SRAM RED XPLR AXS Review: 13-Speed, Lightweight, Durable, and Fast – Josh Weinberg | The Radavist | A group of individuals who share a love of cycling and the outdoors.

Announced today, SRAM’s RED XPLR AXS groupset combines elements of its UDH-compatible mountain bike components with its high-end road group for an all-new gravel-specific product lineup. SRAM designed it to be light, fast, and durable for the needs of today’s gravel racers and riders wanting the highest performing upper echelon groupset.

To discover how RED XPLR AXS stacks up and who it’s best suited for, check out Josh’s review below.

Gravel Racing

An interesting discussion developed in the comment section of our State Ti All Road review last week, followed by the subsequent sharing of SRAM’s Bike Finder for UDH-compatible frames. Some folks wondered if direct-mount derailleurs would be a new way forward for gravel bikes, while others doubted the potential reach of widespread UDH compatibility. With today’s RED XPLR AXS launch, SRAM has made it clear they do see a place for full-mount derailleurs on gravel bikes.

As with other RED-level components, SRAM caters to its most demanding customer base. In the case of RED XPLR, gravel racers desire durable, lightweight, and fast components, as SRAM has explained.

Gravel racing has evolved significantly in recent years. The discipline’s grassroots genesis paved the way for subsequent professionalization and commodification, and the field or racers demand specific high-performance equipment to match their intense outputs and pursuits.

RED XPLR AXS

$3,979 / 2,488 g for complete groupset, including power meter
$3,529 for complete groupset, without power meter

Borrowing design and technology from SRAM’s MTB-centric Transmission, which we’ve been using extensively for nearly two years now, the new RED XPLR rear derailleur features a full-mount UDH (universal derailleur hanger) interface. It is paired with a new crankset and 10-46T 13-speed cassette controlled by the same shift-brake system introduced with the 2x RED AXS road group back in May. The total package is designed to provide “precise shifting with tight jumps between cogs, significant weight savings, and true one-fingered braking.”

Before I break down the features of RED XPLR AXS, let’s look at an important distinction.

RED XPLR AXS VS Eagle Transmission

Remember when Transmission came out, and viral videos were going around with people jumping on their new derailleurs and trying to break them? This was because of SRAM’s claims that directly mounting the derailleur to the frame via its thru-axle and UDH dropout would make it much stronger than a traditional derailleur attached to an external hanger.

This defining characteristic carries over to the new RED XPLR to achieve increased resilience in all conditions. For example, like when derailleur pulleys get clogged with mud and debris, the chain stops spinning, ripping the mech off and sending it straight into the rear wheel.

Like Transmission, RED XPLR is rebuildable and has many individual parts for sale. Both use a flat-top chain, the same cog design, and have the “magic wheel” lower pulley that still spins even if an object becomes lodged in it.

Transmission’s other standout feature is shifting under load. With X-Sync cogs and cassette mapping firmware, shift speed is controlled to engage the chain on a new cog even under pedaling pressure. While this benefits even us non-motorized mountain bikers, the technology is certainly more applicable to the e-MTB world.

For gravel, SRAM designed the system to be more responsive to rider inputs with super-fast shifts. The tradeoff, then, between faster shifting and shifting under load, removes cassette mapping from the equation and incorporates a lighter spring mechanism to achieve better chain management and retention than any other SRAM derailleur.

RED XPLR Derailleur

$700 / 375g

The new RED XPLR is built specifically for gravel riding. Incorporating the hangerless interface and full mount body from SRAM’s T-Type system, it offers precise shifting and resistance to impact. Whether it comes from a stick on a muddy race course or blunt force while traveling from a baggage thrower, SRAM has built this type of derailleur to withstand various impacts and continue functioning in scenarios where hangered derailleurs might have broken off or become damaged.

This is partly because the derailleur directly mounts to the bike’s axle rather than to a separate hanger. The body can pivot on the clutch mech out of the way upon impact and then be easily reset with a simple backward pull. Additionally, as shown in this video, the setup is simple and straightforward, with no adjustment screws necessary. Chain sizing is also very easy according to this handy dandy chart (above), which will even tell you if you can use the same chain for different chainring sizes.

