Abstract:
A bicycle fork and frame assembly comprising a frame having a head tube including an outer dimension, a fork including a fork crown and a steerer tube positioned in the head tube, an upper bearing, and a lower bearing having a diameter. The upper and lower bearings are configured to rotatably support the fork within the head tube. The head tube includes a first end proximal to the fork crown and a second end distal to the fork crown. A ratio is defined by a distance from the first end of the head tube to the lower bearing divided by the diameter of the lower bearing, and the ratio is at least about 0.20, preferably at least about 0.25 and more preferably at least about 0.30. The assembly can further include a transition coupling the fork crown to the steerer tube and defining a transition point between the transition and the steerer tube. The transition has an outer dimension that increases from the steerer tube toward the fork crown, and the lower bearing is located adjacent to the transition point. The steerer tube can include a lower section coupled to an upper part of the transition at the transition point and an upper section coupled to the lower section. Preferably, the lower section has an outer dimension that tapers smaller moving away from the transition (e.g., frustoconical), and the upper section has a substantially constant cross section (e.g., cylindrical). The fork crown defines an arch way that is a distance from the lower bearing. In this aspect, a ratio is defined as the distance divided by the diameter of the lower bearing, and the ratio is at least about 0.7, preferably at least about 0.77, and more preferably at least about 0.83.

Description:
RELATED APPLICATIONS 
   This patent application is a continuation-in-part of and claims priority to U.S. patent application Ser. No. 11/370,750, filed Mar. 8, 2006, the entire contents of which are hereby incorporated by reference. 

   BACKGROUND 
   The present invention relates to a fork assembly for a bicycle. More particularly, the invention relates to a fork and a lower bearing assembly configured for use in the fork assembly. 
   Most bicycles include a front fork that is rotatable to turn a front wheel. The fork typically includes two fork blades, and the front wheel is rotatably supported between the two fork blades. The fork blades are coupled at one end to form a crown, and a steerer tube typically extends from the crown. The steerer tube is rotatably supported within a head tube by at least two bearings, an upper bearing and a lower bearing. The head tube is coupled to and comprises a portion of a frame of the bicycle, and the bearings allow the fork to rotate relative to the head tube and frame. Generally, a handle bar is attached to the steerer tube to allow a rider to rotate the fork and steer the bicycle. 
   SUMMARY 
   The present invention provides a bicycle fork and frame assembly comprising a frame having a head tube including an outer dimension, a fork including a fork crown and a steerer tube positioned in the head tube, an upper bearing, and a lower bearing having a diameter. The upper and lower bearings are configured to rotatably support the fork within the head tube. The head tube includes a first end proximal to the fork crown and a second end distal to the fork crown. A ratio is defined by a distance from the first end of the head tube to the lower bearing divided by the diameter of the lower bearing, and the ratio is at least about 0.20, preferably at least about 0.25 and more preferably at least about 0.30. 
   In one embodiment, the assembly further comprises a transition coupling the fork crown to the steerer tube and defining a transition point been the transition and the steerer tube. The transition has an outer dimension that increases from the steerer tube toward the fork crown, and the lower bearing is located adjacent to the transition point. 
   In another embodiment, the steerer tube includes a lower section coupled to an upper part of the transition at the transition point and a upper section coupled to the lower section. Preferably, the lower section has an outer dimension that tapers smaller moving away from the transition (e.g., frustoconical), and the upper section has a substantially constant cross section (e.g., cylindrical). 
   In yet another embodiment, the fork crown defines an arch way that is a distance from the lower bearing. In this aspect, a ratio is defined as the distance divided by the diameter of the lower bearing, and the ratio is at least about 0.7, preferably at least about 0.77, and more preferably at least about 0.83. 
   Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side view of a bicycle including a fork assembly embodying the present invention. 
       FIG. 2  is an exploded view of the fork assembly of  FIG. 1  and a portion of the frame of the bicycle of  FIG. 1 . 
       FIG. 3  is a cross-section of a portion of the fork assembly taken along line  3 - 3  in  FIG. 1 . 
       FIG. 4  is a cross-section of a portion of the bicycle taken along line  4 - 4  in  FIG. 1 . 
       FIG. 5  is a cross-section of a portion of another fork assembly. 
       FIG. 6  is a cross-section of a portion of the fork assembly of  FIG. 5  mounted in a head tube by an upper bearing assembly and a lower bearing assembly. 
       FIG. 7  is an exploded perspective view of another fork assembly and a portion of another frame of a bicycle. 
       FIG. 8  is a front view of a portion of the fork assembly of  FIG. 7 . 
       FIG. 9  is a cross-section of a portion of the fork assembly taken along line  9 - 9  in  FIG. 8 . 
       FIG. 10  is a cross-section of a portion of the fork assembly of  FIG. 7  mounted in a head tube by an upper bearing assembly and a lower bearing assembly. 
