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[ESokoloff]

Yesterday I adjusted the belt on my 16 DSR & found that the tension varied upwards of 20kg depending on the position of the wheel. 

The following are my notes that I compiled after the task so please correct or confirm the accuracy.


Belt tension is greatest with valve stem in the 10:30 position.  (20/40kg)
(Note: The tension range & wheel location is likely unique to my bike.)

Jacking left screw(bolt) out moves the belt to the right.
Best to get the belt in the correct position/alignment, then adjust tension.
NOTE: Position belt with a right side biases as it will shift to the left when the axle bolt is tightened.   


I wonder if there is a tolerance on the rear sheave to wheel attachment?
I'm theorizing that's the cause of the inconsistency.

 

[Shadow]

Check belt tension 3 to 4 times while turning the rear wheel in a forward direction to get an average, as the rear pinion tolerance is allowed to be out-of-round as you describe.

[rayivers]

I wonder if there is a tolerance on the rear sheave to wheel attachment? I'm theorizing that's the cause of the inconsistency.

I agree.  My older bikes have sprocket studs w/tapered bosses where they enter the hub and my YZ uses counterbores on the sprocket for the screw heads, both of which result in a pretty well-centered sprocket.  My Zero rear pulley has counterbores for the screw washers and a machined hub ring for the pulley center, but the washer & pulley I.D.'s make for a fairly sloppy fit for something intended for a fixed-tension belt drive.  Perhaps replacing the screws with low socket-head or button-head screws that fit the counterbores closely w/o washers might make a difference, I never tried it.

Ray