed well, improves comfort and performance. This is particularly advantageous for mountain bikes, which are often used in rough, hilly terrain. A well- designed rear suspension mechanism improves performance by maximizing traction between the bicycle and the terrain while pedaling, turning and braking with minimum power loss from the pedals to the rear driven wheel as a result of energy being transferred into spring force instead of wheel turning.

The following alphabetically lists some terms and descriptions which are often used in relation to suspension systems of bicycles. Some introduced terms are explained later down the list.

Anti-rise: Anti-rise forces the rear suspension to compress (or “squat”) into its travel while braking, or at least limits extension of the suspension while braking. Squat is more favorable than rise because it slackens and lowers the geometry and keeps the rider's weight back, which provides more stability when going downhill. Too much anti- rise, however, can result in a less active suspension and loss of traction. The level of anti-rise is expressed as a percentage, and is related to how much the bicycle pushes back. During braking it is preferred that the rear of the bicycle squats slightly to counter the rider's mass from shifting forward too much. With an anti-rise value below 100%, the rear suspension will slightly extend (i.e. the rear of the bicycle will rise) when using the rear brake. However, this spreading is significantly less than if the anti-rise value would be 0% or negative. When anti-rise exceeds 100%, the suspension compresses instead of extends when the rear brake is used.

Anti-squat: Anti-squat is the force on a suspension system that is generated by the drivetrain and resists the compression of the suspension caused by mass transfer during acceleration. As the bike accelerates and the bike moves forward, the rider's weight moves rearward causing the suspension to compress or squat. The biomechanics of pedaling also produce a downward force causing the suspension to compress or squat as an effect of each pedal stroke. Anti-squat is the trait that when the chain is pulled forward by the pedaling motion, it creates a force on the suspension system opposite of the squat, caused by the rider and weight transfer, hence the name.

Chain growth: The increase in distance from the bottom bracket to the rear axle as a result of compression of the suspension.

Chain ring: A front sprocket, usually of the type that attaches the crank to a spider.

Instant center of rotation: Many modern designs focus on the instant center of rotation (hereinafter also abbreviated as instant center or IC), because as long as drive forces are pointed into the IC, the suspension is balanced. The trouble is that when the instant center of rotation moves through its path during travel, it will only line up with the chain line once. In other words, this is very sag-dependent. The IC does not move during compression on a classic single pivot design because the IC is in all cases the same as the pivot point at the front end of the chain stay. On modern multi-link designs, IC constantly changes location as the suspension cycles through its travel. This makes adequate sag very important. Finding the instant center of rotation is an intangible point found by drawing an imaginary line forward through the two pivots on each link until they intersect.

Leverage ratio: The relation between the stroke of the shock damper (hereinafter also referred to as "shock") and the rear wheel travel. For instance, 10 cm wheel travel resulting in a 5 cm shock stroke, gives a ratio of 2:1. Usually higher ratios require higher shock pressures to provide correct sag (especially for heavier people).

Pedal kickback: As the rear axle moves throughout travel, its distance in relation to the bottom bracket changes. If this changes too dramatically in backward or upward direction, chain growth results, tugging the chain -and in turn the cranks- back so that the pedals kick back as well. In other words, the forces are translated to an opposite direction, from the suspension through the drivetrain to the rider, resulting in unwanted pedal movement.

Pedaling efficiency: The capability to transfer the energy from the rider to the rear wheel, defined by anti-squat and pedal kickback. Other aspects that influence pedaling efficiency are e.g. tire pressure and drivetrain efficiency.

Rise: Rise occurs when rear braking forces are at odds with the rider's forward momentum and the result is stiffening and extension of the rear suspension. This results in two negatives: The rear wheel loses traction and skips over the ground, and with the rise of the suspension, the rider's weight is transferred forward and over the front wheel while steepening the geometry.

Sag: The percentage of suspension travel compressed by the rider’s weight in a static riding position. Normal rear suspension sag recommendations are 25 to 33 percent, depending on design.

Squat: The force generated when the rider pedals forward must overcome the inertia of the mass of the rider and bicycle. Invariably, some of this force is displaced through compression of the suspension, essentially resulting in a loss of forward motion and efficiency.

Wheel path: During a full compression of the suspension, the wheel axle follows a defined path. The axle path can vary between suspension designs and is controlled by the pivot points of the suspension.

