Abstract:
A bicycle stern has a steering tube clamp with a bore for receiving a steer tube and a pair of parallel spaced arms each having an elongate slot at a distal end. An extension has a proximal end, receivable between the clamp arms, and a bore extending transversely through its proximal end. A pin, extends through the elongate slot in each arm and through the bore in the extension for securing the extension to the steering rube clamp. The pin slots and bore are in non-rotational engagement to prevent rotation of the extension relative to the clamp, and the pin is selectively movable longitudinally within the slots for adjusting reach of the extension.

Description:
FIELD OF THE INVENTION 
       [0001]    The current invention relates to bicycles and in particular o an adjustable stem for a bicycle. 
       BACKGROUND TO THE INVENTION 
       [0002]    A bicycle frame and components are adjustable to fit a particular rider. The bicycle seat height can be adjusted for the correct pedaling geometry of the rider. The rider&#39;s reach from the seat to the handlebars is important for the correct riding position, balance and steering/bicycle control. Reach can be adjusted via the length of the stem connecting the handlebars to the steering tube. It is desirable for the stem to be easily or readily adjustable for setting the correct riding position in combination with the seat height. 
       SUMMARY OF THE INVENTION 
       [0003]    According to a first aspect of the invention there is provided a bicycle stem comprising a steering tube clamp, the steering tube claim having a bore for receiving a steer tube and a pair of parallel spaced arms, each arm having an elongate slot at a distal end, an extension having a proximal end receivable between the arms and a bore extending transversely through the proximal end, and a pin which in use extends through the elongate slot in each arm and through the bore in the extension for securing the extension to the steering tube clamp, the pin slots and bore being in non-rotational engagement to prevent in use rotation of the extension relative to the clamp, and the pin being selectively movable longitudinally within the slots for adjusting a reach of the extension. 
         [0004]    Preferably the bicycle stem further includes a pair of interchangeable spacer disks each having an aperture, the spacer disks cooperating with respective arms and the pin for selectively locating the pin at a longitudinal position within the slots. 
         [0005]    Preferably the spacer disks are removably received within recesses of respective arms. 
         [0006]    Preferably the pin includes a pin sleeve about the pin, the pin sleeve being in the non-rotational engagement with the slots and bore and selectively movable longitudinally within the slots. 
         [0007]    Preferably the slots and bore have an inner non-circular shape, and the pin sleeve has an outer non-circular shape for non-rotational engagement with the slots and bore. 
         [0008]    Preferably the non-circular shape is square. 
         [0009]    Preferably the pin sleeve has a circular aperture and the pin is circular for engagement through the pin sleeve. 
         [0010]    Preferably the bicycle stem further includes an extension sleeve removably received in the bore, the extension sleeve have an aperture for receiving the pin though the extension sleeve within the bore. 
         [0011]    Preferably the extension sleeve and bore are splined for engagement of the extension sleeve and bore at one of a plurality of rotational positions. 
         [0012]    Preferably the bicycle stem includes a set of two or more pairs of spacer disks, each pair of spacer disks within the set having apertures at different locations, the pairs of spacer disks in the set being interchangeable for selectively locating the pin at different longitudinal positions within the slots. 
         [0013]    According to a second aspect of the invention there is provided a bicycle stem comprising a steering tube clamp, the steering tube claim having a bore for receiving a steer tube and a pair of parallel spaced arms, each arm having an elongate slot at a distal end, an extension having a proximal end receivable between the arms and a bore extending transversely through the proximal end, and a pin which in use extends through the elongate slot in each arm and through the bore in the extension for securing the extension to the steering tube clamp, the pin slots and bore being in non-rotational engagement to prevent in use rotation of the extension relative to the clamp, and the pin being selectively movable longitudinally within the slots for adjusting a reach of the extension, and a set of two or more pairs of spacer disks, each pair of spacer disks within the set having apertures at different locations, the pairs of spacer disks in the set interchangeably cooperating with respective arms and the pin for selectively locating the pin at different longitudinal positions within the slots. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The invention will be described with reference to the accompanying drawings in which: 
           [0015]      FIG. 1  is a schematic illustration of a bicycle frame including a stem according to the invention. 
           [0016]      FIG. 2  is an exploded schematic illustration of stem, 
           [0017]      FIG. 3  is a first schematic illustration of the bicycle frame head set and stem in a shorter reach configuration. 
           [0018]      FIG. 4  is a second schematic illustration of the bicycle frame head set and stem in an intermediate reach configuration, and 
           [0019]      FIG. 5  is a third schematic illustration of the bicycle frame head set and stem in a longer reach configuration. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0020]    Referring to the drawings bear is shown a bicycle frame  1  with a bicycle stem  20  according to the invention. The bicycle frame  1  comprises a top tube  2  and down tube  3  connected by a head tube  4  and seat tube  5  in known manner. A bottom bracket  8  is located at the junction of the seat tube  5  and down tube  3 . Extending rearwardly of the bottom bracket  8  to the rear dropout  12  is a chain stay  7 . A seat stay  6  extends from the rear dropout  12  upwardly at an angle towards and upper end of the seat tube  5 . A steering tube  11  extends through the head tube  4  and connects to forks  9  axially below the head tube  4 . The forks  9  and steering tube  11  are held in places by a head set  10  engaged about the steering tube  11  above the head tube  4 . A stem  20  is located about the steering tube  11  above the head set and extends forwardly to a distal end  21  to which is connected a bicycle handlebar (not shown). Also not shown in the drawings are a seat post and seat which are telescopically received in the top end  13  of the seat tube  5 , a crank and sprocket/chain set which is engage with the bottom bracket  8  and wheels rotatably connect at the rear dropout  12  and front dropout  14 . The rear wheel is drove from the crank by a chain and sprocket set as is known in the art. 
