The shimano saint m820 10 speed shadow design rear derailleur a shadow dyna sys 10 speed rear derailleur delivers reliable and precise shifting with a stiff and lightweight open design shimano39s new direct mount rear derailleur system gives more space around the rear frame dropout resulting in easier rear wheel removal but also allows frame designers to shorten chain stays increase axel sizes and move suspension pivots shimano saint m820 10 speed shadow design rear derailleur feat