   

   Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description an should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
   DETAILED DESCRIPTION 
     FIG. 1  illustrates a bicycle  10  that includes a front wheel  15 , a rear wheel  20 , and a frame  25 . The frame  25  can be made from any suitable material, such as steel, aluminum, carbon/epoxy composite, KEVLAR composite, fiberglass composite, or other composites and the like. 
   Referring to  FIGS. 2 and 4 , the frame  25  includes a head tube  30  having an outer dimension D 1  (47 mm in the illustrated embodiment). While the illustrated head tube  30  is cylindrical with a generally constant outer dimension D 1 , in other constructions the head tube  30  can have an outer dimension D 1  that varies. For example, the outer dimension D 1  of the head tube  30  may decrease from a lower portion  35  toward a center portion  40 , then increase from the center portion  40  toward an upper portion  45 . In yet other constructions, the head tube  30  can take shapes other than a cylinder. For example, the head tube  30  can have an outer surface  50  with a plurality of sides, such as three, four, or more sides, or the head tube can be aerodynamically shaped. For purposes of this patent application, the outer dimension D 1  of the head tube  30  should be measured laterally across the lower portion  35  of the head tube  30 . 
   A fork assembly  55  is received and supported by the head tube  30 . The fork assembly  55  includes a fork  60  having a steerer tube  65 , a transition  70 , a fork crown  75 , two fork blades  80 , and two fork dropouts  82 . The illustrated steerer tube  65 , transition  70 , fork crown  75  and fork blades  80  are integrally formed as a single piece made from a carbon/epoxy composite. Of course other materials such as plastics, fiberglass composite, KEVLAR composite, or other composites, and the like can be used to integrally form the steerer tube  65 , transition  70 , fork crown  75  and fork blades  80 . In other constructions, the steerer tube  65 , transition  70 , fork crown  75  and fork blades  80  may not be integrally formed as a single piece. For example, in one construction the fork blades  80  can be made separate from the fork crown  75 , and then the fork blades  80  can be bonded to the crown using epoxy or any suitable adhesive. In yet another construction, the steerer tube  65  can be formed separate from the transition  70  and then coupled to the transition using an adhesive, such as epoxy. Furthermore, the steerer tube  65 , transition  70 , fork crown  75 , and fork blades  80  may not all be formed from composite material. In one such construction the transition  70  can be made from aluminum and the steerer tube  65  and fork crown  75  can be made from a composite material. Other various combinations of materials can also be utilized. 
   Referring to  FIG. 3 , the steerer tube  65  is generally cylindrical and defines a central axis  85 . While the illustrated steerer tube  65  is cylindrical in shape, in other constructions the steerer tube  65  can be frustoconical, such that an outer dimension D 2  (29 mm in the illustrated embodiment) of the steerer tube  65  either increase or decreases from a lower portion  90  toward an upper portion  95 . Furthermore, while the illustrated steerer tube  65  is hollow with a uniform wall thickness, in other constructions the wall thickness may not be uniform. For example, in other constructions the wall thickness can decrease from the lower portion  90  toward the upper portion  95 . 
   Referring to  FIGS. 2 and 3 , the transition  70  extends from the fork crown  75  to couple the fork crown  75  to the steerer tube  65 . An upper transition point  100  is defined by the location where the transition  70  couples to the steerer tube  65 , and lower transition point  101  is defined by the location where the transition  70  couples to the fork crown  75 . The transition  70  has a first outer dimension D 3  (29 mm in the illustrated embodiment) at the upper transition point  100  and a second outer dimension D 4  (40 mm in the illustrated embodiment) where the transition  70  couples to the fork crown  75  at the lower transition point  101 . While the illustrated fork  60  includes a radius portion  102  located between lower transition point  101  and the fork crown  75 , in other constructions the fork  60  may omit the radius portion  102 . Therefore, for purposes of this patent application, the lower transition point  101  will be defined as the point where the transition  70  couples to the radius portion  102 , or in embodiments that omit the radius portion  102 , the lower transition point  101  will defined as the point where the transition  70  couples to the crown  75 . 
   In the illustrated embodiment, the first outer dimension D 3  of the transition  70  is equal the outer dimension D 2  of the steerer tube  65  at the upper transition point  100 , and the first outer dimension D 3  of the transition  70  increases from the upper transition point  100  toward the fork crown  75 . A ratio is defined by the second outer dimension D 4  of the transition  70  divided by the first outer dimension D 3  of the transition  70 . In the illustrated construction, the ratio is about 1.4, and in other constructions the ratio is greater than about 1.2. 
   The frustoconical outer surface of the transition  70  defines an angle α between the outer surface of the transition  70  and the central axis  85  of the steerer tube  65 . The illustrated angle α is about 20 degrees, and in other constructions, the angle α is greater than about 10 degrees. While the illustrated transition  70  is frustoconical in shape, in other constructions, the transition can have a plurality of sides. For example, in other constructions, the transition can have three, four, or more sides. 
