Mr Beanz, I position the seat within the markers that are on the rails, the clamp is inside of those marks and not really close to the limit either, the saddle on the Xcal was installed by the LBS when they built the bike and again it sits on the clamp in an acceptable place. Its driving me nuts! (well it was when I was riding more, now that its cold out the Xcal is sitting and the K2 is on the trainer) Its happened on more than one bike/saddle/post and the only common denominator is the rider...
Maybe I am flexing something when I ride? but why then only on the longer rides? see why it drives me nuts
I like the idea of assembly paste and had seen that as a possible fix when searching on google.
so far looks like I am the only fellow with this problem... any other ideas are appreciated!