Speaking of setup, another point was brought up in the articles mentioned above we published last week. It was around minimum chainstay lengths for compatibility with UDH derailleurs. I asked SRAM to clarify regarding this new groupset, to which they responded:

“To allow for the wider tire clearance that most gravel bikes require, the minimum chainstay length for the XPLR drivetrain system is 415 mm. The XPLR drivetrain system would include the requirement of a UDH dropout and utilizes a wide crank spindle with a 47.5 mm chainline.

For 1x Road and All-Road applications where there is a desire for a wider gear range, the XPLR derailleur and cassette can be paired with a 1x aero crankset with a standard width spindle – but does require the chainstay length between 405mm and 415mm and a frame with a UDH dropout.”

In terms of distinguishing mountain bikes and gravel bikes:

“For the Mountain Full Mount style RDs, the online tool will limit the chainstay selection option for a “hardtail” to a minimum of 425mm. However, they will work with chainstays down to 415mm- that’s kind of a rare stay length, as it’s rather short which would limit overall tire/wheel diameter (depending on frame design).

You can find the chain sizing chart that includes chainstay length to MTB ring sizes (specific to hardtail) in the user manual and bike brand to chain sizing tool.”

Similar in appearance to the T-Type GX-level system Travis reviewed, the RED XPLR derailleur holds its battery on top of its body, tucked in atop the parallelogram rather than behind it like the first T-Type derailleurs released at the XO and XX1 level.

From a durability perspective, the top-mounted battery seems better than the rearward one, as this is how the recent-gen full-mount derailleurs are built. Not that I’ve ever seen or heard of a problem with OG T-Type, but it’ll be interesting to see if SRAM updates the XO and XX1 with this build.

Sliding Dropout UDH Inserts

I might be the only one in the world using the new RED derailleur with Paragon UDH sliding dropout inserts. Thankfully, Scarab was willing to build the Paramo Ultra with sliders, which allowed me to install this new group. Otherwise, I wouldn’t have had a bike for it. So, you heard it here first – it works great! There are a few considerations to consider with this setup, though.

First, the drive-side insert takes up the entire dropout and eliminates the ability to move the rear wheel fore and aft. If you want to go this route, be sure you can commit to a fixed position.

Second, I was able to use the flat-mount mount NDS insert rather than the one Paragon recommends purchasing along with the UDH insert. Of course, in a MTB application, you’d want the post-mount insert, but this gravel group requires flat-mount compatibility. I did need to order a new thru-axle, however, as the original axle’s thread pitch did not align with that of the derailleur.

Third, this might technically be a workaround for direct mount compatibility. While the derailleur is attached to the bike via axle, as required by the UDH interface, it attaches to a machined part connected to the frame rather than the frame itself. Functionally, it fits and works flawlessly. I reached out to SRAM to confirm this fitment conforms to their specifications and this is their response:

“Generally speaking, any significant external side load on the rear derailleur is mostly reacted by the axle. This makes for a very robust mounting point. Paragon’s sliding dropout system is just as robust as any traditional chainstay-to-dropout interface. Their UDH sliders conform to the UDH frame specification- they were one of the first frame parts manufacturers to offer a UDH dropout for the small builder market.”

RED XPLR Cassette

$600 / 288 g

We’re 1000 words into this review, and I’m only now honing in on the fact that the new RED XPLR cassette has 13 cogs for tighter steps and better shifting in the higher and more heavily used gears. Maybe that’s because, at least for me, it’s nice to have rather than a mind-blowing development. With wireless pairing and firmware updates, existing shifters can be programmed to shift through any number of gears SRAM wants. What is mind-blowing is its weight. The 10-44 Force XPLR cassette weighs 378g, while the new RED XPLR 10-46 cassette comes in at 288g. That’s 90g lighter with an additional cog!

There is only one cassette option for RED XPLR, and it’s 10-46. SRAM claims this gives the target RED audience plenty of gearing options, mainly because the RED crank can be paired with large chainrings. For me, where I ride in the mountains, I would love to see at least a 10-48 cassette at some point. The high end of 40 or 42 – 10 ratio is great for going fast and pacelining, but 40-46 leaves much to be desired when the terrain gets steep. I realize I’m not the target audience, as most popular gravel race courses max out around 6% grade, and a lot of my climbing is much steeper. All that said, the 46T big cog is an upgrade of the previous XPLR 10-44T cassettes.

