Abstract:
Unique suspension apparatuses, systems and methods useful for mountain bicycles among other applications are disclosed. In certain exemplary embodiments the suspension is self adjusting to meet different performance objectives. The suspension may utilize pedaling force to substantially stiffen or lock out movement of the suspension, for example, during climbing. The suspension may change its performance under reduced pedaling force to provide performance characteristics desired when a rider is descending. Certain exemplary embodiments include a rocker arm connected to a first frame portion at a first rocker arm pivot, connected to a seatstay at a second rocker arm pivot, and connected to a second link at a third rocker arm pivot. The first link is connected to the first frame portion at a first link pivot, connected to the chainstay at a second link pivot, and connected to the shock and the second link at a third link pivot.

Description:
BACKGROUND 
       [0001]    The present disclosure relates generally to the field of bicycle suspensions and geometry and more particularly mountain bicycle suspensions. Mountain bike suspension has offered a number of advantages to riders including the ability to ride extreme mountain and desert terrain as well as increasing comfort for the more casual rider. While offering certain benefits, current mountain bike suspension systems suffer from a number of limitations, drawbacks and design compromises. For example, mountain bike rear suspension should ideally perform very differently under different riding conditions. While climbing the suspension would preferably be very stiff or locked out and should resist or eliminate rider bob associated with hard pedaling. Furthermore, it would be desirable to change overall frame geometry so that fork rake is steeper and rider position is advanced forward to suit the needs of a climb. In contrast, downhill descents present very different, and apparently conflicting, performance needs. When descending it would be desirable to change frame geometry to move the rider position rearward and provide a less steep fork rake. Furthermore, different spring rate, compression and rebound characteristics would be desired. On relatively level terrain the suspension needs are different still. These are but a few examples of a fundamental and long felt need in mountain bike suspension, namely, the need for different suspension and different frame geometries to accommodate the varied and contrasting riding conditions encountered by a mountain bike. Heretofore many efforts at improved mountain bike suspension have been attempted but have not overcome the what appear to be fundamental design compromises. A number of these attempts and their shortcomings are discussed in my U.S. Pat. No. 7,712,757 (“the &#39;757 Patent”). The &#39;757 patent, and its commercial embodiments in the Kona® MagicLink,™ represent the most significant effort to meet the challenges described above. While these designs provide significant benefits as to performance and function of mountain bicycle suspension, they too are subject to a number of limitations that appear to require fundamental design compromises including needs for multiple shocks and biasing members among others. There remains a long felt, unaddressed need for mountain bike suspension systems that provide fundamentally different performance and geometries across the gamut of potential riding conditions. 
       DISCLOSURE 
       [0002]    For the purposes clearly, concisely and exactly describing exemplary embodiments of the invention, the manner and process of making and using the same, and to enable the practice, making and use of the same, reference will now be made to certain exemplary embodiments, including those illustrated in the figures, and specific language will be used to describe the same. It shall be understood that no limitation of the scope of the invention is thereby created, and that the invention includes and protects such alterations, modifications, and further applications of the exemplary embodiments as would occur to one skilled in the art to which the invention relates. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0003]    Exemplary embodiments are illustrated in referenced figures of the drawings. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than restrictive. 
           [0004]      FIG. 1  is an elevation view showing the bicycle suspension of an exemplary embodiment at rest with substantially no vertical or horizontal loading and with the suspension fully extended. 
           [0005]      FIG. 2  is a detail elevation view showing an embodiment of the link of the bicycle suspension of an exemplary embodiment. 
           [0006]      FIG. 3  is a perspective view showing the link of the bicycle suspension of an exemplary embodiment. 
           [0007]      FIG. 4  is a side elevation view showing the link of the bicycle suspension of an exemplary embodiment in isolation. 
           [0008]      FIG. 5  is a front perspective view showing the link of the bicycle suspension of an exemplary embodiment in isolation. 
           [0009]      FIG. 6  is an elevation view showing the bicycle suspension of an exemplary embodiment under power or forward acceleration with the suspension fully extended; 
           [0010]      FIG. 7  is an elevation view showing the bicycle suspension of the invention under power or forward acceleration while compressed 25% due to rider weight, and shown at full extension in phantom for comparison. 
           [0011]      FIG. 8  is an elevation view showing the bicycle suspension of an exemplary embodiment under bump or braking forces with the suspension sagging (compressing) a normal 25% due to the rider&#39;s weight and shown at full extension in phantom for comparison. 
           [0012]      FIG. 9  is an elevation view showing the bicycle suspension of an exemplary embodiment under compression from 25% to 50% of its total travel and encountering bump and/or braking forces. 
