ULTIMATE GUIDE TO SRAM MOUNTAIN BIKE DRIVETRAINS:
HELPING FIND THE RIGHT DRIVETRAIN FOR YOU.
*UPDATE 6/11/2020: SRAM has just updated their Eagle lineup to include the original 10-50t (500% range) cassette and a new 10-52t (520% range) option. They also updated the cage length and pulley wheel positions to accomodate the larger cassette and improve chain wrap and shifting performance. Alongside those changes they have introduced new color options and a more affordable carbon fiber GX level crankset. The new derailleurs are compatible with both 10-50t and 10-52t cassettes, but the previous generation Eagle and AXS derailleurs are not compatible with the 10-52t cassette. If you are looking to expand your current drivetrain, you would need the 10-52t cassette and the updated derailleur.
Since the advent of the grip shifter in the late 1980s, SRAM has been known for their innovation in mountain bike components. While their product line is in constant evolution, their commitment to performance, durability, and usability remains the same. SRAMs current crop of MTB components provides industry leading performance for all riders, with options for the race-day podium or Sunday park laps. Not only does this American-based company offer a groupset for every discipline and price point, they also maintain cross-compatibly between each, allowing riders to mix-n-match to fine tune their drivetrain to their specific needs and budget. This guide is intended to outline the differences between each groupset to help you make an informed decision on which SRAM MTB groupset is right for you.
ARTICLE SECTIONS
THE 1X REVOLUTION
SRAM changed the game when they pioneered 1x drivetrain (pronounced “one-by”) for many disciplines of riding. By shifting the entire gear range to the cassette, leaving just a single chainring in the front has drastically changed mountain biking. Benefits of 1x drivetrains include a simpler shifting pattern, less drivetrain noise, reduced weight, cleaner handlebar setup and fewer wear parts compared to double- or triple-chainring drivetrain. This configuration has also been widely accepted in the industry, with many enduro and trail bikes being made 1x specific, without even having an option to install a front derailleur.
SRAM’s first 1x drivetrain was paired to an 11-speed cassette ranging from 10-42T. This cassette required the development of a new freehub body standard called XD which allowed space for a 10-tooth cog, where the smallest you could achieve on a standard freehub body was an 11-tooth cog. Luckily, SRAM’s latest 12-speed Eagle drivetrains utilize this same XD freehub body. The XD standard is used on all SRAM MTB drivetrains except for NX and below (these use traditional Shimano HG splined freehub bodies). Choosing the 10-50t or 10-52t cassette options gives you a whopping 500-520% gear range. Eagle offers the overall the gearing capability of a typical triple chainring drivetrain with the simplicity of a 1x setup.
By torture testing their 1x drivetrains over millions of trail miles, SRAM Eagle groups continue to redefine what they believe to be the ultimate 1x drivetrain. More than simply adding an extra cog, Eagle has made improvements to increase chain life along with chainring and cassette wear. Top end SRAM Eagle components are said to last up to 4x longer than the previous generation, resulting in less money over time.
AXS WIRELESS DRIVETRAINS
AXS is SRAM’s latest innovation in drivetrain technologies. SRAM AXS (pronounced “access”) is not only electronic, but also wireless. This means the drivetrain does not actuate with cables or wires, but instead using a wireless communication protocol to speak to the derailleur and dropper seatpost. Being wireless significantly reduces the clutter and headache of cables. This also allows for more customization through SRAM’s AXS phone app. You can tune your drivetrain or reprogram what the shifter buttons do with a simple a few clicks on your smartphone.
All this tech does come with a hefty price tag and a few concerns such as durability, precision and having to charge the batteries. We’ve spent plenty of time with these groups and they’ve proven tough, reliable, and incredibly intuitive. Also, the batteries last surprisingly long between charges and even have indicators to keep you from being caught unaware. AXS is compatible with all the other Eagle drivetrains, so you can just upgrade the shifter and rear derailleur to modernize your existing bike. Plus, you can shave a few grams by eliminating the clutter of cables and housing. If you’re all about the cutting-edge tech and the look of an ultra-clean cockpit, then the AXS groups are a perfect fit.
