Looking to buy a cabon seatpost to replace an aero carbon seatpost that came with my bike. I recently purchased an Easton ec90 that was installed at a Trek Store and it slid way down on my first ride. I took it back because it scratched the hell out of it. I've since read a number of reviews on the ec90 and slipping seems to be a frequent problem. Looking to find a dependable carbon seatpost that won't slip. Any recommendations?