           [0013]      FIG. 10  is an elevation view showing the bicycle suspension of an exemplary embodiment under compression from 50% to fully compressed. 
           [0014]      FIG. 11  is an elevation view showing the bicycle suspension of an exemplary embodiment with the suspension fully compressed and with it fully extended in phantom for comparison. 
           [0015]      FIG. 12  is a graph showing a spring rate curve throughout the range of travel. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0016]    Throughout the following description specific details are set forth in order to provide a more thorough understanding to persons skilled in the art. However, well known elements may not have been shown or described in detail to avoid unnecessarily obscuring the disclosure. Accordingly, the description and drawings are to be regarded in an illustrative, rather than a restrictive, sense. 
         [0017]    The term “bicycle” used herein refers both to chain-driven pedal-powered bicycles and chain-driven motor-powered bicycles or motorcycles. While the exemplary embodiments disclosed herein have particular utility for mountain bicycles, they are also useful for any type of chain-driven bicycle or motorcycle. 
         [0018]    With reference to  FIG. 1 , a rear wheel suspension system is designated as  10  mounted on bicycle frame  12  consisting of a top tube  14 , down tube  16  and seat tube  18 . Rear wheel  20  rotates on an axle (not shown) which is mounted at  53  on the chainstay  26  which is connected to a pair of seatstays  24 . In the illustrated embodiment, the chainstay  26  is pivotally connected to the seatstays  24 , however, in some embodiments the chainstay  26  may be non-pivotally or rigidly connected to the seatstays  24 . Rocker arm  28  pivots on the seat tube  18  at  34  and pivotally links seatstay  24  at pivot axis  36  and driven link  46  at pivot axis  48 . A lower link  40  pivots on frame  12  at pivot axis  42  and is pivotally connected to the upper end of shock absorber  30  at  32 . Driven link  46  is pivotally connected to the upper end of the shock  30  and upper end of link  40  at pivot axis  32 . Chainstay  26  pivotally connects to the lower link  40  at  44 . The lower end of shock absorber  30  is pivotally connected to the frame at connection  15 . 
         [0019]      FIG. 2  is a detail of link  40  illustrating the upper end of link  40  in the rearward position.  FIG. 3  illustrates the link  40  in perspective. In this embodiment link  40  comprises two parallel forks  70 ,  72 , pivotally mounted on the frame  12  at pivot axis  40 , which attach to the upper shock mount  32 . As illustrated, the length of driven link  46  can be changed by the rider using the threaded rod end  60 . This alters the suspension characteristics by altering the geometry.  FIGS. 4 and 5  are additional detailed views of the components illustrated in  FIGS. 1-3 . 
         [0020]    When pedaling power/forward acceleration is applied, as shown in  FIGS. 6 and 7 , the chain pull and reaction force at the tire/ground interface pushes the wheel  20  and chainstay  26  forward relative to the frame  12 . This forces the lower end of link  40  forward and the upper end of link  40  rearward, with the upper shock mount  32  along with it. When the upper end of link  40  moves rearward, it also moves the lower end of driven link  46  to the rear. This changes the motion ratio and rising rate characteristics of the shock  30  to become stiffer in the initial part of the travel. It also causes a steeper (more vertical) fork rake and seat tube angle, and places the rider in a more aggressive position over the pedals, and moves the rider weight bias to the front. Since the lower end of link  40  moves forward, the attached chainstay  26  is at its shortest length relative to the frame, for enhanced, optimized or maximum climbing ability. The harder the pedaling effort, the more the chainstay  26  is forced forward, pushing the lower end of link  40  forward and the upper end of link  40  rearward. 
         [0021]    At one extreme, as shown in  FIG. 6 , the link  40  can rotate to the degree that the vertical force on the rear wheel  20 , acting through the seatstay  24  and the rocker  28 , tries to rotate the top of link  40  further rearward, further delaying/impeding the top of the link&#39;s tendency to rotate to the front under braking and/or bump forces. For example, this might be more desirable for a bike that was made specifically for climbing. 
         [0022]    This alignment of pivots  32 ,  42 ,  48  can be geometrically configured to occur when the upper end of link  40  is pushed to a rearward position due to pedaling/forward acceleration forces. In these conditions, the upper end of link  40  will stay rearward even when the rider&#39;s pedal input (and therefore forward acceleration force) varies with crank frequency. Without this alignment, the link  40  would tend to rotate whenever pedaling pressure was momentarily reduced. This link rotation would allow undesirable effects such as vertical chassis movement, soft/lazy forward acceleration response, and less vertical fork and seat angles. Normally, these effects would cycle freely as those forces varied, but the alignment of the links, combined with the stiff motion ratio, substantially to entirely eliminate those effects. 
