Originally posted by urbanrider
My seat post is a suspension type (Post Moderne).
It does rotate slightly from side to side which seems to be the case with this seat post.
I was concerned also with the weight rating of 20lbs. Seems like a lot for this kind of rack.
The mechanic at your bike shop ought to be able to fix your seatpost so it does not rotate. My Post Moderne (on a Trek hybrid, same as yours, I bet), used to rotate a little, but it does not now.