Abstract:
An adjustable height seat post for bicycles that comprises an inner tube slidably contained within an outer tube which supports a bicycle seat. The outer tube clamps into a bicycle frame and contains a spring which acts to force the inner tube upward. The inner tube is allowed longitudinal movement within the fixed outer tube via a locking mechanism that forces ball bearings into pockets or channels on the inner tube. The locking mechanism can be remotely activated with a handlebar mounted lever or manually with a seat post mounted lever.

Description:
FEDERALLY SPONSORED RESEARCH 
     Not Applicable 
     SEQUENCE LISTING OF PROGRAM 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a multi-position adjustable height seat post, specifically a tube within a tube that allows for the adjustment of seat height to multiple positions while riding a bicycle. 
     2. Description of the Prior Art 
     Cyclists, specifically those involved in mountain biking, find that it is beneficial to have a variety of seat height options while riding a bicycle. Seat height options are desired because they afford the rider greater control of the bicycle over widely varying terrain. 
     Riders descending steep or difficult terrain will benefit from a much lower seat height, thus allowing them to lower their center of gravity increasing their control over the bicycle. While riding on less difficult terrain a rider may want to only slightly lower their seat height for improved cornering, yet still maintain near full leg extension for good power transfer. Riding flat terrain or climbing the rider will want the seat at a ride height so as to obtain near full leg extension while remaining seated for optimal power transfer to the pedals. 
     Other seat posts have been proposed that allow the user to adjust the height of the seat to multiple positions while riding. The typical form exhibited by these seat posts is a tube within a tube with some form of locking mechanism. The outer tube mounts into a bicycle frame, while the inner tube inserts into the outer tube and carries a mount for the seat. The locking mechanisms come in many forms. There are two notable examples currently on the market. The first type, the Gravity Dropper seat post (U.S. Pat. No. 7,025,522 B2), uses a pin type mechanism wherein a pin from the outer tube is used to support the inner tube in multiple positions. The second type, the Speedball seat post by Maverick, is a pneumatically operated tube within a tube allowing infinite adjustability from 0 to 3 inches. 
     While both of these seat posts perform there intended duties we believe they have their shortcomings. In the case of the Gravity Dropper seat post a number of disadvantages are present:
         (a) spring force acting on the inner tube exerts tremendous pressure on the locking pin causing it to become stuck in the inner tube, not allowing the inner tube to release from the outer tube. The rider has to place pressure on the inner tube opposite that of the spring force to release to pin from the inner post. This action creates unnecessary rider movement thus a loss of momentum and power transfer to the pedals.   (b) another issue associated with the Gravity Dropper is that the hole drilled in the inner tube to accept the locking pin of the locking mechanism creates a stress riser which can lead to a failure of the inner tube.   (c) another issue is manual adjustment of rotational and for-aft play with the use of a crimp nut. This adjustment requires the user to be mechanical inclined or requires the service of a mechanic at a local bicycle shop.
 
In the case of the Speedball seat post a number of disadvantages are present:
   (a) seat height adjustment and immobilization is obtained with the use of pneumatic force. Containing the pressure required to operate the pneumatics of the seat post requires the use of seals which may leak causing the failure of the locking mechanism.   (b) the seat post is also limited to larger diameter bicycle seat tubes of 30.9 mm or greater. This large diameter is greater than the most common size seat tube of 27.2 mm in diameter, therefore the Speedball is not available to most of the bicycle market.   (c) the seat post offer no means to adjust rotational or for-aft play as it becomes worn with use.       

     OBJECTS AND ADVANTAGES 
     Accordingly, several objects and advantages of the present invention are: 
     
         
         
           
             (a) to provide a multi-position adjustable height seat post with a locking mechanism that controllably releases irrespective of spring forces exerted upon the inner post; 
             (b) to provide a multi-position adjustable height seat post wherein the locking mechanism does not create a weak point within the inner or outer tube; 
             (c) to provide a multi-position adjustable height seat post that relies solely on mechanical actuation and hence requires no seals; 
             (d) to provide a multi-position adjustable height seat post that is of a diameter as to be compatible with the majority of bicycle frames 
             (e) to provide a multi-position adjustable height seat post that self adjusts with respect to rotational and for-aft movement. 
             (f) to provide a multi-position adjustable height seat post that requires a minimal amount of user maintenance to remain operational. 
           
