Patent Publication Number: US-9839807-B2

Title: Exercise machine with multi-function wheel brake actuator and over center locking mechanism

Description:
TECHNICAL FIELD 
     Aspects of the present disclosure involve an exercise bicycle and a brake adjustment assembly and a locking assembly. 
     BACKGROUND 
     Indoor cycling is a popular and excellent way for people to maintain and improve fitness. Generally speaking, indoor cycling revolves around an exercise bicycle that is similar to other exercise bicycles with the exception that the pedals and drive sprocket are connected to a flywheel rather than some other type of wheel. Thus, while a user is pedaling, the spinning flywheel maintains some momentum and better simulates the feel of riding a real bicycle. To further enhance the benefits of indoor cycling, fitness clubs often offer indoor cycling classes as a part of their group fitness programs. With such a program, an instructor guides the class through a simulated real world ride including simulating long steady flat sections and climbing. In either situation and whether or not in a class setting, the user simulates such riding conditions by adjusting the resistance on the flywheel—the amount of power required by the rider to turn the flywheel. Interval training, which involves a sequence of hard riding followed by recovery, is a popular and proven way to train but conventional indoor cycling bicycles do not provide a convenient and easy way rapidly and predictably change resistance of the flywheel. It is also important to provide an easy and effective mechanism to change the seat height and handlebar height to fit different riders. 
     It is with these issues in mind, among others, that aspects of the present disclosure were conceived. 
     SUMMARY 
     Aspects of the present disclosure involve an exercise machine, such as an exercise bicycle or an indoor cycle, comprising a frame supporting a wheel. A brake arm is pivotally coupled with the frame and moveable between at least a first position and a second position. The brake arm includes at least one resistance element, which may be a friction pad or magnets, positioned proximate the wheel. The first position is associated with a first braking force on the wheel and the second position is associated with a second braking force on the wheel where the second braking force is greater than the first braking force. The exercise machine further includes a brake arm adjustment assembly including a housing coupled with the frame, the housing translationally and rotatable supporting a shaft. A member, such as a collar, is operably fixed relative to the housing, the member defining a first surface separated from a second surface by a distance relating to a separation between the first position and the second position. A lever assembly is operably coupled with the shaft, the lever assembly including at least one projection, which may be provided through a plurality of teeth on a tooth collar. The lever assembly is moveable relative to the housing to move the at least one projection from engaging the first surface to engaging the second surface, the movement causing the shaft to translate and move the brake arm from the first position, associated with the first surface, to the second position, associated with the second surface. 
     In another aspect, the present disclosure involves an exercise machine including a frame supporting a wheel. A member is pivotally coupled with the frame and moveable between at least a first position and a second position, the member including at least one resistance element positioned proximate the flywheel and the first position associated with a first braking force on the flywheel and the second position associated with a second braking force on the wheel, the second braking force greater than the first braking force. A shaft is translationally and rotatably supported relative to the frame and the shaft is coupled with the member. A detent member is operably fixed relative to the housing, the member defining a first surface separated from a second surface by a distance relating to a separation between the first position and the second position. Additionally, a lever assembly is operably coupled with the shaft, the lever assembly including at least one projection, the lever assembly moveable to cause the at least one projection to engage the first surface or the second surface to move the member between the first position and the second position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other objects, features, and advantages of the present disclosure set forth herein will be apparent from the following description of particular embodiments of those inventive concepts, as illustrated in the accompanying drawings. It should be noted that the drawings are not necessarily to scale; however the emphasis instead is being placed on illustrating the principles of the inventive concepts. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than limiting. 
         FIG. 1  is a right side view of an exercise bicycle; 
         FIG. 2  is a right side view of an exercise bicycle frame of the exercise bicycle shown in  FIG. 1 ; 
         FIG. 3  is a right side view of a multifunction brake actuator assembly and some related components of the exercise bicycle of  FIG. 1 ; 
         FIGS. 4A-4C  are representative section views of a multifunction brake actuator assembly finely adjusting a brake arm at an upper (relatively lower braking force), mid and lower (relatively greater braking force) position relative to a flywheel, which is functionally equivalent to the multifunction brake actuator described in  FIGS. 5-8 , but is slightly mechanically different; 
         FIGS. 5A-5C  are representative isometric views of a multifunction brake actuator assembly coarsely adjusted between three interval positions; 
         FIG. 6  is an isometric view of the multifunction brake actuator coupled with the brake arm; 
         FIG. 7  is a view of the multifunction brake actuator; 
         FIG. 8  is an alternative view of the multifunction brake actuator; 
         FIG. 9  is a close up view of a top portion of the multifunction brake actuator and related components; 
         FIG. 10  is a view of a lever assembly and detent collar; 
         FIG. 11  is a top view of the lever assembly; 
         FIG. 12  is an isometric view of the lever assembly; 
         FIG. 13  is a side view of the detent collar; 
         FIG. 14  is a side view of a pin assembly; 
         FIG. 15  is an opposing side view of the pin assembly; 
         FIG. 16  is an isometric view of the pin assembly; 
         FIG. 17  is a top view of the pin assembly; 
         FIGS. 18A-18C  are view of the pin assembly in a neutral, clamped, and released position, respectively; 
         FIG. 19  is a side view of the pin assembly supported on a pin tube coupled with a tube (e.g. seat tube or head tube); and 
         FIGS. 20A and 20B  are views of an alternative lever assembly in an engaged (over-center position) and a release position, respectively, the lever assembly including an over-center linkage. 
