The Cane Creek Seatpost Shims are custom machined alloy (30.9 to 31.6 is plastic) sleeve to space 25.4, 27.2, 30.9, 31.6 and 33.9mm seatposts to larger seat tube diameters.Please note; The Shim for 30.9 to 31.6mm is made from plastic due to its thin body being only approx. 0.7mm.
Best Price: £10.19 from Tweeks Cycles