Abstract:
An improved, lightweight suspension fork for a bicycle with variable travel capability that maintains excellent torsional rigidity. This suspension fork allows for adjustable suspension travel adjusted at the handlebars of the bicycle. The suspension system includes a travel adjustment knob located at the handlebars of the bicycle. The travel adjustment knob is keyed with the main shaft of the suspension system so as to allow turning of the main shaft. Located on the main shaft within the suspension system housing is a length adjuster mechanism. The length adjuster moves linearly with respect to the housing as the main shaft is turned pulling the inner tube member of the suspension housing up or down relative to the outer tube section of the suspension housing, thereby changing the stroke of the suspension system.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    This application claims the benefit of provisional patent application 60/470,726 filed May 15, 2003 by the present inventors.  
         RELATED U.S. APPLICATION DATA  
         [0002]    U.S. CL . . . 280/276; 74/492; 188/271; 267/216; 280/283; 280/284; 280/777 188/319.1, 188/285  
           [0003]    Int. Cl . . . B62K 025/08  
           [0004]    Field of Search . . . 188/281; 188/266.4; 188/312; 188/315; 188/322.11; 188/313; 188/318; 188/319.1; 188/313; 188/317; 188/285; 280/276; 280/279; 280/284; 280/5.513; 280/5.501; 280/5.508; 280/5.514  
           [0005]    References Cited:  
                                                 U.S. PATENT DOCUMENTS                                6,533,459   March 2003   Podhajecki et al.   384/57       6,382,370   May 2002   Girvin   188/299.1       6,360,857   March 2002   Fox   188/281       6,328,291   December 2001   Marzocchi et al.   267/64.5       6,305,704   October 2001   Vignocchi et al.   280/279       6,505,719   January 2003   Gonzalez et al.   188/319.2       6,360,858   March 2002   Gonzalez et al.   188/319.2       6,241,060   June 2001   Gonzalez et al.   188/319.2       5,380,026   January 1995   Robinson   280/276       6,145,862   November 2000   D&#39;Aluisio et al.   280/276       6,135,477   October 2000   D&#39;Aluisio et al.   280/276       6,095,541   August 2000   Turner et al.   280/276       6,042,091   March 2000   Marzocchi et al.   267/64.15       5,634,652   June 1997   Tsai   280/276       5,449,188   September 1995   Ohma   280/276       5,346,236   September 1994   Ohma   280/276       5,320,374   June 1994   Farris et al.   280/276       5,195,766   March 1993   Dohrmann et al.   280/276       5,350,185   September 1994   Robinson   280/276       5,190,126   September 1991   Curnutt   188/269       4,815,763   March 1989   Hartmann   280/276       4,796,871   January 1989   Bauer et al.   267/64.11       4,635,909   March 1987   Gold   267/64.21       4,515,384   May 1985   Honma et al.   280/276       4,344,637   August 1982   Williams Jr. et al.   280/21 R       5,494,302   February 1996   Farris et al.   280/276       5,702,092   December 1997   Farris et al.   280/276       5,924,714   July 1999   Farris et al.   280/276       6,007,056   December 1999   Farris et al.   280/276       6,155,541   December 2000   Farris et al.   280/276       5,509,675   April 1996   Barnett   280/276       5,195,766   March 1993   Dohrmann et al.   280/276       4,971,344   November 1990   Turner   280/276       4,609,202   September 1986   Miyakushi et al.   280/276       6,604,886   August 2003   Kinzler et al.   403/370                  
 
         BACKGROUND OF THE INVENTION  
         [0006]    1. Field of the Invention  
           [0007]    The present invention relates to bicycle suspension systems and more particularly to a suspension fork assembly. This invention is improvements on current suspension systems, especially those incorporating the system first described by Farris et al. U.S. Pat. No. 5,320,374. A key objective of this invention is to achieve a longer length of travel and also to allow adjustable travel length of the bicycle suspension system using light weight components while maintaining a reasonable attitude of the bicycle.  