         [0021]    In order to adjust the optimal fit extension for the rider the seat height can be adjusted by telescopically moving the seat post within the seat tube  5  to adjust the seat height. The height and reach of the handlebars is adjustable via the stem  20 . The stem  20  comprises a steering tube  11  clamp portion and an extension portion  23 . The extension portion  23  is connected with the clamp portion  22  such that the extension portion  23  may be moved pivotally up and down about a connection axis  24  as well as permitting movement of the connection axis longitudinally in a direction A for adjusting the reach of the stem  20 . The clamp portion  22  has a circular bore extending about the steering tube  11 . The height of the stem  20  can be adjusted by moving the clamping portion of the stem  20  up or down the steering tube  11 . When the correct height is reached the clamp portion  22  is secured to the steering tube  11  by fixing means in the form of clamp bolts  25 . 
         [0022]    Turning to  FIG. 2 , which is an exploded diagram of the stem  20 , the internal part of the stem  20  can be seen. The clamp portion  22  of the stem has a pair of forwardly extending parallel arms  25 A and  25 B. The arms  25 A,  25 B are spaced apart and parallel to each other and define a receiving space  26  between the arms  25 A,  25 B. Each arm is provided with an elongate slot  27 A,  27 B respectively which extends from the distal  28  of the arm  25  towards the body  22 A of the clamp  22 . The outer surface of each arm  25  includes a recessed portion  29  that is larger than and encompasses the elongate slot  28 . The elongate slot  28  is provided with a square ends and thus is in the shape of a rectangular elongate slot  28 . A square shaped pin sleeve  30  extends thought the elongate slots  28  between the pair of arms  25  bridging the receiving space  26 . At either end the pin sleeve  30  is received within the elongate slot  28  of the respective arms  25 . The pin sleeve  30  can slide longitudinally within each slot from a position proximately the distal end  28  of the arms  25  towards the body of the clamp portion  22  (that is to say towards and away from the steering tube  11 ). 
         [0023]    The pin sleeve  30  has an aperture  31  passing through it from end to end. A pair of spacer disks  32 A,  32 B is provided for location within respective recesses  29  on the outer surface of the arms  25 . The spacer disks  32 A,  32 B have a corresponding apertures  33 A,  33 B that alien with each other and with aperture  31  of the pin sleeve  30  when the spacer disks are located within the recesses  29 . A pin  34  passes through a first one of the spacer disks, through the aperture  31  in the pin sleeve  30  and to the aperture  33  in the second opposite one of the pair of spacer disks  32 . The pin  34  may be in the form of a bolt having a smooth shank portion  35  which locates within aperture  31  of pin sleeve  30  and a threaded engagement portion  36  at one and which threadably engages within a first one of the apertures, i.e.  33 A, in one of the pair of spacer disks  32 . The opposite end of the pin  34  might have a bolt head  37  of a countersunk type that locates within a countersunk recess  38  of the second one of the pair of spacer disks, i.e.  32 B. The spacer disks  32 A,  32 B via. the position of the apertures  33 A,  33 B in the disks set the longitudinal position of the pin  34  and pin sleeve  30  within the elongate slots  27  of arms  25 . The pin  34  holds the spacer disks  32 A,  32 B and pin sleeve  30  in position. In a preferred embodiment of the invention the stem is preferably, although not exclusively, provided with a set of two or more pairs of spacer disks  32  each pair having the aperture  33  in a different longitudinal location of the disks  32  such that by interchanging the spacer disks  32  the longitudinal position of the pin  34  and pin sleeve  30  within the elongate slots  27  of arms  25  can be adjusted towards or away from the steering tube  11 . As will be evident changing the longitudinal location of the pin  34  and pin sleeve  30  in this way changes the longitudinal position of the connection axis  24  of the extension member  23  of the stem  20  and thus the reach of the stem  20  between the steering tube  11  and the distal end  21  of the extension portion  23  adjacent where the handlebar is attached. Referring to  FIG. 3  with a first pair of spacer disks  32  the pin  34  is located close to the steering tube  11  such that the stem has a short reach. Referring  FIG. 4  with a second pair of spacer disks  32  the pin  34  is located at a mid point of the elongate slots  27  so that the stem has an intermediate reach. By reversing the first pair of spacer disks of  FIG. 3  the pin can be located within the elongate slots  27  proximate distal  28  of the arms  25  providing the third long reach of the stem  20 . 
         [0024]      FIG. 3  shows a spacer disk  32  with aperture  33  at one end proximal the steering tube  11  to configure the stem in a shorter reach configuration.  FIG. 4  shows a spacer disk  32  with aperture  33  in the middle of the disk  32  to configure the stem in an intermediate reach configuration.  FIG. 5  shows a spacer disk  32  with aperture  33  at one end arranged furtherest from the steering tube ii to configure the stem in a longer reach configuration. 
         [0025]    In the preferred embodiment an extension sleeve  39  is located within a bore  41  of the extension  23  and has a square bore  40  through which the square pin sleeve  30  locates. The extension sleeve  39  has an external diameter that is a fit within the interior diameter of the extension bore  41 . The external surface of the extension sleeve  39  and the interior surface of the extension bore  41  have cooperating engagements means for rotatably fixing the extension sleeve  39  within the extension bore  41  in one of a plurality of rotational positions. In the preferred embodiment the cooperating engagements means is splines longitudinally along the external surface of the extension sleeve  39  and corresponding splines along the interior surface of the extension bore  41 . The extension sleeve  39  can be positioned in one of a plurality of rotational rotations within the extension bore  41  relative to the square bore  40  through the extension sleeve  39 . In this way the rotational position of the extension portion  23  in connection with the clamp portion  22  can be adjusted together with the longitudinal reach of the extension portion  23 .