Drive belt assembly for an electric vehicle

1. A vehicle comprising:

a frame;

a powertrain unit coupled to the frame and having an output shaft rotatable in response to operation of the powertrain unit;

a drive sprocket coupled to the output shaft for rotation therewith;

a swing arm having a first end pivotably coupled to the frame and a second end supporting a drive wheel of the vehicle;

a wheel sprocket coupled to the drive wheel for rotation therewith;

a flexible final drive member wrapped around the drive sprocket and the wheel sprocket to establish a driving relationship therebetween, the flexible final drive member forming a loop; and

an idler bracket fixed with respect to the frame and supporting both an upper idler and a backside idler,

wherein the upper idler is positioned within the loop such that the flexible final drive member engages an upper side of the upper idler, and wherein the backside idler is positioned outside the loop such that the flexible final drive member engages an upper side of the backside idler.

2. The vehicle of claim 1 , wherein the powertrain unit includes a motor and a gearbox positioned rearward of the motor, the output shaft extending from the gearbox, and wherein the idler bracket is secured to the gearbox.

3. The vehicle of claim 1 , wherein the idler bracket has a ring portion surrounding the output shaft.

4. The vehicle of claim 1 , wherein the vehicle is a two-wheeled single-track vehicle.

5. The vehicle of claim 1 , wherein the upper idler is positioned by the idler bracket concentric with a swing arm pivot axis about which the swing arm first end is coupled to the frame.

6. The vehicle of claim 1 , wherein the backside idler is eccentrically and adjustably supported by the idler bracket.

7. The vehicle of claim 1 , wherein the upper idler defines an outer diameter that is greater than an outer diameter defined by the backside idler.

8. A vehicle comprising:

a frame;

a powertrain unit coupled to the frame and having an output shaft rotatable in response to operation of the powertrain unit;

a drive sprocket coupled to the output shaft for rotation therewith;

a swing arm having a first end pivotably coupled to the frame and a second end supporting a drive wheel of the vehicle;

a wheel sprocket coupled to the drive wheel for rotation therewith;

a flexible final drive member wrapped around the drive sprocket and the wheel sprocket to establish a driving relationship therebetween, the flexible final drive member forming a loop; and

a first idler positioned within the loop to intersect a tangent line extending between respective upper portions of the drive sprocket and the wheel sprocket such that an upper run of the flexible final drive member is deflected into a serpentine configuration,

wherein the first idler is concentric with a swing arm pivot axis about which the swing arm first end is coupled to the frame such that the first idler and the wheel sprocket define a fixed center-to-center distance for the full range of motion of the swing arm.

9. The vehicle of claim 8 , further comprising a second idler positioned outside the loop in contact with a lower run of the flexible final drive member to deflect the lower run into a serpentine configuration.

10. The vehicle of claim 9 , wherein the first and second idlers are supported on a common bracket.

11. The vehicle of claim 9 , wherein the second idler has an upper extent positioned at a height above the output shaft.

12. The vehicle of claim 9 , wherein the second idler is eccentrically and adjustably supported on the motorcycle.

13. The vehicle of claim 9 , wherein the first idler defines an outer diameter that is greater than an outer diameter defined by the second idler.

14. The vehicle of claim 8 , wherein the first idler is an idler sprocket having a toothed outer surface.

15. The vehicle of claim 8 , wherein the vehicle is a two-wheeled single-track vehicle.

16. A vehicle comprising:

a frame;

a powertrain unit coupled to the frame and having an output shaft rotatable in response to operation of the powertrain unit;

a drive sprocket coupled to the output shaft for rotation therewith;

a swing arm having a first end pivotably coupled to the frame and a second end supporting a drive wheel of the vehicle;

a wheel sprocket coupled to the drive wheel for rotation therewith;

a flexible final drive member wrapped around the drive sprocket and the wheel sprocket to establish a driving relationship therebetween, the flexible final drive member forming a loop including a drive side and a slack side; and

an idler positioned below the loop to intersect a tangent line extending between respective lower portions of the drive sprocket and the wheel sprocket such that the slack side of the flexible final drive member is deflected into a serpentine configuration,

wherein the idler is fixedly positioned relative to the drive sprocket, and

wherein the idler has an upper extent positioned at a height above the output shaft.

17. The vehicle of claim 16 , wherein the idler is fixedly positioned by an eccentric bolt, and loosening of the eccentric bolt provides adjustment of an intersection of the idler with the tangent line.

18. The vehicle of claim 16 , further comprising an additional idler positioned within the loop to intersect a tangent line extending between respective upper portions of the drive sprocket and the wheel sprocket, the additional idler positioned concentric with a swing arm pivot axis about which the swing arm first end is coupled to the frame.

19. The vehicle of claim 16 , wherein the vehicle is a two-wheeled single-track vehicle.