Abstract:
An assembly for enabling continuous seat post function during extreme conditions is described and includes: a first valve at least partially, slidably disposed within a stationary piston and for controlling a first fluid pathway there through, wherein the first fluid pathway runs from a first portion and to a second portion of the oil chamber, wherein the stationary piston separates the oil chamber into the first portion and the second portion; and a second valve at least partially disposed within the stationary piston and disposed in series with the first valve and having a second fluid pathway disposed through the first valve and the second valve, being in parallel with the first fluid pathway, running from the first portion to the second portion of the oil chamber, and providing a bypass for oil to flow from the first portion to the second portion when the first fluid pathway is closed.

Description:
BACKGROUND 
       [0001]    Field of the Invention 
         [0002]    Embodiments generally relate to a seat support assembly for a vehicle. More specifically, embodiments of the invention relate to a height adjustable seat support. 
         [0003]    Description of the Related Art 
         [0004]    A conventional seat post for a bicycle includes a suspension system that comprises an upper post telescopically positioned within a lower post. Within the upper and lower posts are positioned at least an oil chamber and a gas chamber sealingly separated by an internal floating piston (IFP). The conventional suspension system further may include an adjustable piston rod connected to a main piston, wherein the main piston divides the oil chamber into portion “A”, that portion of the oil chamber closest to the seat saddle, and portion “B”, that portion of the oil chamber closest to the gas chamber. These conventional seat posts are adjustable upon the actuation of a lever mechanically and/or remotely connected with the piston rod. The movement of the piston rod ultimately results in the opening and closing of flow ports within the main piston. 
         [0005]    During times of extreme conditions (e.g., high temperatures, sudden changes in terrain, etc.), the portion “A” of the oil chamber furthest away from the IFP may experience an increase in pressure that causes a condition commonly known as hydrostatic lock. The term, “hydrostatic lock”, generally is understood to describe a condition in a suspension in which a volume of an incompressible fluid exceeds its maximum available volume in which it resides; such a condition may render surrounding components at least temporarily non-functional. 
         [0006]    Therefore a need exists for a seat post that avoids hydrostatic lock conditions during extreme conditions. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0007]    The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments of the present technology for a seat post, and, together with the description, serve to explain the principles discussed below: 
           [0008]      FIG. 1A  depicts a conventional seat post, having a suspension system that supports a saddle thereon. 
           [0009]      FIG. 1B  depicts a block diagram of the conventional suspension system of  FIG. 1A . 
           [0010]      FIG. 2  depicts a conventional suspension system, including an upper and lower post. 
           [0011]      FIG. 3  depicts a conventional top mount lever for mechanical connection to the piston rod. 
           [0012]      FIG. 4  depicts a conventional under mount lever for remote connection to the piston rod. 
           [0013]      FIG. 5  depicts a conventional external adjustment mechanism disposed on a lower post. 
           [0014]      FIG. 6  depicts an infinite adjust seat post with a pressure relief valve, in accordance with an embodiment. 
           [0015]      FIG. 7  depicts the first portion and the second portion of the infinite adjust seat post of  FIG. 6 , including the pressure relief valve, in accordance with an embodiment. 
           [0016]      FIG. 8  depicts an enlarged view of the first portion of the infinite adjust seat post of  FIG. 7 , in accordance with an embodiment. 
           [0017]      FIG. 9  depicts an infinite adjust seat post with a pressure relief valve, having an actuation assembly disposed external to the seat post, in accordance with an embodiment. 
           [0018]      FIG. 10  depicts the components associated with the upper post and the lower post of the infinite adjust seat post, analogous to the upper and lower posts of  FIGS. 6-9 , in accordance with an embodiment. 
           [0019]      FIG. 11  depicts an exploded view of the upper post and portions of the piston assembly that is inserted into the upper post, in accordance with an embodiment. 
           [0020]      FIG. 12  depicts the cross section of the piston assembly of  FIG. 11 , assembled, in accordance with an embodiment. 
