Hi, i also have this problem... I bought the SP version of the MT-09, which comes with this shock preinstalled, and I tried to setup suspension the same way as you and I also have 0 static sag with all preload out...
I found some suapension tehnician and can't wait to go and see what he has to say, because I have another problem - My weight is 69kg with full gear and rear spring is to hard for me.
Can you unwind the top adjuster ring more? Do you have some space? If you do, you dont have a problem. If you cant, jut buy 85N/mm. And you have whole 10mm from prload knob of preload to add to fine tune it.
My problem is that i cant fix it.
Ohlins Rear spring for mono ohlins, 01092-26 85, Shock Absorber, Suspension, by Ohlins, Description Our springs comes in a few different colors, with the typical and well recognized Öhlins yellow the most common. Our springs are developed s...
www.omniaracing.net
My R1-R2 now with 115 is 0. And my R2-R3 is 34. If i get softer 170mm spring i will overshoot the R1-R3. And the damn spring rate is fine for me, it is not to hard, i can bottom it out while riding on bumps with COMP and 12. Im fanatic allways riding with zip ties both on shocks and forks...
I got response from Ohlins. No word on collar, bit as i asked about spring replacement with 160mm. Answer is that i can go with 160mm,
BUT there is a catch that i knew. And that is that i CANT go lower than 149 of preloaded spring (spring free leng is shorter. That gives me 11 mm of max preload. There is another damn catch that Ohlins doesnt have harder 160mm spring for STX than 01091-39 110N/mm.
My mental calculations gave me 120N/mm for my problem for 160mm spring.
Ohlins guy is respected race tuner with lots of expirience, he thinks 110 N/mm 160 is enough, i dont.
My options by order of best solutions.
1. Get lower spring clip, 3mm lower clip should change averything, and that should be cheapest
2. Get 105N/mm 170mm and lose 10kgs

I planed to lose weight...but damn corona

3. Listen to the Ohlins tuner get 160mm 110N/mm and gamble like with 5mm of preload from upper ring, and 5mm of adjustment from knob,a and i cant use all knob (up to 10mm).
I dont know who did calculations for this shock on this bike but Ohlins recomends 14mm of preload for this bike (thats 135kgs of preloaded force!!!), and no mater the linkage and geometry this is simply 2 much for this light bike to have free sag.