There are numerous bicycle suspension systems in use today to improve performance, or at least to make the overall performance of the bicycle predictable under both pedaling and braking. Many of these systems are designed to minimize suspension motion as response to pedaling and/or braking. Preferably, the systems also provide a progressive leverage ratio. Last but not least, it is also desired that the centre of gravity is as low to the ground as possible for optimal bicycle handling.

There are currently four prevalent types of suspension on the market, which are summed up as follows.

Single pivot: In this relatively simple suspension design, the rear axle is connected to the main frame by a chain stay, without pivots in-between. The axle moves in a constant arc, centered on the pivot point. In a true single pivot, the shock is connected directly to the chain stay. A disadvantage of this design is the lack of control over the leverage curve. True single pivot bikes are generally quite linear, whereby the force required to move the rear wheel through its travel does not ramp up towards the end (to resist bottom out) as it does with a more progressive design.

Linkage-driven single pivot: A linkage-driven single pivot design which uses an uninterrupted chain stay which connects the rear axle directly to the frame. Some form of linkage is provided to drive the shock. This allows designers to manipulate the leverage curve, thus controlling the frame’s progressivity, i.e. how much the suspension firms up towards the end of the stroke. Horst-link or four-bar: This suspension design is characterized by a rear pivot located below the rear axle on the chain stay. This means that the rear axle is not directly connected to the frame, thus moving in a path which is defined by its instant center of rotation, which may move as the suspension cycles through its travel. This layout allows designers more control over the desired levels of anti-squat throughout the suspension’s travel, as well as more control over anti-rise levels throughout the suspensions travel and as such improve sensitivity and/or road contact.

Twin-link: These use a rigid rear triangle, articulating on a pair of short links which connect it to the mainframe. It works in a similar way to a Horst-link design. Basically, moving the Horst-link’s chain stay pivot much closer to the frame results in a twin-link system. The real difference is the length of the lower link. As with the Horst-link design, here the axle’s direction is tangential to a moving instant centre of rotation, which defines the way in which the axle path curves through its travel. The way the instant center of rotation migrates as the bike moves through its travel is quite different for each configuration. Twin-link or horst-link bikes with co-rotating links often exhibit anti-squat behavior, similar to a single-pivot bike. Counter-rotating links can produce an anti-squat profile which peaks in the middle of the travel, and which in turn is desirable for balancing pedal efficiency with pedal kickback.

Several solutions for a rear suspension system have been proposed in patent publications, of which a few are discussed below.

USA patent application publication 2018/0297661A1 by Level One Engineering LLC is summarized as a bicycle with a front triangle and a rear suspension system that couples the front triangle to a rear wheel which is dampened by a shock absorber. The rear suspension system has a six-bar linkage with two ternary links separated from each other by binary links, such that the two ternary links do not share a common joint. One of the ternary links may be a chain stay.

USA patent application US5509679A by Leitner is summarized as a rear wheel suspension for a bicycle which includes paired lower arm members pivotally connected to the bicycle frame seat tube such that they can pivot about an axis situated above the center of the bottom bracket, paired upper arm members adapted to receive the rear wheel axle at hub points located on an axis situated above their lower ends and pivotally connected to the respective lower arm members such that they can pivot about an axis near the rear ends of the lower arm members, and means associated with the upper ends of the upper arm members and pivotally connected to an upper pivot point on the seat tube for limiting the path and the extent of movement of the upper ends of the upper arm members. 5

DISCLOSURE OF INVENTION It is an object of the present invention to increase performance and handling of a bicycle provided with a rear suspension. More particular, it is an object of the invention to provide a rear suspension system which limits movements and/or increases predictability of movements of the suspension system in response to pedal and/or brake input. It is a further object of the invention to provide a rear suspension system which limits impact on or increases predictability of the impact by the suspension system on pedal movement, pedaling efficiency and/or brake performance. Yet a further object of the invention is to increase predictability of the responses of the bicycle to various parameters such as pedal input, brake input, movement of the suspension system, and characteristics of the drive train in various conditions. The object is realized in the manner as described in the following clauses.

