Choose proper size for your frames seat collar. The Campagnolo seatpost clamp uses an asymmetrical clamp to relieve stress on carbon or any seatpost. The asymmetrical design of the Campagnolo clamp and the proximity of the locking screw to the seat tube are intended to prevent damage. This smart and simple design decreases irregular pressure on the circumference of the seat post and ensures uniform band pressure over the entire circumference of the tube.
Select Outside Diameter of Seat Tube. We do not have manufacturer sizing charts. You must measure your seat tube outside diameter and order the appropriate size.
The stock clamp that that came with my 2008 Cervelo R3 creaked like crazy. It took a few months to figure out that it wasnt the seatpost, the headset, the seatpost rails, etc. Turns out that the stock clamp for the Cervelo is either too big or flexy. Either way, I replaced the stock clamp with the Campagnolo clamp. The size to use is 35.5 as it is a perfect fit (you may need to use a 2mm allen key to slightly widen the clamp, but it is a perfect fit and goes on without scraping paint, etc.). All creaking noises are gone.