Classic & Vintage - Shim for Peugeot seat tube from 28 to 28.6, what kind of material?

Hello, I'm trying to use an standard band for a modern front derailleur, and I'm trying to shim the band with rubber that I had for shimming a rack to the seat post, but under force, it slips. Would exists a better material for this? thank you very much.

Aluminum shim made from a beer or pop can.....the miracle shim stock.....

I used electrical tape to get mine up and running. I thought it would slip but it's been 4 months and so far so good!

Use a beer can. I would rather make a thin strip of beer can material and wrap it around and then use a piece of tape to hold it in place while you mount the derailleur.

However plastic would work fine too. Plastic doesn't really compress. Rubber compresses which is why you are having a problem.

As a matter of fact, I think some new derailleurs come with plastic shims to allow multiple tube diameters. One of those should work too.

Aluminum shim made from a beer or pop can.....the miracle shim stock.....
...preferably a French beer can - maybe Davey can send some over... :D

Really thanks, I'll go the drunken route then.

Fold a shim from soda can that's 3 layers thick, then pound flat with a plastic mallet or wood dowel.

I would form the folded shim 10mm wide or so, then wrap around a broom dowel and massage it flat with light blows from a hammer or just roll it on a hard surface.

Each thickness of the soda, wrapped fully around the seat tube. can will increase diameter by 0.2mm

I would scrub the slippery polymer coating off of the sheet metal using wet ScotchBrite before folding and cutting the shim.

Note that larger diameter cans are made with thicker walls, so use 2 layers instead of 3 if the can is a 24oz beer can.