I managed to check and set the sag for my 260 lbs human body to Zero's recommended ~2 inches -- on my own for my 2013 Zero S. As you may have read that the rear shock is factory set for a 180 lbs person. I had to DIY it, so I came up with this method.
Parts required:
1 18 inch expanding curtain rod from Lowes (like 2 dollars)
1 wire twist-tie.3 inches of velcro strap.>>vlecro'd the top of the curtain rod to the left turn signal, it tops out touching the fender. You could clamp this to the fender as well. Just make sure that it is fully extended after removing your weight when measuring, if it is only velcro'd to the turn signal.
1 clamp. >> clamped the other end of the rod to the underside of the frame on the left side directly beneath the left turn signal. Pad with a cloth so as to not harm the frames finish.
one ink pen.gloves and spanner wrench.tape measure.I used a mallet and a center punch to gently tap loose the locking ring above the rear spring adjuster since my spanner wrench could not quite do it.
See Photo: It is like the curtain rod was designed for this. It really works well. Make your first mark, while lifting up on the back end, with the ink pen at the intersection where the upper rod enters the lower half of the rod. Place the twist-tie so that it gets moved when the curtain rod collapses under your weight and then stays with the upper rod when it expands again. Where it ends up is your second mark. Measure the difference between the twist tie and the line, adjust the rear spring and then measure again.
This would have worked better for the first mark if I had a stand to put the bike upon. And that is zero's recommendation. So this method is going to be less precise because I did not quite lift it off of the ground. I am sure I got it to as far as it was going to extend though by lifting the back end up and placing the first mark. That was the hardest part.
I got it set to 2 inches, per the manual, using this method and now I am going to test ride. Will fine tune from there. Cheers.
[I used to watch MacGyver a lot.]