1. A rear wheel suspension system (100) for a bicycle, the bicycle comprising a frame (200), whereby the rear wheel (300) is pivotably coupled to the frame by a multi-bar linkage, allowing pivoting of the rear wheel around an instant center of rotation, characterized in that the multi-bar linkage comprises: - a binary-link-type chain stay (101), coupled at a front-end portion by a first joint (501) to the frame (200) and coupled at a rear end portion by a second joint (502) to a ternary-link-type rear bar (102); - the rear bar (102) coupled at a rear end portion by the rear wheel axle (503) to the rear wheel (300); - the rear bar (102) coupled at a front-end portion by a third joint (504) to a ternary- link-type first rocker arm (103); - the first rocker arm (103) coupled by a fourth joint (505) to the frame (200); - the first rocker arm (103) coupled by a fifth joint (506) to a ternary-link-type second rocker arm (104); - the second rocker arm (104) coupled by a sixth joint (507) to a binary-link-type lever (105);

- the lever (105) coupled by a seventh joint (508) to the frame (200); - the second rocker arm (104) coupled by an eighth joint (509) to a shock absorber (400); - the shock absorber (400) pivotably coupled by a ninth joint (510) to the frame (200).

2. The rear wheel suspension system according to clause 1, characterized in that the arrangement of the first rocker arm (103) and the second rocker arm (104) are part of a four-bar linkage suspension system.

3. The rear wheel suspension system according to clause 1 or 2, characterized in that the rear wheel suspension system is arranged for moving the instant center of rotation (601) towards a position behind the first joint (501) when the rear wheel (300) is forced in an upward direction.

4. The rear wheel suspension system according to any one of the preceding clauses, characterized in that the third joint (504) is in a position lower than the position of the eighth joint (509) during pivoting of the rear wheel (300).

5. The rear wheel suspension system according to any one of the preceding clauses, characterized in that second rocker arm 104 is indirectly coupled by joint 508 to frame 200 via lever 105, thus preventing torsion forces passing from rear wheel 300 through rear bar 102 to rocker arm 104.

6. The rear wheel suspension system according to any one of the preceding clauses, characterized in that the suspension system is arranged for defining leverage ratio independently of characteristics such as anti-squat and/or anti-rise.

The invention provides an increased number of links in the linkage, which allows tuning pedal performance parameters to behave predictably to the rider.

Because there is separation between pedal performance variables and shock tuning variables, it is possible to adjust the geometry of the bicycle without making changes to the leverage ratio. Geometry can be adjusted more easily for different sizes of bicycles without changing key kinematic relationships of the suspension system. An important change of geometry comprises changing the position of the rear axle relative to the bottom bracket.

The kinematics of the invented suspension system provide an acceleration anti- squat effect. This effect is tuned such, that a weight transfer rearward as a result of forward acceleration does not result in varying amounts of suspension compression throughout the compression of the system.

A value of 100% anti-squat results in no suspension compression as a result of weight transfer.

The known systems that employ anti-squat to tune the compression of the suspension generally display a curved relationship of percent anti-squat vs. vertical wheel travel... This results in an optimally tuned system that is very predictable throughout the range of suspension motion.

In short, the invention provides the following advantages: - Less unsprung mass, which results in a more responsive and active rear suspension for better traction and grip. - Cutting edge geometry for long reach, slack head tube and short rake for confidence inspiring ride. - Progressive suspension: by a progressive leverage ratio for bottomless feel, and with biggest leverage ratio around sag point for a plush ride. - A stable pedal platform due to a single chain line (single chainring and sprocket), whereby anti squat values are optimal throughout the whole gear range. - A low Centre of Gravity (abbreviated as CoG), whereby the low, forward oriented CoG and steep seat angle make for an excellent climbing bike. - The gearbox is integrated in the design, which provides quickest shifting and 600% evenly distributed gear range.

These and other advantages are further explained below.

Constant anti squat: Most importantly the anti-squat values are constant throughout the gear range.

Throughout the suspension travel the anti-squat does shift a bit.

Typically, the anti-squat value may go from 121% to 93%, providing an optimal 115% anti squat at around the sag point, of which 100% to prevent peddle bob caused by the torque the rider is putting through the pedals and another approximate 15% to account for the body movement on the bike.

The anti-squat level decreases slightly throughout the suspension travel which is quite favorable as it livens the suspension further and pedal efficiency is less of an issue the very second the rider is landing a big drop.

Optimized pedal kickback: A further advantage of the invented suspension is the little pedal kickback at high speed.

