Axiom Trekk Seat Post Collar Clamp with Rack Mounts

Choose from 34.9mm, 31.8mm, 29.8mm or 28.6mm seat tube frame diameter Adds rack mounts to bikes without upper strut brazons   Forged aluminum.  Replaces stock seatpost collar found on most bikes. Clamp design minimizes stress on frames and seatposts. Creates two 5mm upper rack eyelets on almost any frame Be sure to measure the outside diameter of your frame's seat tube. Your seatpost size is going to be smaller than the diameter needed for this clamp to fit over your seat tube. Seatpost size is not the same as seat clamp size.