Originally Posted by
rpenmanparker
Perhaps a question of more interest is why your seat post has so little extension. Since most CF frames are compact design with sloping top tube, and you only need about 4 inches exposed for the clamp, that suggests the frame is considerably too large for you. Not a definitive conclusion, but that is my first guess.
It could be that the clamp itself is quite long. My clamp is 4.25" long. The clampable length of my 54cm carbon bike is 4.5", so it's a pretty tight fit to begin with.