The suspension works well with tougher gears, whereby reduced pedal kickback is essential as the suspension should remain fully active during quick descends.

The bike equipped with the invented suspension features as little as 5,5° pedal kickback in the toughest gear, whereas current mountain bikes feature pedal kickback of over 10° in a similar gear ratio.

We achieved this by a combination of the integrated gearbox and compact rockers causing very little chain growth. In the lighter gears the pedal kickback is a little more, but this actually helps providing a stable pedaling platform at low speeds and/or steep climbs.

Progressive anti-rise: Yet a further advantage comprises that anti rise level is progressive, meaning that when the rear suspension is further compressed the anti- rise levels increase. This ensures that the kinetic energy stored in the shock is less likely to catapult the rider forward off his/her bike. We also ensured that throughout the first 100mm of travel the anti-rise is less than 100% to make sure the suspension keeps the rider balanced on the bike, whilst not stiffen up too much.

Progressive leverage ratio: The invented suspension enables to tweak the leverage ratio (defining the progressiveness of the suspension) relatively independent of the anti- squat and anti- rise levels. This is unique for a four-bar mechanism and allows for optimizing the leverage ratio to go from 3 at 0% compression down to 2,5 at the end of the suspension travel. This causes a favorable progressive feel. Up to the sag point (first 20%) the leverage ratio is regressive to minimize the sag ratio and any stick slip effect. From the sag point onwards, the bike's behavior is predictably progressive, which provides an almost bottomless feel for the rider, which enables maximizing the potential of the bike.

Upward axle path: The invented suspension offers a vertical wheel path around the sag point (approximately 25% of travel). A vertical (or rearward) axle path makes it easier for the rear wheel to activate the rear shock because the vectors of the force are converted into the shock being compressed, rather than the bike being held back. This favorable wheel (or axle) path is achieved through the combination of the pivot just in front of the rear axle the compact primary rocker.

Compact rockers: The compact rocker arms (also referred to as "rockers") are very light (typically approximately 50grams each), thereby providing very low inertia, which allows for a very active rear suspension. The rockers are preferably provided with low friction ball and needle bearings.

Free moving shock: The shock is decoupled from the primary rocker, which prevents torsional forces to be transferred between the rear end of the bike and the shock, which in turn makes the shock operate freely. In this way, the shock is not a structural element of the bike, thereby prolonging the shock's life.

Reducing unsprung weight: Unsprung weight is reduced, resulting in a responsive and active rear suspension for better traction and grip. By moving all shifting components from the rear axle to the frame (gearbox), the unsprung mass is substantially reduced. Typically, a reduction of unsprung mass of 649-766gr, in comparison to current drive trains, is feasible.

BRIEF DESCRIPTION OF THE DRAWINGS The figures show views of embodiments in accordance with the present invention. FIGURE 1 shows a bicycle with a rear wheel suspension system in accordance with the present invention in a default position.

FIGURE 2 shows a detail of the invented suspension system in the default position. FIGURE 3 shows a detail of the invented suspension system with a part of the rear bar, chain stay and rear wheel in the default position.

FIGURE 4 shows a bicycle with a rear wheel suspension system in accordance with the present invention whereby the rear wheel is lifted.

FIGURE 5 shows a detail of the invented suspension system whereby the rear wheel is lifted.

FIGURE 6 shows a detail of the invented suspension system with a part of the rear bar, chain stay and rear wheel whereby the rear wheel is lifted. FIGURE 7 show a perspective view of a detail of the invented suspension system in a default rear wheel position.

FIGURE 8 shows perspective view of a detail of the invented suspension system as in figure 7, when the rear wheel is partly lifted, and the shock absorber is partly compressed.

FIGURE 9 shows perspective view of a detail of the invented suspension system as in figure 8, when the rear wheel is further lifted, and the shock absorber is further compressed.

FIGURE 10 shows a detail of the invented suspension system 100 in a default wheel position, whereby an instant center of rotation is visualized. FIGURE 11 shows a detail of the invented suspension system 100 whereby rear wheel 300 is lifted, whereby an instant center of rotation is visualized.

DETAILED DESCRIPTION

The invention is now described by the following aspects and embodiments, with reference to the figures.

To facilitate reading of the figures hereinafter references are listed with a short description.