           [0008]    2. Description of the Prior Art  
           [0009]    Various suspension systems have been proposed and developed for bicycles. Many of these systems utilize a pair of telescoping assemblies between which the front wheel is mounted. Each assembly comprises an outer tube and an inner tube which is free to move in and out of the outer tube and is cushioned by a damper of one sort or another. The outer tubes are connected at the lower ends to the bicycle axle of the front wheel and the upper ends of the inner tube are connected together in a fashion similar to the usual upper end of a bicycle fork.  
           [0010]    As is known to those skilled in the art, these types of suspension systems use pairs of anti-friction bushings to allow free movement of the inner tube within the outer tube. These bushings, by themselves, have undesirable static friction called “stiction.” Because of this, the suspension systems using such bushings tend to stick and release. In addition, the two telescoping assemblies also have to be fixed together in some manner as through a “U” shaped yoke at the upper ends of the tubes to eliminate twisting. Even with this “U” shaped yoke the torsional stiffness of these types of assemblies is still limited. These forks are also heavy. They incorporate two sets of tubes, a yoke or other means to eliminate twisting and a steering tube designed to connect to the head tube of the bicycle frame.  
           [0011]    A prior art example of a system which overcomes stiction is shown in Farris et al. U.S. Pat No. 5,320,374 and subsequent applications. In this example an improved form of suspension system is described using an outer tube which is adapted to be mounted in and extend through the head tube of the bicycle frame and an inner tube connected to the fork of the bicycle which telescopes within the outer tube. The inner surface of the outer tube and the outer surface of the inner tube each have a plurality of axially arranged opposing longitudinal flat sections such as four on each tube. A plurality of hardened steel inner race shims are positioned longitudinally on the flats of the inner tube. A plurality of hardened steel outer race shims are positioned longitudinally on the flats of the outer tube. A plurality of needle bearings are disposed between the tubes in between the respective inner and outer race shims. This arrangement allows the two tubes to freely telescope in and out with respect to one another without any significant static friction and also serves to transmit the torsional steering force from the outer tube to the inner tube. This particular system is used extensively today because it can bear a combination of loads comprising very high radial loads and at the same time provide stable and tight rotational motion in steering of the front wheel through the suspension system from the handlebars.  
           [0012]    Bicycle riders using suspension systems continue to desire long travel suspension systems to increase plushness, They also desire lightweight systems. Many suspension forks now employ a minimum of 80 mm and the industry trend is to go to 100 mm of travel and greater. In addition, riders would like some form of adjustability to the stroke length of the front suspension systems. Riders would like to shorten the suspension system while traversing uphill so as to lower the attitude of the bicycle while climbing. Subsequently, they would like to lengthen travel once again going on a straight path or downhill to take advantage of the plushness of a longer suspension system. Riders continue to desire to adjust these features at the handlebars vs. leaning over or stopping to make suspension system adjustments.  
           [0013]    With the current needle bearing system, several problems exist to incorporate the torsional rigid features it provides with longer travel and suspension length adjustment. Described in the prior art, the highly stressed inner tube must be formed of a material and in a manner such that it bends rather than breaks. High strength steel is commonly used for the inner tube for this purpose, but it is heavy and counter to the consumer&#39;s preference. Lighter materials such as Aluminum in combination with strengthening processes such as shot-peening to strengthen the outer skin have been used as a material for the inner tube. Here-to-for, unfortunately, telescope assemblies whose inner tube connects to the fork crown with greater than 70 mm length of travel have been unable to pass stress testing using the present art as described in the aforementioned patents despite the additional costly process of shot-peening and use of expensive high-strength aluminum alloys. Attempting to increase the diameter of the tubes to add strength is also impractical as larger tube diameters increase cost, obsolete existing factory tooling and is generally counter to the consumer&#39;s aesthetic preference. Improvements in the design as outlined in U.S. Pat. No. 6,604,886 Kinzler et al have allowed travel to extend to 80 mm using lightweight materials.  
