The Shimano Ultegra R8000 rear derailleur is part of the successive groupset to the popular Ultegra 6800 groupset. The R8000 shares many features with the R9100 rear derailleur. This R8000 rear derailleur copies the complete Dura Ace Shadow design, for instance. That ensures the derailleur is more protected underneath the cassette. A huge advantage for riders who find themselves riding in tightly packed groups, in which case a rear derailleur could potentially get hit. The rear derailleur comes in a short cage (SS) design suitable for 11-25T up to 11-30T cassettes, and a long cage (GS) version suitable for 11-28T up to 11-34T cassettes.