   Referring to  FIGS. 2 and 4 , the fork assembly  55  also includes an upper bearing assembly  105  and a lower bearing assembly  110 . The upper bearing assembly  105  includes an upper bearing  115 , a compression ring  120 , an upper cup  125 . The upper cup  125  is rotationally fixed with respect to the head tube  30  and supports the upper bearing  115  within the head tube  30 . The compression ring  120  is located between the steerer tube  65  and the upper bearing  115  and is generally fixed with respect to the steerer tube  65 . The upper bearing  115  is located between the upper cup  125  and compression ring  120  and provides for relative rotation between steerer tube  65  and the head tube  30 . The upper bearing  115  can be any suitable bearing, such as a loose ball bearing, a retainer ball bearing, a cartridge type bearing, and the like. 
   Referring to  FIG. 3 , the fork crown  75  includes a brake mount in the form of an opening  103  extending through the fork crown  75  and defining a brake-mounting axis  104 . The function and operation of the opening  103  is well known to one of ordinary skill in the art. It should be understood that other types of brake mounts could be used with the present invention. 
   The lower bearing assembly  110  includes a lower bearing  130 , a crown race  135 , and a lower cup  140 . The crown race  135  can be made from any suitable material, such as aluminum, steel, plastic, composite, etc. The crown race  135  is coupled to the fork  60  circumferentially around the upper transition point  100  such that the crown race  135  is fixed with respect to the fork  60 . In the illustrated construction, the crown race  135  is co-molded to the fork  60 , while in other constructions the crown race  135  can be bonded to the fork  60 . 
   The lower cup  140  is coupled to the head tube  30 , such that the lower cup  140  is rotationally fixed with respect to the head tube  30 . The lower cup  140  can be made from any suitable material, such as aluminum, steel, plastic, composite, etc. 
   The lower bearing  130  is located between the crown race  135  and the lower cup  140 , such that the lower bearing  130  is circumferentially around the upper transition point  100 . The lower bearing  130  can be any suitable bearing, such as a loose ball bearing, a retainer ball bearing, a cartridge type bearing, and the like. The illustrated lower bearing  130  has a diameter D 5  of approximately 36 mm. In other constructions, the lower bearing  130  can have any suitable diameter D 5 . 
   The illustrated lower bearing  130  is located at a distance D 6  from an end of the head tube  30 . In the illustrated construction, the distance D 6  is approximately 15 mm and in other constructions is at least about 8.5 mm. In yet other constructions, the lower bearing  130  can be located either above or below the upper transition point  100 . 
   The upper transition point  100  and the lower bearing  130  are located at a distance D 7  from the brake-mounting axis  104 . In the illustrated embodiment, this distance D 7  is 33 mm for the upper transition point  100  and 35 mm for the lower bearing  130 . In addition, the upper transition point  100  and the lower bearing  130  are located at a distance D 8  from the lower transition point  101  (essentially, the length of the transition  70 ). In the illustrated embodiment, this distance D 8  is 16 mm for the upper transition point  100  and 18 mm for the lower bearing  130 . 
   A first ratio is defined by the distance D 6  from the end of the head tube  30  to the lower bearing  130  divided by the outer dimension D 1  of the head tube  30 . In the illustrated embodiment, the first ratio is about 0.33. In other embodiments, the first ratio is at least about 0.28 and in yet other embodiments the ratio is at least about 0.23. 
   A second ratio is defined by the distance D 6  from the end of the head  30  to the lower bearing  130  divided by the diameter D 5  of the lower bearing  130 . In the illustrated embodiment, the second ratio is about 0.42. In other embodiments, the second ratio is at least about 0.30 and it yet other embodiments the ratio is at least about 0.25. 
   A third ratio is defined by the distance D 7  from the brake-mounting axis  104  to the lower bearing  130  divided by the diameter D 5  of the lower bearing  130 . In the illustrated embodiment, the third ratio is about 0.97. In other embodiments, the third ratio is at least about 0.8 and preferably at least about 0.7. 
   A fourth ratio defined by the distance D 7  from the brake-mounting axis  104  to the lower bearing  130  or the upper transition point  100  divided by the dimension D 4  of the transition  70  at the lower transition point  101 . In the illustrated embodiment, the fourth ratio is about 0.81. In other embodiments, the fourth ratio is at least about 0.63 and preferably at least about 0.5. 
   A fifth ratio is defined by the distance D 7  from the brake-mounting axis  104  to the lower bearing  130  or the upper transition point  100  divided by the outer dimension D 1  of the head tube  30 . In the illustrated embodiment, the fifth ratio is about 0.70. In other embodiments, the fifth ratio is at least about 0.60 and preferably at least about 0.50. 
   The upper and lower bearing assemblies  105 ,  110  allow the steerer tube  65  to rotate with respect to the head tube  30  while maintaining the steerer tube  65  in a generally fixed location with respect to the head tube  30  in both axial and radial directions. The upper and lower bearing assemblies  105 ,  110  also position the fork  60  within the head tube  30  such that a gap  145  is formed between the lower cup  140  and the crown  75 . 
