Abstract:
The present invention provides a compound, system, and method for retrofitting and converting standard bicycle rims and tires having tubes to be tubeless. Standard tube tires are retrofitted by installing either rim tape or a rim strip with integral valve stem around the inner channel of the rim, mounting the first bead of the tire, injecting a liquid sealing compound into the tire cavity, finishing mounting the tire, inflating, and installing the tire on a bicycle. The sealing compound may additionally contain propylene glycol or an aggregate material to encourage the sealing of the tires as punctures occur when the tire system is placed into use.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The present invention relates generally to tubeless bicycle tires, and more particularly to a compound for sealing tubeless tires, and a system and method for retrofitting and converting bicycle tires having tubes to tubeless tires. 
     2. Description of Prior Art 
     Tubeless tires for bicycles and other wheeled vehicles are known in the art. Generally, tubeless tires are manufactured from thicker gauge rubber and often contain additional material on the inside of the tire to insure an airtight seam with the tire rim. Tubeless tires also require special rims which are designed to provide an airtight seal with the tire. 
     The specially manufactured tubeless tires and rims are typically more expensive than non-tubeless tires and rims. Tubeless tires and rims are also heavier than the non-tubeless tires and rims, due in part to the extra materials and design components necessary to an provide airtight seal between the tube and rim. 
     OBJECTS AND ADVANTAGES 
     It is a principal object and advantage of the present invention to provide a system for retrofitting non-tubeless tires to run tubeless. 
     It is an additional object and advantage of the present invention to provide a tubeless tire system which is lighter than conventional systems. 
     It is a further object and advantage of the present invention to provide a tubeless tire system which is cheaper than conventional systems. 
     It is another object and advantage of the present invention to provide a compound for sealing punctures as they are formed in a tire. 
     Other objects and advantages of the present invention will in part be obvious, and in part appear hereinafter. 
     SUMMARY OF THE INVENTION 
     In accordance with the foregoing objects and advantages, the present invention provides a compound and system for retrofitting and converting traditional bicycle tires having tubes to be tubeless. The system comprises a layer of rim tape or a rim strip with integral valve stem disposed on the inner channel of the rim and a latex sealing compound injected into the tire cavity. The sealing compound is a mixture of liquid latex containing ammonia with water. Sealing compound may additionally contain propylene glycol and/or an aggregate material. Standard tube tires are retrofitted by installing the rim tape or rim strip with integral valve stem around the inner channel of the rim, mounting the first bead of the tire, injecting the liquid sealing compound into the tire cavity, mounting the second bead of the tire, and installing the tire on a bicycle. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a traditional bicycle wheel; 
     FIG. 2 is a cross-section of a non-tubeless rim and tire retrofitted according to the present invention; and 
     FIG. 3 is a cross-section of a non-tubeless rim and tire retrofitted according to the present invention. 
     FIG. 4 is a cross-section of a rim strip according to the present invention. 
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawing in which like reference numerals refer to like parts throughout, there is seen in FIG. 1 a traditional bicycle wheel  10  comprising a hub  12 , a plurality of spokes  14  engaged with hub  12  and supporting a circular rim  16 , a tire  18  mounted within rim  16 , and a valve  20  communicating with an inflatable inner tube (not shown) within tire  18 . 
     As seen in FIG. 2, the system of the present invention comprises rim  16 , a single layer of nylon reinforced tape  22  extending along its outer circumference and in complete covering relationship to spoke holes  26 . Nylon tape  22  is preferably a commercial grade tape rated for 300 psi and should be narrower than the base of rim cavity  38  to insure proper seating. Some rims  16  to be retrofitted may already contain an acceptable layer of nylon tape. Rim  16  is also lined with a rubber sealing tape  24  along the outer circumference of its inner cavity  38  and in complete covering relationship to spoke holes  26  and nylon tape  24 . Sealing tape  24  can be any commercially available electrical tape wide enough to cover spoke holes  26  as well as nylon tape  24 . Sealing tape  24  should be conformable to irregularities in rim  16  to insure an airtight seal. 
     A sealing compound  28  fills and seals any leaks, perforations, and punctures and insures an airtight contact between the opposing tire beads  30  and  32  and opposing rim ridges  34  and  36 . Sealing compound  28  comprises a mixture of a natural liquid latex that contains ammonia and a corresponding amount of water. Compound  28  can vary from one to five teaspoons of liquid latex for every ¼ cup of water to form a mixture which is non-viscous enough to seal punctures but viscous enough to flow through tire  18 . Depending on temperature and humidity, sealing compound  28  made with water will generally last one to six weeks, after which more compound should be added to maintain proper tire inflation and protect against punctures. In addition to allowing the conversion of a standard tire to a tubeless tire, the use of sealing compound  28  will also immediately seal any punctures as they occur during operation of the bicycle. 
