Patent Application
20050179228
The present invention generally relates to bicycles, and particularly to handlebars that attach to bicycles.
Bicycles typically include handlebars that attach to the front wheel of the bicycle to allow the rider to steer. Often the handlebars are formed from a metal tube and are clamped directly to a steering stem. The stem attaches to a fork that supports the front wheel for rotation. On some bicycles, the handlebars support bicycle controls, such as shifters and brake levers, in easily accessible positions.
During a bicycle ride, the rider will often encounter bumps or uneven road conditions that cause vibrations. Because most handlebars are rigidly connected to the front wheel, the vibrations are easily transmitted from the front wheel to the handlebars. From the handlebars, the vibrations can pass into the rider's arms and hands. These vibrations can be uncomfortable to the rider.
The present invention provides a bicycle handlebar assembly designed to reduce the transfer of vibrations to the rider. The handlebar assembly includes an outer member (e.g., a cylindrical tube) attached to a stem and an inner member (e.g., handlebars) that is shaped to define hand locations. The outer member at least partially surrounds a portion of the inner member to define a space (e.g., about 1.4 mm thick) between the two members. A damping member (e.g., made from urethane rubber) is positioned between the inner and outer members, and preferably bonds them together. The damping member provides vibration damping to reduce the vibrations transferred to the inner member.
In one embodiment, the damping member extends beyond the ends of the outer member. In another embodiment, the outer member includes a window that exposes a portion of the damping member.
The detailed description particularly refers to the accompanying figures in which:
Before any embodiments of the invention are explained, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements 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 and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof is meant to encompass the items listed thereafter and equivalence thereof as well as additional items. The terms “connected,” “coupled,” and “mounted” and variations thereof are used broadly and encompass direct and indirect connections, couplings, and mountings.
The attachment between the stem 45 and the handlebar assembly 15 is shown in greater detail in
The handlebar assembly 15 includes an inner member in the form of an inner tube 65, an outer member in the form of an outer tube 70, and a damping member 75. The inner tube 65 is similar to standard handlebars and is formed into the desired handlebar shape to include hand positions 80. Adjacent the hand positions 80 are various bicycle controls, such as shifter and brake control levers 85 (shown in
As illustrated in
In most constructions, the inner tube 65 and the outer tube 70 are similarly shaped (e.g., round, as shown in
With reference to
While
The damping member 75 is positioned within the annular space 95, as shown in
The outer tube 70 is formed to have sufficient length to allow it to engage the stem 45. Some constructions may use longer or shorter tubes as may be required to allow for proper engagement with the stem. In addition, the length of the outer tube 70, and thus the ratio of the damping member thickness to the outer tube length, may be varied to change the damping. For example, a construction with a damping member thickness of 1.4 mm and an outer tube length of 25 mm results in a thickness to length ratio of 0.056. Thickness to length ratios are preferably less than about 0.1, and more preferably less than about 0.06.
The handlebar assembly can be produced using a mold like the one shown in
The inner tube clamp surfaces 130 engage the inner tube 65 and hold the inner tube 65 in its desired position. The inner tube clamp surfaces 130 and the inner tube 65 cooperate to define a seal that inhibits the flow of damping material past the end of the tapered end portion surfaces 140. The outer tube clamp surface 135 engages the outer tube 70 and holds it in its desired final position. The mold half 115 illustrated in
The tapered surfaces 140 are shaped to define the tapered end portions 110 when the molding process is complete. The tapered surfaces 140 also provide a convenient inlet into the space 95 between the inner tube 65 and the outer tube 70. As such, the flow path 145 extends from each of the tapered surfaces 140 to a common feed point 150. The feed point 150 is located outside of the mold half 115 to facilitate the injection of the damping material into the assembled mold.
The flow path 145 is shaped to guide the damping material into the annular space 95 as well as the tapered end portions 110 adjacent the ends of the outer tube 70. In addition, the mold halves 115 allow the damping material to flow at least partially into any windows 105 defined within the outer tube 70.
To manufacture the handlebar assembly 15, the outer tube 70 is cut to size and windows 105 in the outer tube 70 are formed (e.g., cut, machined, punched, and the like). The outer tube 70 is then positioned over the inner tube 65, and the inner tube 65 is bent to the desired handlebar configuration. Alternatively, the outer tube 70 can be positioned over the inner tube 65 after the inner tube 65 has been bent. The inner tube 65 and the outer tube 70 are then clamped into the mold 115 in their desired final positions. The mold 115 is then closed and the damping material is injected in a liquid form into the mold 115 through the common feed point 150. The damping material flows between the inner tube 65 and the outer tube 70 and into the windows 105. The resilient material is allowed to cure to bond the inner tube 65 to the outer tube 70 and complete the assembly 15.
In preferred constructions, a two-part urethane rubber compound is used to form the damping member 75. The two parts are mixed together to form a liquid that is injected into the mold and subsequently cured to form the damping member 75. In other constructions, the damping member could be positioned between the inner tube 65 and the outer tube 70 in a solid form. In addition, other materials could be used (e.g., polyurethane, plastic, natural rubber, cork, and the like).
To improve the bond between the inner tube 65 and the outer tube 70, some constructions roughen the outer surface of the inner tube 65 and/or the inner surface of the outer tube 70. Sanding, scoring, knurling, sandblasting, or any other suitable process can roughen the surfaces. The roughened surface produces more surface area and improves the bond between the resilient material and the roughened tube.
In use, the handlebar assembly 15 is attached to the stem 45 of the bicycle 10 by clamping the outer tube 70 with the split clamp 60. The rider steers the bicycle 10 by rotating the inner tube 65 and the stem 45 to turn the front wheel 40. Vibrations picked up by the front wheel 40 are transmitted to the fork 35, the stem 45, and the outer tube 70. The damping member 75 provides damping between the outer tube 70 and the inner tube 65, thus isolating the rider from at least a portion of the vibrations encountered by the front wheel 40.
The thickness and durometer of the damping member 75, along with the position, quantity, size, and shape of the windows 105 are chosen to achieve the desired damping, while still maintaining the desired “feel” between the rider and the bicycle 10. For example, a material with an improper durometer and thickness may provide significant damping but may feel “soft” to the rider. On the other hand, a high durometer coupled with a thin damping member 75 may result in insufficient damping.
Testing has shown that a damping member 75 having a durometer of about 80 on the A scale and a thickness of about 1.4 mm provides adequate damping without adversely affecting the feel of the bicycle 10 to the rider. Of course, other constructions with higher or lower durometer values and thinner or thicker damping members 75 may achieve suitable results depending on the particular application.
An alternative embodiment of the present invention is illustrated in
The split damping member 202 is molded separate from the other parts and includes a longitudinal split 206 that facilitates mounting the damping member 202 onto a handlebar (not shown in
The outer tube portions 204 are dimensioned to be positioned over the damping member 202 and bonded or otherwise secured in place. The outer tube portions 204 sandwich the damping member 202 and, when secured in place, create a unified handlebar assembly. One of the outer tube portions 204 covers most of the longitudinal split 206 of the damping member 202. Each outer tube portion 204 includes cutouts 210 that correspond to the shape of the raised portions 208 so that the raised portions 208 are positioned between the cutouts 210 when the assembly is complete.
Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of the invention as described and defined in the following claims.