         
       
    
     Further objects and advantages are to provide a multi-position adjustable height seat post that is simple to operate, easy to maintain, light weight, and very robust. Still further objects and advantages will become apparent from a consideration of the ensuing description and drawings. 
     SUMMARY OF THE INVENTION 
     The invention provides for a multi-position adjustable height bicycle seat post assembly comprising an inner tube slidably supported within an outer tube. The outer tube at a diameter so as to be received in the seat tube of a bicycle. The inner tube is adjustable, moving freely within the outer tube when not in a locked position. The direction of movement is based upon rider input. Either downward via rider weight or upward via spring force. The outer tube accommodates a locking assembly consisting of ball bearings, a lock ring, a compression lever, a spring, and an upper and lower retaining unit. The locking mechanism works by forcing ball bearings via the lock ring into corresponding pockets on the inner tube through holes in the outer tube. The inner tube can have multiple positions of height adjustability depending on the number of pockets provided in the inner tube. The lock ring is cut with a steep angle at its top portion transitioning to a shallower angle below the steep angle. In the locked position the lock ring is forced upwards onto its shallow angle via spring force which holds the ball bearings in the corresponding pockets within the inner tube. This shallow angle along with constant spring force on the lock ring allows the locking mechanism to self adjust along the shallow angle of the lock ring as the seat post wears into its working position. Unlocking the mechanism consists of forcing the lock ring off its shallow angle position, past its steep angled position, and onto an upper zero angled position. This allows the ball bearings clearance to exit the pockets of the inner tube so that the inner tube moves freely within the outer tube. 
     Secondarily, the ball bearings are used to keep the inner post from twisting side to side as it travels longitudinally from position to position. This is done by forcing the ball bearings to track within channels of the inner tube. The channels run vertically from pocket to pocket along the inner tube. The inner tube is under constant force from a spring contained within the outer tube acting to extend the inner tube to its most extended position. 
    
    
     
       DRAWINGS 
         FIG. 1   a  is an exploded view of the adjustable height seat post; 
         FIG. 1   b  is an exploded close up view of the remotely operated locking mechanism; 
         FIG. 2  is an exploded close up view of the manually operated locking mechanism; 
         FIG. 3   a  is top down side view of the lock ring; 
         FIG. 3   b  is a cross sectional view of the lock ring; 
         FIG. 4   a  is a cross sectional view of the locking mechanism in locked position. 
         FIG. 4   b  is a cross sectional view of the locking mechanism in unlocked position. 
     
    
    
     DRAWINGS 
     Reference Numerals 
     
       
         
               
               
               
               
             
           
               
                   
               
             
             
               
                 102 
                 outer tube 
                 104 
                 inner tube 
               
               
                 106 
                 pocket 
                 108 
                 channel 
               
               
                 110 
                 hole 
                 112 
                 ball bearing 
               
               
                 114 
                 lock ring 
                 116 
                 compression lever 
               
               
                 118 
                 wave spring 
                 120 
                 lower retention ring 
               
               
                 122 
                 C-clip 
                 124 
                 top clamp 
               
               
                 126 
                 bottom clamp 
                 128 
                 bolt rod 
               
               
                 130 
                 retaining bolts 
                 132  
                 retaining nuts 
               
               
                 134 
                 compression spring 
                 136 
                 retention plug 
               
               
                 137 
                 catch cable 
                 138 
                 snap ring 
               
               
                 202 
                 manual compression lever 
                 204 
                 manual retention ring 
               
               
                 302 
                 lower zero degree angle 
                 304 
                 five degree angle 
               
               
                 306 
                 forty-five degree angle 
                 308 
                 upper zero degree angle 
               
               
                 402 
                 actuation lever 
                 404 
                 actuation cable housing 
               
               
                 406 
                 actuation cable 
               
               
                   
               
             
          
         
       
     