           [0014]    Single tube suspension systems mounted in the head tube of the bicycle are unique and preferable over twin tube systems as they eliminate a considerable amount of weight. The main drawback of these systems is their limitation on the length of travel of the suspension system. The longest single telescoping suspension fork system of this configuration presently marketed is 80 mm of travel. Trying to increase this length to 100 mm poses significant problems. The bearing system described by Ferris et al has linear bearings in excess of 4 inches. The length of a 100 mm telescoping suspension portion of the fork using this approach would be in excess of 9 inches putting the attitude of the bike at a steep undesirable angle. Even then the stress on the inner tube member would be so great as to fail during use. There is a limit then on the conventional designs to limit travel to 80 mm or less when connected to a fork style unit. Attempts have been made to use a single-sided suspension system to position the suspension system to one side of the wheel allowing greater travel. While these systems work they are costly and heavy. They also bias the center of gravity of the bicycle pulling the bicycle to one side.  
           [0015]    Prior art as described in Farris et. al use a cartridge damper system that exacerbates the length of the suspension portion. Such a restriction adds to the overall length of the telescoping system as the size of the damper components are greater than the space available in the inner tube. The damper commonly extends beyond the inner tube adding to the length of the telescoping system. In addition, such cartridge dampers utilize a coil or air rebound spring located in the inner tube member which places even further restrictions on the stroke length to 80 mm or less.  
           [0016]    In the prior art, flats on the outer tube and inner tube of the suspension housing have flats running the entire length of the assembly. This design allowed for hard steel races to be easily installed and for easy installation of the needle bearings from one end. Unfortunately, the race stock is heavy steel and as the suspension system length grows, the length of the race stock grows increasing the weight of the system.  
           [0017]    In current designs using the needle bearing system, the radial bearing capacity of the suspension system stops where the linear bearing sits. For much of the travel the bearing is significantly inside the suspension housing allowing flexing of the inner tube. Currently, a collar on the telescope assembly is used to prevent the bearing needles from exiting the telescope at the bottom of its excursion. If the bearing needles escape, the entire front fork may come apart. This is prevented by closing down the internal diameter of the collar. Because of the flexing, however, it cannot be closed down enough to encounter the full length of the bearing cage because the bending of the inner tube when under load may cause it to rub against the collar. A compromise must be made that places severe restrictions on the design, including the outside diameter of the inner tube. As the length of travel is increased this compromise becomes more difficult to make.  
           [0018]    Currently no adjustable mechanism exists for Ferris et al. designed suspension forks with the ability to change suspension length at the handlebars.  
         Damper Systems and Adjustable Travel  
         [0019]    Damper systems of most suspension forks other than those incorporating the single tube suspension unit described by Farris et al. are adjustable at the top of the crown or at the bottom of the suspension fork which is inconvenient for the user to make adjustments. It would be beneficial to allow all these adjustments at a convenient location such as the handlebars for the rider. Damper systems allowing for adjustability at the handle bars allow adjustment for rebound, but not low-speed compression. In addition, many damper systems do not progressively stiffen as the length of travel is used causing topout of the damper and unnecessary roughness. It would be beneficial to add progressivity damping characteristics to a suspension fork that allow the suspension system to increase in stiffness as the travel is used up.  
           [0020]    Adjusting ride height if performed at all is also done at the top of the crown not where it is convenient. These systems employ a knob that is turned. The rider must then push down on the fork to let the fork release to its new position. These devices are not infinitely adjustable between two fixed travel positions therefore they do not allow the rider to adjust to a convenient position. It would be beneficial to allow all these adjustments at a convenient location for the rider such as the handle bars and allow the rider to adjust ride position infinitely as the riding is taking place.  
         OBJECTS AND ADVANTAGES  
         [0021]    Several objects and advantages of the present invention are:  
           [0022]    1) to provide an improved, lightweight suspension fork with increased travel capability that maintains torsional rigidity, but increases radial rigidity. The suspension fork allows for adjustable suspension travel adjusted at the handlebars of the bicycle.  
           [0023]    2) to provide a unique method of adjusting suspension travel in an extremely tight space without negatively impacting either the outer or inner tube&#39;s strength and with convenient user access for adjustment in the field.  
           [0024]    3) to provide a rebound spring external to the inner damper tube to shorten the telescoping length to mitigate an undesireable attitude of the rider and fatigue stress on the inner tube.  
           [0025]    4) to provide the suspension damping adjustments at the handlebars for user convenience.  
           [0026]    5) to provide the suspension system with progressive damping characteristics that stiffen the suspension as the travel of the suspension fork is used up.  