Whenever the word "joint" is used, this refers to a coupling means, which allows rotation in both directions of the parts that are coupled, in relation to each other.

Although the invented suspension system is effective by providing single elements, hereinafter the elements may comprise two parts on left and right sight of the bicycle.

This may increase stability.

To achieve the same stability with a single side element, much more rigid and strong materials would be needed.

The skilled person is able to determine where double elements (left and right) are feasible and create benefits. 101 chain stay 102 rear bar 103 first rocker arm coupled by fourth joint 505 to frame 200 104 second rocker arm coupled by fifth joint 506 to first rocker 103 (left and right) and by joint 507 to lever 105 105 lever coupled by seventh joint 508 to frame 200 113 exemplary mirrored first rocker arm on the other side, similar to first rocker arm 103, and coupled by a similar joint to frame 200 200 frame 300 rear wheel . 400 shock absorber coupled by ninth joint 510 to frame 200 501 first joint coupling chain stay 101 to frame 200 502 second joint of ternary-link-type rear bar 102 503 rear wheel axle 504 third joint coupling rear bar 102 to first rocker arm 103 505 fourth joint coupling first rocker arm 103 to frame 200 506 fifth joint coupling first rocker arm 103 to second rocker arm 104 507 sixth joint coupling lever 105 to second rocker arm 104 508 seventh joint coupling lever 105 to frame 200 509 eighth joint coupling second rocker arm 104 to top of shock absorber 400. 510 ninth joint coupling shock absorber 400 at the bottom to frame 200 511 joint coupling a crank (driven by right pedal, which is not shown) through a gearbox to the chainring crown wheel 601 instant center of rotation (also known as virtual pivot point)

700 road surface 701 bump FIGURE 1 shows a bicycle 900, such as an all-terrain bicycle (ATB) or mountain bike, with a rear wheel suspension system in accordance with the present invention in a default position on a (flat) road surface 700. Sections A1 and B1 are further shown in detail in figure 2 and figure 3 respectively.

FIGURE 2 shows a section A1 corresponding with section A1 of Figure 1, with a detail of the invented suspension system 100 in the default position. First, figure 3 is described and reference is made to figure 2 for a view on more detailed elements, when necessary for clarification.

FIGURE 3 shows a detail of the invented suspension system with a part of the rear bar, chain stay and rear wheel in the default position. Rear wheel 300 of bicycle 900 is pivotably connected to a frame 200 of the bicycle. Rear wheel 300 is rotatable around rear wheel axle 503. When the bicycle encounters an obstacle such as a bump in the road, rear wheel 300 is moved in a general upward direction, in order to follow the contours of the obstacle. Rear wheel 300 is unsprung mass, and the other parts of the bicycle are mostly sprung mass. In principle the frame, enhanced by the weight of the rider, provides inertia, which, when operating optimally with the sprung mass, provides a relatively smooth ride for the rider, even in tough bumpy terrain. The invented geometry of the rear wheel suspension system allows rear wheel 300 to follow the contours of a bump as much as possible, without rear wheel 300 losing contact from the surface of the road. The upward movement encounters a counter force which is exerted by a spring-loaded shock absorber 400, which is a well-known device and often used in ATBs.

Wheel travel of rear wheel 300 is vertical or very near vertical along a great part of the suspension travel when starting from a point below a horizontal position of chain stay 101. This is achieved by creating an Instant center of rotation (VPP) 601 which follows the line of the chain stay 101. Positioning of VPP 601 to a lower and more backward position than most current bicycles have, is realized by allowing rear bar 102 to pivot around a second joint 502 (which creates an intermediate pivot point) which pivotably connects rear bar 102 with chain stay 101. Rear wheel axle 503 is in this way positioned behind second joint 502. Positioning the intermediate pivot point at joint second 502 allows that third joint 504, which pivotably connects rear bar 102 with a first rocker arm 103, to be pivoted upwards and forwards around joint 505, when rear wheel

300 is rotating in an upward direction.. Typically, in the proposed configuration wheel travel around sag point, which is typical 27% of a wheel travel of 150mm, i.e. approx.