Still, the RED shifters are compatible with T-type derailleurs for building a mullet setup. But I bet there are riders out there who want wide-range gearing with the weight savings and performance of the new RED XPLR system. From the looks of it, RED XPLR and T-Type cages are the same length and can theoretically shift into large cogs of the same size. It will be interesting to see what SRAM does next. Could a future XPLR cassette be a 13-speed 10-48? 10-50? Remember, when APEX launched last year, they offered XPLR and Eagle.

RED XPLR Crankset and Power Meter

$1,100 crankset + power meter / 516g
$550 crank arms + chainring / 427g

Like the shift-brake system, RED XPLR uses the same cranks, arms, and interfaces as 2x RED AXS. This means the hollow carbon crank arms can accommodate Thread Mount chainrings (non-aero from 38T—46T) and an optional threaded power meter spider. With the threaded interface, upgrading to a power meter is now super easy. Crank arms are now available from 175mm to 160mm. Chainrings require the special Thread Mount tool to install and are designed to maximize tire clearance with high stiffness and shift accuracy.

SRAM has also streamlined crank widths and landed on a 47.5 mm chainline for the 1x RED system with the DUB Wide spindle. This is opposed to standard DUB spacing used in most 2x road applications, which helps accommodate wider tires and offers a more stable riding platform over rough surfaces.

Integrated technology, including power meters and cycling computers, has come such a long way. SRAM’s crank power meter claims +/—1.5% accuracy and can communicate with various head units, including their Hammerhead Karoo, Garmin, and Wahoo. The last power meter I used was in a set of road pedals, which weren’t my favorite, so I ended up scrapping them and returning to my preferred SPDs.

Adding the meter to the crank spider seems like a no-brainer – it adds minimal weight and is unobtrusive. According to SRAM, I’m not the only one thinking this way, and based on sales patterns of 2x RED AXS, they plan to sell many more RED cranks with power meters than without.

RED XPLR Shifters and Brakes

$675 for each side / 692 g for complete system

When SRAM updated RED AXS earlier this year, I didn’t get a chance to use it, but the revised hood and lever design looked like a big step forward. Before this, I thought Shimano had the best shifters on the market, with the GRX ergonomic hoods and textured surface levers I wrote about last year.

Shifter hoods come with “Bonus Buttons” that can be programmed to do various things. They are set as auxiliary shifters out of the box, but using the SRAM app, they can be changed to control an ANT+ device or even actuate a Reverb dropper post. And if the bonus buttons arent enough, the AXS system can incorporate a total of eight wireless blips.

From a power perspective, RED brakes require 80% less force when braking from hoods and 30% less from drops than the previous versions. This, of course, is also a result of improvements in calipers as well. The polished silver units are lighter and stiffer than before, with increased pad clearance to reduce rotor rub and pistons spaced slightly further apart.

RED brakes use the HydroHC platform, which provides impressive power and modulation. They certainly muddy the stigma of flat-mount brakes not having enough stopping power for some of the applications they’ve been used in since their introduction years ago—like fast gravel, loaded touring, and on the bikes of heavier riders.

Wrap Up

It’s been ten years since SRAM’s original 1x gravel (and/or ‘cross at the time) CX1 group was released. It’s remarkable to see how far the technology has come since then, which, of course, is in tandem with the progression of dirt road cycling in a relatively short time. While RED XPLR AXS is at a premium price point, it delivers premium performance.

Modern gravel-oriented drivetrains from SRAM (and other brands like Microshift and Shimano) have thus far been wide-ranging and cater to everyone from professional racers to long-distance riders and recreationists alike. With RED XPLR, SRAM is narrowing its focus to the sharp end of the rider continuum. And it’s hard to blame them, considering the segmentation of gravel racing with the sport’s explosion and increasing professionalization. But I would be remiss not to wish for a bit more range from this high-end group.