TOMAS
Senior Retro Guru
As others have pointed out... I also run a lot of post with a lots of my bikes, mainly steel, some Ti, some alloy but I weigh in at over 14 stone too. Creaking/cracking noises are usually the plastic shell of the saddle moving around the ends of the seat rails. Some brands are a lot worse for it than others, take post out and clean inside of frame/post and also all around the underside of the saddle, especially where the metal rails go into the saddle shell. Sometimes a wax type lube or something which goes in wet and sets harder such as spray white grease etc in the saddle rail mounts can take away the noise for a while but often it comes back I find. Seatpost just apply a smear of grease, you don't need to go mad otherwise it can make it slip easily.