I have a 20 speed XT group with a RD 781 rear mech and a 785 front crank.
I want to convert it to a single ring setup with a sunrace 11-42 rear cassette.
I'm clear on how to do the chainring conversion, but I'm not sure if this particular rear mech is compatible with a 42 tooth cog. I think it probably is with either a [url= http://shop.18bikes.co.uk/m9b162s599p2459/LINDARETS-Goatlink-2015/RS_GB/11510?gclid=CjwKEAjw19vABRCY2YmkpO2OzTsSJAAzEt8suQz0_4NKtkz71_VJIMgpX60F929bsbroJzgXYbEcWhoC2Tzw_wcB ]goatlink[/url] or a [url= http://www.chainreactioncycles.com/oneup-components-rad-shimano-rear-derailleur-cage/rp-prod141762?gs=1&gclid=CjwKEAjw19vABRCY2YmkpO2OzTsSJAAzEt8s01rEvpQYpzEoLNa9cbv2WDwX9IQ1jA0hFVqTzlMhLxoCguPw_wcB&gclsrc=aw.ds ]Oneup Rad cage[/url] or both. But I'm not absolutely sure if this mech is compatible with either or both of these products.
Can anyone advise? cheers