40 mm, is vertical, or at least not forward, whereas current four-bar type bike constructions allow only a vertical wheel travel of maximum 17% of 150mm, i.e. approx. 25 mm. At 100% wheel travel, rear wheel axle 503 moves only 8% of wheel travel of 150mm, i.e. 12 mm forward, whereas current constructions 12%, i.e. 18 mm is more common, Figure 2 shows a detail of suspension system 100, whereby first rocker arm 103 is pivotably connected to frame 200 by fourth joint 505. As chain stay 101 is rotated upward by the upward rotation of rear wheel 300, first rocker arm is rotated upward around pivot point of fourth joint 505. This upward movement is enhanced by the above discussed increase of the angle between rear bar 102 and chain stay 101. Because of the upward rotation of joint 504, fifth joint 506 of second rocker arm 104 is pulled downward. Second rocker arm is pivotably connected at eighth joint 509 to the top of a piston which is arranged for a somewhat linear movement in and out shock absorber

400. As second rocker arm is pivotably connected to lever 105 by sixth joint 507, and lever 105 is pivotably connected to frame 200 by joint seventh joint 508, the whole of rocker 104 is pulled downward, pulling eighth joint 509 in a substantially straight line downward in the direction in which the piston of shock absorber 400 is moving when the spring in shock absorber 400 is compressed.

In this way, the geometry of the suspension system, by its clever working together of rockers, lever, chain stay and rear bar, provides an as smooth as possible translation of an upward rotation of rear wheel 300 into a predictable movement of the piston of shock absorber 400. Moreover, torsion forces from rear bar 102 and/or chain stay 101 are not transferred to shock 400. This allows a smooth movement of the piston, with less friction and occurrence of stick-slip. The phenomenon stick-slip is hereby to be understood as the spontaneous jerking motion that can occur while two objects are sliding over each other. It is a desire of many suspension system developers to find a configuration wherein friction and stick-slip within a shock absorber is eliminated, in order to have full control of the spring and dampening characteristics of the shock and to increase durability and lifespan of the shock. The present invention provides this solution in a compact, efficient and reliable manner. Furthermore, the proposed geometry provides a decoupling of pedal impact and suspension, i.e. anti-squat and anti-rise.

On the one hand, the proposed configuration with two relatively small rocker arms 103,104 working together, effectively increases leverage (as if a much larger lever was used), and on the other hand the configuration increases stiffness of the suspension system. The small size of the first rocker arm 103 is in particular determined by the distance from third joint if rear bar 102 to fifth joint 506 which couples first rocker arm 103 to second rocker arm 104.

The configuration of the rear bar 102, rocker arm 103 and rocker arm 104 is such that joint 504 will move below the top of the piston of shock absorber 400, i.e. below eighth joint 509, along the whole of suspension travel, thus allowing a compact rear suspension with a low CoG. Apart from that, the relatively small rockers allow CoG to travel less than in many conventional (four-bar) layouts. Furthermore, obstructive dead points in the movement of the mechanism are prevented. A further advantage comprises that rear bar 102 may be configured in a compact manner with little travel relative to frame 200.

FIGURE 4 shows the exemplary bicycle 900 of figure 1, with a rear wheel suspension system 100 in accordance with the present invention whereby the rear wheel is lifted, because of bump 701 on surface 700. Sections A2 and B2 are further shown in detail in figure 5 and figure 6 respectively.

FIGURE 5 shows a detail of the invented suspension system 100 whereby rear wheel 300 is lifted.

FIGURE 6 shows a detail of the invented suspension system 100 with a part of the rear bar 102, chain stay 101 and rear wheel 300 whereby rear wheel 300 is lifted.

FIGURE 7 shows a perspective view of a detail of the invented suspension system in a default rear wheel position. Because of the compactness and overlapping construction of the rocker arms and levers, a detailed perspective view is shown. First rocker arm 103 is coupled by fourth joint 505 to frame 200. Second rocker arm 104 is coupled by fifth joint 506 to first rocker 103, and by joint 507 to lever 105.

FIGURE 8 shows perspective view of a detail of the invented suspension system as in figure 7, when the rear wheel is partly lifted, and the shock absorber is partly compressed.

FIGURE 9 shows perspective view of a detail of the invented suspension system as in figure 8, when the rear wheel is further lifted, and the shock absorber is further compressed.