         SUMMARY  
         [0027]    In accordance with the present invention, a long travel suspension fork for a bicycle comprising an elongated inner tube and outer tube co-axially mounted together to telescope with each other that incorporates a main shaft and a travel adjustment apparatus coupled together. By rotating the main shaft the position of the inner tube relative to the outer tube is changed thereby adjusting the length of travel of the suspension system. Inherent to accomplishing the length of travel, the suspension unit incorporates a slidable seal between the inner and outer tubes so as to form a rebound gas spring thus eliminating the need for the rebound spring to be housed within the inner tube. This external spring effectively shortens the needed length of the tubes improving strength characteristics of the suspension fork and ride attitude. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]    [0028]FIG. 1 shows a simplified view illustrating the preferred form of suspension fork according to the present invention.  
         [0029]    [0029]FIG. 2A is an exploded view of the telescoping assembly in its preferred embodiment illustrating inner and outer tubes, a needle bearing assembly, an inner race, outer race and collar.  
         [0030]    [0030]FIG. 2B is a partial view of a needle bearing assembly showing the relationship of the cage and needle.  
         [0031]    [0031]FIG. 2C is a cross-sectional view illustrating the relationship of outer races, bearing assemblies, inner races, inner tube and outer tube in assembly form.  
         [0032]    [0032]FIG. 3 shows the detailed configuration of the preferred embodiment of the suspension system.  
         [0033]    [0033]FIG. 4 shows a detailed cross-sectional view of the damping system housed in the inner tube.  
         [0034]    [0034]FIG. 5A shows a detailed cross-sectional view of the piston and flow during compression.  
         [0035]    [0035]FIG. 5B shows a detailed cross-sectional view of the piston and flow during rebound.  
         [0036]    [0036]FIG. 6 shows a cross-sectional views of the damping adjustment mechanisms for rebound and compression.  
         [0037]    [0037]FIG. 7A shows a cross-section view of the suspension stroke length adjustment mechanism at the full travel position.  
         [0038]    [0038]FIG. 7B shows a cross-section view of the suspension system stroke length adjustment mechanism at a smaller length of travel position. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
     Telescoping Housing Mechanism  
       [0039]    [0039]FIG. 1 shows a bicycle frame (partial)  101  along with a head tube  102 . A fork crown (partial)  103  has an inner tube  104  of a telescoping assembly affixed into it. The outer tube, comprised of two pieces  105 A and  105 B of the telescoping assembly is pressed into the head tube  102  using upper and lower journal bearings (not shown) to allow for steering rotation. The upper end of the outer tube  105 B is connected to the handlebar stem (not shown). It should be noted that for this embodiment the outer tube is comprised of two pieces, however, the outer tube could be one piece.  
         [0040]    [0040]FIG. 2A is an exploded view of the telescoping assembly showing parts germane to this invention. Over a specific length in the outer wall of the inner tube  104  depicts a plurality of axially extending longitudinal flat surfaces or flats of which one is shown  801 . In the preferred embodiment there are four such flats, however there can be more or less flats used. Over a specific length in the inner wall of the outer tube  105 A, there are axially extending flats of which one is shown  805  that are opposing the corresponding flats on the inner tube. Contained between the inner and outer tube sets of flats are sets of outer races  807 - 810  of which one is shown, bearing needle assemblies of which one is shown  811  and inner races of which one is shown  814 . The inner and outer races are commonly made of hardened steel. There are a corresponding number of sets of bearing needle assemblies with the number of flats on the outer tube and inner tube. In the preferred embodiment there are 4 sets of bearing assemblies, however, there could be more or less. Housed within the outer tube section  105 A is a lubricious bushing  110  to provide additional radial load bearing support.  
