I am having an odd problem with the Selle Italia Flite saddle I have on my Centurion. I am using the original SR Laprade type seat post and the seat keeps sliding to the rear, no matter what I do. It seems to fit fine, appears to tighten down ok, but after I ride a short distance, especially if I climb a hill, the seat has slipped to the rear. The weird thing is I don't feel it slip, it just moves slowly and gradually.

I changed the seat to a Fizik Aliante (the seat for my Canopus), and it works fine, no slipping.

Am I missing something or doing something wrong?