     
    
    
     DETAILED DESCRIPTION 
     Aspects of the present disclosure involve an exercise machine, such as an indoor cycle, and mechanisms for adjusting braking resistance of a wheel or fixing one member relative to another member. With respect to the adjustment of braking resistance, a multifunction brake actuator is provided that allows a user to both finely adjust braking force and coarsely adjust braking force, which may be useful for interval training when used in an exercise bicycle. Generally speaking, the exercise machine includes a flywheel and a brake arm that may be moved relative to the brake arm to position magnets to induce a braking force on the flywheel through eddy currents. The brake actuator, however, may also be used with a friction resistance element to create a frictional braking force on a wheel. A person using the exercise machine must use some amount of power to overcome the induced braking force. The brake actuator allows a user to finely adjust the braking force by rotating a knob. The brake actuator also allows a user to turn a lever to coarsely adjust the brake arm between one of a plurality (e.g., three interval settings) different interval settings where different set resistances are placed on the wheel. The baseline for the interval settings may be established by fine adjustment. 
     The user may also fix one member to another member through a locking assembly, which may be a pop-pin assembly. To adjust the height of a seat or handlebars, for example, the locking assembly is released so that the seat or handlebars may be raised or lowered. When adjusted properly, the user engages the pin assembly to lock the members. Unlike conventional pin assemblies used in exercise equipment, such as exercise bicycles but also including weight machines and other equipment, the pin assembly includes an over-center cam assembly that allows a user to lever a pin into a hole to tightly couple any two members. Moreover, the pin assembly includes a fine adjustment that allows a user to adjust the clamping force. 
     Referring now to  FIGS. 1 and 2 , one example of an exercise bicycle  10  is shown. Various concepts discussed herein reference an exercise bicycle and particularly an indoor cycling style exercise bicycle; however, the concepts are applicable to other exercise machines. The exercise bicycle is configured for use by a variety of riders in a club environment or for a single or limited number of riders in a home or other personal use environment. The exercise bicycle includes a frame  12  adjustably supporting an adjustable seat assembly  14  at the rear of the frame and adjustably supporting an adjustable handlebar assembly  16  at the front of the frame. The adjustable seat and handlebar assemblies provide fore and aft adjustment of a respective seat  18  and handlebar  20 . Further, the seat and handlebar assemblies may be vertically adjusted and fixed at various possible positions. Hence, the exercise bicycle provides for many different possible seat and handlebar positions to fit different riders and to provide riders with different configurations depending on the exercise being performed. Examples of seat and handlebar adjustment assemblies that may be used are described in U.S. Pat. No. 8,827,871 titled “Exercise Bicycle Frame with Bicycle Seat and Handlebar Adjustment Assemblies,” issued on Sep. 9, 2014, which is hereby incorporated by reference herein. 
     The frame includes a seat tube  22  that receives a seat post or “stem” portion  24  of the seat assembly  14 . The seat post may be moved up and down relative to the seat tube to adjust the height of the seat assembly, and particularly to adjust the height of the seat  18  that is a part of the seat assembly. A pop pin  26  is connected with the seat tube (second member) and is configured to engage one of a plurality of apertures  28  defined in the seat post (first member), and thereby secure the seat at a desired height. The pop pin may be spring-loaded such that it is biased in the locked position engaging the aperture. 
     The pop pin is shown extending forwardly from the seat tube. This configuration provides easy access for a rider to adjust the seat up or down. In many instances, ease of seat height adjustment is simply to accommodate riders of different heights. The pop pin is positioned for easy access by the rider. It is possible, however, to position the pop pin on the back side of the seat tube or at another location. Additionally, it is possible to use other mechanisms to facilitate seat height adjustment with or without pop pins. For example, a pawl on the fore and aft seat and handlebar assemblies may be used to vertically adjust the seat post (or tube) as well as the handlebar post. 
     In one particular implementation, the seat tube is rearwardly angled at approximately 72 degrees. The seat tube angle, along with other adjustment and dimensional relationships discussed herein, is optimized so that riders of all sizes can best fit the exercise bicycle. The seat tube  22 , along with other frame members discussed herein, is extruded aluminum. Other frame member shapes and materials may be used, such as steel square tubing or steel round tubing, in the construction of the frame assembly. However, the extruded aluminum race track shaped tubing provides a unique balance between strength, overall exercise bicycle weight and aesthetic appearance. Additionally, while the seat post is shown as telescoping out of the seat tube, this relationship may be reversed such that the post fits over the tube. This relationship may also be reversed for other tube and post arrangements discussed herein. 