         [0041]    [0041]FIG. 2B shows a detailed view of the bearing needle assemblies. These assemblies are a plurality of hardened chrome steel needle bearings  819  typically 5 needle bearings housed in a plastic cage  820  and ride in between corresponding inner and outer races. It is important to note that current systems that incorporate needle bearings employ 22 needles and that the overall length of the needle cage assembly is approximately 4 inches. For travel of 100 mm using these long cage assemblies, the length of outer tube sections  105 A and  105 B would be in excess of 9 inches making the fork too long and causing the outer tube section  105 B to protrude too far above the handle bars or put the rider at an undesirable angle. In addition as shown in FIG. 2A, the length of the flats (one shown  801 ) on the inner tube is significantly long decreasing the cross-section area of the inner tube along the length. Because the inner tube  104  is captured and held at crown  103 , tremendous flexing can occur. Inner tubes traditional have been made from steel with limited travel to limit stress levels in the inner tube  104 . Unique to this suspension system is the combination of a load bearing bushing, sealed gas chamber between the inner tube  104  and the outer tube sections  105 A and  105 B and a smaller linear bearing system employing a cage with far fewer needles. By using a combination of a load bearing bushing  110  and a smaller bearing cage assembly containing 5 needles, the length of flat required for 100 mm of travel is less and thus shortens the required length of outer tube sections  105 A and  105 B. In addition, the desired torsional rigidity of the system is maintained. The cross-sectional area of the tube is increased for most of the tube thus allowing for decreased stress levels. Lightweight aluminum can be used as the inner tube  104 .  
         [0042]    [0042]FIG. 2C shows a cross-sectional view of the preferred embodiment of the telescope highlighting the relationship of the inner tube  104 , the outer tube section  105 A, the inner races  815 - 818 , the outer races  807 - 810  and the needle bearing assemblies  811 - 814 .  
         [0043]    The needle bearing assemblies  811 - 814  allow the inner tube  104  to travel freely in an axial direction with respect to the outer tube sections  105 A. Additionally, the needle bearing assemblies in conjunction with the associated flats on the inner tube, inner races  815 - 818 , outer races  807 - 810  and outer tube  105 A enable the steering torsional or rotary action to be imparted from handlebars connected to the handlebar stem via the telescoping tubes to the fork and to the front wheel (not shown). The needle bearings bear high radial loads from the fork during movement over rough terrain. The length of the flats on the inner tube determine the amount of telescoping action. Typically the amount of telescoping action is desired to be 80 mm to 130 mm.  
       Integral Damping System  
       [0044]    [0044]FIG. 3 illustrates the integral damping system consisting of a progressive gas rebound spring system comprised of chambers  107  and  108  and an integral damping unit  113  generally shown being housed in inner tube  104 . Outer tube section  105 A contains a seal  40  which is housed in the outer tube wall and rides along a specific length of inner tube  104  and a lubricious bushing  41  which provides axial stability of the inner and outer tubes. A collar  37  serves to prevent the seal  40  from exiting the outer tube section  105 A. Outer tube section  105 B, which is threaded to outer tube section  105 A, contains a piston  49  and an end cap  53 . Together the seal  40 , outer tube sections  105 A and  105 B, piston  49  and end cap  53  provide a pair of gas chambers  107  and  108  which serve as a rebound spring for the integral damping system. The gas volume in gas chamber  108  is pressurized between 50 and 150 psi through port  114 , depending on the desired ride quality and weight of the rider. This pressurization forces piston  49  downward until the pressure in chamber  107  equals the pressure in  108 . During riding, as the rider encounters rough terrain like a rock or bump that forces the inner tube  104  upward, the pressure in chamber  107  starts to increase, piston  49  moves axially upward to compensate for the increase in pressure until pressures in chambers  107  and  108  are in equilibrium. After the bump is traversed, the combined gas pressure in chambers  107  and  108  push the inner tube  104  back to the equilibrium ride position.  
         [0045]    Pressurized gas is contained in volume  108  serves as a progressive gas rebound spring. The progressivity of the gas spring is dependent on the contact or lack of contact of the inner tube  104  with the piston  49 .  
         [0046]    Unique to this suspension mechanism is the use of the split air chamber design separating gas chambers  107  and  108 . Gas chamber  108  can be charged to a higher pressure than chamber  107  due to the fact that as gas chamber  108  is charged piston  49  moves axially downward until it touches retaining clip  42  at the interface point of outer tube section  105 A and  105 B. Retaining clip  42  holds piston  49  even though additional pressurization is applied to chamber  108 . This differential pressure set up allows inner tube  104  to eventually touch piston  49  during compression of the fork. At that point the additional spring pressure provided by chamber  108  engages and resists further movement of inner tube  104  upward, creating even further resistance to movement. The pressures in chambers  107  and  108  can be modulated to achieve different rebound spring progressivity.  
