A typical soda can is about .1mm thick -- unfortunately for you, it's maybe just a tad thicker. Getting one bent to the right shape and held in place will probably be a bit of a challenge (maybe fold over the top a couple of times to give it some body along the top edge (be careful, they're quite sharp)).
Actually, I just tried that...it works pretty well. It'll only be possible if the top of your seat tube is straight all around (or a simple shape).
Steel would make a better shim...much less likely to tear and end up down inside your seat tube (Sharpie your name and phone number on whatever you use so you can later claim it was in there for theft-retrieval purposes). You can also pick up sheets of brass or stainless steel shim stock and avoid the rust issue. Any good machine tool shop or garage should be willing to sell/give you a piece plenty big for your needs.
I don't know of anybody who produces such a shim as a product. Nitto sells a pair of handlebar diameter shims (about 170 degrees each) that'll get you from 25.4mm to 26.0mm bars (depending on the specifics of your situation, you might be able to use one smile of one of those) -- they want a stupid amount of money for them, though.
Or just crank down on it and then let the next owner have the problem that Peter's experiencing. No, don't. I just recently escaped wasting money on a 27.0mm seatpost for a frame that seemed to need/want one before I took a really close look and discovered that what it *really* needed was to be pried back apart just a tad to address the plastic deformation caused by a previous owner (or a ham-fisted bicycle mechanic) having "fit" a post that was too small (it's now a perfect 27.2mm).
Scott Minneman San Francisco, CA, USA
-----Original Message----- From: classicrendezvous-bounces@bikelist.org [mailto:classicrendezvous-bounces@bikelist.org] On Behalf Of GCJ Sent: Tuesday, January 02, 2007 6:37 PM To: Classic Rendezvous Subject: [CR]Seat Stem / Cluster Fitting Problem
I have the reverse of the seat stem/cluster fitting problem being discussed. The ID of the cluster measures 26.8 mm, and I have two stems with ODs measuring 26.6 mm. that I'd like to use. I figure a 0.1 mm or 0.003 in. shim would take up the space. Is there a manufactured 0.003 in. shim with a lip on the top edge to hold it in place? If so, who sells it? If not I'll have to improvise with some brass or SS shim stock. I just don't want to buy a whole sheet of the stuff for the little I'd need. I don't have a micrometer, but maybe someone who has used soda can metal can tell me its thickness. Thanks
George Jones Dallas, Texas USA