     Returning again to the discussion of the frame  12  and referring primarily to  FIG. 2 , a down tube  32  extends from a lower rear area of the exercise bicycle to an upper forward area of the exercise bicycle. Particularly, the down tube extends between a mid-portion of the seat tube  22  and supports a head tube  34  at the forward end of the down tube. The down tube is also a racetrack type extruded aluminum member. The down tube, in one particular arrangement, is curved descending at a relatively steeper angle  36  at the head tube and curving to a shallower angle  38  at the seat tube. The down tube is welded to the seat tube, although other means of attachment and arrangements are possible. A bottom bracket tube  40  extends downward and rearward from the down tube to a bottom of the seat tube. The bottom bracket tube connects to the seat tube below the down tube. The bottom bracket tube supports a bottom bracket  42 , which in turn supports a crank assembly  44 . The bottom bracket tube, down tube and seat tube, collectively form a structurally rigid triangle  46 . 
     The head tube  34  is connected to the front of the down tube  32 . A portion  48 A of the head tube extends upwardly from the down tube and a portion  48 B of the head tube extends downwardly from the head tube. The head tube (second member) receives a handlebar post  50  (first member) that extends downwardly from the fore and aft adjustable handlebar assembly  16 . The handlebar post may be moved vertically relative to the head tube to adjust the height of a handlebar assembly, and particularly to adjust the height of a handlebar  20  of the handlebar assembly. A second pop pin  52  is connected with the head tube  34  and is configured to engage one of a plurality of apertures (not shown) defined in the handlebar post, and hence secure the handlebars at a desired height. Other mechanisms may also be used in place of the pop pin, and the position of the pop pin or any other mechanism may be altered in alternative exercise bicycle implementations. 
     In the frame configuration illustrated herein, a front fork assembly  54 , which supports a flywheel  56  between opposing left  58  and right  60  fork legs, is coupled to the down tube  32  at a point between the head tube  34  and the seat tube  22 , and proximate the head tube. In the frame configuration shown, the forks are set at about the same angle as the seat tube. The exercise bicycle discussed herein is particularly configured for indoor cycling and therefore includes a flywheel. It is nonetheless possible to deploy the frame and other components discussed, whether alone or in combination, in an exercise bicycle that does not include a flywheel, to use different sized flywheels or to position the flywheel and frame members differently. 
     The exercise bicycle further includes the crank assembly  44  configured to drive the flywheel  56 . A drive sprocket is rotatably supported in the bottom bracket  42 . A belt (not shown, behind the cover  62 ) connects the drive sprocket to the flywheel sprocket, although other mechanisms, such as a chain, may be used to connect the sprockets. The drive sprocket is fixed to a pair of crank arms and the flywheel is fixed to the flywheel sprocket such that the drive sprocket and flywheel sprocket do not freewheel. Hence, clockwise rotational force on the crank arms, such as in conventional forward pedaling, rotates the flywheel in a clockwise manner. However, if the rider discontinues exerting a pedaling force on the cranks, the spinning flywheel will continue, via the belt, to drive the crank arms. It is, however, possible to include freewheel mechanisms with the drive or flywheel sprocket or other components. As discussed below, a rider may rapidly stop the spinning flywheel and the associated crank arm rotation by depressing a multi-function brake actuator  64 . 
     Brake Actuator 
     Referring first to  FIG. 3 , which has many of the bicycle components removed to better illustrate the brake actuator, brake arm  66 , is controlled with a multi-function brake actuator  64 . The brake arm supports one or more permanent magnets  67  that induce eddy currents in the flywheel, depending on the proximity of the magnets to the flywheel. The induced resistance on the flywheel by the relative position of the magnets determines how much power is required to spin the flywheel. The exercise bicycle or any other exercise machine using a rotating wheel, such as an elliptical machine or recumbent bike, may also use a brake arm that presses a friction element on a wheel to create a frictional resistance rather than a magnetic resistance. The friction element may be in the brake arm or provided directly by the brake actuator. Such an embodiment works similarly but the brake arm has a friction element, such as a felt pad or the like, that pushes on the wheel to create resistance. Rotating the knob in such an arrangement places greater force on the friction pad and hence induces greater resistance to rotation of the wheel. Referring again to the magnetic embodiment, in one example, rotation of the flywheel relative to the magnets induces eddy currents in the flywheel that creates braking power ranging from 40 watts, with little or no magnet induced resistive power, to about 700 watts or greater depending on the rpm of the flywheel when the magnets are positioned. The magnets are positioned adjacent to but not in contact with an outer ring  68  of the flywheel. In one particular arrangement, one or more pairs of magnets are positioned substantially equidistant from opposing sides of the flywheel. Braking power (and hence the amount of power required by a rider to spin the flywheel) may be adjusted depending on the position of the magnets relative to the flywheel. Generally speaking, the brake arm actuator is used to pivot the brake arm relative to the flywheel to adjust braking resistance or otherwise the power required to turn the flywheel. 