         [0047]    Also unique to this suspension mechanism is the formation of the gas chamber  107  external to the inner tube. O-ring  40  located in collar  37  supported on either side by backup rings  39  slides along the external surface of the inner tube. Gas chamber  107  is formed in the space between the inner tube  104  and outer tube section  105 A and the piston  49 . Gas chamber  107  then serves as the main rebound spring during compression of the suspension system when inner tube  104  compresses into outer tube section  105 A The advantages of the linear bearing system are still maintained by using a smaller linear bearing system employing a cage with far fewer needles. Using a combination of a load bearing bushing  41  and a smaller bearing cage assembly containing  5  needles, the length of flat on the external surface of the inner tube required for  100  mm of travel is less. The desired torsional rigidity of the system is maintained. The cross-sectional area of the tube is increased for most of the tube thus allowing for decreased stress levels. Lightweight aluminum can be used as the inner tube  104 . By creating a shorter flat region, the external surface of the inner tube  104  for the length of travel is smooth providing an effective sealing surface for O-ring  40 , thus allowing the creation of the gas chamber  107 .  
         [0048]    [0048]FIG. 3 and FIG. 4 illustrate the damping unit  113  housed in inner tube  104 . The damping unit includes a series of shafts  30 , 31  and  34  which have one degree of freedom and operate independent of each other to provide rebound, compression and suspension travel adjustment. The shafts pass through a damper cap  26  which is contained within a stop cap  25 . The stop cap serves to house the damper cap and provide a stop for the needle bearing assemblies  811 - 813  and inner races  814 - 816 . The stop cap prevents the bearing assemblies  811 - 813  and inner races  814 - 816  from migrating past the end of the inner tube  104  during motion. A series of seals  29  provide a fluid seal against shaft  30 . A ported piston assembly  13  generally depicted is connected to the shaft  30  via a piston connect assembly  17 . As the inner tube  104  moves axially being forced by the wheel along the terrain, the piston assembly  13  moves axially relative to the inner tube. The interior of the inner tube  104  is divided into 3 chambers  209 ,  210  and  211 . Chambers  209  and  210  contain damping fluid whereas chamber  211  contains gas under pressure. As the piston assembly  13  moves axially relative to the inner tube, damping fluid progresses through the piston assembly  13  between chambers  209  and  210  to cause damping. Chamber  211  is separated from chamber  210  through a floating piston  08 . Chamber  211  is filled with high pressure gas filled through a port seal  05  in end cap  03 . The gas chamber  211  serves to resist the piston assembly  13  movement, but also serves to compensate for the volume change as the shaft assembly moves in and out of the damping unit. By so compensating, cavitation of the damping fluid is avoided. The floating piston contains a seal  09  which prevents mixing of oil in chamber  210  and gas in chamber  211 . Retaining clip  02  prevents end cap  03  from exiting the bottom of inner tube  104 . O-rings  04  prevent air leakage around end cap  03  when gas in chamber  211  is pressurized.  
       Piston Assembly  
       [0049]    Unique to this invention is a three part piston assembly that allows independent control of low speed and high speed compression as well as rebound adjustment. FIG. 5A shows the piston assembly  13  connected to a piston connect element  17  to the main shaft  30 . The piston assembly  13  is comprised of a lower half piston section  10  a rebound adjustment disc  11  and an upper piston section  12 . During “low speed” compression, the inner tube  104  moves axially upward forcing damping fluid to move from chamber  210  to chamber  209  through the “kidney slots”  407  in central portion of the three-piece piston element  13 . As depicted by flow line  404  for “low speed” compression flow, fluid moves through the center of piston element  13  and out holes  405  in piston connect element  17  underneath O-ring  18 . For “high speed” compression, fluid additionally moves along flow line  406  through “kidney slots” in lower half piston section  10 , through upper piston section pushing shims  64  outward. Fluid flows out from under shims  64  into chamber  209 . As shown in FIG. 5B, ball  15  and spring  16  form a ball valve to prevent flow during compression through rebound adjustment disc  11 . In FIG. 5B, rebound flow moves fluid from chamber  209  to  210  along path  408 . Fluid flow moves through radial slots  410  on top side of upper half piston section  12 . Fluid moves through holes in upper half piston section  12  through a hole in rebound adjustment disc  11  located between upper and lower piston halves  12  and  10  respectfully and out slots in lower half piston section  10 . O-ring  18  prevents fluid flow through piston connection element  17 .  