     Sealing compound  28  may optionally contain propylene glycol to slow the drying of compound  28 . To prepare a quart of sealing compound  28  according to this embodiment, six ounces of liquid latex should be mixed with 14 ounces of water and 12 ounces of propylene glyco. Compound  28  should first be prepared by mixing liquid latex with water and then adding the propylene glycol. In addition to providing a tackier, longer-lasting compound  28 , this mixture will also resist freezing at operating temperatures below 32 degrees Fahrenheit. 
     Sealing compound  28  may additionally contain approximately ½ ounce of an aggregate material. Aggregate material is comprised of a mixture of different size particles which aid in filling larger punctures which may develop in tire  18  by helping to fill in the large space formed by a puncture while sealing compound fills the interstitial gaps. The size of the particles in aggregate material should vary between about 0.15 mm to 0.60 mm. A substance which can serve as the aggregate material is commercially available ground cornmeal. One useful sample of cornmeal contained 41.6 percent of particles between about 0.30 mm and about 0.6 mm and 39 percent of particles between about 0.15 mm and about 0.30 mm. Stabler compounds, such as polymer resins, which can be formed into the appropriate diameter ranges may also be used. 
     Retrofitting a non-tubeless wheel involves first removing tire  18  and disposing of the tube and rim strip, if any. Rim  16  should be thoroughly cleaned with an appropriate lacquer thinner or enamel reducer to remove excess debris. Rim  16  should also be sanded with a scouring pad or fine sand paper to debur spoke holes  26 . If rim  16  contains any spoke alignment holes, the holes should be filled with a fast setting epoxy. The hole left by the removal of the inner tube valve stem  20  should be at least {fraction (19/64)} of an inch and should be drilled out if smaller and then deburred. 
     Nylon reinforced tape  22  is first applied to the outer circumference of rim  16  so that spoke holes  26  are entirely covered. As some rims to are retrofitted may already contain a layer of tape, this step is optional. First end of tape  22  is placed between adjacent spoke holes  26  and then wrapped around the base of channel  38  for one revolution and allowed to overlap the first end by approximately two inches. Sealing tape  24  is applied in the same manner, avoiding any wrinkling or undue stretching of tape  24 . The hole through which the inner tube valve stem  20  formerly passed must be cleared for insertion of a replacement valve stem  44  by inserting a pointed implement, such as a phillips head screwdriver through nylon tape  22  and sealing tape  24 . The hole for valve stem  44  should subsequently be cleaned using downward strokes with a round file or similar instrument to remove any excess tape  22  or  24 . 
     Installation of a replacement valve stem  44  involves using of a small amount of sealing compound  28  onto the rubber portion  46  of valve stem  20 . Valve stem  20  is then inserted into the prepared valve stem hole and a valve nut  48  is tightened by hand onto threaded portion of valve stem  20  while maintaining pressure on base  50 . 
     As seen in FIGS. 3 and 4, a rim strip  60  with an integral valve stem  70  may be used instead of the double seal provided by nylon tape  22  and sealing tape  24 . Rim strip  60  can be made from butyl rubber molded into a circular strip. The outer edges  62  and  64  of rim strip  60  have an increased thickness from median portion of rim strip  60 . Rim strip  60  is wide enough so that outer edges  62  and  64  will engage rim ridges  34  and  36  when rim strip  60  is seated into rim channel  38 . The diameter of rim strip  60  should be less than the diameter of rim  16  to insure a tight fit after installation. The width of rim strip  60  can vary depending on the size of rim  16  as commercially manufactured rims  16  are made in a variety of widths and diameters. An airtight seal is formed by beads  30  and  32  engaging outer edges  62  and  64  and rim ridges  34  and  36 , correspondingly. Installation involves stretching rim strip  60  over rim  16  and into rim channel  38 . Integral valve stem  70  is placed into valve stem hole  66  and rim strip  60  is allowed to radially contract into contact with base of rim channel  38 . 
     Mounting of tire  18  is accomplished by resting rim  16  in a horizontal plane and aligning lower bead  30  of tire  18  within the rim channel  38  and in contact with rim ridge  34 . Sealing compound  28  is then poured inside tire cavity  40  and upper bead  32  is seated inside corresponding rim ridge  36 . Tire  18  can now be inflated via valve stem  44 , preferably by an air compressor as inflation may require substantial amounts of air while sealing mixture  28  seals beads  30  and  32 , as well as any other avenues from which air may escape. Wheel  10  should be held in vertical plane while inflating so beads  30  and  32  are not distorted. Rotation of wheel  10  after inflation will allow sealing compound  28  to thoroughly coat the inner surfaces of channel  28  or tire cavity  40  and seal any leaks. Wheel  10  can then be installed onto a bicycle, which should be ridden for a minimum of thirty minutes to ensure proper distribution of sealing compound  28  throughout the rim channel  38  and tire cavity  40 .