http://www.use1.com/
Ultimate Sports Engineering makes many innovative parts for bicycles including seat post shims. An example is a current CR member need for a 26.2mm dia. post. I have a 25.0mm dia Campagnolo seat post I offered and with the use of a 25.0 mm to 26.2 mm shim mine would work. They are hardy noticed. I used a 25.0 Dura Ace seat post for my 27.2mm frame using their shims. Starting size needs to be 25.0 mm or 27.2mm however Charles Nighbor Walnut Creek, CA