SRAM XX1 EAGLE
XX1 Eagle is the pinnacle of SRAM’s 12-speed groupsets. Engineered from the strongest and lightest materials, XX1 Eagle is designed to be the most efficient and precise drivetrain in the Eagle lineup. There’s no sacrifice in durability for weight savings, as XX1 Eagle can take the abuse of even the most challenging world-class courses. This is the top tier drivetrain with all the bells and whistles: mechanical and AXS wireless options, lightweight, Match Maker X shifter pods, X-Horizon technology and SRAM’s latest Type 3 roller bearing clutch. XX1 Eagle is perfect for the racer or the rider who demands the best and wants to make the most of every watt put down through the pedals.
SRAM X01 EAGLE
SRAM X01 Eagle is the best choice for the enduro rider who needs a hard-wearing drivetrain but isn’t overly concerned with weight. While it retains much of the performance of XX1 Eagle, X01 comes with some material changes to improve durability and decrease price. For example, X01 is built with a foam-core carbon crankset instead of the fully hollow XX1 crankarms. Production changes like these add up to a very minor weight penalty of around 60 grams over XX1 Eagle while maintaining all the same features and technologies including wireless electronic option. X01 Eagle is the best choices for riders seeking top-end 12-spd performance, but who are willing to sacrifice a few grams to save a few dollars.
SRAM GX EAGLE
GX gets straight to business. No claims at being the lightest weight or having fanciest features or build. Just a simple, reliable 1x12 drivetrain that provides the gear range you want at more attainable price point. Still benefitting from crisp Zero Loss shifts along the 10-50t or 10-52t cassettes, the primary difference between GX Eagle and its fancier siblings comes down to materials and machining. Without focusing on shaving grams, the machining processes are dramatically simplified, ultimately driving down costs. The most significant weight gain is found in the stamped and pinned cassette at ~450g, but this is competitive with cassettes like the Shimano XT. Also, because GX still uses the XD freehub body, you could always mix-n-match and run a higher-end cassette on your GX drivetrain to lighten the overall weight. Additionaly, SRAM did just introduce a GX-level carbon crankset that sheds some weight at a more affordable price.
SRAM NX EAGLE
NX is the perfect drivetrain for breathing new life into your favorite bike. The primary difference with the NX groupset is the cassette. The 11-50t cassette does not use SRAMs propriety XD freehub body, instead utilizing the traditional slide-on Shimano HG style. This is great for those looking for the range of a 1x12 drivetrain but who cannot fit a XD freehub body to their rear hub. While you lose some of the top-end range compared to 10-50t or huge range of the 10-52t, this makes the cassette much more affordable and makes it possible to go 1×12 to almost any bike!
DOWNHILL GROUPS - X01 DH & GX DH
X01 DH is the downhill racer’s choice. When fractions of a second count, SRAM knows you need complete confidence in your drivetrain. With feedback from World Cup pros, SRAM developed a 7-speed X01 group worthy of any podium. Downhill don’t require the same gear range as typical trail riding, which is why this option uses a 7-speed XD cassette. The X01 DH cassette has a 10-24T gear range and an integrated spoke guard to prevent the chain from bouncing into the spokes. The compact range also allows for a shorter derailleur cage, preventing the derailleur from getting snagged on obstacles.
Knowing that downhill rigs are often focused more on durability than weight savings, SRAM also offers a GX version of this DH line. Like the standard GX groupset the primary difference lies in less expensive materials and changes in machining processes. The GX DH 7-speed cassette is not XD driver-specific but mounts to a standard 8/9/10/11 speed freehub. This saves the cost of having to purchase an aftermarket XD driver for your wheels, but also reduce the gear range to 11-24t.
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