     The brake actuator  64  may provide fine adjustment, coarse adjustment, and provide for immediate flywheel braking to cause a complete stop, and hence is referred to herein as a multi-function actuator. It possible that an implementation may provide only one or two of the three disclosed functions, and hence may not be multi-function. Nonetheless, with reference to the multi-function brake actuator illustrated, a user may rotate a knob  70  to move the brake arm downward or upward and finely adjust the braking force imparted on the flywheel  56 .  FIGS. 4A, 4B, and 4C  are section views of the brake actuator and brake arm (and other components) and illustrating the brake actuator finely adjusted at an upper most position (least braking resistance), a mid-position and a lower most position (greatest braking resistance). A user may also actuate an interval lever  72  to move the brake arm between a plurality of coarse adjustment settings where the brake arm moves a fixed distance between settings, and hence moves the brake arm between a plurality of different resistance settings.  FIGS. 5A, 5B, and 5C  illustrate the interval lever, the actuation of the brake actuator and the position of the brake arm in three possible interval positions (upper, middle and lower) associated with three relative degrees of braking resistance ranging from a relatively lower resistance, to a relatively higher resistance with a mid-level resistance between. Such a coarse adjustment may be useful in interval training where a user rides between a recovery resistance (the upper position) and one or more training resistances (the middle and lower positions) where it takes more power to spin the flywheel relative to the recovery resistance. Finally, the user may push down on the knob causing the actuator to press the brake arm down to engage a mechanical friction brake to stop the flywheel. Typically, such an action is used when the rider wants to quickly stop the flywheel from spinning, such as at the end of an exercise routine or if the rider wants to quickly dismount the exercise cycle for any number of reasons. 
     In one particular implementation, the brake arm  66  is pivotally mounted at a bracket  74  coupled with a bottom of the head tube  34 . The brake arm extends rearwardly and downwardly from a pivot  76 . In this way, or in other ways, a torsion spring  78  is coupled to the brake arm at the pivot  76  and provides an upward force on the brake arm, and also provides a return or upward force on components of the brake actuator as discussed in more detail herein. A coil spring, compression spring, extension spring, or other spring may be positioned between the brake arm and the frame to provide the return force. 
     Distal from the pivot, the brake arm has a clam shell opening  80  defining a channel configured to receive and secure a magnet assembly  82  housing the magnets  67 . In the implementation illustrated, the brake arm is mounted generally above the flywheel, and the discussion herein refers to moving the brake arm downward or upward to induce more or less braking power, respectively. It should be recognized, however, that the brake arm and actuator may be positioned in various different ways to cause relative movement of the brake arm (and magnets) relative to the flywheel. For example, in a recumbent bike, the actuator might be positioned to face a seated rider, and the brake arm might move fore and aft to achieve resistance changes. Moreover, the brake actuator might be employed with magnets coupled directly to a feature of the brake actuator rather than a brake arm. 
     The pivotal position of the brake arm relative to the flywheel may be finely adjusted by way of the multifunction brake adjustment assembly. The brake actuator includes a tube  84  fixed to the down (or top) tube  32  of the exercise bicycle  10 . Many of the functional components of the actuator are supported in, or relative to, the tube. The knob is coupled with a shaft  90  extending through the tube. The knob  70  defines a cavity  86  that fits over a top portion  88  of the support tube  84 . In the implementation illustrated, the tube defines a circular cross section. However, the tube may be of other shapes and dimensions, and serves as a housing and structural support for various actuator components. Proximate the knob  70 , the shaft  90  extends through a bore (or aperture) defined in a cap  92  pressed into the top of the tube. The end cap defines a top collar  94  above the tube and of approximate the same outer diameter as the tube. The collar retains the cap at the top of the tube. The cap also defines an extension  96  that extends within the tube and is about the same inside diameter of the tube. The cap may be press fit, threaded, or otherwise secured in the tube. 
     The shaft defines a threaded portion  98 , distal the knob  70 , to which is coupled a brake arm connector  100 . The threaded portion of the shaft is connected at a threaded aperture  102  defined in the connector. The brake arm connector is translationally supported in the tube but rotationally fixed. An end  99  of the connector is coupled with the brake arm  66 . A friction element or magnetic element may, however, be operably connected directly to the connector. Generally speaking, rotating the knob causes rotation of the shaft  90  to translate the connector within the tube through the interaction between the threaded portion of the shaft and the threaded aperture. Thus, rotating the knob  70  finely pivots the brake arm relative to the flywheel to adjust braking power to whatever braking resistance is desired by the rider. 
     To rotationally fix the connector  100 , the tube defines a pair of opposing slots  104  at an end proximate the brake arm. In one arrangement, the slots run longitudinally along a lower length of the tube, and are positioned with about 180 degrees of separation. The connector includes a pair of keys  106  that fit with the respective slots. Thus, when the shaft  90  is rotated, it drives the actuator within the tube but the interaction between the keys and slots prohibits the rotation of the shaft from rotating the actuator within the tube. More or less slots and keys are possible as are other ways of rotationally fixing the connector, or translationally supporting the connector. 
