A drivetrain system for a reverse trike configured to transmit power from the motor to the rear wheel includes a first and a second drive chain being the only two drive chains utilized. A jackshaft has at one end a first universal joint connected to a first jackshaft sprocket and at an opposite end has a second universal joint connected to a second jackshaft sprocket. The first drive chain is connected between the motor output sprocket and the first jackshaft sprocket. The second drive chain is connected between the second jackshaft sprocket and the rear wheel drive sprocket. The first jackshaft sprocket is rotatably attached to the frame and configured to be movable away from and towards the motor output sprocket. The second jackshaft sprocket is rotatably attached to the frame and configured to be movable away from and towards the rear wheel drive sprocket.