I’ve been making small changes to my Giant Escape gravel grinder over the winter. The latest is the addition of a derailleur hanger extension to get the 10-speed SRAM X9 rear derailleur to play nice with the 11-42 tooth Sunrace cassette and Shimano chain.
In the side-by-side comparison below (each time with the chain wrapped around the 42 tooth cog), the derailleur is shown 1) without the Wolf Tooth RoadLink, but with the B-limit screw reversed then backed all the way out to clear the cog (left), 2) with the RoadLink installed, no other change, and 3) with the RoadLink installed and the B-limit screw in its original orientation, allowing the top jockey wheel closer to the cog.
With this change, downshifts are more accurate, though Wolf Tooth doesn’t support use of the extension with anything wider than a 10-speed 11-40 cassette in combination with one or two chainrings. (The Giant has a single chainring: a 40-tooth Wolf Tooth with a 130mm bolt circle mounted on a Shimano 600 crank arm.)
In other words, don’t assume this same set-up automatically works on your bicycle. As Wolf Tooth points out, individual results can vary due to different derailleur hanger geometry, chainstay length, chainring size, B-screw adjustment and, if you’re dealing with a mountain bike, suspension configuration.
But it worked for me.