     Course or “interval” adjustment is achieved by rotating the interval lever  72  to cause the shaft  90  to be moved between a plurality of set positions. In one specific example, the lever can cause the shaft to move between three distinct positions and hence move the brake arm between three distinct positions, such as illustrated in  FIGS. 5A-5C . The lever is part of a lever assembly  107  operably coupled with the shaft. To provide for further exercise resistance customization, the interval adjustment acts in concert with fine adjustment. A user first sets the fine resistance for one of the different interval settings, and then the interval resistances are based on the fine adjustment. So, for example, a user may finely adjust resistance, as discussed above, with the interval lever in the upper most interval position, which might be the easiest or recovery resistance. When the user moves the lever to the middle or lower positions, the resistance will be relative to the set recovery resistance, such that when the user returns the lever to the upper position, the resistance will be as finely adjusted. The user can finely adjust any of the different positions. 
     In one example, the lever assembly includes a tooth collar  108  rotationally supported on the shaft by a pair of opposing bushings  110 . The tooth collar defines four equidistantly spaced teeth  112  projecting upwardly from an annular surface  114  of the collar. As discussed further below, the teeth interact with a plurality of detent ramps  116  defined on a detent, or interval, ramp collar  117  to cooperatively drive the shaft and brake arm through the interval positions. 
     The lever assembly also includes a sleeve  118  of a slightly larger outside diameter than the tube  84 . The sleeve moves both rotationally and translationally relative to the tube when the lever is actuated. The sleeve and lever arm are connected to the tooth ring by way of an interconnecting member  120  extending between the collar  108  and the sleeve/lever arm. The sleeve is separated by a gap  122  with the sleeve on the outside of the tube and the collar on the inside of the tube. The interconnecting member extends through a slot  124 , in the form of an inverted T, defined from the top of the tube, at the cap, downward. 
     More specifically, the slot defines a relatively wider section  126  below a relatively narrower section  128 . When turning the lever to move between an upper (lower resistance) position through the intervals, the lever handle and interconnecting members moves within the wider lever slot portion between the upper right corner (upper, lower resistance interval), downward and across, to the lower left corner (lowest, greatest resistance interval). The ramps and collar might be reversed such that actuation of the lever moves it from the upper left corner, downward and across to the lower right corner. Regardless, the slot is sized and dimensioned to accommodate the lever through its range of motion both rotationally and translationally relative to the tube. 
     As introduced above, the respective teeth  112  of the tooth collar  108  interact with a respective plurality of detent ramps  116  defined in the interval ramp collar  117 . The interval ramp collar is positioned below the cap  92  and above the lever assembly. The interval ramp collar defines a first bore  119  or aperture through which extends the shaft. The interval collar also defines a second bore  121 , larger than the first, that supports a coil spring  123  fixed between the cap and the collar, which takes up any slack in the components within the tube. The interval collar also defines a tab  130  projecting from a side of the collar and received in the upper  128 , narrow, portion of the inverted T-slot. The tab prohibits the collar from rotating. 
     The annular surface of the interval collar facing the tooth collar defines a plurality of interval ramp/detent structures  116 . In the implementation shown, there are four interval ramp/detent structures corresponding to the four teeth  112 , and the four interval structures are equidistantly spaced like the teeth such that a respective tooth engages a respective interval structure. Each ramp/detent structure provides three detent or “interval” locations. As shown, an interval structure defines a first—or, upper—detent  132 A defined on the collar surface from which project the ramp/detent structures. Each ramp/detent structure defines a first ramp  134 A and a second ramp  134 B with the first, a second (or “mid”)  132 B, and a third—or, lower—detent  132 C separated by the first ramp and the second ramp. 
     Referring to the tooth collar, a tooth has a long face  136 A intersecting a short face  136 B to define a point  138 . With the points engaging the upper detents  132 A, the long face  136 A of each tooth abuts the first (upper) ramp. In this position, the brake arm is in its upper interval position (lowest braking resistance of the three interval resistances). Further, in this position, the interval lever and interconnecting member are positioned at the upper right corner of the larger width portion of the inverted T-slot. 
     When a user rotates the lever clockwise (to the left), the long face  136 A of a tooth, abutting an upper ramp  134 A, drives the tooth collar portion of the lever and the interconnected shaft downward until the points  138  of the teeth set in the respective mid-detents  132 B. Thus, the brake arm  66  moves relative to the flywheel from a first position (e.g. as shown in  FIG. 5A ), associated with the upper detent, to a second position (with greater resistance than the first position) associated with the mid-detent (e.g., as shown in  FIG. 5B ). The travel distance of the brake arm is set by the distance between the upper detent and the mid-detent (distance D 1 ). From the mid-detent, a user may rotate the lever clockwise (to the lower detent) or counterclockwise back to the upper detent. If clockwise, the long faces of the teeth are abutting the respective lower ramps  134 B. Rotating the lever pushes the tooth face against the ramp, pushing the lever arm assembly and the attached shaft downward so that the brake arm moves relative to the flywheel to a third position (with greater resistance than the second position). The travel distance of the brake arm is set by the distance between the mid-detent and the lower detent (distance D 2 ). Due to the return or upward force on the brake arm due to the torsion spring  78 , the interaction of the teeth and detent notches act as detents due to the retention of the teeth in a detent caused by the spring force. Also as discussed in more detail herein, should the user depress the knob to effect an immediate braking action, the torsion spring force on the brake arm returns the shaft and other components to the normal position (fully upward), after the user stops pushing on the brake knob. The interaction of the teeth and the detent recesses also arrests the rotation of the lever between positions and provide a discernible feeling on the lever when the teeth snap into the recesses. 