     DETAILED DESCRIPTION 
     Referring to the figures wherein like numerals represent like parts throughout several views. 
     Referring to  FIGS. 1   a  and  2 , the seat post assembly consists of a hollow inner tube  104  inserted slidably into a hollow outer tube  102 , a compression spring  134  working to extend the inner tube  104  within the outer tube  102 , and a locking mechanism. The locking mechanism, shown close up in  FIG. 1   b  and cut away in  FIGS. 4   a  and  4   b , works to lock the inner tube  104  with respect to the outer tube  102  at a plurality of longitudinal positions. The locking mechanism can be operated by various means to unlock or lock the inner tube  104 . There are two representative models of the locking mechanism assemblies. The first is a cable actuated assembly shown in  FIGS. 1   a  and  1   b , which is operated remotely via an actuation lever  402  and the second is a manually actuated lever assembly shown in  FIG. 2 . Their construction and operation will be described in detail below. 
     Preferably, the inner and outer tubes  104 ,  102  are fabricated of a lightweight metal that is resistant to corrosion and mechanical deformation. The preferred material for the inner and outer tubes  104 ,  102  is aluminum that has been hard anodized. However, any material that is capable of withstanding the stresses associated with this invention could be substituted, such as carbon fiber, all types of steel, titanium, etc. 
     Referring to  FIGS. 1   a  and  2 , the outer tube  102  is configured at its lower end to be received by a standard seat tube receptacle of a bicycle frame in the same manner as a standard bicycle seat post. The upper end of the outer tube  102  is configured to accept the lower end of the inner tube  104 . The upper end of the inner tube  104  is fitted with mounting hardware  124 - 132  suitable to accept a bicycle seat and the weight of a bicycle rider. The mounting hardware consists of a top clamp  124 , a bottom clamp  126 , a bolt rod  128 , retaining bolts  130 , and retaining nuts  132 . As shown in  FIGS. 1   a ,  1   b ,  2   4   a , and  4   b , ball bearings  112  preferably, but not limited to, one-hundred-fifty-six thousandths of an inch in diameter, and consisting of, but not limited to, stainless steel are inserted into the outer tube  102 . The current preferable number of ball bearings  112  is four, however any number of ball bearings  112  could be used. The ball bearings  112  protrude inward through holes  110  in the outer tube  102  contacting the inner tube  104  in either a plurality of pockets  106  or a plurality of channels  108 . The currently preferred number of pockets  106  is four. However, there are various possibilities with regards to the number of pockets  106  within the inner tube  104 . The currently preferred number of pocket  106  positions along the vertical axis of the inner tube  104  are three. However, there are various possibilities with regards to the number of pocket  106  positions within the inner tube  104 . The currently preferred position of pockets  106  are at zero, one and three inches along the vertical axis of the inner tube  104 . However, there are various possibilities with regards to the position of pockets  106  within the inner tube  104 . The currently preferable number of channels  108  within the inner tube  104  are four. However, there are various possibilities with regards to the number of channels  108  within the inner tube  104 . The currently preferred orientation of the channels is vertical along the axis of the inner tube  104  from pocket  106  to pocket  106 . However, there are various possibilities with regards to the orientation of channels  108  within the inner tube  104 . The balls bearings  112  are used both as guides, tracking along vertical channels  108  within the inner tube  104 , and as locking elements when forced into pockets  106  on the inner tube  104 . As guides, the ball bearings  112  track from pocket  106  to pocket  106  along the channels of the inner tube  104  preventing rotational movement of the inner tube 
       104  with respect to the outer tube  102 . The ball bearings  112  along with a catch cable  137  limit the outward movement of the inner tube  104  preventing complete separation of the inner tube  104  from the outer tube  102 . A retention plug  136 , held in place by snap rings  138  is used to contain a compression spring  134  within the outer tube  102 . The compression spring  134  acts with constant spring force upon the inner tube  104  to extend the inner post  104  longitudinally outward of the outer post  102  to its fully extended position. 
     The locking assembly shown in  FIGS. 1   a ,  1   b ,  2 ,  4   a  and  4   b  with close ups of the lock ring  114  in  FIGS. 3   a  and  3   b  mounts externally to the outer tube  102 . The locking assembly comprises an upper retention C-clip  122 , a compression lever  116 , a lock ring  114 , ball bearings  112 , a wave spring  118 , and a lower retention ring  120 . The locking assembly acts to lock or release the inner tube  104  with respect to the outer tube  102  by forcing or releasing ball bearings  112  into or out of pockets  106  on the inner tube  104  through holes  110  on the outer tube  102 . Outward radial movement of the ball bearings  112  is either permitted or not permitted by the longitudinal position of the lock ring  114  along the axis of the outer tube  102  with respect to pockets  106  in the inner tube  104 . A central component to the locking assembly is the lock ring  114  which consists of a material compatible with the outer tube  102  such as, but not limited to, stainless steel. The inner side of the lock ring  114  consists of, but is not limited to, four angles that act upon the ball bearings  112  outer tube  102 . Starting from the lower end of the lock ring  114  the angles are, but are not limited to, a lower zero  302 , five  304 , forty-five  306 , and an upper zero  308 . 