   Referring to  FIG. 1  the steerer tube  65  extends through and above the head tube  30  to provide an attachment point for a steering assembly  150 . The steering assembly  150  includes a handlebar  155 , a stem  160 , and a sleeve  165 . The stem  160  is coupled to the steerer tube  65  and retains the sleeve  165  that surrounds the steerer tube  65 , between the stem  160  and the head tube  30 . The sleeve  165  includes a cap (not shown) that covers the upper bearing assembly  105  to substantially prevent dirt, debris, liquid and the like from contacting the upper bearing  115 . While the illustrated upper bearing assembly  105 , stem  160 , and sleeve  165  are in a configuration similar to a conventional threadless headset, it should be understood that in other constructions a threaded headset can be utilized. In such a construction, an additional threaded nut is provided and the threaded nut is coupled to the steerer tube  65 , which is also threaded, thereby coupling the stem  160  and sleeve  165  to the steerer tube  65 . 
     FIGS. 5 and 6  illustrate another embodiment of a fork assembly  215 .  FIG. 6  shows the fork assembly  215  mounted in a head tube  200  that is tapered or smoothly transitioned from an upper portion  205  to a lower portion  210 . The upper portion  205  has an outer dimension D 11  (48 mm in the illustrated embodiment), and the lower portion  210  has an outer dimension D 12  (58 mm in the illustrated embodiment). In other constructions, the head tube  200  can be cylindrical with a generally constant outer dimension D 11  or D 12 . In yet other constructions, the head tube  200  can take shapes other than a cylinder (e.g., an outer surface with a plurality of sides, such as three, four, or more sides), or the head tube  200  can be aerodynamically shaped. 
     FIGS. 5 and 6  show that the fork assembly  215  includes a steerer tube  225 , a transition  230 , a fork crown  235 , and two fork blades  240  (one shown). The fork assembly  215  also includes two fork dropouts (not shown) that are similar to the fork drop outs  82  discussed above with regard to  FIG. 2 . The illustrated steerer tube  225 , the transition  230 , the fork crown  235  and the fork blades  240  are integrally formed as a single piece made from a carbon/epoxy composite. Of course other materials such as metals, polymers, fiberglass composite, KEVLAR composite, or other composites, and the like can be used to integrally form the steerer tube  225 , the transition  230 , the fork crown  235  and the fork blades  240 . 
   As discussed above with regard to  FIGS. 1-4 , the steerer tube  225 , the transition  230 , the fork crown  235 , and the fork blades  240  may not be integrally formed as a single piece. For example, the fork blades  240  and/or the steerer tube  225  can be formed separate from other components (e.g., the fork crown  235 , the transition  230 , etc.), and then coupled together using an adhesive (e.g., epoxy). Furthermore, one or more of the steerer tube  225 , the transition  230 , the fork crown  235 , and the fork blades  240  can be made from aluminum, while the remaining components not made from aluminum can be formed from other materials, such as a composite material. Other various combinations of materials can also be utilized. 
     FIG. 5  shows the fork assembly  215  removed from the head tube  200 . The steerer tube  225  defines a central axis  245 , and is generally cylindrical in shape. The steerer tube  225  smoothly transitions or tapers from an upper portion  250  to a lower portion  255  without sharp corners in the steerer tube  225 . In other constructions, the steerer tube  225  can be substantially cylindrical in shape. Furthermore, while the illustrated steerer tube  225  is hollow with a uniform wall thickness, in other constructions the wall thickness may vary. For example, in other constructions the wall thickness of the steerer tube  225  can increase or decrease from the upper portion  250  toward the lower portion  255 . 
   The fork crown  235  is in communication with the lower portion  255  of the steerer tube  225 , and includes an archway  260  disposed between the fork blades  240  to accommodate the front wheel  15 . The fork crown  235  also includes a brake mount in the form of an opening  265  that extends through the fork crown  235  and that defines a brake-mounting axis  267 . 
   The upper portion  250  includes an outer dimension D 13  (29 mm in the illustrated embodiment).  FIGS. 5 and 6  show that the lower portion  255  includes a taper or elongated curved portion  270  extending from the upper portion  250  of the steerer tube  225  toward the transition  230 . In the illustrated construction, the taper  270  is curved from the upper portion  250  to the lower portion  255 . In other constructions, the taper  270  can be substantially straight between the upper portion  250  and the lower portion  255 . 
   The illustrated taper  270  includes an upper transition point  275  defined by the location where the taper  270  couples to the upper portion  250  of the steerer tube  225 , and a lower transition point  280  defined by the location where the taper  270  couples to the transition  230 . The upper transition point  275  is located at a distance D 14  from the archway  260  (116 mm in the illustrated embodiment). In other constructions, the distance D 14  can be longer or shorter than 116 mm. The taper  270  also has a first outer dimension D 15  (29 mm in the illustrated embodiment) at the upper transition point  275 , and a second outer dimension D 16  (39 mm) at the lower transition point  280 . In the illustrated embodiment, the first outer dimension D 15  of the taper  270  is equal to the outer dimension D 13  of the upper portion  250 . 