           [0021]      FIG. 13  depicts an exploded view of the piston assembly of  FIGS. 11 and 12 , in accordance with an embodiment. 
           [0022]      FIG. 14  depicts an exploded view of the upper post and the lower post, similar to that view shown in  FIG. 10 , but including an external adjustment mechanism, in accordance with an embodiment. 
           [0023]      FIG. 15  depicts an exploded view of the pressure relief valve of  FIG. 13 , in accordance with an embodiment. 
           [0024]      FIG. 16  depicts a cross sectional view of the pressure relief valve of  FIG. 15 , in accordance with an embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0025]    Reference will now be made in detail to embodiments of the present technology, examples of which are illustrated in the accompanying drawings. While the technology will be described in conjunction with various embodiment(s), it will be understood that they are not intended to limit the present technology to these embodiments. On the contrary, the present technology is applicable to alternative embodiments, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. 
         [0026]    Furthermore, in the following description of embodiments, numerous specific details are set forth in order to provide a thorough understanding of the present technology. However, the present technology may be practiced without these specific details. In other instances, well known methods, procedures, and components have not been described in detail as not to unnecessarily obscure aspects of the present disclosure. 
         [0027]    The following discussion will first describe conventional seat post technology, and the limitations associated therewith, with reference to  FIGS. 1A-5 . The discussion then turns to a description of an infinite adjust seat post with a pressure relief valve, in accordance with an embodiment and with reference to  FIGS. 6-16 . 
         [0028]    With reference to  FIG. 1A , a conventional seat post is shown, having a conventional suspension assembly within a suspension system  100  that supports a saddle  125  thereon and comprises an upper post  105  (at a first end  115 ) telescopically positioned within a lower post  110  (at a second end  120 ). With reference to  FIG. 1B , a block diagram of a portion  105 , in the upper post  105 , of the conventional suspension system  100  is shown. Within the upper post  105 , is the upper post  112  telescopically positioned with a lower post  114 . Within the upper post  112  and the lower post  114  is an internal floating piston (IFP)  155  that sealingly separates an oil chamber  180  and a gas chamber  160  positioned therein. A main piston  175 , with flow ports A  140  and flow ports B  145  there through, separates the oil chamber  180  into portion “A”  130  and portion “B”  150 . Portion “A”  130  is that portion of the oil chamber  180  that is closest to the saddle  125 . Portion “B”  150  is that portion of the oil chamber  180  closest to the gas chamber  160 . Further, a first end of an adjustable piston rod  170  connects with an actuation assembly  205  ( FIG. 2 ) located at and external to the second end  120  of the suspension system  100 . The second and opposite end of the piston rod  170  extends in length to connect with the main piston  175 . One end of a spool valve  190  is positioned partially within the main piston  175  and is also positioned to receive the second end of the piston rod  170  upon movement of the piston rod  170 . When the piston rod  170  is adjusted via the actuation assembly  165 , it pushes against the spool valve  190 , which in turn slides up and away from the direction of the IFP  155 . The seals  135 A and  135 B on the outer walls of the spool valve  190  slide over flow port A  140  gaps in the walls of the main piston  175 , thereby leaving open these flow ports A  140 , and thereby allowing fluid to flow there through from the portion “A”  130  to the portion “B”  150 . 
         [0029]    These conventional suspension assemblies  100  are adjustable upon the actuation of an actuation assembly  205  at the second end  120  of the suspension system  100 , shown at  FIG. 2 . The piston rod  170  is communicatively coupled with the actuation assembly  205  via a cable or through the use of remote technologies common in the field of technology.  FIG. 3  shows a top mount lever  300  that may be attached to the bicycle handle bars and also be mechanically attached to the actuation assembly  205  via a cable.  FIG. 4  shows an under mount lever  400  that may be attached to the bicycle handle bars and communicatively and remotely coupled with the piston rod  170  or the actuation assembly  205  through remote technologies commonly known in the art.  FIG. 5  shows an example of an external adjustment mechanism  500  that is used to adjust the piston rod  170  and/or to adjust the spool valve  190 . The movement of the piston rod  170 , and hence the spool valve  190 , ultimately results in the opening and closing of flow ports A  140  within the main piston  175 . 
         [0030]    As noted, when the flow ports A  140  in the main piston  175  are open, if the oil from portion “B” may flow through the main piston  175  and into portion “A”  130 , then the upper post  105  of the suspension system  100  extends and raises the saddle  125  attached to the suspension system  100 . If force is applied to the suspension system  100 , such as by the rider sitting on the saddle  125 , and the flow ports A  140  remain open, then oil flows from the portion “A”  130 , through the main piston  175 , and into the portion “B”  150 . Such flow is slowed and/or stopped when: 1) the flow ports A  140  are subsequently closed (through an actuation of a mechanical or remote lever); or 2) when fluid pressure (via the oil) that is applied against a first side of the IFP  155  (that divides the oil chamber  180  and the gas chamber  160 ) is met by an equal or greater pressure applied against a second side of the IFP  155  by the gas within the gas chamber  160 , wherein the second side of the IFP  155  is opposite the first side of the IFP  155 . 
         [0031]    Thus, as seen, the conventional mechanical and/or remotely connected lever is designed, upon actuation, to move the piston rod  170 . The movement of the piston rod  170  moves the spool valve  190 . The movement of the spool valve  190 , the sliding up and down within the main piston  175 , opens or closes flow ports A  140 , respectively, within the main piston  175 . The opened and closed flow ports A  140  causes the volume of oil within the oil chamber  180  to shift between the portion “A”  130  and the portion “B”  150 . The shifting of the oil, from one chamber of oil to another chamber of oil, causes the suspension system  100  to expand or compress. The expansion or compression of the suspension system  100  causes the saddle  125  resting upon the suspension system  100  to move up or down, respectively. 
         [0032]    In the situation in which the flow ports A  140  within the main piston  175  are closed, and the temperature internal to the suspension system  100  increases correspondingly to the temperature external to the suspension system  100 , then the oil within the portion “A”  130  and portion “B”  150  also thermally expands. The thermally expanded oil within the portion “B”  150  increases in volume and pressing against and moves the IFP  155  in the direction of the gas chamber  160 , thereby making the gas chamber  160  smaller while enlarging the portion “B”  150 . However, the thermally expanded oil within the portion “A”  130  does not increase in volume since this oil presses against sliding  185  and sealing  135 A and  135 B elements that serve as valves (gates) through the flow paths A  140  of the main piston  175 , keeping them from opening and creating more volume. As previously noted, in one instance, a lever mechanically or remotely, upon actuation, causes the piston rod  170  to move and thereby moves the adjacent spool valve  190 . The spool valve  190  movement translates into sliding up and down within the main piston  175 . The walls of the spool valve  190  are made of “sliders”  185  and have seals extending there from and are attached thereto. When in the “open” position, the seals  135 B are positioned on one side of the flow ports A  140 , toward the saddle  125  direction. While in the open position, the flow pathway A  140  remains unblocked. While in the “closed” position, the seals  135 B are positioned on the other side of the flow ports A  140 , toward the gas chamber  160  direction. While in the closed position, the flow pathway after entering and exiting the flow port A  140  remains blocked by the seals  135 B, such that oil may not pass there through (within the main piston  175 ) from the portion “A”  130  to the portion “B”  150 . 
         [0033]    At some point, the increase in the pressure within the portion “A”  130  of the oil chamber  180  becomes so great that the lever (e.g., the top mount lever  300  of  FIG. 3 ) that is connected to the piston rod  170  cannot be pushed down (without extreme force) to cause the piston rod  170  to move. Since the piston rod  170  cannot be moved, the spool valve  190  cannot be moved, and the seals  135 B extending from the slider  185  of the spool valve  190  remain in place and continue to block the flow pathway A  140 . Since oil is unable to flow from the portion “A”  130  to the portion “B”  150  and vice versa, the suspension system  100  succumbs to what is commonly known as hydrostatic lock, wherein the suspension system  100  cannot compress or expand upon actuation of a lever. 
         [0034]    As the foregoing illustrates, what is needed in the art are improved techniques for adjusting seat post heights while avoiding and/or overcoming a potential hydrostatic lock situation. 
       Example Infinite Adjust Seat Post with Pressure Relief Valve 
       [0035]    Embodiments of the present technology provide for an infinite adjust seat post with a pressure relief valve that prevents and eliminates hydrostatic lock by using the increase in pressure, which would normally occur in situations producing hydrostatic lock, to open a pressure relief valve. The pressure relief valve is strategically positioned in series with a spool valve, taking advantage of the fluid channel disposed within the spool valve to transfer oil from one side of the main piston to the other side of the main piston. These concepts will be discussed herein. 
         [0036]    Additionally and as will be explained below, the infinite adjust seat post provides for two parallel pathways, each having a different entry point in the main piston, but the same destination. Together, the two pathways function to allow fluid to move from a portion “A” to a portion “B” of the oil chamber. Separately, each flow pathway receives fluid flow non-concurrently. 
         [0037]      FIG. 6  depicts an infinite adjust seat post  600  with a pressure relief valve  685 , in accordance with an embodiment. More particularly,  FIG. 6  shows an upper post  690  telescopically positioned within a lower post  670 . The actuation assembly  660  is shown connected to the second end  650  of the infinite adjust seat post  600 , at the lower post  670 . The actuation assembly  660  includes a set of components (e.g., wire, metal tabs) that function together to, upon actuation, move the piston rod  630  either in a first direction or in an opposite second direction. Interior to the inner walls of the upper and the lower posts,  690  and  670 , respectively, are an oil chamber  615  and a gas chamber  645 . The IFP  635  separates the oil chamber  615  from the gas chamber  645 , and provides a seal there between. Further, the main piston  625  separates the oil chamber into portion “A”  615  and portion “B”  620 . Portion “A”  615  is positioned closest to the saddle and portion “B”  620  is positioned opposite portion “A”, at the other end of the oil chamber  615 . 
         [0038]    The main piston  625  has flow ports A  705  and flow ports B  710  ( FIGS. 7 and 8 ) disposed therein that enable oil to flow from the portion “A”  615  to the portion “B”  620  and vice versa. The first end  665  of the piston rod  630  connects with the actuation assembly  660 , while the second end  675  of the piston rod  630  connects with and resides within the main piston  625 . More particularly, the main piston  625  provides a guided slot  725  ( FIG. 7 ) central thereto and there through that allows for the movement of the piston rod  630  back and forth therein. The second end  675  of the piston rod  630 , upon its movement in a direction toward the main piston  625 , butts up against and pushes on a first end of the spool valve  680 . The walls of the spool valve  680 , called sliders  815  (functioning to slide back and forth within the main piston  625 ) ( FIG. 8 ), have extensions thereon, called seals  820  ( FIG. 8 ). These seals  820  fit snugly against the inner walls of the main piston  625 , such that fluid may not flow through or around the seals  820 . Upon being pushed at its first end, the spool valve  680  slides in a direction that is toward the portion “A”  615  of the oil chamber  615 , opening up flow ports B  710  ( FIGS. 7 and 8 ) disposed within the main piston  625 , thereby allowing oil to flow there through. A pressure relief valve  685  is shown, disposed in series with the spool valve  680 , disposed partially within the interior of the main piston  625 , and disposed partially within the portion “A”  615  side of the main piston  625 . 
         [0039]      FIG. 7  depicts the first portion  610  and the second portion  640  of the infinite adjust seat post  600  of  FIG. 6 , including the pressure relief valve  685 . However, in order to exhibit a higher degree of detail, the middle portion of the infinite adjust seat post  600  of  FIG. 6  has been redacted. Shown in  FIG. 7  is the upper post  690  telescopically disposed within the lower post  670 . The actuation assembly  715  is positioned at the second end  650  of the infinite adjust seat post  600 , at the lower post  670 . The IFP  635  separates the gas chamber  645  from the oil chamber  615 . The oil chamber  615  is divided into the portion “A”  615  and the portion “B”  620  by the main piston  625  there between. The main piston  625  has flow ports A  705  and flow ports B  710  disposed therein. The pressure relief valve  685  and the spool valve  680  are shown positioned in series with each other and also partially positioned within the main piston  625 . The first end  665  of the piston rod  630  is shown connected to the actuation assembly  715  and the second end  675  of the piston rod  630  is shown disposed within the guided slot  725  of the main piston  625 . Additionally, anti-rotation pins  720  are shown. As positioned, these anti-rotation pins  720  prevent the upper post  690  from rotating circularly within the lower post  670 . 
         [0040]      FIG. 8  depicts an enlarged view of the first portion  610  of the infinite adjust seat post  600  of  FIG. 7 , in accordance with an embodiment. The flow ports A  705  and flow ports B  710  within the main piston  625  and the flow pathways A  825  within the upper post  690  are more clearly visible and will be described below. Again, the piston rod  630  is shown connected within the guided slot  725  of the main piston  625 . Disposed within the walls of the main piston  625  are flow ports A  705  and flow ports B  710 . Flow pathway A  825  is also shown, traveling from the portion “A”  695  of the oil chamber  615 , into and out of the flow ports A  705 , into the interior of the main piston  625 , into and out of the flow ports B  710 , and then into the portion “B”  620  of the oil chamber  615 . Further, in other embodiments, the flow pathway A  825  is reversed. Also shown, in  FIG. 8  is the pressure relief valve  835  and the spool valve  680 . The outer walls of the spool valve  680  include the sliders  815  and the seals  820  extending from the sliders  815 . The pressure relief valve  835  includes the ball  805  and the spring  810 . Flow pathway B  830  is shown, traveling from the portion “A”  695  of the oil chamber  615 , into and through the gap  845  left by the ball  805  being pushed against the spring by the pressurized oil, into the interior of the main piston  625 , into and out of the flow ports B  710 , and into the portion “B”  620  of the oil chamber  615 . 
         [0041]    With reference to  FIG. 8 , the effects of thermally expanded oil within the oil chamber  615  and the application of the pressure relief valve  835  to prevent hydrostatic lock of the infinite adjust seat post  600  is now explained. In this case, the pressure relief valve  835  of the infinite adjust seat post  600  provides for the release (and relief) of the build-up of pressure within the portion “A”  695  of the oil chamber  615 , due to, in some embodiments, the thermal expansion of the oil. In one example, initially, the slider  815  and the seal  820  of the spool valve  680  are positioned on the saddle side of the flow ports A  705 . (Not shown; of note,  FIG. 8  shows the seal  820  positioned to one side of the flow ports A  705 , toward the direction of the gas chamber.) In this position, oil from the portion “A”  695  of the oil chamber  605  is allowed to travel along the flow pathways A  705 , from the portion “A”  695 , into and out of the flow ports A  705 , through the interior of the main piston  625 , into and out of the flow ports B  710 , and into the portion “B”  620 , and vice versa. 
         [0042]    Situations in which the flow ports A  705  would be “open” include at least the following scenarios: 1) when no force is being applied against the saddle; and 2) when the second end  675  of the piston rod  630  is pushing against the spool valve  680 , and in which the spool valve  680  is pushed in the direction toward the saddle, thereby leaving flow ports A  705  open. 
         [0043]    Situations in which the flow ports A  705  would be “closed”, and could cause hydrostatic lock include at least the following scenarios: 1) the piston rod  630  is not actuated to push against the spool valve  680  and much force is being continuously applied to the saddle; 2) the piston rod  630  is not actuated to push against the spool valve  680  (in the direction toward the saddle), and the bicycle goes over a large unexpected bump, driving the rider further onto the saddle during impact with the ground, causing the upper piston  850  to push against the upper part of the spool valve  680  during compression. The spool valve  680  then slides downward in the direction toward the gas chamber, and its seals block the flow pathways A  825 ; and 3) during thermal expansion of the oil, the volume within the portion “A”  695  of the oil chamber  615  cannot expand into the portion “B”  620 , since the initial thermal expansion of the oil in portion “A”  695  causes the spool valve  680  to be pushed downwards toward the gas chamber, thereby blocking the flow pathways A  825 . 
         [0044]      FIG. 8  depicts the pressure relief valve  835 , which functions to release the pressure being applied against the seals  820  (when the seals  820  are in the position shown in  FIG. 8  [on one side of the flow ports A  705 , in the direction of the gas chamber, blocking the flow pathways A  825 ), and eliminate the possibility of hydrostatic lock from occurring. The pressure relief valve  835  includes an annular wall  840 , surrounding a ball  805  that sits on top of a spring  810 . The spring  810  comprises a predetermined spring pressure. When a particular amount of pressure is applied against the ball  805 , the ball  805  pushes downward against the spring  810 , overcoming the spring force. Thus, when the oil is pressurized to a higher degree than the spring  810  holding the ball  805 , then the ball  805  pushes the spring  810  downwards and exposes the gap  845  through which pressurized oil may flow. This pressurized oil flows along the flow pathway B  830 . Just enough pressurized oil flows through the gap  845  and past the ball  805  to lower the amount of pressure being experienced by the oil remaining in the portion “A”  695  of the oil chamber  615 . When oil is pressurized and applies force to the ball  805  that is a degree lower than the force applied an the opposite side of the ball  805  from the spring (having a particular spring constant), then the force being applied against the ball  805  is not enough to overcome the spring constant and push the spring  810  downwards. 
         [0045]    However, by opening up the gap  845  to allow for some pressurized oil to flow through, the amount of oil left in the portion “A”  695  is less than was there before, while the area remains the same, thus increasing the volume for the oil that is left. Thus, by the formula, PV=nRT, it can be seen that as the volume increases, the pressure decreases (given a constant temperature). Thus, the pressure that is holding the seals  820  in the position that blocks the flow pathway A  825  is reduced. It is reduced enough to enable the piston rod  630  to move the spool valve  680  against the remaining pressure being applied to the seal  820 . Thus, after the pressure relief valve  835  opens up, thereby reducing the pressure within the oil remaining in the portion “A”  695  and also reducing the force being applied against the seal  820 , that was holding the spool valve  680  in place, the bicycle rider is now is able to physically pull or push the lever and actuate the piston rod  630  (causing the piston rod  630  to move). 
         [0046]    As can be seen, the present technology uses the increased pressure caused by a hydrostatic lock scenario to its benefit, harnessing this pressure to actuate the pressure relief valve  835 . Upon actuation, the pressure relief valve  835  opens to let pressurized oil flow from the over-pressurized volume of the portion “A”  695  and into the expandable volume of the portion “B”  620 . Such an innovative process provides for a hydrostatic lock-free existence, regardless of the riding scenario. 
         [0047]    In conventional designs, and without the pressure relieve valve  835 , the spool valve  680  would end up stuck in a hydrostatic lock position, blocking the flow of any oil from the portion “A”  695  to the portion “B”  620  of the oil chamber  615  through the flow paths A  825 . As noted herein, the pressure relief valve  835  is situated in series with the spool valve  680 , such that the flow pathway B  830  travels through both components before exiting the main piston  625  and entering the portion “B”  620  of the oil chamber  615 . Additionally, and significantly the two flow pathways, A  705  and B  710 , have different points of entry into the main piston  625 , but the same destination point. This is significant since the seal  820  blocking the origination point of the flow pathway B  830  is concurrently entering a hydrostatically locked position, while the pressure potentially causing the hydrostatically locked position is that which triggers the flow pathway B  830  to open, thereby alleviating or eliminating any pre-hydrostatic lock symptoms. As such, the infinite adjust seat post  600  with the pressure relief valve  835 , in accordance with embodiments, does not experience hydrostatic lock. 