     Depending on the number of teeth and detent ramps, the size of the tube and interval ramp collar, the shape of the ramps, and other factors, the number and distance between distinct positions may be more or less than three, and the distance difference between positions may not be same. For example, the tooth collar may have two teeth, 180 degrees separated, and there may be only two relatively larger ramp structures on the interval ramp with two detents between an upper and lower detents, and separated by an additional ramp providing four interval positions. Other similar variations are possible. 
     Besides the brake adjustment assembly allowing a rider to adjust the brake force by finely pivoting the brake arm to position the magnets relative to the flywheel or by using the interval lever to coarsely adjust the brake force, the brake adjustment assembly also allows a rider to stop the flywheel by forcing a brake pad  183 , transverse between the magnet in the upper part of the housing  80 , down on flywheel  56 . At an upper end of the tube, distal the brake arm, the brake adjustment assembly includes the brake knob  70  fixed to the shaft  90 . The brake knob includes or otherwise defines the cavity  86  suitable to receive the top of the tube and for the knob to fit over the tube and any components associated therewith. 
     To rapidly stop the flywheel, a rider may press downward on the handle which moves the shaft  90  downward within the tube. The cavity  86  of the knob is pressed downward over the tube  84 . Further, the shaft, through engagement with the brake arm, pivots the brake arm  66  downward such that the brake pad  83  contacts the flywheel. When the rider releases the knob or reduces the force on the knob, the spring  78  acting on the brake arm, pushes the shaft and knob upward to disengage the pad and release the flywheel. 
     Pop-Pin 
     Aspects of the present disclosure further involve a pop-pin  26  that may be finely adjusted and then actuated to engage or disengage through use of a lever. When adjusted and engaged, the pop-pin secures a pin  202  into a mating hole but also does so tightly. In comparison to conventional pins that require multiple steps to loosen, disengage, adjust, engage and tighten; the present pop-pin allows a user to disengage, adjust and engage (or vice versa)—effectively eliminating two actions. Thus, there are fewer steps involved to adjust the seat height or handlebar height, when used on an exercise bicycle. Moreover, the loosening and tightening steps that are eliminated, allow the user to make quick and easy adjustments that are simply not possible through conventional arrangements. Further, the clamping force tightly locks the members in a way not possible or which would substantially greater effort in conventional design. 
     More particularly, the pop-pin, which may also be referred to herein as a pop-pin assembly, is coupled to a first tube (e.g. seat tube  22  or head tube  34 ) at a pin tube  204 . The pop-pin is also a form of an over-center clamp. The pin tube extends from and is coupled to the first tube. The first tube houses a second tube (e.g. the seat post  24  or the handle bar post  50 ) defining a plurality of holes  206 . In one possible example, the first tube is the seat tube and the second tube is the seat stem. Generally speaking, when the pin  202  is engaged with one of the plurality of holes  206 , the first tube is fixed relative to the second tube (while referenced as “tubes,” it should be recognized that other members, besides tube style structures may be used). When the pin is withdrawn from the hole, the second (inner) tube may be adjusted relative to the first (outer) tube (e.g. to raise or lower the seat  18  or the handlebars  20 ). 
     As shown, the pin tube  204  is fixed in a corresponding opening in the first tube. The pin tube defines a pin aperture  208 , which is a channel through which the pin  202  traverses between an engaged (clamped) position and a disengaged (release) position. The pin tube includes a flange  210  to which a pivot bracket and housing  212  is mounted. The housing supports many of the functional components of the pop-pin. The housing may further include a cover  213 , within which are many of the various functional components of the assembly. 
     The pin includes a collar  214  defining a bore  217 . As shown, the pin portion  202  extends into one of the apertures  206  in the tube fixing the relative movement between the tubes. It should be noted that the pop-pin assembly, or more generally engagement assembly, is discussed with respect to a pin that engages an aperture. It is possible, however, that the shaft may support some other form of structure such as a flat face or a roughened face that presses on the inner tube to form a resistance fit, or presses on and depresses a ball detent or other structure in the tube. Hence, the shaft creates the engagement between the tubes, and the description of a pin is but one way. Nonetheless, referring again to the pin, an outward face  219  of the collar  214  abuts the tube circumferentially around the pinned aperture  206 A. As will be discussed in more detail below, when the pop-pin is engaged, the outward face of the pin collar presses on the tube, and depending on the arrangement, will tightly couple the first tube to the second tube by pressing the second tube (e.g., seat post or handlebar stem) against the wall opposing the wall to which the pin tube is attached thereby tightening the tubes to reduce or eliminate any sloppiness or looseness between the tubes. 
