By Price: $2,838 to $4,158
Weight: 1,868 to 2,553g
Primary use: Road, gravel, cyclocross
Gearing: 2x12, 1x12
Shifting: Electronic
Brakes: Cable actuated; hydraulic disc
SRAM Red eTap AXS Detail Gallery
Integrated Power Meter
The integrated power meter is claimed to be more accurate.
Flat Top
Material was added to the top of the chain for strength.
New Texture
The hood shape hasn’t changed, but the covers have a new texture.
More Clearance
The front derailleur was reshaped to increase tire clearance.
Lucky Thirteen
All chainring combinations have a 13-tooth jump.
SRAM’s second-generation Red eTap 12-speed electronic drivetrain arrives today. Really, today. The new Red eTap AXS groups are available to buy right now. Groupset prices start at $2,838 for a 1x with rim brakes, and go all the way up to $4,158 for a 2x disc-brake group with power meter.
Additionally, several bike brands have Red eTap AXS bikes available in shops today, or will have them very soon. Almost all of these bikes are disc brake-equipped, carbon road-racing bikes that sell for $9,000 or more. Specialized, Trek, BMC, Giant, Orbea, and Cannondale all confirmed they will have AXS-equipped bikes.
What’s New
Almost everything is new, the exceptions being the brake calipers (rim and disc) and hood shapes, which carry over from the previous generation and get only graphic updates.
The new Red eTap fits into SRAM’s AXS (say “access”) ecosystem of interconnected parts. This means you can control the new Eagle AXS mountain bike derailleur, and the new RockShox Reverb AXS dropper post from the Red eTap AXS controls. It also provides improved customization and control from SRAM’s AXS app.
There are significant changes to the gearing. The most prominent is the jump to a 12-speed cassette, which brings with it a new driver-body standard, and a new chain. There’s also a new gearing scheme, a damper in the pulley cage, increased tire clearance, integrated chainrings and power meters, 1x drivetrain options, and a slight change to the shape of the brake levers.
SRAM also stated that a Force-level version of eTap AXS will be released later this year. More details will be shared in April.
How Much Does It Weigh?
Here’s what a 2x disc brake group with power meter weighed on my scale:
That’s pretty light considering its a complete group with hardware, bottom bracket cups, power meter, and two 160mm center lock rotors.
SRAM’s claimed group weights can be found in the image below.
1x- and 2x-Ready
The new eTap AXS rear derailleur has a damper. A speed-sensitive fluid damper, actually. And don’t you dare call it a “clutch.”
In normal situations, the pulley cage can rotate forward easily, which saves battery power. But if a bump tries to violently bounce the cage, the damper slows the cage’s movement, which prevents chain bounce and improves chain security.
This additional chain security is what makes the new Red eTap AXS not only gravel and CX friendly in 2x formats, it also officially brings 1x compatibility to SRAM’s highest-end drop-bar parts.
Faster Shifts
The Red eTap AXS derailleurs have new chips and new motors, while the shifters have new electronics as well. This provides noticeably faster and more responsive shifting than the previous generation of Red eTap.
The front derailleur was reshaped to create more tire clearance: It’s now rated to clear up to 42mm-wide tires.
Though there is a lot about the group that is new, it uses the same batteries as the previous generation of SRAM Red eTap.
New Gearing
The switch to 12 speeds isn’t the only drivetrain news. SRAM also shrunk the sizes of its chainrings and cassettes, arguing that shifting performance is better with the smaller-diameter rings and cogs, and smaller is lighter as well.
All cassettes have a 10-tooth small cog. Three cassette sizes are offered: 10-26 (260 percent range), 10-28 (280 percent range), and 10-33 (330 percent range). These cassettes require SRAM’s XDR driver body. Construction is the same as the 11-speed Red cassette: Most of the cogs are machined from a single piece of steel, with the largest cog made of aluminum and pressed on. Noise-damping rings reside between the cogs.