         [0023]      FIG. 6  illustrates that the bicycle suspension of an exemplary embodiment  10  under high to maximum power or forward acceleration, such as a climb, while the suspension is fully extended, has a tendency to keep the upper end of link  40  rearward and the suspension fully extended until a bump and/or braking force is encountered. 
         [0024]      FIG. 7  shows the suspension compressed 25% due to rider weight, while under forward acceleration. This would be a condition seen on level ground, pedaling hard. As in  FIG. 6 , the horizontal force from forward acceleration on rear wheel  20  pushes the chainstay  26  forward, rotating the bottom of link  40  forward and the top of link  40  rearward. This horizontal force is less than in  FIG. 6 , which could only occur during extreme climbing. In  FIG. 7 , this force is not strong enough to counteract the rider&#39;s weight, thus the suspension will not extend to a position less than 25% compressed. But, this force is strong enough to resist any vertical force inputs due to motion of the rider or to any suspension compression effects due to pedaling and chain pull that afflict conventional suspension designs. The result is a very firm suspension feel, with a stiff response to pedaling efforts. There is highly mitigated to substantially no unwanted bobbing or cycling of the suspension due to normal chain pull induced suspension compression of conventional designs. 
         [0025]    At this position in the suspension travel, any effort to extend the suspension further is also met by increased rebound damping due to the increased motion ratio in that direction. This results in increased stability in rough terrain where the rear suspension might have a tendency to extend too fast and kick the back of the bike up. 
         [0026]      FIGS. 8 and 9  illustrate the effect of a bump or braking on rear wheel  20  when the suspension is either fully extended, or compressed 25% due to rider weight, respectively. Either force will cause the bottom of link  40  to rotate rearward, driving the upper end of link  40  forward. 
         [0027]      FIG. 8  shows that even if the suspension had been fully extended due to high to maximum acceleration during a climbing effort, a bump or braking force would initiate a sequence of events that would allow the suspension to compress and absorb the bump. The horizontal component of the bump force on the rear wheel  20 , acting in the opposite direction of the previous high to maximum forward acceleration and chain force, would pull the chainstay  26  to the rear and thus rotate the bottom of link  40  to the rear. The subsequent rotation of the top of link  40  to the front initiates shock compression. At the same time the mechanical leverage of the driven link increases in ability to compress the shock due to vertical bump forces. 
         [0028]    The rotation of link  40  changes the alignment of all the aforementioned pivot points, such as the upper shock mount  32  and the chainstay pivot  44 , allowing the main shock  30  to gain a leverage advantage/transmission angle at a point where the extra suspension and all of the other benefits are most needed. 
         [0029]    In this area of suspension travel, between full extension and 25% compressed as shown in  FIGS. 6 ,  7  and  8 , the motion ratio is relatively stiff (under 2:1 as in the embodiment shown) compared to the rest of the suspension travel. This means that the rear wheel will have to experience a larger force to compress the shock than in the later part of the travel, (between 25-50% compressed as shown in  FIG. 9 , where the MR falls to 2.7:1). The result is a very stiff suspension response to any vertical inputs on the rear wheel in this part of the travel, which would only be used for extreme pedaling efforts such as climbing. 
         [0030]      FIG. 9  shows the bicycle suspension of an exemplary embodiment when at a normal compression of 25% due to rider weight, and a horizontal bump or braking force has occurred. As shown in  FIG. 9 , a bump force or braking force is encountered where there is substantially no forward pedaling or acceleration force. This would be representative of traveling on level ground or downhill. The results are similar to that shown in  FIG. 8 . The bump force has a vertical component as well as a horizontal component, which pushes the wheel  20  to the rear. This in turn, pulls the chainstay  26  and therefore rotates the bottom of link  40  to the rear. This causes the upper end of link  40  to move forward. This will enable driven link  46  to compress the shock  30  by increasing its mechanical leverage. This also causes the motion ratio of rear wheel  20  to shock absorber  30 , to rapidly change from 1.8:1 to 2.7:1 in the range of travel between 25% and 50% as shown in  FIG. 9 , right where enhanced, optimal, or maximum compliance and bump absorption are needed. 
         [0031]    This allows the most rapid response for the wheel to roll over the bump with the least resistance, and the least reaction force input to the chassis/rider. 