     An adjustment shaft  216  is connected to the pin at the bore  217 . In one example, the adjustment shaft is connected to the pin with a retaining pin  218  that extends through an aperture in the pin collar and an aligned aperture in the adjustment shaft. Alternatively, one or a pair of spring-loaded ball detents may be defined in the adjustment shaft whereby the ball portion couples the adjustment shaft to the apertures in the pin collar. In yet another alternative, a retaining pin may be threaded and engage a corresponding threaded bore in the adjustment shaft. Regardless of the mechanism, however, the threaded shaft is coupled with the pin. 
     Distal the pin, an adjustment knob  220  is coupled with the shaft  216 . Between the knob and the pin, the adjustment shaft defines a threaded portion  222  that engages a corresponding threaded bore  224  defined in a drive shaft  226 . The adjustment shaft is translationally and rotatably supported in a smooth bore portion  228  of the drive shaft. By rotating the knob, the adjustment shaft rotates and through the interaction between the treads and threaded bore, finely adjusts the position of the adjustment shaft and pin relative to the drive shaft  226 . 
     The drive shaft  226  is translationally supported in a guide passage  230  defined or otherwise provided in the housing. The clamp lever  200  is coupled to the drive shaft at a cam roller  232 . In one example, the cam roller extends from the drive shaft, through a slot  234  in the guide passage, and is supported in a cam slot  236  defined in or otherwise provided with the clamp lever. In the particular implementation shown, the drive shaft includes a pair of cam rollers ( 232 A,  232 B) extending from opposing sides of the drive shaft, and through opposing slots ( 234 A,  234 B) in the guide passage. Similarly, the clamp lever defines opposing cam slots ( 236 A,  236 B) defined in opposing ears ( 238 A,  238 B) extending from a handle portion of the lever. The lever is pivotally coupled with the housing at a pivot axle  240 . Generally speaking, pivoting of the lever causes the cam slot to extend the drive shaft to engage the pin or to retract the drive shaft to disengage the pin from a hole  206 . 
     Referring again to the adjustment shaft, a first spring  242 , which may be a coil spring, is positioned between the tolerance adjustment knob  220  and the drive shaft. The first spring provides a force between the drive shaft and the knob to put pressure on the knob to hold it in place. The knob  220  includes a collar  244  that traps the adjustment knob and the attached adjustment shaft in the guide passage  230 . 
     At an end of the drive shaft  226  proximate the pin collar  214 , a second spring  246  is positioned between a spring collar  248  of the drive shaft and the housing  212 . More specifically, the housing includes a countersunk hole  250 , which may be a bore, formed, molded, etc., depending on the structure of the housing, sufficient to receive the collar  248  and a portion of the pin tube  204  extending from flange  210 . The guide passage, defined in one example as a cylinder smaller than the countersunk hole, is within the countersunk hole. The second spring may be a coil spring surrounding the guide shaft, and abutting the wall of the hole surrounding the guide passage. The second spring forces the pin into the hole by driving the drive shaft outward. This ensures that the pin engages firmly even if the lever is not fully clamped (pushed inward toward the tubes). 
     Referring now to operation of the device and fine adjustment, rotating the adjustment shaft changes the position of the pin  202  relative to the drive shaft  226  thereby finely adjusting the amount of coupling force the pin collar places between the tubes. Typically, a stem (or second tube) fits within a tube (or first tube) with some amount of space between the wall (in the case of circular tubes) or walls (in the case of rectangular, trapezoidal or square tubes). Thus, even if pinned, the stem may be loose within the seat tube unless one or more walls of the tubes are pressed together to frictionally couple the tubes. In the case of the tubes illustrated herein, the pin collar  214  presses the stem (e.g. stem  24 ) rearward so that a rear wall of the stem abuts a rear wall of the tube (e.g. seat tube  22 ). Since the spacing between tubes may vary and the dimensions may vary, having a fixed translational movement of the drive shaft would not cause the correct amount of inter tube coupling unless the space was precisely matched to the gaps. To alleviate this concern, the pop-pin  26  is provided with a fine adjustment to change the pin position relative to the drive shaft. Retracting the adjustment shaft compensates for a relative smaller gap between tubes and extending the adjustment shaft compensates for a relatively larger gap between the tubes. So, for example, if rotating the lever moves the drive shaft a fixed distance from a retracted position to an extended position, and the stem is loose relative to the seat tube, then the user can retract the pin, turn the adjustment knob to extend the pin relative to the guide shaft until a tight coupling between the stem and tube is achieved. Conversely, if the user cannot rotate the lever fully to engage the pin, then the user can rotate the knob to retract the pin relative to the guide shaft until a tight coupling between the stem and tube is achieved. Once the pin is properly adjusted, further adjustments should not be required. An O-ring  252 , or other compliant (flexible or resilient) material or structure may also be included around the pin at the collar to help seat the pin against the tube. 
     Actuating the properly adjusted pin, involves pivoting the clamp lever. The cam slots each define an asymmetric curved slot  236  with a first end  254  and a second end  256 . The first, upper, end defines a fully withdrawn position of the drive shaft. The second, lower, end defines a fully extended position of the drive shaft. Since the cam roller  232  is trapped in the slot, rotating the lever and the cam slot cause the cam roller and drive shaft to move between the fully extended and withdrawn positions. 