   The transition  230  extends from the fork crown  235  to couple the fork crown  235  to the steerer tube  225 , and includes an upper transition point  285  and a lower transition point  290 . The upper transition point  285  is defined by the location where the transition  230  couples to the taper  270 , which is the same location as the lower transition point  280 . The lower transition point  290  is defined by the location where the transition  230  couples to the fork crown  235 . The transition  230  has a first outer dimension D 17  (39 mm in the illustrated embodiment) at the upper transition point  285  and a second outer dimension D 18  (50 mm) where the transition  230  couples to the fork crown  235  at the lower transition point  290 . While the illustrated fork  220  includes a radius portion  292  located between lower transition point  290  and the fork crown  235 , in other constructions the  220  may omit the radius portion  292 . Therefore, for purposes of this patent application, the lower transition point  290  will be defined as the point where the transition  230  couples to the radius portion  292 , or in embodiments that omit the radius portion  292 , the lower transition point  290  will defined as the point where the transition  230  couples to the fork crown  235 . 
   In the illustrated embodiment, the first outer dimension D 17  of the transition  230  is equal the second outer dimension D 16  of the taper  270  at the upper transition point  285 . The outer dimension of the transition  230  increases from the upper transition point  285  toward the fork crown  235 . A first ratio is defined by the second outer dimension D 18  of the transition  230  divided by the first outer dimension D 17  of the transition  230 . In the illustrated construction, the ratio is about 1.3, and in other constructions the ratio is greater than about 1.1 or 1.2. 
   The transition  230  includes a frustoconical outer surface that defines an angle β between the outer surface of the transition  230  and the central axis  245  of the steerer tube  225 . The illustrated angle β is about 25 degrees, and in other constructions, the angle β is greater than about 20 or 15 or 10 degrees. While the illustrated transition  230  is frustoconical in shape, in other constructions, the transition  230  can have a plurality of sides. 
   Referring to  FIG. 6 , the fork assembly  215  also includes an upper bearing assembly  295  and a lower bearing assembly  300 . Generally, the upper bearing assembly  295  includes an upper bearing  305 , a compression ring  310 , and an upper cup  315 , which are similar to the upper bearing  115 , the compression ring  120 , and the upper cup  125  of the upper bearing assembly  105  discussed above with regard to  FIGS. 2 and 4 . As such, the upper bearing assembly  295  will not be discussed in detail. Generally, the upper bearing  305 , the compression ring  310 , and the upper cup  315  are sized to accommodate the outer dimension D 13  of the steerer tube  225  and an inner dimension of the head tube  200 . 
   The lower bearing assembly  300  includes a crown race  320 , a lower cup  325 , and a lower bearing  330 . The crown race  320  can be made from any suitable material, such as aluminum, steel, plastic, composite, etc. The crown race  320  is coupled to the fork  220  circumferentially around the upper transition point  285  such that the crown race  320  is fixed with respect to the fork  220 . In the illustrated construction, the crown race  320  is co-molded to the fork  220 , while in other constructions the crown race  320  can be bonded or press fit to the fork  220 . 
   The lower cup  325  is coupled to the head tube  200  such that the lower cup  325  is fixed with respect to the head tube  200 . The lower cup  325  can be made from any suitable material, such as aluminum, steel, plastic, composite, etc. 
   The lower bearing  330  is located between the crown race  320  and the lower cup  325 , such that the lower bearing  330  is circumferentially around the upper transition point  285 . The lower bearing  330  can be any suitable bearing, such as a loose ball bearing, a retainer ball bearing, a cartridge type bearing, and the like. The illustrated lower bearing  330  has a diameter D 19  of approximately 46 mm. In other constructions, the lower bearing  330  can have any suitable diameter D 19 . 
   The illustrated lower bearing  330  is located at a distance D 20  from an end of the head tube  200 . In the illustrated construction, the distance D 20  is approximately 14.5 mm and in other constructions is at least about 8.5 mm. In yet other constructions, the lower bearing  330  can be located either above or below the upper transition point  285  of the transition  230 . 
   The upper transition point  285  of the transition  230  and the lower bearing  330  are located at a distance D 21  from the brake-mounting axis  267 . In the illustrated embodiment, this distance D 21  is approximately 27 mm for the upper transition point  285  and 30.5 mm for the lower bearing  330 . The upper transition point  285  and the lower bearing  330  are further located at a distance D 22  from the archway  260 . In the illustrated embodiment, this distance D 22  is 40 mm for the upper transition point  285  and 43.5 mm for the lower bearing  330 . In addition, the upper transition point  285  and the lower bearing  330  are located at a distance D 23  from the lower transition point  290 . In the illustrated embodiment, this distance D 23  is 13 mm for the upper transition point  285  and 15 mm for the lower bearing  330 . 
   A second ratio is defined by the distance D 20  from the end of the head tube  200  to the lower bearing  330  divided by the outer dimension D 12  of the head tube  200 . In the illustrated embodiment, the second ratio is about 0.25. In other embodiments, the second ratio is at least about 0.20 and in yet other embodiments the ratio is at least about 0.15. 
   A third ratio is defined by the distance D 20  from the end of the head to the lower bearing  330  divided by the diameter D 19  of the lower bearing  330 . In the illustrated embodiment, the third ratio is about 0.32. In other embodiments, the third ratio is at least about 0.27 and it yet other embodiments the third ratio is at least about 0.22. 
   A fourth ratio is defined by the distance D 21  from the brake-mounting axis  267  to the lower bearing  330  divided by the diameter D 19  of the lower bearing  330 . In the illustrated embodiment, the fourth ratio is about 0.66. In other embodiments, the fourth ratio is at least about 0.62 and preferably at least about 0.58. 
   A fifth ratio is defined by the distance D 21  from the brake-mounting axis  267  to the lower bearing  330  divided by the second outer dimension D 18  of the transition  230  at the lower transition point  290 . In the illustrated embodiment, the fifth ratio is about 0.61. In other embodiments, the fifth ratio is at least about 0.55 and preferably at least about 0.50. 
   A sixth ratio is defined by the distance D 21  from the brake-mounting axis  267  to the lower bearing  330  divided by the outer dimension D 12  of the head tube  200 . In the illustrated embodiment, the sixth ratio is about 0.53. In other embodiments, the sixth ratio is at least about 0.48 and preferably at least about 0.43. 
   A seventh ratio is defined by the distance D 22  from the archway  260  to the lower bearing  330  divided by the diameter D 19  of the lower bearing  330 . In the illustrated embodiment, the seventh ratio is about 0.95. In other embodiments, the seventh ratio is at least about 0.90 and preferably at least about 0.80. 
   An eighth ratio is defined by the distance D 22  from the archway  260  to the lower bearing  330  divided by the second outer dimension D 18  of the transition  230  at the lower transition point  290 . In the illustrated embodiment, the eighth ratio is about 0.87. In other embodiments, the eighth ratio is at least about 0.81 and preferably at least about 0.75. 
   A ninth ratio is defined by the distance D 22  from the archway  260  to the lower bearing  330  divided by the outer dimension D 12  of the head tube  200 . In the illustrated embodiment, the ninth ratio is about 0.75. In other embodiments, the ninth ratio is at least about 0.69 and preferably at least about 0.63. 
   Attachment of the fork assembly  215  to the frame  25  and the head tube  200  is similar to the attachment of the fork assembly  55  to the frame  25  and the head tube  30  described with regard to  FIGS. 1-4 . Operation of the fork assembly  215  within the head tube  200  is also similar to operation of the fork assembly  55  described above. As such, attachment and operation of the fork assembly  215  will not be discussed in detail. 
   Generally, the tapered head tube  200  and the taper  270  of the steerer tube  225  provide additional rigidity and strength to the frame and the fork assembly  215 , respectively. Generally, the larger lower bearing assembly  295  relative to the upper bearing assembly  295  allows the head tube  200  and the steerer tube  225  to be enlarged at its base to allow a relatively larger fork crown  235  and fork blades  240 , which in turn contributes to the stiffness of the bicycle. The relatively small upper portions  205 ,  250  of the head tube  200  and the steerer tube  225 , and the upper bearing assembly  295  provide for operation of the bicycle  10  while maintaining a relatively low overall weight of the bicycle  10 . 
     FIGS. 7-10  illustrate another embodiment for a bicycle  400  (e.g., mountain bicycle) that includes a frame  405 . The frame  405  can be made from any suitable material, such as steel, aluminum, carbon/epoxy composite, KEVLAR composite, fiberglass composite, or other composites and the like. 
     FIGS. 7 and 10  show that the frame  405  includes a head tube  410  that is tapered or smoothly transitioned from an upper portion  415  to a lower portion  420 . The upper portion  415  has an outer dimension D 31  (48 mm in the illustrated embodiment), and the lower portion  420  has an outer dimension D 32  (58 mm in the illustrated embodiment). In other constructions, the head tube  410  can be cylindrical with a generally constant outer dimension D 31  or D 32 . In yet other constructions, the head tube  410  can take shapes other than a cylinder (e.g., an outer surface with a plurality of sides, such as three, four, or more sides), or the head tube  410  can be aerodynamically shaped. 
   Referring to  FIGS. 7 and 10 , a fork assembly  425  is received and supported by the head tube  410 .  FIGS. 8 and 9  show the fork assembly  425  removed from the head tube  410 . The fork assembly  425  includes a steerer tube  435 , a transition  440 , a fork crown  445 , two fork blade assemblies  450 , and wheel attachments  452 . The illustrated steerer tube  435 , the transition  440 , the fork crown  445 , the fork blade assemblies  450 , and the wheel attachments  452  are integrally formed as a single piece made from a carbon/epoxy composite. Other materials such as plastics, fiberglass composite, KEVLAR composite, or other composites, and the like can be used to integrally form the steerer tube  435 , the transition  440 , the fork crown  445 , the fork blade assemblies  450 , and the wheel attachments  452 . As discussed above with regard to  FIGS. 1-6 , in other constructions, the steerer tube  435 , the transition  440 , the fork crown  445 , the fork blade assemblies  450 , and the wheel attachments  452  may not be integrally formed as a single piece. For example, one or more of the steerer tube  435 , the transition  440 , the fork crown  445 , the fork blade assemblies  450 , and the wheel attachments  452  can formed separate from the other components, and then coupled together using an adhesive (e.g., epoxy) or other attachment methods (e.g., welding). Furthermore, one or more of the steerer tube  435 , the transition  440 , the fork crown  445 , the fork blade assemblies  450 , and the wheel attachments  452  can be made from aluminum, while the remaining components not made from aluminum can be formed from other materials, such as a composite material. Other various combinations of materials can also be utilized. 