         [0032]    The suspension will be more plush in the initial stages and on smaller bumps, to better absorb the bumps. It also causes the fork angle and seat tube angle to relax, adding stability (especially at high speeds and/or descending), and shifts rider weight to the rear. The movement of the bottom of link  40  to the rear also means that the chainstay  26  and thus the rear wheel  20  are moving to the rear. This provides the benefit of additional ability to absorb square edge bumps and also aids stability at high speeds and/or descending. 
         [0033]    When the link  40  rotates to rear, the changes in the shock motion ratio mean that the rear wheel  20  will have more vertical travel for each increment of shock compression. This results in a suspension that has more travel available when it is needed most (i.e. hitting bumps) as shown in  FIGS. 8 and 9 , and less suspension travel when it is not needed (i.e. climbing) as shown in  FIGS. 6 and 7 . The result is two different suspension systems on one bike, as well as two different frame geometries on one bike. Both of these attributes change immediately and automatically in response to the forces acting on the bike. The rider need not make any adjustment for the changes to occur, just ride the bike and let the forces compensate for the conditions. 
         [0034]    Under braking, the horizontal force pulling the wheel to the rear is magnified, and the changes are more aggressive, making those benefits more pronounced when they are needed most. The larger the bump force, or more aggressive the braking effort, the more the bottom of link  40  wants to rotate to the rear. During braking, the advantages of better bump absorption, more rearward rider weight bias and geometry changes result in much more rear wheel traction, allowing a much higher braking force from the rear wheel  20 . During combined descending and braking over bumps, these advantages are magnified. High speed stability of the bicycle under braking is also enhanced due to the rearward weight transfer and less vertical fork rake angle. 
         [0035]      FIG. 10  shows the suspension being compressed from 50%-100%. In this area of suspension travel, resistance to “wallowing,” or remaining too deep in the travel, and resistance to bottoming are top priorities. Normally a large, fast bump or jump landing has occurred to cause the suspension to compress to this extent. The falling rate motion ratio shown in  FIG. 9 , would no longer be suitable. Thus the motion ratio shown in  FIG. 10  can be configured to be a linear or rising rate to insure a bottomless feel to the largest impacts. This is also shown in the graph of  FIG. 12 . 
         [0036]    Thus it is possible to manipulate the force level required to rotate the link, allowing the ability to configure the link to suit various priorities, such as pure climbing or descending. The horizontal force input from the forward or rearward acceleration acting on the chainstay  26  can also be manipulated to modify its effect on the rotation of link  40 . The lever arm and angle of transmission both have an effect, as illustrated in  FIG. 11 . 
         [0037]      FIG. 11  illustrates the comparison of the link in the forward and rear positions with the shock  30  extended and compressed (in phantom). In the preferred embodiment for bicycles, several force relationships are utilized to create the unique interactions. As shown in  FIG. 11 , the alignment of connecting pivot points in the link  40  can be manipulated such that any initial vertical force at the rear wheel  20 , acting through the chainstay  26  and rocker  28  will have little to no leverage to compress the shock  30  or activate the link  40  causing it to rotate. By aligning the pivots  32 ,  42 ,  48  as shown in a nearly straight line, the vertical input force from the rear wheel  20  (mainly due to rider weight or vertical motion by the rider) is transmitted to the link  40  with the worst possible transmission angle and leverage for purposes of rotating the link and compressing the shock. This means that all vertical input forces from the rider; i.e. static weight or pedaling input, have less ability to cause the upper end of link  40  to rotate to the front, and less ability to compress the shock  30  and allow the rear wheel to travel up or the bike to travel downward. 
         [0038]    It shall be understood that the exemplary embodiments summarized and described in detail above and illustrated in the figures are illustrative and not limiting or restrictive. Only the presently preferred embodiments have been shown and described and all changes and modifications that come within the scope of the invention are to be protected. It shall be appreciated that the embodiments and forms described below may be combined in certain instances and may be exclusive of one another in other instances. Likewise, it shall be appreciated that the embodiments and forms described below may or may not be combined with other aspects and features disclosed elsewhere herein. It should be understood that various features and aspects of the embodiments described above may not be necessary and embodiments lacking the same are also protected. In reading the claims, it is intended that when words such as “a,” “an,” “at least one,” or “at least one portion” are used there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. When the language “at least a portion” and/or “a portion” is used the item can include a portion and/or the entire item unless specifically stated to the contrary. Furthermore, while a number of exemplary aspects and embodiments have been discussed above, those of skill in the art will recognize certain modifications, permutations, additions and sub-combinations thereof It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope.