Height-adjustable seatposts for bicycles

Abstract

This document describes height-adjustable seatposts for bicycles. An exemplary height-adjustable seatpost comprises an upper tube and a lower tube arranged telescopically. The height-adjustable seatpost includes a piston in the upper tube, which divides the upper tube into a first chamber and a second chamber. The piston defines a fluid passage between the first and second chambers. The height-adjustable seatpost further includes a plug in the fluid passage. The plug is movable in a linear direction between an open position, in which fluid flow through the passage is possible, and a closed position, in which fluid flow through the passage is blocked. The height-adjustable seatpost further includes a motor and a cam assembly for converting the rotary motion of the motor into a linear motion of the plug.

Description

This application claims priority to U.S. Provisional Patent Application No. 63 / 516,574, filed July 31, 2023, the contents of which are hereby incorporated by reference in their entirety.FIELD OF DISCLOSUREThis disclosure relates generally to bicycle components and, more particularly, to height adjustable seat posts for bicycles.BACKGROUNDBicycles are known to be equipped with a seat or saddle that holds a rider in a seated position. The seat is usually connected to the bicycle frame via a seat post. In most bicycles, the seat post can be adjusted manually to increase or decrease the height of the seat and thus adapt to riders of different body sizes. The height can also be adapted to different driving conditions. Normally, the seat post is mechanically clamped to a tube of the bicycle frame. When the clamp is released, the seat and support are slidable up and down relative to the tube of the bicycle frame to adjust the height of the seat. In some recent bicycles of higher quality, the seat post is height-adjustable by using some type of hydraulic auxiliary mechanism during travel. For example, manually operated hydraulically height adjustable seatposts or "dropout" seatposts may use a hydraulic pressure difference in the support and the height of the seatpost is adjusted by manual operation. Some products may utilize ANT+ wireless communication technology that allows the rider to wirelessly adjust the seat post.GENERAL DESCRIPTIONAn example height adjustable seatpost for a bicycle disclosed herein includes an upper tube and a lower tube that are telescopically disposed. The lower tube is couplable to a frame of the bicycle and the upper tube is couplable to a seat. The height adjustable seat post includes a piston in the upper tube. The piston divides the upper tube into a first chamber and a second chamber. The first and second chambers are filled with fluid. The piston defines a fluid passage between the first chamber and the second chamber. The height adjustable seat post further includes a plug in the fluid passage. The plug is linearly movable between an open position permitting fluid flow through the fluid passage and a closed position blocking fluid flow through the fluid passage. The height adjustable seat post further includes a motor and a cam assembly for converting rotational movement of the motor into linear movement of the plug.An example bicycle component disclosed herein includes a first tube and a second tube telescopically disposed, and a valve disposed in the first tube and dividing the first tube into a first chamber and a second chamber. The first and second chambers are filled with fluid. The valve is operable between a closed state in which the fluid is prevented from flowing between the first and second chambers via the valve and an open state in which the fluid is allowed to flow between the first and second chambers via the valve. The bicycle component further comprises a cam assembly having a first cam, a second cam, and a ball between the first cam and the second cam. At least one of the first cam and the second cam has a recess with a ramp profile. The ball is disposed in the recess, and rotation of the second cam causes the ball to move the first cam in a linear direction to open or close the valve.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a side view of an example bicycle in which one of the example height adjustable seat posts disclosed herein may be used. FIG. 2 is a side view of an example height adjustable seat post in a fully extended position. FIG. 3 is a side view of the example height adjustable seat post of FIG. 2 in a partially retracted position. FIG. 4 is an enlarged view of an example control module that may be used on the example height adjustable seat post of FIG. 2. FIG. 5 is a cross-sectional view of the example height adjustable seat post of FIG. 2 in the fully extended position. FIG. 6 is a cross-sectional view of the example height adjustable seat post of FIG. 3 in the partially retracted position. FIG. 7 is an enlarged view of the upper portion of FIG. 5 showing an example valve for adding pneumatic gas to the example height adjustable seat post. FIG. 8 is an enlarged view of the portion of FIG. 6 and a cross-sectional view of an example piston assembly with an example cam assembly used in the example height adjustable seat post. FIG. 9 is an exploded view of an example engine assembly and an example engine assembly housing adjacent a lower end of the example height adjustable seat post of FIG. 2. FIG. 10 is an exploded view of the example engine assembly of FIG. 9. FIG. 11 shows the assembled example engine assembly of FIG. 10. FIG. 12 is an enlarged view of the lower portion of FIG. 5 and a cross-sectional view of the example motor assembly at the lower end of the example height adjustable seat post. FIG. 13 is a cross-sectional view of the example motor assembly of FIG. 12 taken along a plane perpendicular to the cross-sectional view of FIG. 12. FIG. 14 is an exploded view of the example piston assembly and valve rod of the example height adjustable seat post of FIG. 2. FIG. 15 is an enlarged view of the example cam arrangement of the example cutout in FIG. 14. FIG. 16A is a cross-sectional view of the example piston assembly and valve rod of FIG. 14 showing an example valve of the example piston assembly in a closed state. FIG. 16B shows the example valve of FIG. 16A in the open state. FIGS. 17A, 17B, 17C, 17D, and 17E are different views of an example second (lower) cam of the example cam assembly of FIG. 15. FIGS. 18A, 18B, and 18C are various views of an example first (upper) cam of the example cam assembly of FIG. 15. FIG. 19A is a plan view showing two recesses of the first and second cams of the example cam assembly of FIG. 15 in a first (closed) valve position. FIG. 19B shows the two recesses in a second (open) valve position. FIG. 20 is an example diagram showing a current profile for opening the example valve of FIGS. 16A and 16B. FIG. 21 is an example diagram showing a current profile for closing the example valve of FIGS. 16A and 16B. FIG. 22 is an example diagram showing a current profile for the pulsing opening of the example valve of FIGS. 16A and 16B. FIG. 23 is an example diagram showing a current profile for drawing energy when closing the example valve of FIGS. 16A and 16B. FIG. 24 is a cross-sectional view of the example height adjustable seat post similar to FIG. 2, but with the example engine assembly installed in an example upper tube with the example piston assembly. FIG. 25 is an enlarged view of the lower portion of FIG. 24, showing a lower end of an example lower tube of the example height adjustable seatpost. FIG. 26 is an enlarged view of the upper portion of FIG. 24, showing the example piston assembly and motor assembly in the example upper tube. FIG. 27 shows an example integrated valve rod and carrier that may be used in any example seat post disclosed herein. FIG. 28 is a cross-sectional view of the example piston assembly showing an example plug with an example co-molding sealing material. FIG. 29 is a perspective view of the example plug and example co-molding sealing material of FIG. 28. FIG. 30 ais a perspective view of another example plug that may be used in any example seat post disclosed herein. FIG. 30 bis an exploded perspective view of the example plug of FIG. 30 a. FIG. 30 cis a side view of the exemplary plug of FIG. 30 a. FIG. 30 dis a cross-sectional view of the example plug of FIG. 30 a taken along section line 30 d- 30 din FIG. 30 c.The figures are not to scale. The thickness of the layers or regions in the drawings may instead be shown in an enlarged manner. In general, the same reference numerals are used in the drawing(s) and the accompanying written description to refer to the same or similar parts.The terms "first / r / s", "second / r / s", "third / r / s", etc. are used herein to refer to multiple elements or components that may be separately referred to. Unless otherwise indicated or apparent from the context of use, these terms have no meaning for a priority or temporal sequence, but serve merely to identify a plurality of elements or components for easier understanding of the disclosed examples. According to some examples, the term "first / r / s" may be used to refer to an element in the detailed description, while for the same element in a claim, a different term such as "second / r / s" or "third / r / s" may be used. In such cases, such terms are used merely for convenience to refer to multiple elements or components.DETAILED DESCRIPTIONSome modern bicycles are equipped with a height adjustable seat post, sometimes also referred to as a Dropout seat post. This type of seat post allows the rider to change the height of the seat during travel. For example, the rider may actuate a seat post actuator on the handlebar and then press the seat downward (e.g., with the buttocks) to allow the seat post to retract or contract, thereby decreasing the seat height. When the rider no longer actuates the seat post actuator, the seat post remains in the retracted position. If the rider then wishes to raise the seat, he may re-actuate the seat post actuator, whereupon the seat post extends or expands to restore the seat to the original height. This lowering possibility can be advantageous if the rider wishes to drive with the bicycle steeply downhill. For example, the seat is lowered while driving downhill, so that the driver can stand up and lean rearward without the seat touching the buttocks. This lowering possibility can also be used to lower the seat before the driver comes to a slope at which he normally stands up and steps into the pedals. This adjustability can also be used in many further scenarios.In some dropper seat rods, the height of the seat rod is varied by hydraulic fluid and / or pneumatic pressure controlled by a mechanically or hydraulically operated valve. Recently, for flipper seat posts, battery powered motors are used that are controlled by an electrical signal to actuate the valve. The valve controls fluid flow between a positive chamber and a negative chamber in the seat post. The fluid mass is exchanged back and forth between the positive and negative chambers to vary the ride height of the seat post with a closing-opening-closing cycle of the valve. Some known dropout seat posts have a complex gear system for converting a rotational motion of the motor into a linear motion for operating the valve. However, in these known transmission systems, it is necessary for the motor axis to be offset from the valve axis. In other words, the motor is axially offset from the valve and the other components of the flipper seat post. This offset therefore requires a larger cylindrical volume for the seat post. Furthermore, these known transmission systems have a high friction, which reduces the electrical efficiency when the valve is actuated. Other known dropout seat posts use lead screws to eliminate the offset, but also have electrical inefficiencies due to inherent sliding friction. Furthermore, these known dropout seat posts require a position sensor to monitor the position or condition of the valve. These position sensors add weight, complexity and cost to the seat post.Disclosed herein are example height adjustable seat posts having a motor controlled valve and a cam assembly that converts rotational movement of the motor into linear movement to change valve state. In particular, the valve may be a linear valve, e.g., a poppet valve, that includes a flow control element (e.g., a plug) that is linearly movable to actuate the valve between an open state in which the seat post can extend or retract and a closed state in which the seat post is maintained in a particular position (corresponding to a particular seat height). The rotational motion output by the motor is transformed or transformed into a linear motion by the cam assembly to move the flow control member in the linear direction. The example cam assembly disclosed herein is configured such that the motor may be axially aligned with the valve. This eliminates the motor-valve offset that occurs with other known Dropout seat posts. The disclosed examples thus allow for a smaller cylindrical volume for the seat post. Moreover, the example cam assembly disclosed herein uses one or more ball bearings that have lower friction and thereby improve electrical efficiency in converting engine rotational motion to linear motion to change valve state. According to some examples, the seat post also does not require a position transmitter, as is customary in known dropout seat posts. This significantly reduces the weight, complexity, and cost associated with the seat post.An example height adjustable seat post disclosed herein includes an upper tube and a lower tube that are telescopically disposed. The lower tube is coupled or attached to the bicycle frame and the seat is coupled to the upper tube. The upper tube may be slid relative to the lower tube to adjust the height of the seat. The upper tube is sealed at both ends and forms a pneumatic chamber which is filled with a pressurized gas (e.g., air, nitrogen). The seat post includes a shaft coupled to the lower tube and extending into the upper tube. The seat post includes a piston or valve assembly disposed in the upper tube and coupled to the shaft. The piston assembly comprises a piston (which may also be considered a valve body) which divides the pneumatic chamber into an upper pneumatic chamber or positive gas chamber and a lower pneumatic chamber or negative gas chamber. The positive gas chamber biases the upper and lower tubes away from each other, and the negative gas chamber biases the upper and lower tubes toward each other. The piston has one or more channels or openings defining a fluid passage through the piston and between the upper and lower pneumatic chambers. The piston assembly includes a plug, e.g., a poppet, that is linearly movable (e.g., up and down) in the fluid passage to control fluid flow between the two chambers. The piston and plug form a valve operable between a closed state and an open state. The seat post further includes a motor that actuates the valve between the closed and open states. When the valve is in the closed state, it blocks or prevents gas flow between the two chambers. As regards the terms "blocking" or "preventing", for purposes of the following discussion, the terms "blocking" or "preventing" refer to the most restricted gas flow that may be achieved or desired. Thus, according to one example, the term "blocking" or "preventing" means that the entire gas flow between both chambers is interrupted. However, according to another example, the term "blocking" or "preventing" means that substantially all gas flow between both chambers is interrupted. The pressure in the upper pneumatic chamber is sufficient to support the weight of the rider. If the seat is to be raised or lowered, the motor is activated to open the valve. When the valve is open, gas can flow between the upper and lower pneumatic chambers via the piston. This allows the rider to move the upper tube up or down relative to the lower tube, thereby increasing or decreasing the height of the seat. Once a desired seating position is reached, the motor is activated to close the valve, thereby maintaining the seat post in the current position.The example seat post disclosed herein includes a cam assembly that converts rotational movement generated by the motor into linear movement of the plug to actuate the valve between the open and closed states. According to some examples, the cam assembly is disposed in the piston. The cam assembly includes a first cam, a second cam, and one or more ball bearings between the first and second cams. According to some examples, the first and second cams are axially aligned with the plug. According to some examples, the first and second cams are disk shaped. The first cam is disposed between the second cam and an end of the plug. The first cam is linearly slidable in the valve, but is prevented from rotating in the piston. The second cam is rotatable in the piston relative to the first cam. The first and second cams have recesses with a ramp profile. The ball bearings are disposed in corresponding recesses in each of the first and second cams. The second cam is operatively coupled to the motor (e.g., via a valve rod and / or a reduction system). When the motor is activated, the motor rotates the second cam. By this rotation, the ball bearings roll in the recesses between the deeper portions of the recesses and the shallower portions of the recesses. For example, when the motor is activated to rotate the second cam in a first direction, the balls are rolled from the deeper portions of the recesses to the shallower portions of the recesses. This linearly displaces the second cam away from the second cam, thereby linearly moving the plug from a closed position to an open position. When the motor is activated to rotate the cam in the opposite direction, the ball bearings are rolled back into the deeper portions of the recesses, whereby the first cam moves towards the second cam and the plug can thus move back into the closed position. The cam assembly therefore converts rotational movement of the motor into linear movement of the plug of the valve. The exemplary ball bearings produce very little, if any, friction. As a result, the valve can be opened and closed with little energy. Further, the example cam arrangement enables axial alignment of the motor with the piston and the plug. This reduces (e.g., minimizes) the cylindrical space needed to accommodate the parts.According to some examples, the ramp profile of the recesses is configured to maintain the ball bearings in certain positions corresponding to the open and closed states. As a result, the valve can be self-locking. Therefore, the valve can be maintained in the open or closed state against the chamber pressure bias without electric power being consumed. Further, the plug (e.g., the poppet) may be arranged such that the plug is biased to the closed position by the chamber pressure. This allows the plug to be held in the closed position when the valve is in the closed state. According to some examples, the motor control module detects the ramp profile changes by motor current draw and may determine the valve state to discontinue supplying the motor with electrical energy. This eliminates the need for a position transmitter. Moreover, the power consumption is further reduced by the interruption of the power supply after a drop in the motor current consumption before a blocking state, and thus the electrical efficiency is improved.According to some examples disclosed herein, the engine is coupled to and / or otherwise disposed on a lower end of the lower tube. According to these examples, the seat post includes a valve rod extending through the shaft between the engine and the piston assembly. The motor may be activated to rotate the valve rod and control the state of the valve. In some cases, this position of the motor is advantageous because it can be made physically larger (e.g., with a larger diameter). According to some examples, the seat post includes a control module having a power supply (e.g., a battery) for operating (e.g., activating or deactivating) the engine. According to some examples, the control module is coupled to the power supply on an outer surface of the lower tube, e.g., at or near the clamping ring at the upper end of the lower tube. According to some examples disclosed herein, the seat post includes a network of conduits and / or electrical connectors that electrically connect the control module disposed outside the tubes to the motor coupled to the bottom end of the seat post. According to further examples disclosed herein, the engine is coupled to and / or otherwise integrated with the piston assembly in the upper tube. The seat post may include additional leads extending through the shaft to electrically couple the control module to the engine.Referring now to the figures, FIG. 1 shows an example of a human-powered vehicle in which the example seat pillars disclosed herein may be employed. In this example, the vehicle is a possible type of bicycle 100, e.g., a mountain bike. In the illustrated example, the bicycle 100 includes a frame 102, and a front wheel 104 and a rear wheel 106 rotatably coupled to the frame 102. In the example shown, the front wheel 104 is coupled to the front end of the frame 102 via a front fork 108. A front and / or front direction or orientation of the bicycle 100 is indicated by the direction of arrow A in FIG. 1. Thus, a forward moving direction for the bicycle 100 is indicated by the direction of arrow A.In the example illustrated in FIG. 1, the bicycle 100 includes a seat 110 (sometimes also referred to as a saddle) coupled to the frame 102 (e.g., proximate the rear end of the frame 102 relative to the forward direction A) via a seat post 112 constructed in accordance with the teachings of the present disclosure. In the example shown, the seat post 112 is coupled to a seat tube 114 of the frame 102. According to some examples, the seat post 112 is coupled to the seat tube 114 via a clamp 116. The seat post 112 is height adjustable to raise or lower the seat 110. According to some examples, the bicycle 100 includes a button for operating the seat post 113 to control the seat post 112, the operation of which is exemplarily disclosed in detail herein. The bicycle 100 further includes a handlebar 118 coupled to the frame 102 and the front fork 108 (e.g., proximate a front end of the frame 102 relative to the forward direction A) to enable the bicycle 100 to be steered. According to some examples, the seat post 113 actuation button is attached to the handlebar 118 to allow the rider to interact with the seat post 113 actuation button while driving the bicycle 100. The bicycle 100 is shown on a riding surface 120. The travel surface 120 may be any travel surface, e.g., the ground (e.g., an unpaved path, a sidewalk, a road, etc.), an artificial structure over the ground (e.g., a wooden ramp), and / or other surface.In the illustrated example, the bicycle 100 includes a drive train 122 that includes a crank assembly 124. The crank assembly 124 is operatively coupled via a chain 126 to a sprocket assembly 128 mounted to a hub 130 of the rear wheel 106. The crank assembly 124 includes at least one, typically two, crank arms 132 and pedals 134, and at least one front sprocket or chain ring 136. A rear gear change device 138, e.g., a derailleur, is disposed on the rear wheel 106 to move the chain 126 between various sprockets of the sprocket assembly 128. Additionally or alternatively, the bicycle 100 may include a plurality of front chain rings and a front gear changer to move the chain 126 between the plurality of chain rings.The example bicycle 100 may include a suspension system having one or more suspension components. In the illustrated example, the bicycle 100 includes a rear suspension component 140. In this example, the rear suspension component 140 is embodied as or comprises a shock absorber. According to some examples, the front fork 108 is also configured as a front suspension component. For example, a spring can be integrated in one of the legs and a damper can be integrated in the other leg. The front fork 108 and the rear suspension component 140 absorb shocks and vibrations during travel with the bicycle 100 (e.g., travel on rough terrain). According to further examples, the front fork 108 and / or the rear suspension component 140 may be incorporated into the bicycle 100 in other configurations or arrangements.According to some examples, one or more components of the bicycle 100 may include electronic components for controlling and / or monitoring various aspects of the bicycle 100. For example, the bicycle 100 of FIG. 1 includes a control device or cycle computer 142 mounted on the handlebar 118. The bicycle computer 142 can wirelessly communicate with the seat post 112, the rear gear changer 138, the front fork 108, and / or the rear suspension component 140 to collect data and / or control the operation of the respective components. The cycle computer 142 may also wirelessly communicate with a power meter 144 of the crank assembly 124. The aforementioned components may be coupled to a wireless network.Although the example bicycle 100 illustrated in FIG. 1 is a mountain bike, the example height adjustable seatposts disclosed herein may be applied to bicycles of other types. For example, the example seatposts disclosed herein may be used on racing bicycles as well as bicycles with mechanical (e.g., cable, hydraulic, pneumatic, etc.) and non-mechanical (e.g., wired, wireless) drive systems. The example seat pillars disclosed herein may also be used with other types of human-powered two-, three- and four-wheeled vehicles. Moreover, the example seat pillars disclosed herein may be used on other types of vehicles, e.g., motor vehicles (e.g., motor cycles).FIG. 2 is a perspective view of the example height adjustable seat post 112 that may be used on the bicycle 100 of FIG. 1. The seat post 112 may also be referred to as a dropout seat post or seat post assembly. The length or height of the example seat post 112 is adjustable such that the height of the seat 110 (FIG. 1 ) may be increased or decreased. In the illustrated example, the seat post 112 includes a first tube 202, referred to herein as a lower tube 202, and a second tube 204, referred to herein as an upper tube 204. The lower and upper tubes 202, 204 may also be referred to as seat post portions or segments. As shown in FIG. 2, the lower and upper tubes 202, 204 are coaxially disposed and aligned along an axis 206. The axis 206 corresponds to a central or longitudinal axis of the seat post 112. The lower tube 202 includes a first end 208, referred to herein as upper end 208, and a second end 210 opposite the upper end 208, referred to herein as lower end 210. The upper tube 204 also includes a first end 212, referred to herein as upper end 212, and a second end 500 (shown in FIGS. 5 and 6 ) opposite the upper end 212, referred to herein as lower end 500. The upper tube 204 and the lower tube 202 are telescopically disposed. More specifically, in this example, the upper tube 204 extends into an opening 213 in the upper end 208 of the lower tube 202. Thus, the upper tube 204 is at least partially disposed within the lower tube 202. The upper tube 204 can be slid into and out of the opening 213 in the lower tube 202, thereby allowing the overall height or length of the seat post 112 to be varied. According to further examples, the lower and upper tubes 202, 204 may be formed such that the lower tube 202 extends into the lower end 500 of the upper tube 204.In the illustrated example, the seat post 112 includes a seat clamp 214 coupled (e.g., welded, bolted, threaded, etc.) to the upper end 212 of the upper tube 204. The saddle clamp 214 is used to couple the seat 110 (FIG. 1 ) to the seat post 112. In this example, the saddle clamp 214 includes two threaded fasteners 216, 218 (e.g., bolts) that can be tightened to secure the seat 110 to the upper tube 204. According to further examples, the seat post 112 may include other mechanisms for attachment to the seat 110. In the illustrated example, the seat post 112 includes a motor assembly 220. The motor assembly 220 includes a motor used to actuate a valve in the seat post 112, as disclosed in detail herein. In this example, the motor assembly 220 is coupled to the lower end 210 of the lower tube 202. The motor assembly 220 may also be referred to as an end cap at the lower end 210 of the lower tube 202. According to further examples, the motor assembly 220 may be located in other locations, an example of which is described in conjunction with FIGS. 24-26.When the seat post 112 is installed on the bicycle 100 (FIG. 1 ), the lower tube 202 is coupled to the frame 102 (FIG. 1 ). For example, the lower tube 202 may be inserted into the seat tube 114 (FIG. 1 ) and secured by the clamp 116 (FIG. 1 ). The upper tube 204 extends upward from the lower tube 202 and retains the seat 110 (FIG. 1 ). As disclosed in detail herein, the seat post 112 includes an internal valve that allows the upper tube 204 to move (e.g., slide) downward relative to the lower tube 202 and provides a repulsive force to move the upper tube 204 upward relative to the lower tube 202. Thus, it is easy for a driver to decrease the height of the seat 110 or increase the height of the seat 110. The seat post 112 is adjustable between a fully extended position (sometimes referred to as an upper end position) as shown in FIG. 2 and a fully retracted position in which the upper tube 204 is moved into the lower tube 202 until a stop or limit is reached. The seat post 112 may also be extended / retracted and maintained in any position between the fully extended and fully retracted positions. For example, FIG. 3 shows an example in which the upper tube 204 has been partially moved into the lower tube 202. This would lower or bring the seat 110 (FIG. 1 ) closer to the ground compared to the position in FIG. 2.In the example illustrated in FIG. 2, the seat post 112 includes a control module 222, which may also be referred to as a controller or controller. The control module 222 includes a power supply (e.g., a battery) and circuitry (e.g., a processor circuit, a logic circuit, etc.) for actuating the internal valve. In this example, the control module 222 is coupled to an outer surface 223 of the lower tube 202 at or near the upper end 208 of the lower tube 202. In some known dropout supports, the control module is arranged on the saddle clamp. However, this location may impair the freeness of the rear tire. Therefore, it may be advantageous to locate the control module 222 at the upper end 208 of the lower tube 202 adjacent the overlap area to improve the freeness of the rear wheel. This location also helps maintain a minimum drop height to total length ratio.If a driver wishes to lower the seat 110 (FIG. 1 ), he actuates, for example, a seat post actuator, as in the present example, the button for actuating the seat post 113 (FIG. 1 ). In FIG. 1, the button for operating the seat post 113 is attached to the handlebar 118 such that the rider can operate the button for operating the seat post 113 with a finger (e.g., thumb). Alternatively, the button for operating the seat post 113 may be a lever or a type of user interface, for example, a display device having a touch screen. When the seat post operation button 113 is pressed, the seat post operation button 113 transmits a signal (e.g., a wireless signal) to the control module 222. The control module 222 receives the signal from the button to actuate the seat post 113 and activates the motor assembly 220 to open the internal valve disposed in a pneumatic chamber in the upper tube 204, as disclosed in detail herein. As long as the internal valve is open, the operator may push seat 110 downward, pushing upper tube 204 into lower tube 202, as shown in the position of FIG. 3. According to some examples, the driver may apply this force by seating on the seat 110 and applying the downward force with the buttocks. When the seat 110 has reached the desired height, the driver can release the button for actuating the seat post 113. The control module 222 then closes the internal valve, thereby maintaining the upper tube 204 in position relative to the lower tube 202. If the driver wishes to raise the seat 110, he can press the button again to actuate the seat post 113. The control module 222 receives the signal and opens the internal valve. When no or little downward force acts on the seat 110, the internal pneumatic system forces the upper tube 204 upward from the lower tube 202, thereby moving the seat 110 upward. Once the desired position is reached, the rider may release the button to actuate the seat post 113 to close the internal valve and maintain the seat post 112 in the current position. The seat post height can therefore be easily adjusted by the rider.According to some examples, the rider presses and holds the button to actuate the seat post 113 to activate the internal valve. As long as the button for operating the seat post 113 is pressed, the valve is maintained in the open state, whereby the upper tube 204 can slide up or down relative to the lower tube 202. When the rider releases the button for operating the seat post 113, the internal valve is closed, thereby holding the upper tube 204 in position. However, according to further examples, the system may be configured such that the rider may press and release the seat post 113 operation button to open the valve, and then press the seat post 113 operation button a second time to close the valve.FIG. 4 is an enlarged view of the control module 202 around lower tube 202. In the illustrated example, the control module 222 includes a clamp ring 400, a control housing 402 coupled to the clamp ring 400, and a power supply, in this example, a battery 404 coupled to the control housing 402. The clamp ring 400 wraps around the lower tube 202 and serves to couple the control module 222 to the lower tube 202. In this example, the clamping ring 400 includes a first portion 406 aand a second portion 406 bcoupled together and thus clamped around the lower tube 202. According to some examples, the first and second portions 402 a, 402 bare coupled by a snap fit and / or threaded fasteners (e.g., screws, bolts, etc.). The control housing 402 includes electronic components for receiving control signals and operating the internal valve (e.g., opening the valve, closing the valve, etc.). For example, FIG. 4 shows a block diagram of the control housing 402. The control housing 402 includes a processor circuit 408 and a wireless communication device 410. The wireless communication device 410 includes a receiver. The wireless communication device 410 may receive wireless control / command signals from the button for operating the seat post 113 and / or another bicycle component such as the bicycle computer 142. According to some examples, the wireless communication device 410 may additionally include a transmitter (e.g., a transceiver) and transmit wireless control / command signals to the button to actuate the seat post 113 and / or other bicycle components such as the bicycle computer 142. For example, in response to receiving a command, the processor circuit 408 activates a motor (e.g., by applying current or voltage to the motor) in the motor assembly 220 to open the valve in the upper tube 204 to allow the seat post 112 to extend or retract. When the seat post actuation button 113 is released, no control / command signals are received and the processor circuit 408 activates the motor to close the valve and thereby maintain the seat post 112 in position. According to further examples, a second or separate control / command signal is received when the button is released to actuate the seat post 113. The wireless communication device 410 is configured to communicate wirelessly and therefore includes one or more antennas. The wireless communication device 410 enables wireless communication in any known or later developed format. Although the present description describes components and functions that may be implemented in certain embodiments with reference to certain standards and protocols, the examples disclosed herein are not limited to such standards and protocols. For example, standards for transmission over the Internet and other packet switched networks (e.g., TCP / IP, UDP / IP, HTML, HTTP, HTTPS) are examples of the prior art. These standards are periodically replaced by faster or more efficient equivalents having substantially the same functions. Blue-tooth® ANT+TM, ZigBee, WiFi, and / or AIREA™ standards may also or alternatively be used. Accordingly, replacement standards and protocols having the same or similar functions as disclosed herein are considered equivalents.As used herein, the term "processor circuit" includes (i) one or more special purpose electrical circuits structured to perform particular operations and including one or more semiconductor-based logic devices (e.g., electrical hardware implemented by one or more transistors), and / or (ii) one or more general purpose semiconductor-based electrical circuits that can be programmed with instructions to perform particular operations and include one or more semiconductor-based logic devices (e.g., electrical hardware implemented by one or more transistors). Examples of processor circuits include programmable microprocessors, field programmable gate arrays (FPGAs) that can instantiate instructions, central processor units (CPUs), graphics processor units (GPUs), digital signal processors (DSPs), XPUs or microcontrollers, and integrated circuits such as application specific integrated circuits (ASICs). An XPU may be implemented, for example, by a heterogeneous computer system that includes multiple types of processor circuitry (e.g., one or more FPGAs, one or more CPUs, one or more GPUs, one or more DSPs, etc., and / or a combination thereof) and application programming interface(s) (API(s)) that may / may assign a computing task(s) to the / those of the multiple types of processor circuitry that is / are best suited for executing the computing task(s).The battery 404 powers the electronic components of the control housing 402 that controls the motor assembly 220. The battery 404 also provides power to power or activate a motor of the motor assembly 220 (FIG. 2 ). According to some examples, the battery 404 is removable, e.g., by pressing an unlock tab or button or by pushing the battery 404 in a particular direction away from the control housing 402 (FIG. 4 ). According to some examples, the battery 404 may be removed, charged, and reattached to the control housing 402. According to further examples, the battery 404 may be fixed to the seat post 112 such that it needs to be disassembled for removal (e.g., by removing one or more screws). According to some examples, the battery 404 may be charged while the battery 404 is mounted to the control housing 402. The battery 404 may be charged by cable or wirelessly. For example, the battery 404 may include a charging port or a load surface for charging. According to further examples, the battery 404 may not be rechargeable and needs to be replaced with a new battery. In this example, the power supply to the motor is attached to the clamp ring 400 at the upper end 208 of the lower tube 202. According to some examples, the battery 404 is fixed relative to the lower tube 202 (via the clamp ring 400) and relative to the lower tube 202 when mounted to the bicycle 100 (FIG. 1 ). According to further examples, the battery 404 may be disposed at various locations, e.g., at the clamp 116 (FIG. 1 ), the clamp ring 400 (FIG. 4 ), or the lower end 210 of the lower tube 202. The battery 404 may be oriented horizontally, vertically, or at an angle. According to some examples, the battery 404 may be disposed forward of the axis of the lower tube or rearward of the axis of the lower seat tube. According to some examples, the battery 404 may be disposed on both sides of the axis of the lower tube such that the center plane of the bicycle 100 does not intersect the battery 404. The battery 404 may also be mounted remotely from the seat post 112 and connected to the seat post 112 via electrical leads (e.g., one or more leads extending through or along the frame 102).According to some examples, as shown in FIG. 4, the control module 222 includes a control button 412 and a light 414 (e.g., a light emitting diode (LED)). The button 412 may be used to turn the control module 222 on and off and / or to control various functions of the control module 222. The light 414 may illuminate (e.g., blink, maintain a color, change color, etc.) to indicate various modes or states of the control module 222. For example, the button 412 may be pressed to initiate a pairing process for coupling the seat post 112 to the button to actuate the seat post 113 on the handlebar 118 and / or other devices such as the bicycle computer 142. In response to pressing the button 412, the light 414 may blink indicating that the pairing process has begun. For example, once the seat post 112 and the bicycle computer 142 have been successfully coupled, the light 414 can flash rapidly indicating to the rider that the coupling was successful.FIG. 5 is a cross-sectional view of the seat post 112 in the fully extended position corresponding to FIG. 2, and FIG. 6 is a cross-sectional view of the seat post 112 in a partially retracted position corresponding to FIGS. 3, 5, and 6 will be described together. As shown in FIGS. 5 and 6, the upper tube 204 has a lower end 500. The lower end 500 is disposed in the lower tube 202. The lower and upper tubes 202, 204 overlap in an overlap region. In FIG. 5, the lower and upper tubes 202, 204 overlap by a length L 1, and in FIG. 6, the lower and upper tubes 202, 204 overlap by a length L 2 greater than L 1. Thus, the height or length of the seat post 112 in FIG. 6 is less than the height or length of the seat post 112 in FIG. 5.As shown in FIGS. 5 and 6, the upper tube 204 defines a chamber 502. The chamber 502 is filled with fluid (e.g., pneumatic gas) as detailed herein. The seat post 112 includes an upper plug 504 (e.g., an upper seal or bushing) coupled to the upper tube 204 and disposed within the upper tube 204 at or near the upper end 212. The seat post 112 further includes a lower plug 506 (e.g., a lower seal or bushing) coupled to the upper tube 204 and disposed in the upper tube 204 at or near the lower end 500. The upper and lower plugs 504, 506 seal the ends of the upper tube 204 to retain the fluid in the chamber 502.In the example shown in FIGS. 5 and 6, the seat post 112 includes a shaft 508 which may be referred to as a rod or valve rod housing. The shaft 508 is disposed within the lower tube 202 and coupled to the lower tube 202 (e.g., proximate the lower end 210) such that the shaft 508 is fixed relative to the lower tube 202. The shaft 508 extends upwardly through the lower tube 202 and through the lower plug 506 and into the upper tube 204. More specifically, the shaft 508 extends through the lower plug 506 and into the chamber 502 defined in the upper tube 204. The lower plug 506 is slidable up and down along the shaft 508 as the seat post 112 extends or retracts.In the example shown in FIGS. 5 and 6, the seat post 112 includes a piston assembly 510 disposed in the upper tube 204. The piston assembly 510 may also be referred to as a valve assembly or a flow control assembly. The piston assembly 510 is disposed in the chamber 502 of the upper tube 204 and coupled to the shaft 508. As the seat post 112 extends or retracts, the piston assembly 510 moves toward or away from the upper and lower ends 212, 500 of the upper tube 204. The piston assembly 510 includes a piston 512 sealed against an inner surface 514 of the upper tube 204. The inner surface 514 of the upper tube 204 is slidable up and down along the piston 512 as the seat post 112 extends or retracts. The piston assembly 510, particularly the piston 512, divides the chamber 502 of the upper tube 204 into a first chamber 516 (between the piston 512 and the upper plug 504) and a second chamber 518 (between the piston 512 and the lower plug 506). The first and second chambers 516, 518 may also be referred to as upper and lower chambers, respectively. The first chamber 516 is defined by the piston assembly 510, the upper plug 504, and the upper tube 204. The second chamber 518 is defined by the piston assembly 510, the lower plug 506, the upper tube 204, and the shaft 508. The volumes of the first and second chambers 516, 518 change as the upper tube 204 moves up and down relative to the piston assembly 510. The first and second chambers 516, 518 are filled with a fluid. In this example, the seat post 112 is based on a pneumatic platform. Thus, the first and second chambers 516, 518 may be filled with a pressurized gas, e.g., nitrogen or air. According to further examples, the first and second chambers 516, 518 may be filled with other type of compressible gas. The piston assembly 510 controls fluid flow (e.g., pressurized gas) across the piston 512 and between the first and second chambers 516, 518.In the example illustrated in FIGS. 5 and 6, the seat post 112 includes a valve 520. In this example, the valve 520 is incorporated and / or integrated with the piston assembly 510. The valve 520 is disposed in the upper tube 204 and at least partially in an overlap region (e.g., L 1 or L 2) between the upper tube 204 and the lower tube 202. In this example, the valve 520 is a poppet valve having a poppet movable in a linear direction to open or close the valve 520. However, according to further examples, valves of a different type can also be used. The valve 520 may be actuated (e.g., opened or closed) to control gas flow across the piston 512 between the first and second chambers 516, 518. Specifically, the valve 520 is operable between a closed state in which the fluid (e.g., pressurized gas) is prevented from flowing between the first and second chambers 516, 518 via the piston 512, thereby maintaining the lower and upper tubes 202, 204 in the current position, and an open state in which the fluid can flow between the first and second chambers 516, 518 via the piston 512, thereby allowing the upper tube 204 to move relative to the lower tube 202 to adjust the height of the seat 110 (FIG. 1 ).To actuate or control the valve 520, the motor assembly 220 includes a motor 522. Therefore, the motor 522 controls the state of the valve 520. However, according to further examples, the valve 520 may also be actuated by a solenoid or other type of actuator. In the illustrated example, the motor assembly 220 (including motor 522) is coupled to the lower end 210 of the lower tube 202. According to further examples, the motor assembly 220 may be coupled to or integrated with the piston assembly 510 in the upper tube 204 (an example of which is disclosed in connection with FIGS. 24-26 ).Turning briefly to FIG. 7, FIG. 7 is an enlarged view of the cutout 524 of FIG. 5 showing the top plug 504. The upper plug 504 includes a valve 700 for a user to supply or remove pneumatic fluid from the chamber 502 in the upper tube 204. The valve 700 is disposed in an opening 702 through the top plug 504. In this example, the valve 700 is configured as a Schrader valve. According to further examples, however, the valve 700 can also be designed as a valve of another type, for example as a presta valve. The valve 700 includes a valve body 704 (sometimes referred to as a stem) and a core 706 (e.g., a poppet valve) that controls fluid flow through the valve body 704. A user may remove saddle clamp 214 and gain access to valve 700 to supply or remove pneumatic fluid to chamber 502.Returning to FIGS. 5 and 6, in the example illustrated, the first chamber 516 is a positive pressure chamber and the second chamber 518 is a negative pressure chamber. The first chamber 516 and the second chamber 518 are pressure-tight chambers. The lower tube 202 defines a third chamber 526 between the lower plug 506 and the motor assembly 220. The third chamber 526 is considered as a pressure regulating chamber. The volume of the third chamber 526 changes depending on the operation position. According to some examples, the third chamber 526 is vented to atmosphere and thus contains air at atmospheric pressure. However, according to further examples, the third chamber 526 is also a pressure-tight chamber (e.g., with compressed air or nitrogen). In this example, the air in the third chamber 526 may be compressed as the upper tube 204 is moved downward. This compressed air may generate a biasing force to return the seat post 112 to the fully extended position. According to further examples, the third chamber 526 may include other mechanisms for compensating for the volume change, such as a floating piston or a deformable bladder. The first chamber 516, the second chamber 518, and the third chamber 526 may have any number of shapes and / or sizes. For example, the first chamber 516, the second chamber 518, and the third chamber 526 may be cylindrically shaped (e.g., having outside diameters between 27 millimeters (mm) and 35 mm) and sized for a particular maximum post setting (e.g., 150 mm).As shown in FIGS. 5 and 6, the piston 512 has a first side 528 facing the upper plug 504, and a second side 530 opposite the first side 528 and facing the lower plug 506. An axial surface area (as viewed along axis 206) of the first side 528 of the piston 512 is greater than an axial surface area of the second side 530 of the piston 512. This is because a portion of the axial surface of the second side 530 is reduced by the cross-sectional area of the shaft 508. When the valve 520 is in the closed state and the seat post 112 is in the fully extended position (FIG. 5 ), the first chamber 516 acts as a spring and is configured to bias the upper tube 204 toward the fully extended position of the seat post 112. The first side 528 and the second side 530 of the piston 512 are sized and shaped and correspondingly pressurize the first chamber 516 and the second chamber 518 when the seat post 112 is in the fully extended position such that the gas in the first chamber 516 supports the weight of the rider. According to some examples, the seat 110 lowers on the seat 110 by less than 10 mm by the weight of the rider when the seat post 112 is in the fully extended position. The seat post 112 is effective because the axial surface of the first side 528 of the piston 512 against a pneumatic pressure relationship between the first chamber 516 and the second chamber 518 maintains the rider based on the force calculation. This also depends on the volume of the second chamber 518 in the fully extended position of the seat post 112. In the example illustrated in FIG. 5, the volume of the first chamber 516 is greater than the volume of the second chamber 518 when the seat post 112 is in the fully extended position. According to some examples, the volume of the second chamber 518 may be no more than twenty percent of the volume of the first chamber 516 when the seat post 112 is in the fully extended position. According to further examples, the first and second chambers 516, 518 may have a different volume ratio in the fully extended position. For example, the volume of the second chamber 518 may be no more than ten percent, five percent, or three percent of the volume of the first chamber 516 when the seat post 112 is in the fully extended position. As a result, the seat post 112 acts like a prestressed pneumatic spring without negative pressure. This is the principle that maintains the driver and gives him a feeling of stability. When the seat post 112 is in the fully extended position, the seat 110 may move slightly, but this movement is typically imperceptible to the rider.For example, assume that the seat post 112 is in the fully extended position shown in FIG. 5 and the rider wishes to lower the seat 110 (FIG. 1 ). The rider presses a button to actuate the seat post 113 (FIG. 1 ) on the handlebar 118 (FIG. 1 ), and the control module 222 activates the motor 522 to open the valve 520. When the valve 520 is open, a downward force may be applied to the seat 110 to compress the seat post 112. For example, the driver may seat (or partially seat) on the seat 110 to apply pressure downward with the buttocks. This downward pressure forces the fluid (e.g., pressurized gas) to flow from the first chamber 516, through the valve 520, and into the second chamber 518 via the piston 512. This allows the upper tube 204 to move downward relative to the lower tube 202, thereby lowering the seat 110. As the upper tube 204 is moved downward, the volume of the first chamber 516 decreases and the volume of the second chamber 518 increases. The rider may move (e.g., lower) the seat 110 to any position between the fully extended and fully retracted positions. FIG. 6 shows the seat post 112 in an intermediate position between the fully extended and fully retracted positions.When the seat 110 is in a desired position, e.g., the position shown in FIG. 6, the rider may release the button to actuate the seat post 113 (FIG. 1 ). The control module 222 activates the motor 522 to close the valve 520. When the valve 520 is closed, fluid (e.g., pressurized gas) is prevented from flowing between the first chamber 516 and the second chamber 518 via the piston assembly 510. This limits or prevents further relative movement of the upper tube 204 relative to the lower tube 202. When the valve 520 is closed, there is a balance of forces in the system such that the axial compressive force acting on the first side 528 of the piston 512 is approximately equal to the axial compressive force acting on the second side 530 of the piston 512. By using a compressible fluid such as air, the pressure chamber may act as a compression spring when a downward force is applied to the upper tube 204. Thus, when the rider sits on the seat 110, the seat post 112 may support the weight of the rider. In some examples, when the seat post 112 is in an intermediate position (between the fully extended and fully retracted positions), the seat 110 may lower slightly (e.g., 40 mm or less) by the weight of the rider. The seat post 112 may be maintained in any position between the fully extended and fully retracted positions. When the seat post 112 is moved to the fully retracted position, the seat clamp 214 contacts / contacts the upper end 208 of the lower tube 202 and / or the lower plug 506 contacts a washer 1208 (shown in FIG. 12 ) in the lower end 210 of the lower tube 202. This produces a hard stop which prevents further movement. When the seat post 112 is in the fully retracted position, the seat 110 cannot lower due to this hard stop. According to some examples, the piston 512 engages an upper end of the lower plug 506 when the seat post 112 is in the fully extended position (FIG. 5 ). This forms a boundary or stop that prevents the upper tube 204 from moving further upward relative to the lower tube 202.When the seat post 112 is to be raised back to the fully extended position, the rider presses the seat post actuation button 113 (FIG. 1 ) and the control module 222 activates the motor 522 to open the valve 520. Without an external downward force acting on the seat 110 (FIG. 1 ), the pressure in the first chamber 516 of the upper tube 204 causes the upper tube 204 to move upward relative to the lower tube 202 back to the fully extended position. This is because the axial surface area of the first side 528 of the piston 512 is greater than the axial surface area on the second side 530 of the piston 512. Thus, the force of pressure in the first chamber 516 acting on the first side 528 of the piston 512 is greater than the force of pressure in the second chamber 518 acting on the second side 530 of the piston 512. As a result, the upper tube 204 is pushed upward to the fully extended position. As the upper tube 204 moves upward, fluid flows from the second chamber 518 into the first chamber 516 via the valve 520. The axial compressive force imbalance therefore biases the seat post 112 toward the fully extended position. This allows the seat post 112 to automatically return to the fully extended position shown in FIG. 5. When the seat post 112 is fully extended, the rider may release the button to actuate the seat post 113, thereby activating the motor 522 to close the valve and thereby maintain the seat post 112 in the fully extended position. The pressurized gas in the first chamber 516 therefore biases the upper and lower tubes 204, 202 away from each other, and the pressurized gas in the second chamber 518 biases the upper and lower tubes 204, 202 toward each other.As disclosed above, the third chamber 526 is vented to atmosphere, in some examples. The third chamber 526, therefore, exerts only a minimum, if any, biasing force on the upper tube 204. However, according to further examples, the third chamber 526 may be sealed and pressurized. In such an example, as the upper tube 204 is moved downward, the volume of the third chamber 526 decreases, thereby increasing the pressure in the third chamber 526. This pressure acts upwardly on the lower plug 506 and helps bias the upper tube 204 to the fully extended position.As disclosed above, the control module 222 includes the processor circuit 408 (FIG. 4 ) configured to control and operate the motor 522 to open and close the valve 520. In the example shown in FIGS. 5 and 6, the control module 222 is disposed on the outer surface 223 of the lower tube 202 at or near the upper end 208 of the lower tube 202, while the motor 522 is coupled to the lower end 210 of the lower tube 202. The seat post 112 may include one or more wires and / or electrical connections to form an electrical path between the control module 222 and the motor 522. This allows for the transmission of power and / or command signals between the control module 222 and the motor 522. For example, as shown in FIGS. 5 and 6, the seat post 112 includes first and second conduits 532, 534 disposed in the lower tube 202. According to some examples, the first and second lines 532, 534 are positive and negative lines. The first and second lines 532, 534 are electrically coupled to the control module 222. The first and second conduits 532, 534 extend through the lower tube 202 to the motor assembly 220. In other words, in this example, the first and second conduits 532, 534 extend between the upper end 208 and the lower end 210 of the lower tube 202. In the example shown, the first and second conduits 532, 534 are disposed along an inner surface 536 of the lower tube 202. According to some examples, the first and second conduits 532, 534 are provided with corresponding channels along the inner surface 536 of the lower tube 202. According to some examples, the channels are formed of the same material (e.g., aluminum) as the lower tube 202. According to further examples, the channels may be formed through the wall of the bottom tube 202. In the example shown, the first and second conduits 532, 534 are disposed on opposite sides of the lower tube 202. This may be advantageous in order to achieve a separation between the positive and negative lines. However, according to further examples, the first and second conduits 532, 534 may also be arranged side-by-side. According to some examples, each lead 532, 534 includes an insulated jacket. According to further examples, the leads 532, 534 may be sheathed together.The seat post 112 includes a valve rod 538 to transmit rotational motion from the motor assembly 220 to the piston assembly 510. The valve rod 538 is aligned along the axis 206 of the seat post 112. In the example shown in FIGS. 5 and 6, the valve rod 538 is disposed in the shaft 508. More specifically, the valve rod 538 extends through the shaft 508 and between the piston assembly 510 and the motor assembly 220. The valve rod 538 is rotatable within the shaft 508. The ends of the valve rod 538 are coupled to the piston assembly 510 and the motor assembly 220. Thus, the motor 522 may be activated to rotate the valve rod 538 and change the state of the valve 520. For example, the motor 522 may be activated to rotate the valve rod 538 in a first direction to open the valve 520 and in a second direction (the opposite direction) to close the valve 520. In some examples, motor 522 is a brushless, coreless direct current (DC) motor. According to further examples, motors of another type can also be used. The motor 522 is powered or activated by the control module 222. As disclosed above, the conduits 532, 534 are routed through the lower tube 202 between the control module 222 and the lower end 210 of the lower tube 202 to electrically connect the control module 222 to the motor 522.As shown in FIGS. 5 and 6, the motor 522 is axially aligned along the axis 206. Thus, the motor 522 is axially aligned with the piston assembly 510 with the valve 520 and a plug 822 (FIG. 8 ) of the valve. This reduces the horizontal or cylindrical size requirements of the seat post 112.FIG. 8 is an enlarged view of the cutout 600 of FIG. 6 As shown in FIG. 8, the lower plug 506 is threadably coupled to the lower end 500 of the upper tube 204, thereby sealing the lower end 500 of the upper tube 204. The seat post 112 includes a shaft seal 800 between the lower plug 506 and the shaft 508 to prevent leaks in the lower plug 506. The shaft seal 800 also allows the lower plug 506 to slide up and down easily along the shaft 508 as the seat post 112 extends and retracts. The seat post 112 includes a first outer seal 802 between the lower plug 506 and the inner surface 514 of the upper tube 204 and a second outer seal 804 between the lower plug 506 and the inner surface 536 of the lower tube 202. The seat post 112 further includes first and second seals 806, 808 between an outer surface 810 of the upper tube 204 and the inner surface 536 of the lower tube 202. According to further examples, the seat post 112 may include more or fewer seals and / or the seals may be arranged in other configurations.In the example illustrated in FIG. 8, the piston assembly 510 includes the piston 512. The plunger 512 may also be referred to as a valve body. The piston 512 is coupled to the shaft 508. In particular, in this example, the piston assembly 510 includes a fitting 812. The fitting 812 is threadably coupled to the piston 512 (e.g., a bottom side of the piston 512), and the shank 508 is threadably coupled to the fitting 812. The piston 512 is thus coupled to the shaft 508 via the fitting 812. Disposed between the piston 512 and the fitting 812 is a fitting seal 814 (e.g., an O-ring) that helps separate the chamber vacuum outside the piston 512 from atmospheric pressure in the lower portion of the piston 512. According to some examples, the piston 512 and the fitting 812 may be considered a first piston body portion and a second piston body portion that together form or define the piston 512. According to some examples, the piston 512 and the fitting 812 are made of metal and / or a plastic polymer. According to further examples, the piston 512 may be directly coupled to the shaft 508 and / or to the shaft 508 via other attachment techniques (e.g., welding, fasteners, etc.).The piston 512 has a head portion 816 that is sealed against the inner surface 514 of the upper tube 204. More specifically, in this example, the piston assembly 510 includes a seal 818 (e.g., an O-ring), which may be referred to as a chamber seal or piston seal, around the head portion 816 for sealing against the inner surface 514 of the upper tube 204. Thus, the piston 512 divides the chamber 502 of the upper tube 204 into the first chamber 516 (formed above the head portion 816) and the second chamber 518 (formed below the head portion 816). In the illustrated example, the piston 512 defines a central channel 820 (e.g., a bore, a passage, etc.). The central channel 820 forms a portion of a fluid passage through the head portion 816 that fluidly connects the first chamber 516 and the second chamber 518, as disclosed in detail herein. In the example shown, the valve 520 is disposed within and / or at least partially formed by the piston 512. The valve 520 is operable between a closed state in which fluid flow across the piston 512 is blocked and an open state in which fluid can flow across the piston 512. In the example shown, the valve 520 includes a plug 822, which in this example may also be referred to as a poppet. The plug 822 is slidably disposed in the central channel 820. The plug 822 is linearly movable between a closed position and an open position. In the example shown, the plug 822 is aligned with and movable along the axis 206. In the closed position shown in FIG. 8, the plug 822 blocks fluid flow through the central passage 820 and across the piston 512. This prevents fluid from flowing between the first and second chambers 516, 518 via the piston 512. In the open position, the plug 822 permits fluid flow through the central passage 820 and across the piston 512 between the first and second chambers 516, 518.In the illustrated example, the seat post 112 includes a cam assembly 824 for transferring or converting rotational movement of the motor 522 into linear movement of the plug 822 to open or close the valve 520. In particular, as disclosed above, the plug 822 is linearly movable between the closed position and the open position. The valve rod 538 extends through the fitting 812 into the central passage 820 of the piston 512. The valve rod 538 is rotatable by the motor 522. The cam assembly 824 converts the rotational movement of the valve rod 538 (and thus the motor 522) into linear movement of the plug 822. The cam assembly 824 includes a unique arrangement of cams and balls disclosed in detail herein. In this example, the cam assembly 824 is disposed within the piston 512.As shown in FIG. 8, the piston assembly 510 includes a seal 826 (e.g., a crush washer) between the shaft 805 and a shoulder 828 in the fitting 812. The seal 826 prevents or limits leakage of the fluid between the second chamber 518 and the central passage 820. As disclosed above, the interior of the shaft 508 may be at atmospheric pressure. Therefore, the cam assembly 824, which is located in the lower portion of the piston 512, may also be at atmospheric pressure with the valve rod 538. Thus, in this example, the cam assembly 824 is not within the casing of the positive or negative chamber. However, according to further examples, the cam assembly 824 may be disposed in other locations.The valve rod 538 extends through and is rotatable within the shaft 508, the fitting 812, and a thrust bearing 1400 (FIG. 14 ) within the piston 512. The piston assembly 510 includes a first rod bushing 830 aand a second rod bushing 830 b(FIG. 14 ) disposed about the valve rod 538 and separating the valve rod 538 from the shaft 508 to avoid higher degrees of friction. Therefore, by the first and second rod bushings 830 a, 830 b, the valve rod 538 can easily rotate and remain centered in the shaft 508. According to some examples, the first and second rod bushings 830 a, 830 bare made of a low friction material, e.g., a polymer. According to some examples, the valve rod 538 is made of aluminum, steel, or a polymer. According to further examples, the first and second rod bushings 830 a, 830 band / or the valve rod 538 may be made of other materials.In the example shown in FIG. 8, the seat post 112 includes a spacer 832 in the first chamber 516 in the upper tube 204. The spacer 832 is slidable up and down the upper tube 204. The piston assembly 510 may engage the spacer 832 during a compression movement. According to some examples, the spacer 832 acts like a shock absorber in the lower end position. According to some examples, spacer 832 is made of a compliant material (e.g., rubber). The spacer 832 receives the excess volume in the first chamber 516 (the positive chamber) for different ride heights to maintain the desired air spring rate and lift range. Depending on the desired stroke range, spacers of different sizes can be used. For example, a larger spacer may be used for a shorter stroke length, while a shorter spacer may be used for a larger stroke length.FIG. 9 is an exploded view of the motor assembly 220 and an example motor assembly housing 900 adjacent the lower end 210 of the lower tube 202. When the seat post 112 is assembled, the motor assembly housing 900 is coupled (e.g., threadably coupled) to the lower end 210 of the lower tube 202, and the motor assembly 220 is at least partially disposed within the motor assembly housing 900. According to some examples, the first and second housing screws 902, 904 serve to couple the motor assembly 220 within the motor assembly housing 900. Also shown in FIG. 9 is a seal 906 (e.g., an O-ring) that may be disposed between the engine assembly 220 and the engine assembly housing 900 to dampen the vibrations of the engine 522.FIG. 10 is an exploded view of the example motor assembly 220. The motor assembly 220 includes a reduction system or transmission 1001 to reduce the speed between the motor 522 and an output of the motor assembly 220 connected to the valve rod 538 (FIG. 5 ). In this example, the reduction system 1001 is a two-stage planetary gear. This two-stage planetary gear provides a relatively high gear ratio between the motor 522 and the output of the motor assembly 220. In the illustrated example, the motor assembly 220 includes the motor 522, a first sun gear 1000 coupled to an output (e.g., a driveshaft) of the motor 522, a motor seal 1002 (e.g., an O-ring), a motor housing 1004, motor screws 1006, a first washer 1008, a first set of planet gears 1010, a first carrier 1012 with a second sun gear 1014, a second washer 1016, a second set of planet gears 1018, a second carrier 1020, and a cap 1022 with an internally toothed ring gear 1024. A portion of the first and second conduits 532, 534 is also shown in FIG. 10. The first and second leads 532, 534 are electrically connected to the motor 522.FIG. 11 shows the assembled motor assembly 220. As shown in FIG. 11, the motor housing 1004 and the cap 1022 are coupled (e.g., by a snap fit) and form an overall housing structure. The motor 522 and the other parts of the motor assembly 220 are disposed in the housing structure formed by the motor housing 1004 and the cap 1022. The first and second leads 532, 534 extend along the exterior of the motor housing 1004 and then bend around the end of the motor housing 1004 and are electrically connected to the motor 522. The second carrier 1020 extends from the cap 1022. When the motor assembly 220 is assembled and installed on the seat post 112 (FIG. 2 ), the valve rod 538 (FIG. 5 ) is coupled to the second carrier 1020. According to this example, as shown in FIGS. 10 and 11, the second carrier 1020 includes a notch or slot 1026. A tab on the valve rod 538 (FIG. 5 ) extends into the slot 1026 that rotatably couples the second carrier 1020 and the valve rod 538. According to further examples, the valve rod 538 and the second carrier 1020 may be coupled by another technique (e.g., a threaded fastener). According to further examples, the valve rod 538 and the second carrier 1020 may be constructed as a single unitary piece (e.g., a monolithic structure). The construction of the valve rod 538 and the second carrier 1020 as a single unitary piece helps to maintain the valve rod 538 concentric and reduce or avoid frictional losses.For example, when the motor 522 is activated, the motor 522 rotates the first sun gear 1000. The first sun gear 1000 rotates the first set of planet gears 1010, which are meshed with the ring gear 1024 to rotate about the first sun gear 1000. The first set of planet gears 1010 rotate the first carrier 1012. The second sun gear 1014 (which is part of the first carrier 1012) rotates the second set of planet gears 1018 which, via the cooperation with the ring gear 1024, circle about the second sun gear 1014. The second set of planet gears 1018 rotate the second carrier 1020, which then rotates the valve rod 538 (FIG. 5 ). The motor assembly 220 utilizes this two-stage planetary gear to provide a relatively high gear ratio between the motor 522 and the second carrier 1020 (the output of the motor assembly 220). For example, a reduction ratio of 5:1 may be present in the first planetary gear stage and a reduction ratio of 5:1 may also be present in the second planetary gear stage. Thus, the two-stage planetary gear has a reduction ratio of 25:1 (higher or lower in other examples). This results in a large speed reduction between the motor 522 and the second carrier 1020, and thus between the motor 522 and the valve 520 (FIG. 5 ). This increases the torque delivered to the second carrier 1020 while the motor 522 continues to be operated at a relatively high speed, which is typically more efficient and stable. According to further examples, the motor assembly 220 may use a single stage planetary gear or other type of reduction system (e.g., a two speed system). According to still other examples, the motor assembly 220 may not utilize a reduction system. Instead, the output of the motor 522 may be directly or indirectly coupled to the valve rod 538 without a reduction system.FIG. 12 is an enlarged view of the cutout 540 of FIG. 5 and a cross-sectional view of the motor assembly 220 installed on the lower tube 202. FIG. 13 is a cross-sectional view of the motor assembly 220 installed on the lower tube 202 taken along a plane perpendicular to the cross-sectional view of FIG. 12. As shown in FIGS. 12 and 13, the seat post 112 includes a body 1200 (e.g., a plug, a seal, a bushing, a grommet) that is partially disposed within the lower tube 202 and extends outwardly from the lower end 210 of the lower tube 202. The seat post 112 includes retaining rings 1202, 1204 disposed in corresponding notches on the inner surface 536 of the lower tube 202 to secure the body 1200 within the lower tube 202. The shaft 508 extends at least partially into the body 1200. As shown in FIG. 13, the seat post 112 includes the first and second threaded cross-pins 1300, 1302 that are threaded into the respective threaded openings in the body 1200 and extend through the grooves formed in the side of the shank 508. This prevents the shaft 508 from moving and / or rotating linearly relative to the body 1200. Thus, the body 1200 holds the shaft 508 securely in the lower tube 202 and thereby couples the shaft 508 to the lower tube 202. In the example shown, the seat post 112 includes a plate 1206 and a disc 1208 in the lower tube 202 above the body 1200. The conduits 532, 534 pass through openings or notches in the disc 1208, the plate 1206, and the body 1200.In the illustrated example, the motor assembly housing 900 is threadably coupled to the body 1200 and engages the lower end 210 of the lower tube 202. As shown in FIG. 12, the motor assembly housing 900 has the openings 1210, 1212. The first and second conduits 532, 534 extend through the openings 1210, 1212 and along an exterior of the motor assembly housing 900, wrap around a lower end of the motor assembly housing 900, and extend into the motor assembly 220 to connect to the motor 522. In this example, therefore, a portion of the first and second leads 532, 534 are exposed outside the motor assembly housing 900. However, when the seat post 112 is coupled to the bicycle 100 (FIG. 1 ), the motor assembly housing 900 is disposed within the seat tube 114 (FIG. 1 ), whereby the first and second conduits 532, 534 are protected by the frame 102 (FIG. 1 ) of the bicycle 100. According to further examples, the leads 532, 534 may be routed differently so as to be fully hidden within the motor assembly housing 900. According to some examples, the lines 532, 534 are directly connected to the motor 522. According to further examples, the conduits 532, 534 may be connected to the motor 522 via a quick connect coupling between the lower tube 202 and the motor assembly housing 900.As illustrated in FIGS. 12 and 13, the motor assembly 220 is disposed in the motor assembly case 900. The seal 906 is disposed between the motor assembly housing 900 and the motor housing 1004 and helps reduce or dampen vibrations of the motor 522. As shown in FIG. 13, the housing screws 902, 904 extend through the motor assembly housing 900 and into the motor housing 1004 and the cap 1022 coupling the motor assembly 220 to the motor assembly housing 900.As illustrated in FIGS. 12 and 13, the motor 522 is disposed in the motor housing 1004. The motor screws 1006 (one of which is shown in FIG. 12 ) serve to couple the motor 522 within the motor housing 1004. Further, the motor seal 1002 is disposed between the motor 522 and the motor housing 1004 to retain the motor 522 within the motor housing 1004.As shown in FIGS. 12 and 13, the reduction system 1001 (i.e., the two-stage planetary gear) is located between the motor 522 and the valve rod 538. The valve rod 538 has a tab 1214 that extends into the slot 1026 in the second carrier 1020. Thus, the valve rod 538 and the second carrier 1020 are splined together. Therefore, when the motor 522 is activated, the motor 522 rotates the second carrier 1020 via the two-stage planetary gear and the second carrier 1020 rotates the valve rod 538. Motor 522 is a bi-directional motor that can be activated to rotate valve rod 538 in both directions. In this example, the tab 1214 has a rectangular cross-sectional shape. According to further examples, the tab 1214 and the slot 1026 may be shaped differently. According to still other examples, the valve rod 538 can be integrally formed with the motor assembly 220 and / or the reduction system 1001.FIG. 14 is an exploded view of the piston assembly 510 and the valve rod 538. Also shown in FIG. 14 are the first and second rod bushings 830 a, 830 b, which in the assembled state are arranged on the valve rod 538 between the valve rod 538 and the shaft 508 (FIG. 5 ). In the illustrated example, the piston assembly 510 includes the fitting 812, the fitting seal 814, a thrust bearing 1400, the cam assembly 824, a spring 1402, the piston 512, a poppet seal 1404, a valve seal 1406 (e.g., a seat), the plug 822, and the seal 818. As disclosed above, the piston 512 includes the central channel 820 that extends between the first and second bottom sides 528, 530 of the piston 512. As shown in FIG. 14, the piston 512 further includes one or more radial openings or channels 1408 extending between the outer surface of the piston 512 and the central channel 820. In this example, the piston 512 includes four radial apertures 1408 (one of which is shown in FIG. 14 ) spaced 90° apart. According to further examples, the piston 512 may have more or fewer radial openings. The radial openings 1408 and a portion of the central passage 820 form a fluid passage through the piston 512 between the first and second chambers 516, 518 (FIG. 5 ).As disclosed above, the cam assembly 824 converts rotational movement of the valve rod 538 (from the motor 522) into linear movement of the plug 822. According to this example, the cam assembly 824 includes a first cam 1410, a second cam 1412, and a plurality or set of balls 1414 (e.g., ball bearings) between the first cam 1410 and the second cam 1412. When the piston assembly 510 is assembled, the first cam 1410, the second cam 1412, and the balls 1414 are stacked and disposed in the piston 512. The first cam 1410 may also be referred to as an upper cam, and the second cam 1412 may also be referred to as a lower cam. As disclosed in detail herein, the second cam 1412 is rotatable within the piston 512 while the first cam 1410 remains constrained in the piston 512 from rotating. Rotation of the second cam 1412 causes axial displacement of the first cam 1410 within the piston 512, thereby moving the plug 822 to open or close the fluid passage within the piston 512.FIG. 15 is an enlarged view of the cutout 1416 of FIG. 14 showing the thrust bearing 1400 and the cam assembly 824. In this example, the cam assembly 824 includes three balls, designated 1414a-1414c. However, according to further examples, the cam assembly 824 may also include more or fewer balls (e.g., one, two, four, five, etc.). In the example shown, the first and second cams 1410, 1412 are disk-shaped. The first cam 1410 has a first side 1500, a second side 1502 opposite the first side 1500, and an outer peripheral edge 1504. The second cam 1412 also includes a first side 1506, a second side 1508 opposite the first side 1506, and an outer peripheral edge 1510. When the cam assembly 824 is assembled, the first side 1506 of the second cam 1412 faces the second side 1502 of the first cam 1410. The first and second sides of the cams 1410, 1412 may also be referred to as surfaces. According to further examples, the first and second cams 1410, 1412 can be shaped differently.As shown in FIG. 15, the first side 1500 of the first cam 1410 has a circular recess 1514. When the piston assembly 510 is assembled, a portion of the spring 1402 is disposed in the circular recess 1514. This allows the spring 1402 to be held in a central position within the piston 512 and engaged with the first cam 1410.In the example illustrated in FIG. 15, the second cam 1412 has an opening 1512 (e.g., a key slot) that extends between the first and second sides 1506, 1508. The opening 1512 is sized and shaped to receive an end 1418 (FIG. 14 ) of the valve rod 538 (FIG. 14 ). Thus, the valve rod 538 and the second cam 1412 are splined together. Thus, rotation of the valve rod 538 causes rotation of the second cam 1412 and vice versa.In the illustrated example, the first side 1506 of the second cam 1412 has three recesses 1516 (one of which is shown in FIG. 15). The second side 1502 of the first cam 1410 has mating recesses, as detailed herein. Each recess 1516 has a ramp profile or surface with a deeper portion or region and a shallower portion or region. As disclosed in detail herein, the balls 1414a-1414c are disposed in respective recesses in the first and second cams 1410, 1412. When the second cam 1412 is rotated, the balls 1414a-1414c move between the shallower and deeper portions of the recesses, causing the first cam 1410 to move linearly toward or away from the second cam 1412. This linear movement causes linear movement of the plug 822 (FIG. 14 ), thereby opening or closing the valve 520.FIGS. 16A and 16B are cross-sectional views of the piston assembly 510 and the valve rod 538. FIG. 16A shows the valve 520 of the piston assembly 510 in a closed state and FIG. 16B shows the valve 520 of the piston assembly 510 in an open state. Referring to FIG. 16A, the central passage 820 of the piston 512 includes an upper portion 1600, a middle portion 1602, and a lower portion 1604. The first cam 1410, the balls 1414 (one of which is shown in FIG. 16A ), the second cam 1412, and the thrust bearing 1400 are stacked and disposed in the lower portion 1604 of the central channel 820. The components are clamped or disposed between the piston 512 and the fitting 812. As shown in FIG. 16A, the first and second cams 1410, 1412 are axially aligned with the plug 822 along the axis 206. The spring 1402 is disposed between a shoulder 1606 of the piston 512 and the first cam 1410. Thus, the spring 1402 biases the first cam 1410 toward the second cam 1412 (downward in FIG. 16A ). The first cam 1410 is movable up and down within the piston 512 but is locked or restricted in its rotational movement. The valve rod 538 extends into the opening 1512 in the second cam 1412. The valve rod 538 and the second cam 1412 are restricted in their rotational movement. The second cam 1412 is rotatable within the piston 512 and is thus rotatable relative to the first cam 1410. The second cam 1412 is also freely axially movable, but remains generally in the same axial position. The thrust bearing 1400 is disposed between the second cam 1412 and the fitting 812. The thrust bearing 1400 reduces rotational friction of the second cam 1412 under biasing force. According to some examples, thrust bearing 1400 is a ball bearing. According to further examples, other types of bearings and / or features may be used, e.g., a thrust roller bearing, a thrust washer, a low friction washer, or surfaces and low friction treatments.As shown in FIG. 16A, the plug 822 is disposed in the central passage 820 of the piston 512. The plug 822 includes a first sealing portion 1608 (e.g., a head), a second sealing portion 1610, and a shaft 1612 between the first and second sealing portions 1608, 1610. The plug 822 is movable (e.g., slidable) up and down (linearly) within the central channel 820 between a closed position (shown in FIG. 16A ) and an open position (shown in FIG. 16B ). As shown in FIG. 16A, the cup seal 1404 is disposed in the central portion 1602 of the central channel 820 and sealed against the second sealing portion 1610 of the plug 822. The cup seal 1404 fluidly separates the upper portion 1600 of the central channel 820 and the lower portion 1604 of the central channel 820 from each other. The upper portion 1600 is filled with fluid from the first and second chambers 516, 518 (the positive and negative pneumatic chambers), while the lower portion 1604 may be filled with atmospheric air from the shaft 508 (FIG. 5 ).As shown in FIG. 16A, the radial openings 1408 intersect the upper portion 1600 of the central channel 820. The upper portion 1600 of the central channel 820 above the plug 822 is exposed to the fluid in the first chamber 516 (FIG. 5 ), and the radial openings 1408 are exposed to the fluid in the second chamber 518 (FIG. 5 ). The piston 512 therefore defines a fluid passage 1611 between the first chamber 516 and the second chamber 518. In particular, the fluid passage 1611 is formed by the upper portion 1600 of the central channel 820 and the radial openings 1408. The plug 822 is at least partially disposed in the fluid passage 1611. The plug 822 is linearly movable between the open position in which fluid flow through the fluid passage 1611 is possible and a closed position in which fluid flow through the fluid passage 1611 is blocked.As shown in FIG. 16A, the valve seal 1406 is disposed in a gland 1614 in the upper portion 1600 of the central channel 820. As shown in FIG. 16A, when the plug 822 is in the closed position, the first sealing portion 1608 of the plug 822 sealingly engages the valve seal 1406. This blocks or prevents fluid from flowing through the fluid passage 1611 and thus between the first and second chambers 516, 518. According to some examples, the plug 822 is made of metal (e.g., high surface quality stainless steel) and / or a plastic polymer and the poppet and valve seal 1404, 1406 is made of rubber and / or a plastic polymer. According to further examples, the plug 822 and / or the poppet and valve seal 1404, 1406 may be made of other materials.As shown in FIG. 16A, a lower end 1616 of the plug 822 is disposed in the lower portion 1604 of the central channel 820 and above the first cam 1410. According to some examples, the bottom end 1616 of the plug 822 is spaced apart from the first side 1500 of the first cam 1410 when the plug 822 is in the closed position. For example, the lower end 1616 may be spaced apart from the first cam 1410 by 0.2 millimeters (mm). According to further examples, the bottom end 1616 of the plug 822 engages the first side 1500 of the first cam 1410.To move the plug 822 upward to the open position to open the valve 520, the motor 522 (FIG. 5 ) is activated to rotate the second cam 1412 (via the valve rod 538) in a first direction. The second cam 1412 rotates relative to the first cam 1410. In the position shown in FIG. 16A, the balls 1414 are disposed in the deeper portions of the recesses 1516 (one of which is shown in FIG. 16A ) in the second cam 1412 and the recesses 1518 (one of which is shown in FIG. 16A ) in the first cam 1410. As the second cam 1412 rotates, the interaction between the rotation of the second cam 1412 and the balls 1414 causes the balls 1414 to roll along the recesses 1516, 1518 to the shallower portions of the recesses 1516, 1518. For example, as shown in FIG. 16B, the balls 1414 (one of which is shown in FIG. 16B ) are rolled to the shallower portions of the recesses 1516, 1518 (one of which is shown in FIG. 16B ) such that the balls 1414 push the first cam 1410 upward away from the second cam 1412. When the first cam 1410 moves upward, the first cam 1410 compresses the spring 1402. Moreover, the first side 1500 of the first cam 1410 engages the bottom end 1616 of the plug 822 and then forces the plug 822 upward. Thus, the first sealing portion 1608 of the plug 822 is moved away from the valve seal 1406. As shown in FIG. 16B, this creates a flow path (shown by the arrows) to allow fluid to flow through the upper portion 1600 of the central channel 820 and the radial openings 1408. As a result, fluid may freely flow through the fluid passage 611 of the piston 512 between the first and second chambers 516, 518 (FIG. 5 ). This allows the seat post 112 to extend or retract as disclosed above. Fluid may flow in either direction depending on whether the seat post 112 is retracted or extended.To close the valve 520, the motor 522 (FIG. 5 ) may be activated to rotate the second cam 1412 in a second direction that is opposite the first direction to open the valve 520. As a result, the balls 1414 roll back to the deeper portions of the recesses 1516, 1518 in the position shown in Fig. 16A. The spring 1402 biases the first cam 1410 downward and into engagement with the balls 1414. The second cam 1410 moves downwardly away from the lower end 1616 of the plug 822, allowing the plug 822 to move downwardly to the closed position shown in FIG. 16A, thereby closing the valve 520. Rotation of the second cam 1412 in a first direction therefore causes the first cam 1410 to move toward the plug 822 to move the plug 822 to the open position, wherein rotation of the second cam 1412 in a second direction allows the first cam 1410 to move away from the plug 822 to allow the plug 822 to move to the closed position. Cam assembly 824 thus converts or transforms rotational movement of motor 522 into linear movement of plug 822 to open and close valve 520. As can be seen, the valve 520 is a type of volume-shifting valve in this example, as a small volume in the first and second chambers 516, 518 changes as the plug 822 is moved between the open and closed positions. However, according to further examples, valves of a different type can also be used.As shown in FIGS. 16A and 16B, the piston assembly 510 does not include a spring or other mechanical means for biasing the plug 822 downward toward the closed position. Instead, the plug 822 is biased downwardly and into the valve seal 1406 by the pressure differential acting across the first and second seal portions 1608, 1610, thereby automatically closing the valve 520. The pressure differential across the plug 822 and the bias of the spring 1402 thus help to move or push the first cam 1410 back down to the lower position shown in FIG. 16A when the second cam 1412 is rotated in the second direction. Further, when the plug 822 is in the closed position (FIG. 16A ), the plug 822 is biased into the valve seal 1406 by the pressure differential across the plug 822 and thus the plug 822 remains in the closed position. For example, the poppet seal 1404 may have a first diameter, e.g., 3 mm, while the valve seal 1406 may have a second diameter, e.g., 4.5 mm, that is greater than the first diameter of the poppet seal 1404. The poppet seal 1404 separates the second chamber 518 (the negative chamber) from atmospheric pressure, while the valve seal 1406 separates (in the closed state) the positive and negative pressures in the first and second chambers 516, 518 (FIG. 5 ). This creates a higher downward biasing force to keep the plug 822 sealed downwardly and against the valve seal 1406 when in the closed position than when in the open position. However, when the valve 520 is open, the effective pressure area decreases from 4.5 mm to 3 mm, so that the downward biasing force on the plug 822 is less. According to further examples, the plug 822 may have additional or fewer portions and / or different diameters. According to some examples, the piston assembly 510 may include a spring or other mechanical means to assist in movement of the plug 822 towards the closed position.As disclosed above, the first cam 1410 is movable up and down to move the plug 822. According to some examples, the first cam 1410 moves a total of about 1.7 millimeters (mm) between the open and closed positions. According to further examples, the first cam 1410 may be movable a greater or lesser distance. According to some examples, the distance is limited by the distance between the first cam 1410 and a shoulder 1618 (FIG. 16B ) formed in the piston 512.FIGS. 17A-17E are different views of the second cam 1412. FIG. 17A is a perspective view of the first side 1506 of the second cam 1412. In this example, the second cam 1412 has three recesses, labeled 1516a, 1516b, 1516c, formed in the first side 1506 of the second cam 1412. The recesses 1516 a- 1516 cmay also be referred to as cam surfaces or ramps. The recesses 1516a-1516c are equally spaced apart. The recesses 1516a-1516c have the same profile with a deep portion and a shallow portion. For example, as shown in FIG. 17A, the first recess 1516 aincludes a first portion, referred to herein as a flat portion 1702 a, at one end of the first recess 1516 a, and a second portion, referred to as a deep portion 1704 a, at the opposite end of the first recess 1516 a. The deep portion 1704 aextends further into the first side 1506 than the flat portion 1702 a. The second and third recesses 1516b, 1516c also have shallow and deep portions 1702b, 1702c, 1704b, 1704c, respectively. These profiles allow balls 1414 (FIG. 14 ) to move first cam 1410 in a linear direction. FIG. 17B is a side view of the second cam 1412. In this example, the second cam 1410 has a substantially constant thickness.FIG. 17C is a plan view of the first side 1506 of the second cam 1412 showing the three recesses 1516a-1516c. FIG. 17D is a cross-sectional view of the second cam 1412 taken along line A-A of FIG. 17C. The recesses 1516a-1516c have an effective diameter (e.g., 3.2 mm) that is slightly larger than the diameter of the balls (e.g., 3 mm) to secure the balls 1414. This helps the balls 1414 to remain in the respective recesses 1516a-1516c.FIG. 17E is a cross-sectional view of the second cam 1412 taken along line B-B and showing the first recess 1516 a. As illustrated, the first recess 1516 aincludes the flat portion 1702 aand the deep portion 1704 a. The deep portion 1704 aextends further into the first side 1506 than the flat portion 1702 a. For example, the deep portion 1704 ahas a first depth D 1 and the shallow portion 1702 ahas a second depth D 2 less than the first depth D 1. The deep portion 1704 acorresponds to a valve position 1 corresponding to the closed state of the valve 520 (FIG. 5 ), and the flat portion 1702 acorresponds to a valve position 2 corresponding to the open state of the valve 520. For example, if the first ball 1414 a(FIG. 15 ) is disposed in the deep portion 1704 aof the first recess 1516 a, the first ball 1414 aextends further into the first side 1506 of the second cam 1412. This allows the first cam 1410 (FIG. 14 ) to remain closer to the second cam 1412, and thus the plug 822 is in the closed position (FIG. 16A ). When the second cam 1412 is rotated, the first ball 1414a is rolled into the flat portion 1702, also moving a larger portion of the first ball 1414a outward from the first side 1506 of the second cam 1412. This forces the first cam 1410 away from the second cam 1412, thereby moving the plug 822 to the open position (FIG. 16B ).As shown in FIG. 17E, the first recess 1516 aincludes a protrusion 1706 abetween the shallow and deep portions 1702 a, 1704 a. The protrusion corresponds to a valve position 3 between valve position 1 and valve position 2. protrusion 1706 ais less deep than shallow and deep portions 1702 a, 1704 a. For example, the bump 1706a has a third depth D3 that is less than the first depth D1 and the second depth D2. The first recess 1516 ais thus formed between the elevation 1706 aand the shallow and deep portions 1702 a, 1704 ain an inclined or ramped manner. As a result, the pressure and spring force may bias the first ball 1414a (FIG. 15) towards the valve position 1 (closed) or the valve position 2 (open). For example, when the first ball 1414a rolls over the boss 1706a, the first ball 1414a naturally falls into the shallow or deep portion 1702a, 1704a which moves and holds the first cam 1410 in the valve position 1 (closed) or valve position 2 (open). According to some examples, the maximum depth in valve position 1 is less than half the diameter of first ball 1414a to prevent first side 1506 (the top surface) of second cam 1412 from contacting second side 1502 (the bottom surface) of first cam 1410. Valve position 1 and valve position 2 are of sufficient depth to act as ball bearing stops at the ends of the first recess 1516a. Valve position 3 is of sufficient depth to keep first ball 1414a radially guided in the center of first recess 1516a. The second and third recesses 1516 b, 1516 chave the same ramp profile as the first recess 1516 aillustrated in FIG. 17E.FIGS. 18A-18C are different views of the first cam 1410. To prevent the first cam 1410 from rotating within the piston 512 (FIG. 5 ), the first cam 1410 includes an anti-rotation feature that engages a corresponding anti-rotation feature of the piston 512. For example, as shown in FIGS. 18A and 18B, the peripheral edge 1504 of the first cam 1410 has flattened surfaces 1802 a, 1802 b. The flattened surfaces 1802a, 1802b engage corresponding flattened surfaces in the central channel 820 of the piston 512. This prevents the first cam 1410 from rotating in the piston 512. Thus, the first cam 1410 and the piston 512 are splined together. This prevents rotation of the first cam 1410, but permits linear movement (e.g., sliding) of the first cam 1410 within the piston 512. According to further examples, the first cam 1410 and / or the piston 512 may include other shaped anti-rotation or keying features (e.g., splines, protrusions, and notches).The first cam 1410 has the same recess pattern as the second cam 1412. As shown in FIGS. 18A and 18B, the first cam 1410 has three recesses, designated 1518 a- 1518 c, that extend into the second side 1502 of the first cam 1410. The recesses 1518 a- 1518 chave the same profile as the recesses 1516 a- 1516 cof the second cam 1412 in FIG. 17E. When the first and second cams 1410, 1412 are installed in the piston 512 (FIG. 5 ), a portion of each recess 1516 a- 1516 cis axially aligned with the corresponding recess 1518 a- 1518 c. FIG. 19A is, for example, a top view of the second cam 1412 with the first recess 1516 a, and the first recess 1518 aof the first cam 1410 (not shown) is shown in dashed lines. The remaining recesses are not shown. As shown in FIG. 19A, the deep portions of the first recesses 1516 a, 1518 aare axially aligned. In FIG. 19A, the first ball 1414 ais partially disposed in the deep portions of the first recesses 1516 a, 1518 a. This position corresponds to the closed position of the valve 520. FIG. 19B shows the second cam 1412 rotated clockwise. Thus, the first recess 1516 aof the second cam 1412 has rotated clockwise relative to the first recess 1518 aof the first cam 1410. Thereby, the first ball 1414a rolls into the flat portions of the first recesses 1516a, 1518a. As shown in FIG. 19B, the flat portions of the first recesses 1516 a, 1518 aare now axially aligned. This position corresponds to the open position of the valve 520. As disclosed above, this movement causes the first cam 1410 in the piston 512 to be pushed axially upward to open the valve 520. To close the valve 520, the second cam 1412 is rotated in the opposite direction, thereby rolling the first ball 1414a back into the deep portion of the first recesses 1516a, 1518a. As a result, the first cam 1410 can move linearly in the direction of the second cam 1412. The second and third balls 1414b, 1414c are also disposed in the second and third recesses 1516b, 1516c and 1518b, 1518c, respectively. Thus, upon rotation of the second cam 1412 in the first direction, the balls 1414a-1414c are rolled from the deep portions of the recesses 1516a-1516c, 1518a-1518c to the shallow portions of the recesses 1516a-1516c, 1518a-1518c to move the first cam 1410 in a linear direction away from the second cam 1412, and upon rotation of the second cam 1412 in the second direction, the balls 1414a-1414c are rolled from the shallow portions of the recesses 1516a-1516c, 1518a-1518c to the deep portions of the recesses 1516a-1516c, 1518a-1518c to allow the first cam 1410 to move in a linear direction toward the second cam 1412. According to some examples, the balls 1414 a- 1414 only rotate and do not slide as they move along the recesses. This rolling motion of balls 1414a-1414c results in little or no frictional losses as compared to lead screw designs.When the second cam 1412 is rotated relative to the first cam 1410, the second cam 1412 rotates about the central axis at the same speed as the valve rod 538, whereas the ball bearings roll along the cams 1410, 1412 about the central axis at a rotational speed that is half as great as that of the valve rod 538. This is because the total rotation angle of the second cam 1412 relative to the first cam 1410 is twice as large as the rotation angle of the movement of the balls. For example, as shown in FIG. 19B, the second cam 1412 has rotated 120° from the position shown in FIG. 19A, whereas the first ball 1414 has moved only 60° from the position shown in FIG. 19A. However, according to further examples, the cams 1410, 1412 and the recesses may be configured to rotate by different amounts.According to some examples, the first and second cams 1410, 1412 are made of a polymer such as Delrin or nylon, a metal such as aluminum or steel, and / or ceramic such as alumina. According to further examples, the first and second cams 1410, 1412 can be made of other materials. According to some examples, the balls 1414 are made of hardened steel. According to further examples, the balls 1414 may be made of other materials.According to some examples, the use of three balls 1414 helps the first cam 1410 to remain parallel to the second cam 1412 throughout the cam motion. However, according to further examples, more or fewer balls may be used. For example, the cams 1410, 1412 can each have one recess, two recesses or more than three recesses. Thus, any number of recesses and balls can be used. According to some examples, the profiles of the recesses 1518 a- 1518 con the first cam 1410 may be different than the recesses 1516 a- 1516 con the second cam 1412 to achieve other types of motions. According to some examples, the recesses are formed in only one of the cams 1410, 1412. For example, the second cam 1412 can have the three recesses 1516a-1516c, while the first cam 1410 has no recess. Instead, the balls 1414a-1414c may rotate on the second side flat surface 1502. According to some examples, the second side 1502 may include three hemispherical recesses to retain the balls 1414 a- 1414 crelative to the first cam 1410, but the balls 1414 a- 1414 cmay not slide relative to the first cam 1410. Further, while in this example the second cam 1412 rotates and the first cam 1410 moves linearly (but does not rotate), according to further examples, the first cam 1410 can rotate and move linearly. For example, the second cam 1412 can be held in a fixed position in the piston 512. The valve rod 538 can extend through the second cam 1412 and be coupled to the first cam 1410. The valve rod 538 can rotate the first cam 1410. By this rotation, the first cam 1410 slides linearly along the valve rod 538 in the piston. Therefore, only one of the cams can rotate and slide while the other cam remains fixed.As disclosed above, the motor 522 (FIG. 5 ) is controlled by the processor circuit 408 (FIG. 4 ) of the control module 222 (FIG. 2 ). The control module 222 may activate the motor 522 to rotate the second cam 1412 between the valve position 1 and the valve position 2 to open and close the valve 520. For example, when a rider presses the seat post actuation button 113 (FIG. 1 ) on the handlebar 118 (FIG. 1 ), the processor circuit 408 activates the motor 522 to rotate the second cam 1412 to move the plug 822 to the open position (FIG. 16B ). When the second cam 1412 reaches valve position 2, the motor 522 may be deactivated and the valve 520 remains in the open state. Specifically, the valve 520 remains in the open state due to the locking function caused by the balls 1414a-1414c in the flat portions of the recesses. While the valve 520 is open, the seat post 112 may be extended and / or retracted to change the height of the seat 110. According to some examples, the motor 522 rotates in a positive voltage closing direction and a negative voltage opening direction, or vice versa. When the rider releases the seat post actuation button 113, the processor circuit 408 applies an opposing voltage to the motor 522 and the motor 522 receives the current required to move the second cam 1412 to the valve position 1, thereby closing the valve 520. The cycle is complete when the valve 520 is in the closed state. Thus, when the rider presses the seat post operation button 113, the motor 522 is activated to open the valve 520 and then deactivated (while the valve 520 remains in the open state), and the rider releases the seat post operation button 113, the motor 522 is activated to close the valve 520 and then deactivated (while the valve 520 remains in the closed state). The example cam assembly 824 makes the valve 520 self-locking. In other words, once the valve 520 is in the open or closed state, the motor 522 may be deactivated and the valve 520 remains in the same state. Thus, no energy is required to remain in one state or the other. This helps maintain the life of the battery because battery power is used only to open and close the valve 520.According to some examples, the motor assembly 220 (FIG. 2 ) does not use a locator. The processor circuit 408 may instead use the motor current draw to determine when the valve 520 is in the open or closed state. According to some examples, processor circuit 408 may determine when to deactivate motor 522 based on a detected change (e.g., an increase) in current to motor 522, examples of which are disclosed in detail in connection with FIGS. 20-23. Compared to known seat post motor systems, this reduces complexity and cost. However, according to further examples, a position sensor or position sensor may be used to determine when to stop the motor 522 in the open and closed positions.FIG. 20 is an example electric current (in mA) versus time (in milliseconds (ms)) diagram 2000 showing an example current profile as output by the example control module 222 to the motor 522 upon opening of the valve 520. In the range of 0-3 ms, flow builds up to rotate the valve rod 538. In the range of 3-10 ms, the second cam 1412 (the lower cam) starts rotating. As a result, the first cam 1410 (the upper cam) moves upward against the bias of the spring 1402, and compensates for any fit gaps (e.g., the gap between the first cam 1410 and the lower end 1616 of the plug 822, the clearance between the valve rod 538 and the second cam 1412, etc.) until the first cam 1410 engages the lower end 1616 of the plug 822 (at 10 ms). In some examples, the distance between these parts may be 0.1 mm to 0.5 mm, but in other examples may be larger or smaller. In the range of 10-25 ms, motor 522 receives current and continues to rotate second cam 1410 and exerts an upward force on plug 822. In the range of 25-55 ms, the first cam 1410 must overcome the bias of the spring 1402 plus the compressive biasing force against the valve seal 1406 (e.g., 4.5 mm in diameter). At 55 ms, the plug 822 disengages the valve seal 1406 to open the valve 520, allowing fluid to flow over the piston 512 and between the first and second chambers 516, 518. The current begins to drop at 55 ms, since the compressive force bias on the now acting seal on the cup seal 1404 (e.g. with a diameter of 3 mm) decreases. At 70 ms, balls 1414a-1414c are located at the elevations of each recess and plug 822 has reached maximum displacement. After 70 ms, balls 1414a-1414c enter a free fall region where plug 822 begins to move in the direction of the compressive force bias. The motor current begins to decrease more quickly, whereupon the control module 222 detects this current decrease and more quickly chokes the current to the motor 522. The throttling rate may be adjusted to be faster or slower to conserve power and / or maintain some motor current to minimize rebound as the balls 1414a-1414a move to the flat portions (valve position 2) of the recesses. When the balls 1414a-1414c seat in the flat portions of the recesses 1516a-1516c, 1518a-1518c, the current goes to zero. Here, the throttle rate (in a concave shape) may transition to a zero current for a smooth stop. The compressive bias on plug 822 locks cams 1410, 1412 in valve position 2 without requiring current while the rider varies the height of seat post 112. According to further examples, other motor current profiles may be implemented where current increases after balls 1414a-1414c assume valve position 2. The current is then throttled from a predetermined current value that is greater than the lowest current value in the valve position 2. According to further examples, other flow profiles may be implemented by the control module 222 to open the valve 520.FIG. 21 is an example graph 2100 showing electrical current (in mA) versus time (in milliseconds (ms)) as output by the control module 222 to close the valve 520. When the valve is in an open state, the first cam 1410 (the upper cam) is in contact with the plug 822. In the range of 0-10 ms, current increases to move the second cam 1412 (the lower cam) against the cam spring bias and pressure bias to move the balls 1414a-1414c from valve position 2 to valve position 3. Once valve position 3 is overcome, the compressive bias against plug 822 begins to move in the direction of the compressive biasing force, while balls 1414 a- 1414 cmoves down the ramp to free fall and motor current begins to decrease. The control module 222 detects the free fall range and reduces or chokes current to zero when the second cam 1412 returns to valve position 1. This reduces the power consumption compared to methods for switching off the blocking current according to the prior art. No current is then needed to keep the valve 520 fully closed and the ride height of the seat post is fixed for the rider. The cycle valve closed-opened-closed by the driver for height adjustment is completed. According to some examples, less time and energy is required for the valve closing cycle than for a valve opening cycle. Alternatively, the cam ramps, the compressive bias, the poppet geometry, and / or the current profile may be configured such that the valve closing cycle consumes more time and / or energy than the valve opening cycle. The cam ramp profile may be adjusted and / or current controlled according to various profiles to extend battery life, achieve the desired opening and closing speed, reduce load at engine start and stop, handle the detachment of the bonded seal, and / or add redundant triggers for power shut-downs. Alternatively or in conjunction with current throttling, smooth engine deceleration may further be used to maintain position, reduce start / stop load, reduce rebound, and / or extend battery life by temporarily short-circuiting the positive and negative motor cables via the control module 222.In some cases, such as after prolonged unused, the plug 822 may partially stick to the poppet seal 1404 and / or the valve seal 1406. This high friction event may be detected by the control module 222 based on a maximum current value and / or steep slope of the motor current slope as a function of time. According to some examples, the control module 222 is configured to execute a particular pulsating current profile to release the plug 822. For example, FIG. 22 is an example graph 2200 showing electrical current (in mA) versus time (in milliseconds (ms)) during a high friction event when valve 520 opens. Between 10 and 15 ms, the control module 222 detects a current or slope that reaches or exceeds a predetermined value. The control module 222 outputs a pulse current after 10-20 ms, pauses, and then causes the motor 522 to resume pulsating current. According to some examples, this duty cycle is repeated five or more times to overcome the high seal friction and bring the valve 520 to the open state. When the plug 822 overcomes the friction and starts to move, the motor current draw reaches a maximum value that is lower than the maximum impulse current for a period of time during which the plug 822 disengages from the valve seal 1406. The control module 222 detects this time period and terminates the pulsing events. According to some examples, the control module 222 may perform the pulse cycle automatically during all opening cycles. According to further examples, the control module 222 may only perform the duty cycle after the system has been powered down and powered up again (e.g., after a battery change or charging) and / or when a predetermined time has elapsed since the last actuation.In some cases, free fall of the balls 1414a-1414c may be accelerated due to the low friction of the cam assembly 824 and the plug compression bias and drive the motor 522 at a higher speed during a closing operation. This may result in a reversal of voltage and current to motor 522. In other words, the motor 522 becomes a generator that outputs energy that can be obtained and stored in the battery 404. FIG. 23 is, for example, an example diagram 2300 of a current profile during a closing operation. As shown in Figure 23, the flow returns to motor 522 from a free fall event. The return flow flows until the valve position 1 is reached. The area below the x-axis and above the current curve represents the energy that can be fed back into the battery 404. Additionally or alternatively, this energy may be stored in a capacitor and / or used to perform other functions. Some or all of the energy may be stored and / or used to improve system efficiency or perform other functions.According to further examples, the recesses may have other geometries. The recesses may have multiple ramp profile changes or detents and / or linear, upwardly concave and / or downwardly concave profiles to achieve the desired performance. As disclosed above, valve position 1 and valve position 2 are lock positions and therefore do not require energy to hold these positions. According to further examples, the cutout profiles may be configured to have three or more detents or locking positions.While in the examples shown in FIGS. 2-16B, the engine assembly 220 (with the engine 522) is coupled to and / or otherwise disposed on the lower end 210 of the lower tube 202, in further examples, the engine assembly 220 (with the engine 522) may be adjacent to the piston assembly 510 in the upper tube 204. For example, FIG. 24 is a cross-sectional view of the seat post 112 in which a motor assembly 2420 is coupled to or integrated with the piston assembly 510. Therefore, the motor assembly 2420 is disposed in the upper tube 204 around the overlap of the upper and lower tubes 202, 204. FIG. 25 is an enlarged view of the cutout 2400 of FIG. 24 showing the lower end 210 of the lower tube 202. In this example, a cap 2500 is coupled to the body 1200. The cap 2500 may not be airtight, so that the third chamber 526 in the lower tube 202 can be vented to the atmosphere. As shown in FIG. 25, the first and second conduits 532, 534 extend around the lower end of the shaft 508 and then into the shaft 508 and to the motor assembly 2420 (FIG. 24 ).FIG. 26 is an enlarged view of the cutout 2402 of FIG. 24, showing the piston assembly 510 and motor assembly 2420 in the upper tube 204. The motor assembly 2420 with the motor 522 is coupled to the piston 512 and disposed in the upper tube 204. Specifically, in this example, a motor housing 2604 is coupled (e.g., threadably coupled) to the upper end of the shaft 508 and the piston 512 is coupled (e.g., threadably coupled) to an upper end of the motor housing 2604. Thus, the piston 512 overlies the motor assembly 2420 in the upper tube 204. The motor 522 and the reduction system 1001 are disposed in the motor housing 2604. The motor 522 and the reduction system 1001 are exposed to atmospheric pressure through the shaft 508. In the example shown, a valve rod 2638 extends between the second carrier 1020 and the second cam 1412, similar to the valve rod 538, except that the valve rod 2638 is relatively short. According to some examples, the valve rod 2638 and the second carrier 1020 are coupled (e.g., splined together). However, according to further examples, the valve rod 2638 and the second carrier 1020 are constructed as a single unitary piece (e.g., a monolithic structure). For example, FIG. 27 is an example in which the valve rod 2638 and the second carrier 1020 are constructed as a single unitary piece. In some cases, the construction of the valve rod 2638 and the second carrier 1020 as a single unitary piece helps to maintain the valve rod 2638 concentric and reduce or avoid frictional losses. A valve rod seal 2600 and a valve motor seal 2602 isolate atmospheric pressure in the motor assembly 2420 from the pressurized gas in the first chamber 516 (the positive chamber) and the second chamber 518 (the negative chamber). The first and second leads 532, 534 extend through the shaft 508 and into the motor housing 2604 and are electrically connected to the motor 522. According to some examples, the piston assembly 510 includes a retainer 2606 (e.g., a snap ring) coupled to the plug 822 to prevent the plug 822 from being ejected upward and removed from the piston 512. The remaining portions of the valve 520 and the motor assembly 2420 are substantially the same as disclosed above and are not repeated herein.According to the examples disclosed above, the motor assemblies 220, 2420 are disposed in the atmospheric pressure range. However, according to further examples, the motor assemblies 220, 2420 may be disposed in the positive or negative pressure region (e.g., in the first or second chambers 516, 518). According to some examples, the engine assemblies 220, 2420 and / or the conduits 532, 534 may have a sealing surface such that they are partially in the positive or negative pressure region on one side of a seal and partially in an atmospheric pressure region on the other side of the seal. According to some examples, the battery 404 and / or the control housing 402 may be installed in the over or under pressure region. According to some examples, instead of the motor 522, a magnet may be used to control the valve 520.According to some examples, the valve seal 1406 (FIG. 14 ) may be co-molded together with the plug 822. For example, FIG. 28 shows an example in which a layer of sealing material 2800 is formed around the first sealing portion 1608 (the dish head) of the plug 822. This eliminates the need for a separate valve seal in the piston 512. For example, when the plug 822 is in the closed position, as shown in FIG. 28, the sealing material 2800 sealingly engages a shoulder 2802 of the piston 512 in the central channel 820. This creates a sealing surface that blocks fluid flow through the central channel 820. According to some examples, the sealing material 2800 is made of rubber and / or a polymer material, while the plug 822 is made of metal (e.g., stainless steel, aluminum). FIG. 29 is a perspective view of the plug 822 and the sealing material 2800. In this example, the sealing material 2800 covers the top, sides, and bottom (which forms the sealing surface) of the first sealing portion 1608. According to some examples, the layer of sealing material 2800 is formed by immersing the first sealing portion 1608 of the plug 822 in liquid sealing material and then curing and / or curing the sealing material. According to some examples, an adhesive layer is applied between the sealing material 2800 and the surface of the plug 822 to couple the sealing material 2800 to the plug. According to some examples, the dish seal 1404 may be similarly co-molded around the second seal portion 1610 of the plug 822.FIGS. 30 a, 30 b, 30 c, and 30 d illustrate another example of a plug 922. The plug 922 may be generally provided in a seat post as in other examples described herein. For example, plug 922 may be implemented as plug 822 as shown in FIG. 8. According to various examples, the plug 922 is linearly movable between a closed position and an open position as described above with reference to FIG. 8. As shown in Figure 30a, the plug 922 includes a plug cap 914 attachable with a plug fastener 916. The illustrated plug fastener 916 is a threaded fastener, but may also be a rivet, press fit, or other type of fastener. As shown in FIG. 30 b, the plug fastener 916 may at least partially retain a first sealing portion 908. The illustrated first seal portion 908 is an O-ring, but may be provided in any suitable configuration, such as a mechanical seal, flange seal, sealing plate, or other seal arrangement. The first sealing portion 908 may be made of rubber and / or a polymeric material. The first sealing portion 908 may be removable as shown in FIG. 30 b, for example to facilitate service or maintenance work.The plug fastener of Figure 30b is shown in a disassembled state relative to a seal mounting portion 920. The seal attachment portion 920 may include a threaded attachment as shown in FIG. 30 b. The first seal portion 908 is sized and shaped such that a seal is formed between the first seal portion 908 and the seal attachment portion 920, as well as between the first seal portion 908 and the plug cap 914. The first seal portion 908 may be positively disposed and / or biased between the plug cap 914 and the seal attachment portion 920. As shown in FIG. 30 d, one or more plug vents 918 may be provided. As described above, a seal is generally formed between the first seal portion 908 and both the plug cap 914 and the seal attachment portion 920. However, high pressure fluid may bypass the first sealing portion 908 and enter, for example, the restricted space between the first sealing portion 908 and the plug cap 914. In such a scenario, the plug vent 918 serves to relieve the pressure so as not to compromise the sealing properties or retention of the first sealing portion 908. As shown in FIGS. 30 aand 30 b, the plug vent 918 may include a plurality of separate plug vents. It is also true that a single plug vent 918 may alternatively be provided.As shown in FIG. 30 c, the plug 922 further comprises a second sealing portion 910, for example for sealing against a central channel (compare the central channel 820 as described with reference to FIG. 8 ). The plug 922 may further include a plug retention feature 912. For example, the plug retention feature 912 may interact with one or more corresponding features of a seat post assembly to retain the plug 922 throughout the movement. As shown in FIGS. 30 a- 30 d, the plug retention feature 912 may be a recess to retain, for example, a snap ring, an E-clip, a retaining ring, or other retaining device (not shown). The plug retention feature 912 may interact directly or indirectly (e.g., with a retaining ring) with other features, as is the case with the retainer 2606 described above with reference to FIG. 26.While the example piston assemblies, valves, cam assemblies, and motor assemblies disclosed herein are described in connection with pneumatic platform seat rods, the examples disclosed herein may also be used in connection with hydraulic platforms. For example, instead of pneumatic chambers filled with pressurized gas, the chambers 516, 518 may be filled with hydraulic fluid, e.g., oil. Thus, the examples disclosed herein may be used in conjunction with valves for compressible or incompressible fluids. While a battery is used in the control module as a power supply for activating the engine according to the examples disclosed herein, the engine may be activated by another power supply, e.g., an electric bicycle battery or another battery mounted on the bicycle according to other examples. Although the example cam arrangements disclosed herein are employed to convert rotational motion to linear motion, the example cam arrangements may be reconfigured to convert linear motion from a linear actuator to rotational motion of a valve.The example piston assemblies, valves, cam assemblies, and motor assemblies may also be used in other types of bicycle components. For example, the example piston assemblies, valves, cam assemblies, and motor assemblies may be used in suspension components (e.g., a shock absorber, a front fork). A suspension component often comprises a first tube and a second tube arranged telescopically. The example piston assemblies and valves disclosed herein may be used as a damper or spring component to control fluid flow between two chambers in the tube(s).Example systems, devices, and articles of manufacture for bicycles (and / or other vehicles) are disclosed herein. Examples and combinations of examples disclosed herein include the following:Example 1 is a height adjustable seat post for a bicycle. The height adjustable seatpost includes an upper tube and a lower tube that are telescopically disposed. The lower tube is couplable to a frame of the bicycle and the upper tube is couplable to a seat. The height adjustable seat post includes a piston in the upper tube. The piston divides the upper tube into a first chamber and a second chamber. The first and second chambers are filled with fluid. The piston defines a fluid passage between the first chamber and the second chamber. The height adjustable seat post further includes a plug in the fluid passage. The plug is linearly movable between an open position permitting fluid flow through the fluid passage and a closed position blocking fluid flow through the fluid passage. The height adjustable seat post further includes a motor and a cam assembly for converting rotational movement of the motor into linear movement of the plug.Example 2 includes the height adjustable seatpost of Example 1, wherein the cam assembly is disposed in the piston.Example 3 includes the height adjustable seatpost of example 1 or 2, wherein the cam assembly includes a first cam, a second cam, and a plurality of balls between the first cam and the second cam.Example 4 includes the height adjustable seat post of example 3, wherein the first and second cams are axially aligned with the plug.Example 5 includes the height adjustable seatpost of example 3 or 4, wherein the second cam is rotated relative to the first cam when the motor is activated.Example 6 includes the height adjustable seatpost of example 5, wherein rotation of the second cam in a first direction causes the first cam to move toward the plug to move the plug to the open position, and wherein rotation of the second cam in a second direction allows the first cam to move away from the plug to allow the plug to move to the closed position.Example 7 includes the height adjustable seatpost of Example 6, wherein the second cam has a first side facing the first cam, wherein the first side has recesses, and wherein the plurality of balls are disposed in the respective recesses.Example 8 includes the height adjustable seatpost of example 7, wherein each recess has a deep portion having a first depth and a shallow portion having a second depth less than the first depth.Example 9 includes the height adjustable seatpost of Example 8, wherein the plurality of balls are rolled from the deep portions of the recesses to the shallow portions of the recesses upon rotation of the second cam in the first direction to move the first cam away from the second cam in a linear direction, and wherein the plurality of balls are rolled from the shallow portions of the recesses to the deep portions of the recesses upon rotation of the second cam in the second direction to allow the first cam to move toward the second cam in a linear direction.Example 10 includes the height adjustable seatpost of example 9, further comprising a spring to bias the first cam toward the second cam.Example 11 includes the height adjustable seatpost of any one of Examples 1-10, wherein the motor is coupled to a lower end of the lower tube.Example 12 includes the height adjustable seatpost of any one of Examples 1-10, wherein the motor is coupled to the piston and disposed in the upper tube.Example 13 includes the height adjustable seatpost of any one of Examples 1-12, further comprising: a control module to activate the engine, the control module coupled to an outer surface of the lower tube, and conduits extending between the control module and the engine through the lower tube.Example 14 is a height adjustable seat post for a bicycle. The height adjustable seatpost includes a first tube and a second tube telescopically disposed. The first tube or the second tube is couplable to a frame of the bicycle, and the other of the first tube or the second tube is couplable to a seat, respectively. The height adjustable seat post includes a piston in the first tube. The piston divides the first tube into a first chamber and a second chamber. The first and second chambers are filled with fluid. The piston defines a fluid passage between the first and second chambers. The height adjustable seat post further includes a plug in the fluid passage of the piston. The plug is movable between an open position and a closed position to control fluid flow between the first and second chambers. The height adjustable seat post further includes a cam arrangement in the piston. The cam assembly includes a first cam, a second cam, and a plurality of balls between the first and second cams. Rotation of the second cam causes the first cam to move in a linear direction to move the plug between the open position and the closed position.Example 15 includes the height adjustable seatpost of Example 14, wherein the plurality of balls includes three balls.Example 16 includes the height adjustable seatpost of example 14, wherein the first and second cams are disc-shaped.Example 17 includes the height adjustable seatpost of any one of Examples 14-16, wherein the first cam includes a rotation lock feature to prevent rotation of the first cam within the piston.Example 18 includes the height adjustable seatpost of any one of Examples 14-17, further comprising a motor to rotate the second cam, wherein the motor is axially aligned with the plug.Example 19 includes the height adjustable seat post of any of Examples 14-18, further comprising a layer of sealing material formed around a portion of the plug.Example 20 is a bicycle component including a first tube and a second tube telescopically disposed, and a valve disposed in the first tube and dividing the first tube into a first chamber and a second chamber. The first and second chambers are filled with fluid. The valve is operable between a closed state in which the fluid is prevented from flowing between the first and second chambers via the valve and an open state in which the fluid is allowed to flow between the first and second chambers via the valve. The bicycle component further comprises a cam assembly having a first cam, a second cam, and a ball between the first cam and the second cam. At least one of the first cam and the second cam has a recess with a ramp profile. The ball is disposed in the recess, and rotation of the second cam causes the ball to move the first cam in a linear direction to open or close the valve.Example 21 includes the bicycle component of Example 20, wherein the fluid is a compressible fluid.Example 22 includes the bicycle component of Example 20 or 21, wherein the valve includes a valve body and wherein the cam assembly is disposed in the valve body.Example 23 includes the bicycle component of any one of Examples 20-22, wherein the recess includes a deep portion having a first depth, a shallow portion having a second depth less than the first depth, and a protrusion between the shallow portion and the deep portion, the protrusion having a third depth less than the first depth and the second depth.The figures of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. The figures are not a full description of all elements and features of devices and systems that utilize the structures or methods described herein. Many other embodiments will be apparent to those skilled in the art upon review of the disclosure. Other embodiments may be utilized and derived from the disclosure such that structural and logical substitutions and changes may be made without departing from the scope of the disclosure. Moreover, the figures are merely representative and may not be drawn to scale. Certain proportions in the figures may be exaggerated, while other proportions may be minimized. Accordingly, the disclosure and figures are to be regarded as illustrative rather than restrictive.While this specification contains many details, these should not be construed as limitations on the scope of the invention or the claimed subject matter, but as descriptions of features specific to particular embodiments of the invention. Certain features described in this specification in connection with individual embodiments may also be realized in combination in a single embodiment. Conversely, various features described in connection with a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination. Moreover, although features are described above as acting in certain combinations and even originally claimed as such, one or more features from a claimed combination may in some cases be taken out of the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.Although certain embodiments are illustrated and described herein, any arrangement that performs the same or similar purpose may replace the embodiments shown. This disclosure is intended to cover any later adaptations or variations of the various embodiments. Combinations of the above embodiments and other embodiments not specifically described herein will be apparent to those skilled in the art upon review of the specification.The Abstract of the Disclosure is provided in accordance with 37 C.F.R. §1.72(b) and is submitted with the proviso that it is not used to interpret or limit the scope or meaning of the claims. Moreover, in the foregoing detailed description, various features may be summarized or described in a single embodiment to simplify the disclosure. This disclosure is not to be understood as requiring more features than are expressly recited in the individual claims. Rather, as the following claims reflect, the subject matter of the invention may be directed to less than all features of any of the disclosed embodiments. Therefore, the following claims are incorporated into the Detailed Description, with each claim standing on its own and defining the claimed subject matter separately.The foregoing detailed description is to be regarded as illustrative rather than restrictive, and the following claims, including all equivalents, are intended to define the scope of the invention. The claims are not to be understood as limited to the described order or elements unless noted. Therefore, all embodiments which fall within the scope of the following claims and their equivalents and are within the scope thereof are claimed as the invention.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedUS 63 / 516,574

[0001]

Claims

A height adjustable seatpost for a bicycle, the height adjustable seatpost comprising: an upper tube and a lower tube telescopically disposed, the lower tube couplable to a frame of the bicycle and the upper tube couplable to a seat; a piston in the upper tube, the piston dividing the upper tube into a first chamber and a second chamber, the first and second chambers being filled with fluid, the piston defining a fluid passage between the first chamber and the second chamber; a plug in the fluid passage, the plug being linearly movable between an open position in which fluid flow through the fluid passage is possible and a closed position in which fluid flow through the fluid passage is blocked; a motor; and a cam arrangement for converting the rotational movement of the motor into a linear movement of the plug.The height adjustable seat post of claim 1, wherein the cam assembly is disposed in the piston.The height adjustable seatpost according to claim 1 or 2, wherein the cam assembly comprises a first cam, a second cam, and a plurality of balls between the first cam and the second cam.The height adjustable seat post of claim 3, wherein the first and second cams are axially aligned with the plug.The height adjustable seatpost according to claim 3 or 4, wherein the second cam is rotated relative to the first cam when the motor is activated.The height adjustable seat post of claim 5, wherein rotation of the second cam in a first direction causes the first cam to move toward the plug to move the plug to the open position, and wherein rotation of the second cam in a second direction allows the first cam to move away from the plug to allow the plug to move to the closed position.The height adjustable seat post of claim 5 or 6, wherein the second cam has a first side facing the first cam, wherein the first side has recesses, and wherein the plurality of balls are disposed in the respective recesses.The height adjustable seatpost according to claim 7, wherein each recess has a deep portion having a first depth and a shallow portion having a second depth less than the first depth.The height adjustable seatpost according to claim 8, wherein the plurality of balls are rolled from the deep portions of the recesses to the shallow portions of the recesses upon rotation of the second cam in the first direction to move the first cam away from the second cam in a linear direction, and wherein the plurality of balls are rolled from the shallow portions of the recesses to the deep portions of the recesses upon rotation of the second cam in the second direction to allow the first cam to move toward the second cam in a linear direction.The height adjustable seatpost according to any one of claims 3 to 9, further comprising a spring to bias the first cam toward the second cam.The height adjustable seatpost according to any one of the preceding claims, wherein the motor is coupled to a lower end of the lower tube.The height adjustable seat post of any preceding claim, wherein the motor is coupled to the piston and disposed in the upper tube.The height adjustable seatpost of any preceding claim, further comprising: a control module to activate the motor, the control module coupled to an outer surface of the lower tube; and conduits extending through the lower tube between the control module and the motor.A height adjustable seatpost for a bicycle, the height adjustable seatpost comprising: a first tube and a second tube telescopically disposed, the first tube or the second tube couplable to a frame of the bicycle and the other of the first tube or the second tube couplable to a seat; a piston in the first tube, the piston dividing the first tube into a first chamber and a second chamber, the first and second chambers being filled with fluid; the piston defining a fluid passage between the first and second chambers; a plug in the fluid passage of the piston, the plug movable between an open position and a closed position to control a flow of fluid between the first and second chambers; and a cam arrangement in the piston, the cam arrangement comprising: a first cam; a second cam; and a plurality of balls between the first and second cams, wherein rotation of the second cam causes the first cam to move in a linear direction to move the plug between the open position and the closed position.The height adjustable seat post of claim 14, wherein the plurality of balls comprises three balls.The height adjustable seat post of claim 14 or 15, wherein the first and second cams are disk shaped.The height adjustable seat post of any of claims 14 to 16, wherein the first cam includes a anti-rotation feature to prevent rotation of the first cam within the piston.The height adjustable seat post of any of claims 14 to 16, further comprising a motor for rotating the second cam, the motor being axially aligned with the plug.The height adjustable seat post of any of claims 14 to 18, further comprising a layer of sealing material formed around a portion of the plug.A bicycle component comprising: a first tube and a second tube telescopically disposed; a valve disposed in the first tube and dividing the first tube into a first chamber and a second chamber, the first and second chambers being filled with fluid, the valve operable between a closed state in which the fluid is prevented from flowing between the first and second chambers via the valve and an open state in which the fluid is allowed to flow between the first and second chambers via the valve; and a cam assembly comprising: a first cam; a second cam; a ball between the first cam and the second cam, at least one of the first cam and the second cam having a recess with a ramped profile, the ball disposed in the recess, wherein rotation of the second cam causes the ball to move the first cam in a linear direction to open or close the valve.The bicycle component according to claim 20, wherein the fluid is a compressible fluid.The bicycle component according to claim 20 or 21, wherein the valve comprises a valve body and wherein the cam assembly is disposed in the valve body.The bicycle component according to any one of claims 20 to 22, wherein the recess includes a deep portion having a first depth, a shallow portion having a second depth less than the first depth, and a protrusion between the shallow portion and the deep portion, the protrusion having a third depth less than the first depth and the second depth.

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