SR Suntour SP12 NCX Seatpost with a bushing insert

I did the same and used a 100mm seatpost shim with my 27.2mm 400mm Cirrus Kinekt Bodyfloat on my Radrover when I needed 30.9mm to transfer over the seatpost to my Himiway Cobra Pro. Zero issues with movement with paved road or trail riding. Still have the Radrovers and I can now flip-flop my suspension seatpost between ebikes.