This project began with the desire to run 11s Shimano derailleurs and shifters with SRAM 10-42t XD cassettes. Granted the combination can work without modification- but performance wasn't quite what we'd expect from Shimano and SRAM's finest. When used with a 10-42t cassette, the GoatLink 11 re-positions M8000 XT and M9000 XTR rear derailleurs such that free chain is within 1% of what Shimano intended while engagement is improved by 27%. But we didn't stop there. Knowing that certain situations call for a range beyond that provided 10-42t or 11-42t cassettes, we tweaked the GoatLink 11 to also significantly improve Shimano 11s rear derailleur performance with extended-range like the Wolf Tooth GCX44 modified 10-44t XX1 or X01 cassette. So now you too can have it all: ideal performance from 10-42t XD cassettes and wide-range capability for bigger days. Compatibility: 11-40 Not Required 11-42 Not Required 11-45 GS/SGS Derailleur 11-46 GS/SGS Derailleur 10-42 GS/SGS Derailleur 10-44 GS/SGS Derailleur (Wolf Tooth GCX44) 10-45 Not Optimized 9-44 Not Optimized Other notes: The GoatLink 11 is compatible with M8000 (XT) and M9000 (XTR) series eleven-speed Shimano rear derailleurs. The GoatLink 11 mounts only to standard derailleur hangers. Double chainrings (2x) is supported and requires a long cage (SGS) rear derailleur with no more than a 12t difference in front chainrings (with an 11-46 cassette). Triple chainrings are not supported. Direct Mount-native frames and SRAM derailleurs are not supported.