SRAM’s new chainring combinations are 50/37, 48/35, and 46/33. Each combination has a 13-tooth jump, which SRAM reps state makes for better front shifts than a larger jump would.
SRAM’s biggest competitor, Shimano, has long stated that larger-diameter rings and cogs are more efficient because they reduce friction. However, SRAM’s representatives state that studies have shown that the increased chain tension created by the smaller-diameter rings improves efficiency. I requested a link to the chain-tension study SRAM’s representatives were referencing, but it has not been provided.
I reached out to Jason Smith, Ceramic Speed’s chief technology officer, who has spent hours studying and analyzing drivetrain efficiency in his Friction Facts lab, for his take on how the size of a drivetrain’s rings and cogs affect efficiency. In an emailed response, he said: “We have lots of recent data (last 10 years) showing larger-diameter rings and cogs are more efficient than smaller-diameter rings and cogs, given the same final gear ratio. Unfortunately, there was a paper from the late ’90s that stated the opposite. Many people still remember that paper, and incorrectly site it.
“The only reason I can think of that SRAM might claim [increased efficiency from higher chain tension] is because of a paper from the 1990s, which I mentioned above. This study (incorrectly) claimed that increased tension increased efficiency. The experimental errors and incorrect assumptions found in this study have been well documented.”
Though smaller, SRAM’s combinations roughly line up with the common 2x road gearing combinations. The 50/37 with 10-26 cassette is roughly equivalent to a 53/39 with 11-25 cassette; 48/35 with 10-28 compares with a 52/36 with 11-28 cassette; the 46/33 with 10-33 cassette is about the same as a 50/34 with 11-32 cassette.
The chart above shows how eTap AXS’s chainring and cassette combinations compare to traditional combos. In most cases, SRAM’s 12-speed systems provide a bit greater range—both higher highs and lower lows—than their traditional analog.
Adding an extra cog to the cassette allows SRAM to tighten up some jumps, and a 12-speed cassette has more one-tooth jumps than an 11-speed cassette. Smaller jumps are nice because they shift better than larger jumps, and because the ratio jumps are smaller, it’s less jarring of a cadence and effort change. The table below shows how SRAM’s eTap AXS cassettes compare to common 11-speed cassettes.
Only one medium-cage rear derailleur and one front derailleur are offered. Riders can change their gearing at their leisure without the need to invest in new derailleurs (though chain-length may need to be adjusted).
1x rings are offered in 36- to 50-tooth, with a 52-tooth ring in development for future release.
If you need lower gears, you can shift the new Eagle AXS rear derailleur, and 10-50 cassette, from the Red eTap AXS shifters.
One-Piece 2x Chainrings
SRAM’s double chainring is one piece and direct mount to the Red crankset using the eight-bolt interface first rolled out in Quarq’s (a SRAM brand) power meters. The one-piece and spiderless design is lighter, stiffer, and better shifting, say SRAM representatives, who claim updated manufacturing processes make the new rings 50 percent more durable, with a lifetime measured in years, plural.
But it also means that if one chainring wears out or is damaged, you’ll need to replace the whole unit.
Integrated Power Meter
Integration is pushed to unprecedented levels with the AXS power meter, which is integrated into the one-piece chainring unit. The benefits, according to SRAM representatives, are weight savings and more consistent and accurate power measurements.
However, when one of the chainrings wears out, or if it gets damaged somehow, you’re not just buying one chainring, not just two chainrings, but two chainrings and a power meter. And the cost of rings and power meter unit is reported to be about $820.
I attended SRAM’s press launch of the new AXS ecosystem in January. When the presenter reached the, “A new chainring and power meter unit will cost more than $800,” part of the presentation, you could hear the air getting sucked out of the room.