     Any of the lock ring angles mentioned above can be altered and still perform a similar function, however these angles are currently preferred. At the lower most end or bottom of the lock ring  114  the lower zero degree angle  302  is machined a diameter a few thousands of an inch over that of the outer tube  102 , and to a length of one-hundred-forty-five thousandths of an inch. However, many different lower zero degree angle  302  lengths are possible to achieve the desired objective. The lower zero degree angle  302  creates a contact point for the lock ring  114  on the outer tube  102  while remaining slidable. The second position up from the bottom of the lock ring  114  is the five degree angle  304 ; the locked position. The five degree angle  304  begins at the upper end of the lower zero degree angle  302  and angles outward in relation to the outer tube  102 . In the locked position the lock ring  114  makes contact with the ball bearings  112  on its five degree angle  304 . The five degree angle  304  forces ball bearings  112  into pockets  106  of the inner tube  104  through holes  110  of the outer tube  102 . This locks the inner tube  104  with respect the outer tube  102 . In the locked position a portion of the ball bearings  112  reside both in the pockets  106  of the inner tube  104  and in the holes  110  of the outer tube  102 , while minimally protruding out of the holes  110  of the outer tube  102  to contact the lock ring  114  at its five degree angle  304 . The length of the five degree angle  304  is currently preferred to be one-hundred-fifty thousandths of an inch, however many different five degree angle  304  lengths are possible to achieve the desired objective. The length of the five degree angle  304  enables the lock ring  114  to self-adjust as the pockets  106  and ball bearings  112  wear with use. 
     The self-adjustment minimizes rotational and for-aft play or movement of the inner tube  104  with respect to the outer tube  102 . Beginning at the upper edge of the five degree angle  304  is a forty-five degree angle  306  which is outwardly angled with respect to the outer tube  102 . The forty-five degree angle  306  is currently preferred at forty thousandths of an inch, however many different forty-five degree angle  306  lengths are possible to achieve the desired objective. The forty-five degree angle  306  transitions the lock ring  114  from its five degree angle  304  to its upper zero degree angle  308 , the unlocked position. The forty-five degree angle  306  allows the ball bearings  112  to transition smoothly from the five degree angle  304  to the upper zero degree angle  308 , and vice versa. The currently preferred length of the upper zero degree angle  308  is one-hundred-ten thousandths of an inch, however many different upper zero degree angle  308  lengths are possible to achieve the desired objective. The upper zero degree angle  308  allows the ball bearings  112  clearance to radially exit the pockets  106  of the inner tube  104 , however not allowing sufficient clearance to exit the channels  108  of the inner tube  104 . In the unlocked position a portion of the ball bearings  112  reside both in the channels  108  of the inner tube  104  and the holes  110  of the outer tube  102 , while protruding out of the holes  110  of the outer tube  102  to contact the lock ring  114  at its upper zero degree angle  308 . In the upper zero angle  308  position the inner tube  104  is free to move longitudinally within the outer tube  102 . A wave spring  118 , preloaded by a lower retention ring  120 , act with constant upward vertical spring force on the bottom of the lock ring  114 . The upward force placed on the lock ring  114  acts to maintain the lock ring in its five degree angle  304  position. 
     Hence, the resting state of the locking assembly is a locked position. To achieve an unlocked state actuation is required. 
     Actuation of the locking assembly is done one of two ways, either remotely,  FIGS. 1   a  and  1   b  or manually,  FIG. 2 . 
     Remote operation of the locking assembly is done with, but not limited to, an actuation lever  402 . The actuation lever  402  is connected to the locking assembly via a standard actuation cable housing  404  and an actuation cable  406 . The lower retention ring  120  has a tab that receives the actuation cable  406  and actuation cable housing  404  from the actuation lever  402 . The actuation cable housing  404  in turn supports the actuation cable  406  which is connected to the compression lever  116  on one end and the actuation lever  402  at the other end. Actuation of the actuation lever  402  works to pull the compression lever  116  downward, hence forcing the lock ring  114  downward. The downward actuation of the lock ring  114  counteracts the upward force exerted by the wave spring  118  on the lock ring  114 , forcing the lock ring  114  into the unlocked position. This allows the ball bearings  112  to exit the pockets  106  of the inner tube  104  allowing the inner tube  104  to move longitudinally within the outer tube  102 . Upon release of pressure from the actuation lever  402  the compression lever  116  relaxes downward force on the lock ring  114  and the wave spring  118  forces the lock ring  114  upward into the locked position. This forces the ball bearings.  112  into the pockets  106  of the inner tube  104  immobilizing or locking it within the outer tube  102 . 
     In the manual locking assembly shown in  FIG. 2  manually actuating the manual compression lever  202  downward forces the lock ring  114  downward. This counteracts the upward force exerted by the wave spring  118  which is preloaded with a manual retention ring  204 , unlocking the locking assembly. The ball bearings  112  exit the pockets  106  of the inner tube  104  allowing the inner tube  104  to move longitudinally within the outer tube  102 . Upon release of the manual compression lever  202  the lock ring  114  is forced upward via the spring force of the wave spring  118  thereby forcing the ball bearings into the pockets  106  of the inner tube  104  immobilizing or locking it within the outer tube  102 . 
     Although the description above contains many specifications, these should not be construed as limiting the scope of the embodiment but as merely providing illustrations of some of the presently preferred embodiments. For example, the lock ring  114  can have other angles that act upon the ball bearings  112  and still provide a similar function, the wave spring  118  can be replaced with a compression spring, etc. 
     Thus the scope of the embodiment should be determined by the appended claims and their legal equivalents, rather than by the examples given.