If you are looking at upgrading to Eagle and confused about all the different models, let me break it down for you. XX1 Eagle is the top of the line with a hollow pin chain and single piece milled Cromoly cassette. X01 saves about two Benjamins and is functionality the same except for weighing 40g more than the XX1. The GX eagle cuts some corners, using a standard chain design and the cassette is stamped and riveted like a normal cassette instead of milled.
FUNCTIONALLY THE GX EAGLE IS THE SAME AS THE XX1 AND X01. I cannot stress this enough. The only reason to go with the X01 or XX1 over the GX eagle is if you are an super extreme XC rider trying to save every gram or just really like gold and willing to drop and extra grand. With that cleared up, onto the review.
The Sram GX eagle is surprisingly straightforward to install. Sram has a fantastic video that breaks down the installation and adjustment to a 10 minute video. With the proper tools it took me an hour, included the time it took to install the XD driver. But if your bike already has an XD driver, installation is a breeze.
The smoothest shifting I have ever had the pleasure of using. With every gear change the chain seems to lock perfectly into the next chainring, even when downshifting 5 or 6 gears at once. With the narrow wide design being utilized on the jockey wheel as well as front chaining, I have had no issue with the chain slipping or coming off, even after testing it off some intense drops on a hardtail. The clutch keeps the chain very taught and prevents it from slapping around on rocky sections.
Overall the best drivetrain for the dollar right now. The only complaint I have about the GX groupset is I am not a fan of the front chainring mounting design on the new cranks. Save some money and use your old cranks and just purchase the drivetrain. I'll take my old XTR four bolt cranks with a Raceface chainring over the Xsync design anyday.