The Shimano Deore XT RD-M772 Shadow rear derailleur is the biggest and boldest innovation in the new XT line. It takes from some old and established design cues to create a derailleur that shifts crisply yet presents a minimal profile for crashing. A paradigm shift for the derailleur? You decide.

Let's begin with where the derailleur attaches to the dropout. Shimano decided that the derailleur mounting bolt would no longer be where the rear derailleur pivots. The mounting bolt holds a small bracket onto which the derailleur is bolted. The new derailleur mount position is back and a bit lower than the traditional pivot, which allows the derailleur to fit better under the right chain stay, shadowing the cassette. When the chain goes through the derailleur to the smallest cog (aka high gear), the derailleur protrudes 15mm less than a traditional derailleur, a profile that means it barely protrudes past the quick release nut in the dropout above. By almost hiding underneath the nut, the derailleur and chain stay, the derailleur is protected from damage in some crash situations, which both preserves the derailleur and the derailleur hanger.