Chain tensioner for motorcycle with rear suspension - has jockey tensioning sprocket positioned to operate under power and on overrun

摘要

The motorcycle with rear suspension has difficulty in maintaining correct driving chain tension because the pivot axis of the swinging arm does not coincide with the axis of the driving sprocket. This can be overcome by correctly choosing the position for the tensioning sprocket (4) in relation to the driving sprocket (1) and the pivot point (3) of the rear suspension. This position is chosen so that the slack in the chain due to the reduction in centre distance between wheel spindle and driving sprocket (1) is equal to the extra length of chain which becomes wrapped around the tensioning sprocket (4). With this arrangement the correct tension is also maintained when using the engine as a brake.