SRAM's XX1 Eagle drivetrain, while not a new offering, is still the highest end drivetrain model from SRAM. With features like 12 speeds, a 500% gear range, and a flashy GOLD finish, there is a lot to talk about. Let's get into it.
Right off the bat when you look at the drivetrain, it's hard not to notice the gold cassette and chain, especially that dinner plate 50-tooth rear cog. With a 10-50t range, it's rather large and if you are not used to seeing this many gears, it might look funny. Take a closer look and you will see some impressive machining and tooling for this bike component. Starting with the 10t high cog all the way up to the 42t cog, it is machined from a single piece of aluminum, much like the 11-speed XX1. The range from the 11-42t is the same as 11-speed, but with the added 50t you get the Eagle 500% range. Using the same xD driver from 11-speed, SRAM was able to get all 12 speeds and the range without making any new standards for your bike. Thanks, SRAM!
Looking at the chain, you will notice it’s gold. This is nothing new since there are already some gold chains on the market. However, upon closer inspection, you will see it is actually a very crucial piece to the Eagle group. With hollow pins that are flush with the outer links and very smooth machining of the links themselves, this chain is what really makes the 12-speed work. The XX1 chain is also offered in black if you are not into the flashy gold. The last bit of the chain you will notice is the master link, or quick link, - it has a different shape than what has been seen before. It is actually slightly directional so that it follows the bend of the cassette and chainring. Plus, its oil slick color is purely to make it look badass.
A newly designed chainring was also an addition to the Eagle family. The new X-Sync 2 chainrings have a new tooth profile, and at first glance, almost look pre-worn. It's actually supposed to improve chain retention and wear life. All X-Sync 2 chainrings are backward compatible with 11-speed systems as well. Available in all size options, you should be able to get the right one to work with your bike. Also, note that when choosing a chainring size for your new Eagle setup, you can often size up if you are comfortable on your 11-speed setup. If you are running 30t on your current 11-speed, you can certainly go up to a 32t or even 34t tooth while still maintaining the same low gear and getting a higher range.
Not much has changed from 11-speed to 12-speed. There is, of course, one morespeed, and a few different internal pieces, but for the most part it's the same. XX1 gets a carbon cover and black or gold logos. The shifter is Matchmaker compatible.
Keeping with the same design from 11-speed offerings, there are some major differences to ease the shifting into lower gears. A longer cage, and a 14t lower pulley wheel help create smooth gear changes and low resistance when shifting. Also updated is the roller bearing clutch, now a version 3.0. Quiet and strong, it helps keep the chain from slapping about and jumping off when it’s least wanted. XX1 and X01 derailleurs are not much different from each other. The only real difference is that XX1 gets a carbon cage and a titanium spring. For those counting grams, it’s about 15 grams lighter, but also comes in the matching gold, or a black version as well.
Now that you have read about each part individually, let's talk about the group as a whole. The full Eagle system provides smooth shifting at any time with one of the largest ranges on the market. I myself was able to run 34t and 36t chainrings while getting more high-end range. At no point have I ever wanted more range or had a chain jump off. Using the Eagle system as a whole unit really makes the experience great. After having it on my bikes for quite a while now, it leaves me with nothing more desired. You can almost hear the bald eagles when riding, rejoicing that SRAM has not soiled their name.