   Referring to  FIGS. 9 and 10 , the steerer tube  435  defines a central axis  455 , and is generally frustoconical in shape. The steerer tube  435  smoothly transitions or tapers from an upper portion  460  to a lower portion  465  without sharp corners in the steerer tube  435 . In other constructions, the steerer tube  435  can be substantially cylindrical in shape. Furthermore, while the illustrated steerer tube  435  is hollow with a uniform wall thickness, in other constructions the wall thickness may not be uniform. For example, in other constructions the wall thickness of the steerer tube  435  can increase or decrease from the upper portion  460  toward the lower portion  465 . 
   The fork crown  445  is in communication with the lower portion  465  of the steerer tube  4355 , and includes an archway  470  disposed between the fork blades  450  to accommodate a front wheel (not shown). 
   The upper portion  460  includes an outer dimension D 33  (28.6 mm in the illustrated embodiment). The lower portion  465  includes a taper or elongated angled portion  475  extending from the upper portion  460  of the steerer tube  435  toward the transition  440 . In the illustrated construction, the taper  475  is substantially straight from the upper portion  460  to the transition  440 . In other constructions, the taper  475  may be curved from the upper portion  460  to the transition  440 . An outer surface of the taper  475  defines an angle ε between the outer surface and the central axis  455  of the steerer tube  435 . The illustrated angle ε is about 3 degrees, and in other constructions, the angle ε is greater than about 5 degrees. While the illustrated taper  475  is frustoconical in shape, in other constructions, the taper  475  can have a plurality of sides. 
   The illustrated taper  475  includes an upper transition point  480  defined by the location where the taper  475  couples to the upper portion  460  of the steerer tube  435 , and a lower transition point  485  defined by the location where the taper  475  couples to the transition  440 . The upper transition point  480  is located at a distance D 34  from the archway  470  (135 mm in the illustrated embodiment). In other constructions, the distance D 34  can be any length. The taper  475  also has a first outer dimension D 35  (29 mm in the illustrated embodiment) at the upper transition point  480 , and a second outer dimension D 36  (38 mm) at the lower transition point  485 . In the illustrated embodiment, the first outer dimension D 35  of the taper  475  is equal to the outer dimension D 33  of the upper portion  460 . 
   The transition  440  extends from the fork crown  445  to couple the fork crown  445  to the steerer tube  435 , and includes an upper transition point  490  and a lower transition point  495 . The upper transition point  390  is defined by the location where the transition  440  couples to the taper  475 , which is the same location as the lower transition point  485  of the steerer tube  435 . The lower transition point  495  is defined by the location where the transition  440  couples to the fork crown  445 . The transition  440  has a first outer dimension D 37  (38 mm in the illustrated embodiment) at the upper transition point  490  and a second outer dimension D 38  (51 mm) where the transition  440  couples to the fork crown  445  at the lower transition point  495 . While the illustrated fork  430  includes a radius portion  497  located between lower transition point  495  and the fork crown  445 , in other constructions the fork  430  may omit the radius portion  497 . Therefore, for purposes of this patent application, the lower transition point  495  will be defined as the point where the transition  440  couples to the radius portion  497 , or in embodiments that omit the radius portion  497 , the lower transition point  495  will defined as the point where the transition  440  couples to the fork crown  445 . 
   In the illustrated embodiment, the first outer dimension D 37  of the transition  440  is equal the second outer dimension D 36  of the taper  475  at the upper transition point  490 . A first ratio is defined by the second outer dimension D 38  of the transition  440  divided by the first outer dimension D 37  of the transition  440 . In the illustrated construction, the ratio is about 1.34, and in other constructions the ratio is greater than about 1.30 or 1.25. 
   The transition  440  includes a frustoconical outer surface that defines an angle θ between the outer surface of the transition  440  and the central axis  455  of the steerer tube  435 . The illustrated angle θ is about 31 degrees, and in other constructions, the angle θ is greater than about 25 or 20 or 10 degrees. While the illustrated transition  440  is frustoconical in shape, in other constructions, the transition  440  can have a plurality of sides. 