         [0048]      FIGS. 9-16  that follow are further figures that help detail various particularities regarding the infinite adjust seat post with a pressure relief valve, in accordance with various embodiments. 
         [0049]      FIG. 9  depicts an infinite adjust seat post  600  with a pressure relief valve  835 , having an actuation assembly  660  being external to the infinite adjust seat post  600 , in accordance with an embodiment. In  FIG. 9 , it is seen that the actuation assembly  660  is mounted at the second end  650  of the lower post  670 .  FIG. 5  also offers another view of the externally mounted actuation assembly (such as seen in  FIG. 5 ). The actuation assembly  660  of  FIGS. 6 and 9  functions to cause the spool valve  680  to slide back and forth (or up and down) within the main piston  625 , thereby opening and closing, respectively, the flow pathway A  825 . 
         [0050]      FIG. 10  depicts the components associated with the upper post  690  and the lower post  670  of the infinite adjust seat post  600 , analogous to the upper and lower posts,  690  and  670 , respectively, of  FIGS. 6-9 , in accordance with an embodiment. According to one embodiment, these components include, and are listed from the top of the depicted infinite adjust seat post to its bottom, the following: a seat post saddle clamp shaft cross pin; a forged upper saddle clamp, a forged lower saddle clamp; a washer fastener for a spherical saddle clamp; a seat post bolt with a conical under head features fastener; an upper post; a pin; a lower post; an internal wire retaining ring; a seat post rocker link; a Loctite; a seat post cable stop bottom cap; a SST dowel; an SS external shaft E-clip; a seat post cable bushing; a headed pin; and a seat post actuation lever. 
         [0051]      FIG. 11  depicts an exploded view of the upper post  690  and portions of a piston assembly that is inserted into the upper post  690 , in accordance with an embodiment. The components of  FIG. 11  are listed, as assembled, from the internal wire retaining ring on the left to the shaft lug on the right, as follows: an internal wire retaining ring; a seat post spool valve cap assembly; a piston assembly; an upper post; an internal wire retaining ring; a seat post IFP assembly; a wire retaining bore retaining ring; a seat post seal head; a ring; a seat post seal; a seat post upper bushing; a seat post lower bushing; and a shaft lug. 
         [0052]      FIG. 12  depicts the cross section of the piston assembly of  FIG. 11 , assembled, in accordance with an embodiment.  FIG. 13  depicts an exploded view of the piston assembly of  FIGS. 11 and 12 , in accordance with an embodiment. The components of  FIG. 13  are listed, as assembled, from the seat post pressure relief valve on the left to the O-ring seals on the right, as follows: seat post pressure relief valve; seat post crush washer; spring music wire; seat post spool valve; seat post piston glide ring; seat post spool valve piston; O-ring; push rod; shaft; and O-ring seals. 
         [0053]      FIG. 14  depicts an exploded view of the upper post  690  and the lower post  670 , similar to that view shown in  FIG. 10 , though including an external adjustment mechanism, in accordance with an embodiment. The infinite adjust seat post of  FIG. 14  further includes, beyond those components shown in  FIG. 14 , the following components, as assembled, from the seat post cable actuation stop; the external retaining ring; the seat post bell crank shaft; the O-ring seals; the seat post pulley; and the flat-head socket cap screw. 
         [0054]      FIG. 15  depicts an exploded view of the pressure relief valve  835  of  FIG. 13 , in accordance with an embodiment. The components of  FIG. 13  are listed in the order to be assembled, from the seat post spool valve cap to the pressure relief valve spring retainer, as follows: the spool valve cap; the steel ball; the detent spring; and the pressure relief valve spring retainer. 
         [0055]      FIG. 16  depicts a cross sectional view of the pressure relief valve  835  of  FIG. 15 , in accordance with an embodiment. Components shown in  FIG. 16  include the ball  805  and the spring  810 . 
         [0056]    While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be implemented without departing from the scope of the invention, and the scope thereof is determined by the claims that follow.