Next week I'll probably buy a new frame to replace my creaking old one, but the Look I'm considering has a 31.8 mm seat tube and my front derailleur, still quite new, has a 34.8 mm clamp. Should I buy a new derailleur, or I should just fill the empty space with a rubber sheet? Will I find geometry or adjustment problems? Any experience or feedback about this case will be much appreciated...
Just buy a replacement derailleur clamp of the right size. They're readily available. Then unscrew your existing der from its clamp and attach to new clamp. 60 seconds/done! No shims, no nuthin'.
So...why the new thread? And by the way, IMV this topic really should've been posted under "cycling equipment"--where you posted it last time; and if you'd searched there, you'd have found prior threads on this exact topic, along with links to sites where replacement clamps can be purchased.