       Damping Adjustment Mechanisms  
       [0050]    Unique to this invention is a three shaft adjustment mechanism that allows independent control of suspension length, compression and rebound suspension features. Each adjustment acts independently of the other. FIG. 6 shows a highlighted sectional view of the damping adjustment mechanisms which allows independent control of rebound and compression characteristics of the damping system at the handlebars. Referring to FIGS. 5B and 6, Rebound Damping adjustment knob  62  is connected to shaft  34  via set screws  63  and is keyed with rebound adjustment disc  11 . By rotating knob  62 , rebound adjustment disc  11  turns. Rebound adjustment disc  11  containing various orifice holes of different sizes. When rebound adjustment disc  11  is rotated, a hole in the rebound adjustment disk aligns with a hole in upper piston half  12  to provide a flow path for fluid between chamber  209  and  210 . Rebound rate is depended on the hole size in the rebound adjustment disk. Oil flows through the rebound rate screw and out the bottom of piston disc  10 . “Low speed” compression adjustment knob  61  is threaded to compression adjustment shaft  31  which connects to “low speed” adjustment screw  20 . As the low speed compression adjustment knob  61  is turned, low speed adjustment screw  20  turns inside piston connect element  17  and moves axially downward or upward depending on the direction of rotation. Low speed adjustment screw  20  moves across holes  405  in piston connect element  17  thus modulating the orifice size  405 .  
         [0051]    O-ring seals  36 , and  33  prevent fluid seepage in between rebound and compression adjustment shafts  31  and  34  and between compression adjustment shaft  31  and main shaft  30 . Back-up elements  32  and  35  are fixed in position on compression adjustment shaft  31  and rebound adjustment shaft  34  to serve as an  0 -ring back-ups for O-rings  33  and  36 , respectfully.  
       Suspension System Stroke Length Adjustment  
       [0052]    Riders would like to shorten the suspension system while traversing uphill so as to lower the attitude of the bicycle while climbing. Subsequently, they would like to lengthen travel once again going on a straight path or downhill to take advantage of the plushness of a longer suspension system. Riders continue to desire to adjust these features at the handlebars vs. leaning over or stopping to make suspension system adjustments. Unique to this suspension system is a suspension travel adjustment mechanism. FIGS. 7A and 7B shows the cross-section view of the suspension length adjustment mechanism. Suspension system stroke length adjustment is obtained by length adjuster  22 , travel adjustment knob  60  and main shaft  30 . Travel of the suspension system is adjusted by turning the travel adjustment knob  60 . The travel adjustment knob  60  is keyed with the main shaft at the underside of the adjustment knob using a standard hex configuration so as to allow turning of the main shaft  30  clockwise or counterclockwise as the travel adjustment knob  60  is turned. Length adjuster  22  is threaded onto the outside of main shaft  30 . As the travel adjustment knob  60  is turned, the main shaft  30  moves linearly relative to length adjuster  22 . Length adjuster  22  does not rotate because of friction between O-ring  23  and the inside wall of inner tube  104 . Referring to FIG. 3, main shaft  30  is fixed to the outer tube  105 B below the travel adjustment knob  60  using a hex nut  58  which resides on top of a cap  57  secured to outer tube  105 B. As the main shaft  30  turns, the inner tube moves relative to the length adjuster  22 . Length adjuster  22  pulls the inner tube  104  up relative to outer tube  105 B, and shortens the suspension stroke as the travel adjustment knob  60  is turned clockwise. Turning the adjustment knob  60  counter-clockwise moves the main shaft  30  up lengthening the suspension stroke.