The 4x9x0.1 shims can be tricky to install on the mechanical derailleurs.
Our detailed rebuild guide videos cover tips on this in detail. With these shims, we include a small green peg that can help with the installation. We recommend to go slow and do not force them in or they will get deformed and add friction to your linkage movement. These shims are critical for long term function of the derailleur so do not skip them in the locations where they are specified.
