The holy grail of touring rear derailleurs: affordable, shifts well, can soak up a huge range of gears, and a clutch for riding on rough roads without chain bounce. This is the ideal derailleur for our Turkey Vulture Supreme gearing system, which uses friction-able 9 speed Shimano bar ends, a 9 speed cassette and chain and this rear derailleur (plus a cable pull modifier) to achieve touring shifting bliss. Run it friction or indexed, it shifts great both ways on a 9 speed cassette. The GX 10 speed rear mech can soak up all the chain needed to run a 11-40 in the back and 44/24 in the front, a huge, super practical range of gears. We put these on most Rivendell builds or ‘traditional’ touring builds.
To work with Shimano 9 speed shifters, you need a cable pull modifier! We usually have plenty in stock, let us know what you're trying to achieve.