       FIG. 18A  illustrates the pop pin in a neutral position,  FIG. 18B  illustrates the pop pin in a clamped (engaged or over-center) position, and  FIG. 18C  illustrates the pop pin in a release (or unengaged). In the unengaged position, the stem (or inner tube) may be moved relative to the outer tube (e.g., the seat may be raised or lowered). As shown, in the unengaged position, the lever is pivoted away from the tubes and the pin and drive shaft are withdrawn. When the tubes are adjusted, the user may release the lever, and the spring  246  will push the drive shaft outward along with the pin. When the pin is aligned with a hole, the spring force will cause the pin to push into the hole as shown in  FIG. 18A . To then clamp the tubes together, the user may push the lever arm toward the tubes forcing the collar against the inner tube wall and causing it to abut the adjacent wall of the outer tube thereby clamping the tubes together to eliminate or substantially reduce wobble or any slop between the tubes. When the pin is properly adjusted relative to the shaft, the user will apply a force sufficient to push the inner tube rearward and the cam roller will move along the cam slot until it is positioned in the most downward portion of the cam slot (or most upward if the cam slot, handle orientation were reversed—handle oriented upward). If the collar includes an O-ring, the compression of the O-ring when the lever is fully engaged helps set the pin and the lever in the fully engaged position, and assist the cam roller in going over center in the cam slot. The center position is proximate the fully extended (locking position) but not at the end of the slot end. The center position is illustrated in  FIG. 14 , where the arc of the cam pushes the cam roller the furthest forward compressing the O-ring. Stated differently, in the center position, the pin may be tightly pressed against the inner tube wall and pressing it tightly against the outer tube such that the O-ring is compressed. When the lever is fully in the engaged (locking or over-center) position, the compression of the O-ring is relaxed slightly while the pin maintains the tight clamping of the tubes. In the over-center position, the cam slot pushes the drive shaft slightly less forward relative to the center position. The over-center position prohibits the spring force on the drive shaft from back-driving the drive shaft. Thus, a user must pull the lever to remove the drive shaft. 
     In place of a cam follower arrangement as discussed above, a link or links may be placed between the lever and the drive shaft.  FIG. 20A  is a side view of a pop-pin assembly in a locked (over-center) engaged position and  FIG. 20B  is a side view of the pop-pin assembly in the unlocked (disengaged) position. Many of the components are the same or similar to the embodiments discussed above with the exception of the over-center linkage. As shown, a link  300  is coupled between the lever  302  and the drive shaft  304 . More specifically, the lever includes a link pivot or axle  306  proximate a lever axle  308 . The link pivot is positioned on an ear  310  extending forwardly from the lever. In a position like the cam roller, a second link pivot  312  is connected with the drive shaft  304 . The pivot may extend through a slot  316  in a fashion similar to the cam roller. 
     In the disengaged position, the link is aligned with the drive shaft. Pressing forward (toward the members), places a forward and upward force on the link, which force translates to pushing the drive shaft (and pin) forwardly to engage the pin. As the lever is pushed forward (against the spring force on the drive shaft), the link pivots upwardly and through a path defined by the path of the link pivot  306  in an arc about the lever axle  308 . The center position, which may also compress an O-ring or other resilient member of the pin or other member pressing on the tubes, is where the three axles ( 306 ,  308  and  312 ) align as shown in  FIG. 20B . A lever stop  318  is positioned to allow the lever to rotate slightly past the alignment (over center orientation), which takes a slight amount of force off the pin but keeps the members locked together. Additionally, by going over center, the over-center linkage prohibits the spring force from back-driving the drive shaft. As with the cam follower embodiment, a user must pull the lever to remove the shaft and disengage the pop-pin. 
     Although various representative embodiments of this disclosure have been described above with a certain degree of particularity, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of the inventive subject matter set forth in the specification. All directional references (e.g., upper, lower, upward, downward, left, right, leftward, rightward, top, bottom, above, below, vertical, horizontal, clockwise, and counterclockwise) are only used for identification purposes to aid the reader&#39;s understanding of the embodiments and do not create limitations, particularly as to the position, orientation, or use of the disclosure unless specifically set forth in the claims. Joinder references (e.g., attached, coupled, connected, and the like) are to be construed broadly and may include intermediate members between a connection of elements and relative movement between elements. As such, joinder references do not necessarily infer that two elements are directly connected and in fixed relation to each other. 
     In some instances, components are described with reference to “ends” having a particular characteristic and/or being connected to another part. However, those skilled in the art will recognize that the present disclosure is not limited to components which terminate immediately beyond their points of connection with other parts. Thus, the term “end” should be interpreted broadly, in a manner that includes areas adjacent, rearward, forward of, or otherwise near the terminus of a particular element, link, component, member or the like. In methodologies directly or indirectly set forth herein, various steps and operations are described in one possible order of operation, but those skilled in the art will recognize that steps and operations may be rearranged, replaced, or eliminated without necessarily departing from the spirit and scope of the present invention. It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting. Changes in detail or structure may be made without departing from the spirit of the invention as defined in the appended claims.