Dear All I am having problems installing my Fizik Arione Kium railed saddle onto my new Bontrager xxx seatpost. It appears that the head of seatpost is too large, and I cannot get rails to fit without splaying rails slightly to get head of post in and once this is done rails seem under tension. Obvisously with carbon post bit concerning. I have previously removed the adjusted cups but sure they are in correctly. Is there some subtle difference in rail width on bontrager saddles compare to fizik ones? Or is this a common problem? Many thanks