Dropper seatpost oscillating - relation to rear shock I have a full suspended bike with a dropper seat post :



I had a dubious setup of my saddle and of the seat post at the blue circles, that I solved, but now when I ride on flat, with the coil of my shock set up quite rigidely (to ride on road) the dropper seatpost oscillates, in the plane of the bike, from front to back, exactely at the red circled region, on which I have no power.

Do you think the dropper seatpost is damaged or ? Other question : could this front to back oscillation damage the rear shock as it make it work more that if there woudnl't be any oscillation in the red region ?

Remark : the dropper seatpost is a KINDSHOCK LEV INTEGRA, 31.6 mm, 150 mm.
So you are basically saying the upper part of the dropper post is loose in the lower. 

There is definitely something broken, possibly a bushing between the upper and lower has broken or worn out. Without knowing the specific model it's not possible to give more advice, you may be able to find a manual for your specific model that provides a drawing or list of parts

The suspension will not be affected at all.