US 20070119645A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2007/0119645 A1 Michelotti (43) Pub. Date: May 31, 2007 (54) MOTORCYCLE DRIVE SHAFT OFFSET Publication Classi?cation ASSEMBLY (51) Int. Cl. (76) Inventor: William M. Michelotti, Stamford, CT B62D 61/02 (2006.01) (Us) (52) US. Cl. ............................................................ .. 180/219 Correspondence Address: ST. ONGE STEWARD JOHNSTON & REENS (57) ABSTRACT LLC 986 Bedford Street Stamford, CT 06905-5619 (US) A poWer transmission assembly for transmitting rotational torque from a motorcycle engine to an oversiZed rear Wheel (21) Appl. No.: 11/564,006 of a motorcycle, the assembly including a front drive shaft, (22) Filed: Nov. 28, 2006 an intermediate offset poWer transmission assembly and a rear drive shaft, all provided in a motorcycle sWingarm. Related US. Application Data +The intermediate offset poWer transmission assembly alloWs for the rear drive shaft to be axially offset relative to (60) Provisional application No. 60/740,917, ?led on Nov. the front drive shaft so as to position the rear drive shaft 30, 2005. outboard of the oversiZed rear Wheel. 122 140 Patent Application Publication May 31, 2007 Sheet 1 0f 5 US 2007/0119645 A1 222.4132,N_\w 0:. \ o2. .UEr Patent Application Publication May 31, 2007 Sheet 2 0f 5 US 2007/0119645 Al m“A_MDUEGH llllirii;.rDnFDQ/l\ llllLwlh.N\v /mow m: N.DE PDnmé MDOEOF Patent Application Publication May 31, 2007 Sheet 3 0f 5 US 2007/0119645 A1 FlG. 3 Patent Application Publication May 31, 2007 Sheet 4 0f 5 US 2007/0119645 A1 o3 .QEw Patent Application Publication May 31, 2007 Sheet 5 0f 5 US 2007/0119645 A1 FIG.5 102120/ 100 138/ US 2007/0119645 A1 May 31, 2007 MOTORCYCLE DRIVE SHAFT OFFSET [0010] The drive shaft of a standard motorcycle typically ASSEMBLY extends rearWard toWard an outboard position adjacent to the rear Wheel of the motorcycle. The drive shaft is designed CROSS-REFERENCE TO RELATED to engage With a Wheel having a particular Width, typically APPLICATIONS the same Width as the front Wheel. HoWever, When an [0001] This application claims the bene?t of the ?ling date oversiZed Wheel (a Wheel having an increased Width) is used, the drive shaft provided from the factory extends into the of US. Provisional Patent Application Ser. No. 60/740,917 oversiZed Wheel. ?led Nov. 30, 2005. [0011] The present invention provides a front drive shaft FIELD OF THE INVENTION coupled to one end of an intermediate o?fset poWer trans mission assembly Which is in turn coupled to a rear drive [0002] The invention relates to poWer transmission assem shaft Which transmits output torque to the oversiZed rear blies in motorcycles and more speci?cally to a poWer Wheel. The intermediate o?fset poWer transmission assembly transmission shaft for transmitting rotational torque to a rear transmits rotational torque input from the front drive shaft to Wheel of a vehicle. the rear drive shaft, Which is longitudinally offset from the front drive shaft. The intermediate o?fset poWer transmission BACKGROUND OF THE INVENTION assembly is provided to longitudinally offset a portion of the [0003] Motorcycles and tWo-Wheeled vehicles are typi drive shaft to a position that is outboard of the oversiZed rear cally equipped With standard equally siZed front and rear Wheel. The axis of the front drove shaft is offset from the Wheels. It is hoWever, a popular pastime among motorcycle axis of the rear drive shaft so that the tWo shafts may be enthusiasts to alter their motorcycles With customizations, considered axially o?fset relative to each other. The inter such as paint and/or structural modi?cations. A popular mediate o?fset poWer transmission assembly may comprise custom feature is the installation of an oversiZed rear Wheel. torque transmission devices including, for example, chain One such custom modi?cation is to provide an oversiZed and sprocket drives, belt drives, a gear set, or even a rear Wheel having a Width Which is Wider than the original hydraulic drive system. The front drive shaft, intermediate equipment manufacturer Wheel. Installation of an oversiZed o?fset poWer transmission assembly, and rear drive shaft are tire adds to the aesthetic appearance of the motorcycle. built into the sWingarm of the motorcycle rear Wheel and serve as the left side of the sWingarm. [0004] HoWever, installation of an oversiZed rear Wheel presents a number of challenges, most particularly, in rout [0012] Other objects of the invention and its particular ing poWer from the transmission to the oversiZed rear Wheel. features and advantages Will become more apparent from There are tWo principle drive designs in use in motorcycles: consideration of the folloWing draWings and accompanying (1) belt or chain drives found on many Harley-Davidson® detailed description. motorcycles, and (2) shaft drive assemblies found on motor cycles such as the Honda® Aero 750 and the BMW® BRIEF DESCRIPTION OF THE DRAWINGS K11200S. Several designs have been presented for routing [0013] FIG. 1 is a block diagram of one advantageous poWer to a rear Wheel in belt or chain drive motorcycles embodiment of the present invention. retro?tted With an oversiZed rear Wheel, such as those disclosed in US. Pat. Nos. 6,755,272 and 6,575,260. [0014] FIG. 2 is a block diagram of the intermediate o?fset poWer transmission assembly according to FIG. 1. [0005] HoWever, With shaft-driven designs, the problem of transferring torque to a Wider rear Wheel becomes excep [0015] FIG. 3 is an illustration of an advantageous tionally dif?cult as the oversiZed rear Wheel Will block the embodiment of the present invention according to FIG. 1. path of the drive shaft to the rear drive coupling. Therefore, [0016] FIG. 4 is an exploded vieW of the advantageous the previously knoWn systems for accommodating and over embodiment according to FIG. 3. siZed rear Wheel cannot be used in a shaft drive assembly. [0017] FIG. 5 is a top vieW of the advantageous embodi SUMMARY OF THE INVENTION ment according to FIG. 3. [0006] What is desired therefore is a system and method DETAILED DESCRIPTION OF THE for transmitting driving torque to the rear Wheel of a shaft INVENTION drive motorcycle, Where the rear Wheel is provided as an oversiZed Wheel. [0018] Referring noW to the draWings, Wherein like ref erence numerals designate corresponding structure through [0007] It is further desired to provide a system and method out the vieWs. for retro?tting a motorcycle With an oversiZed rear Wheel that accommodates the drive shaft assembly of the motor [0019] The present assembly alloWs for retro?tting of a cycle. Wider rear Wheel onto an existing motorcycle frame. The retro?tting process includes replacing the existing sWingarm [0008] It is still further desired to provide a system and method that provides a reliable, simply design for reposi With the sWingarm 121. While a particular siZed rear Wheel is illustrated, many different siZed Wheels may effectively be tioning the drive shaft of a motorcycle to a position outboard used With the assembly. The Wider oversiZed rear Wheel 112, of an oversiZed rear Wheel. the longer elongated housing 118 must be to position rear [0009] These and other objects are achieved in one advan drive shaft 106 outboard of the Wheel. It is contemplated that tageous embodiment by the provision of an intermediate a number of standard siZed housing may be made to coincide o?fset poWer transmission assembly and rear drive shaft. With standard Wheel Widths. US 2007/0119645 A1 May 31, 2007 [0020] FIG. 1 is a block diagram depicting power trans side of oversiZed rear Wheel 112, it is contemplated that the mission assembly 100. Power transmission assembly 100 drive shaft may also be positioned on the right side of generally comprises, front drive shaft 102, intermediate oversiZed rear Wheel 112 in some applications. The right arm o?fset poWer transmission assembly 104 and rear drive shaft 134 has a substantial offset to accommodate the oversiZed 106. As shoWn in FIG. 1, front drive shaft 102 is located rear Wheel 112, hoWever, other different con?gurations and after the motorcycle engine torque output and the transmis shapes may effectively be used. As can further be seen in sion output 108 and extends to the intermediate o?fset poWer FIGS. 3-5, sWingarm 121 includes the front shaft cover 120 transmission assembly 104. Front drive shaft 102 is pro and a support member 136, Which provides a robust cou vided to transmit rotational torque from the motorcycle pling for the left and right sides of the sWingarm 121. engine/transmission assembly to the intermediate o?fset poWer transmission assembly 104. Rear drive shaft 106 [0024] Front drive shaft 102 is coupled to the motorcycle engine by Way of a motorcycle transmission. As best seen in receives rotational torque from intermediate o?fset poWer transmission assembly 104 and transmits the torque to FIG. 4, front drive shaft 102 is contained in front shaft cover 120. Front shaft cover 120 is Welded or otherWise a?ixed to oversiZed rear Wheel 112. Rear drive shaft 106 extends from front Wall 124 of an elongated housing 118 in Which the intermediate o?fset poWer transmission assembly 104 to intermediate o?fset poWer transmission assembly 104 is a rear drive mechanism 110. Rear drive mechanism 110 is located. An opening 126 is located in the front Wall 124 and typically a ring gear or bevel gear mechanism transferring front drive shaft 102 extends into elongated housing 118. poWer from the rear drive shaft 106 to oversiZed rear Wheel 112. Elongated housing 118 extends perpendicularly to front shaft cover 120 and rear shaft cover 122.