Originally Posted by
Al1943
Ok, the 105 medium cage is a new design. Before Shimano road rear derailleurs have always been short and long, not medium. Campagnolo has had a medium for several years.
Not so "new" actually. My quote was about the 5700 series, but they used the same nomenclature for the 5600 series also (i.e., short and medium, not long). It does appear that this wasn't the case for the 5500 series, but that was discontinued 5 or 6 years ago.