   Referring to  FIGS. 7 and 10 , the fork assembly  425  also includes an upper bearing assembly  500  and a lower bearing assembly  505 . Generally, the upper bearing assembly  500  includes an upper bearing  510 , a compression ring  515 , and an upper cup  520 , which are similar to the upper bearing  305 , the compression ring  310 , and the upper cup  325  of the upper bearing assembly  295  discussed above with regard to  FIGS. 5 and 6 . As such, the upper bearing assembly  500  will not be discussed in detail. Generally, the upper bearing  510 , the compression ring  515 , and the upper cup  520  are sized to accommodate the outer dimension D 33  of the steerer tube  435  and an inner dimension of the head tube  410 . 
   The lower bearing assembly  505  includes a crown race  525 , a lower cup  530 , and a lower bearing  535 . The crown race  525  can be made from any suitable material, such as aluminum, steel, plastic, composite, etc. The crown race  525  is coupled to the fork  430  circumferentially around the upper transition point  490  such that the crown race  525  is fixed with respect to the fork  430 . In the illustrated construction, the crown race  525  is co-molded to the fork  430 , while in other constructions the crown race  525  can be bonded to the fork  430 . 
   The lower cup  530  is coupled to the head tube  410  such that the lower cup  530  is fixed with respect to the head tube  410 . The lower cup  530  can be made from any suitable material, such as aluminum, steel, plastic, composite, etc. 
   The lower bearing  535  is located the crown race  525  and the lower cup  530 , such that the lower bearing  535  is circumferentially around the upper transition point  490 . The lower bearing  535  can be any suitable bearing, such as a loose ball bearing, a retainer ball bearing, a cartridge type bearing, and the like. The illustrated lower bearing  535  has a diameter D 39  of approximately 46 mm. In other constructions, the lower bearing  535  can have any suitable diameter D 39 . 
   The illustrated lower bearing  535  is located at a distance D 40  from an end of the head tube  410 . In the illustrated construction, the distance D 40  is approximately 14 mm and in other constructions is at least about 8.5 mm. In yet other constructions, the lower bearing  535  can be located either above or below the upper transition point  490  of the transition  440 . 
   The upper transition point  490  of the transition  440  and the lower bearing  535  are located at a distance D 41  from the archway  470 . In the illustrated embodiment, this distance D 41  is 35 mm for the upper transition point  490  and 38 mm for the lower bearing  535 . In addition, the upper transition point  490  and the lower bearing  535  are located at a distance D 42  from the lower transition point  495  (essentially, the length of the transition  440 ). In the illustrated embodiment, this distance D 42  is 11 mm for the upper transition point  490  and 14 mm for the lower bearing  535 . 
   A second ratio is defined by the distance D 40  from the end of the head tube  410  to the lower bearing  535  divided by the outer dimension D 32  of the head tube  410 . In the illustrated embodiment, the second ratio is about 0.24. In other embodiments, the second ratio is at least about 0.20 and in yet other embodiments the ratio is at least about 0.16. 
   A third ratio is defined by the distance D 40  from the end of the head tube  410  to the lower bearing  535  divided by the diameter D 39  of the lower bearing  535 . In the illustrated embodiment, the third ratio is about 0.30. In other embodiments, the third ratio is at least about 0.25 and it yet other embodiments the third ratio is at least about 0.20. 
   A fourth ratio is defined by the distance D 41  from the archway  470  to the lower bearing  535  divided by the diameter D 39  of the lower bearing  535 . In the illustrated embodiment, the fourth ratio is about 0.83. In other embodiments, the fourth ratio is at least about 0.77 and preferably at least about 0.70. 
   A fifth ratio is defined by the distance D 41  from the archway  470  to the lower bearing  535  divided by the second outer dimension D 38  of the transition  440  at the lower transition point  495 . In the illustrated embodiment, the fifth ratio is about 0.75. In other embodiments, the fifth ratio is at least about 0.70 and preferably at least about 0.65. 
   A sixth ratio is defined by the distance D 41  from the archway  470  to the lower bearing  535  divided by the outer dimension D 32  of the head tube  410 . In the illustrated embodiment, the sixth ratio is about 0.66. In other embodiments, the sixth ratio is at least about 0.60 and preferably at least about 0.54. 
   Attachment of the fork assembly  425  to the frame  405  and the head tube  410  is similar to the attachment of the fork assembly  215  to the frame  25  and the head tube  200  described with regard to  FIGS. 5 and 6 . Operation of the fork assembly  425  within the head tube  410  also is similar to operation of the fork assemblies  55 ,  215  described above. As such, attachment and operation of the fork assembly  215  will not be discussed in detail. 
   Generally, the tapered head tube  410  and the taper  475  of the steerer tube  435  provide additional rigidity and strength to the frame and the fork assembly  425 , respectively. Generally, the larger lower bearing assembly  505  relative to the upper bearing assembly  500  allows the head tube  410  and the steerer tube  435  to be enlarged at its base to allow a relatively larger fork crown  445  and fork blade assemblies  450 , which in turn contributes to the stiffness of the bicycle  400 . The relatively small upper portions  415 ,  460  of the head tube  410  and the steerer tube  435 , and the upper bearing  500  provide for operation of the bicycle  400  while maintaining a relatively low overall weight of the bicycle  400 . 
   Various features and advantages of the invention are set forth in the following claims.