And yes, this a Shimano XT Rapid Rise 9 speed rear derailleur on a 10 speed cassette and it is being shifted with a 10 speed road bar end type shifter and it works perfectly. I also added a Hanger Banger to the skewer to help add support to the RD mount. You can also see the Gore RideOn sealed cable attached to the shifter. So far the fully sealed cable and grub seal seems to do an excellent job of keeping dirt out of the cable. I really like the 10 speed cassette. It has 2 tooth jumps from 11-21 so rides a lot like my road bike at higher speeds, then the 24-28-32-38 tooth cogs are great for the hills. I can physically shift into all 30 gear combinations, although the chain is really slack in the small-small combo so I only use the big 7-8 cogs with the small ring. Likewise, the chain angle is pretty bad in the big-big combo, so I usually avoid that as well, so that leaves 27 useable combinations. I generally shift the front for conditions; small ring on steep hills, big ring for the flats and middle ring for everything else. Then with 10 cogs in back, you can shift up and down and almost never run out of gears!   (9/16)