what can i do to stop it?
its a thomson seatpost in a trex ex9 frame if that makes any difference

i have checked with trek and i have the correct dia seat post

it only slips slightly so not sute if i could get a shim in or not

thanks

Use a Salsa seat post clamp. Nothing else worked for me.

make sure you wipe of all the grease?
make sure the seat clamp lines up with the slits in the frame?

sorry thats all i can think of if the post is the correct diameter

slither of coke can.

ton,

i had a look but don't think there is enough room
perhaps you could have a look next time we ride?

Clean off the grease on the post and inside the frame. Replace with carbon assembly paste. Honest it will work. I got the finish line one of wiggle. Solved the same thing for me!

+1 for salsa seat clamp. Had loads of trouble with posts slipping in my nomad till I bought one.