FIGURE 10 shows a detail of the invented suspension system 100 in a default wheel position, wherein instant center of rotation 601 is situated in front of first joint 501 which couples chain stay 101 to frame 200. Instant center of rotation 601, however is situated relatively close to first joint 501. The instant center of rotation 601 is determined by first drawing an imaginary straight line between third joint 504 which couples rear bar 102 to first rocker arm 103, and fourth joint 505 which couples first rocker arm 103 to frame 200. Then by drawing a second imaginary straight line through second joint 502 of ternary-link-type rear bar 102, and first joint 501, an intersection point results, being the instant center of rotation.

FIGURE 11 shows a detail of the invented suspension system 100 whereby rear wheel 300 is lifted, wherein instant center of rotation is situated behind first joint 501. In this way, the invention provides that instant center of rotation moves backward when the suspension is compressed.

The above described suspension system is suitable for fitting in combination with aregular crank set. The present invention, however, provides in particular a suspension system which may be combined with a gearbox such as a Pinion gearbox. A pinion gearbox is used to convert torque and rotational speed from the power source, usually the rider's legs, to what is desired at the drive wheel. The gearbox is usually incorporated into the frame near the crank, and it may be used in addition to or instead of derailleur gears or a hub gear. Advantages include improved shifting performance, protecting the gearing from damage and exposure to dirt and moisture, as is usually the case with hub gears. The additional mass is located between the two wheels and on the frame where it may be suspended, unlike with hub gears. In a pinion gearbox, the cranks are connected with the gearbox and the gearbox is connected to the chain ring. Thus, the axis of the crank (bottom bracket) and the axis of the chainring are mounted concentrically, but the chainring rotates (depending on resistance) at a different speed than the cranks.

The invented suspension system may also be combined with an electrical drive system of the bicycle.

Furthermore, the invented construction provides flexibility in adjustments of a suspension travel, pedal impact and/or acceleration anti-squat.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that a person skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.

Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim.

The term "and/or" includes any and all combinations of one or more of the associated listed items.

The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

The article "the" preceding an element does not exclude the presence of a plurality of such elements.

In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware.

The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims (4)

CONCLUSIONS A rear wheel suspension system (100) for a bicycle, the bicycle comprising a frame (200}, the rear wheel (1300) being pivotally coupled to the frame by a multi-link connection, allowing the rear wheel to be pivoted around a center of rotation, with the characterized in that, the multiple bar linkage comprises: - a binary link type chainstay (101) coupled to a front portion by a first hinge (501) with the frame (200) and coupled to a rear end section by a second hinge ( 502) to a ternary connection type rear rod (102); - the rear rod (102) coupled to a rear end portion by the rear wheel axle (503) with the rear wheel (300); the rear rod (102) coupled to a front portion by a third hinge (504) on a first rocker arm of ternary connection type {103}; - the first rocker arm (103) coupled by a fourth hinge (505) to the frame {200}; - the first tumbler arm (103) coupled by a fifth hinge (808) to a second tumbler arm of the ternary connection type {104}; - the second rocker arm (104) coupled by a sixth hinge (507) to a binary link type lever (105); - the lever (105) coupled by a seventh hinge {508} to the frame {200}; the second rocker arm (104) coupled by an eighth hinge (508) to a shock absorber {400}; - the shock absorber (400) pivotally coupled by a ninth hinge (510) to the frame (200). The rear wheel suspension system of claim 1, characterized in that the arrangement of the first rocker arm (103) and the twseds rocker arm (104) form part of a quadruple link suspension system. The rear wheel suspension system according to claim 1 or 2, characterized in that the rear wheel suspension system is arranged to move the direct center of rotation {601} to a position behind the first pivot (501) when the rear wheel {300} is in an upward direction. direction word! forced, The rear wheel suspension system according to any one of the preceding claims, characterized in that the third hinge (504) is in a position lower than the position of the rear hinge (509) during the pivoting of the rear wheel (300). . The rear wheel suspension system of any preceding claim, characterized in that second rocker arm 104 is indirectly coupled by hinge 508 to frame 200 via lever 105, preventing torsional forces from passing from rear wheel 300 through rear rod 102 to rocker arm. 104. 6. The rear wheel suspension system according to any one of the preceding claims, characterized in that the suspension system is adapted to determine the lever ratio independent of characteristics such as resistance to spring compression due to acceleration and pedal forces (anti-squal) or resistance to rear elevation due to braking (anti-rise).