Seems like I am giving the GX Eagle a bad reputation. I don´t want to be harsh and I believe the thinking behind it is great. And also that SRAM tried to bring the concept to a much lower price point. And when it works, it is a totally acceptable drivetrain, maybe even a good one...
I do feel, that it isn´t very durable though and it needs to be adjusted not 99% but 100.00% to work. And then to be kept at these 100.00%.
That might be a fun hobby if you care for Bonsai trees, but doesn´t really work for me on a mountainbike.
I´ve put in a lot more miles since my last "rant".
And unfortunately I can´t report too much good stuff.
My rear derailleur is in for warranty, the clutch stopped working and my expensive 12spd carbon sled felt and rattled like a 1998 freeride bike. The bike is 6 weeks old. Hooray for non-adjustable clutches =)
Also the chain is toast. It is really loud and developed a lot of play in all directions. Because it had a missing ring on a pin (not the Powerlock) from the factory my LBS warrantied it also.
What´s great: The x-sync chainring works as advertised.
But: It´s now the only remaining sram part (with crankset and bottom bracket) on my bike. I bought a XT11spd derailleur, 11-42 cassette and ONEUP 50t Shark and cage and an 11spd SLX-Ispec-B shifter (SLX has lighter trigger action and allows for more clutch tension without too much required force for shifting).
I bolted this hacked 11spd 11-50t to the exact same RD hanger the GX Eagle never worked 100% on (from new). And it shifts absolutely perfect and at the same time setup was an absolute breeze. If I want to in/decrease tension of the clutch, I´ll just do so with an allen key. The hanger doesn´t need to be 100%, cable tension is not as critical. Admittedly B-Tension adjustment is also pretty critical.
The same goes for a SRAM 11spd setup. Apart from the clutch going bogus on three derailleurs I never had trouble. And they are LIGHT! I repaired the clutches on SRAM derailleurs before, but they changed to TYPE3 on Eagle and the old hacks don´t work anymore. Warranty...
Regarding chain wear - I measured some NEW GX Eagle chains and they seem to be a bit undersized when new with a Rohloff calibre or other 11spd chain measuring device. So if you check for wear, you´ll think they haven´t gotten longer at all, but they actually did. That´s not a problem, but might be interesting to know and keep an eye on.
If your GX Eagle works and came on your new bike, enjoy it. And I really mean that.
If you´ve got Shimano 11spd stuff on your bike already I don´t see any reason to not go for the ONEUP 50t. I really love it.
(man - re-reading my message - I sound like a cranky, negative prick. It´s just a drivetrain - first world problem =)