Shimano 105 RD-R7100 Rear Derailleur - 12-Speed Direct Mount One Spec Shadow Design 36t Max LowShimano 105 RD R7100 Rear Derailleur 12 Speed Direct Mount One Spec Shadow Design 36t Max Low. The Shimano 105 12 speed rear derailleur combines the smooth and stable shifting that is a staple of Shimano Shadow RD design with direct mount compatibility and a wider gear range capacity. Shadow RD offers a low profile design with single tension construction that prevents the derailleur from hitting the chainstay in rough riding conditions Direct Mount