Perhaps that’s why, the day before SRAM lifted the embargo on the new Red eTap AXS group, Michael Zellmann, SRAM’s senior public relations manager, sent an email to the press that stated in part, “An update that we didn’t share with you, but has been finalized for this spring, is the SRAM RED eTap AXS Power Meter Support Program. If it’s ever time to replace a SRAM RED eTap AXS integrated power meter and chainrings assembly, customers can contact SRAM for a half-price replacement, and we will recycle the old one.”
Good on SRAM for offering this program—though it seems a little hurried; perhaps it figured that $820 chainrings would not be well received by the public.
But even at half price, $410 for a chainring still seems crazy. And tossing a perfectly good power meter because a ring is worn seems unnecessarily wasteful.
And it’s not like Quarq’s power meters were so wildly inaccurate. Quarq’s (SRAM’s) Dzero power meters were already at 1.5 percent accuracy. But I get this too: The point of training with power is precision, and if you’re trying to wring out every small bit of fitness, then better than 1.5 percent accuracy is better.
I’m really curious to see how the public votes with their wallets on this. Because what you do will decide how much further SRAM, and other companies, venture down this path.
And if this is not the path you wish to take, SRAM offers the rings without power meters. And there seems to be tremendous opportunity for aftermarket companies to rush in and fill the void. But these aftermarket options will take time.
Some of the eTap AXS 1x cranks with power meters use a nonintegrated power meter and chainring. When the ring wears out, you replace the ring and only the ring.
It’s (Almost) All DUB Now
Red eTap AXS adopts the DUB crank-axle standard that debuted in its mountain bike product. This standard uses a 28.99mm aluminum axle that’s longer than a BB30 axle. The idea is DUB offers most of the weight and stiffness benefits of BB30, but is more compatible and offers better bearing life. And, with the right bottom bracket, DUB will fit in almost any bike.
But the DUB axle doesn’t work in all bikes, so SRAM still offers Red cranks in its 24mm GXP standard. These cranks fit in Trek’s bikes—which use the company’s BB92 standard—and bikes with Italian-threaded BB shells like Pinarello’s Dogma
A Chain With a Flat Top
To fit the 12 cogs into pretty much the same space as 11 cogs, SRAM needed to tighten things up. That meant a narrower chain. But when a chain is made narrower, it loses strength.
So SRAM’s engineers came up with a workaround to regain the strength lost to the narrower profile. One of the outer links’ traditional scoops was filled in, which gives the eTap AXS chain its signature smooth look. SRAM calls it FlatTop, and it weighs about as much the company’s 11-speed Red chain. It’s also claimed to run quieter and shift more accurately.
The Flattop chain has its own quick link, and it’s not compatible with SRAM’s mountain bike groups.
New Parts Pains
Anytime a drivetrain undergoes a significant change, it starts a domino effect of collateral changes. It’s no different with Red eTap AXS.
The new driver-body standard is the most significant hurdle for riders looking to upgrade their existing bikes. SRAM released the XDR standard a while ago, so hub brands have known it’s coming, and many already offer compatible drivers. Zipp, a SRAM brand, has XDR drivers for many of its wheels, and so does Industry Nine, Mavic, and DT-Swiss (which covers many Bontrager and Roval wheels). SRAM maintains a website dedicated to the XD and XDR standard, which provides information about the standard itself, as well as a list of brands that offer compatible drivers.
If you use a direct-drive trainer, you’ll need a new driver body (and spare cassette) for that. SRAM representatives stated that trainer companies were given advanced warning so they had time to prepare compatible XDR driver bodies for their products. A representative for Wahoo stated, “[We] are aware of the new group and are working on a solution,” but stated that no timing or pricing information was available.
Note that the XDR driver is slightly wider than the XD driver standard SRAM introduced with its Eagle mountain bike groups. This is needed for clearance between the largest cog and the spokes. The mountain driver doesn’t need to be as wide because the massive 50t cog can be dished thanks to the angle of the spokes as they approach the rim. With a spacer, SRAM’s narrower mountain bike 12-speed cassette can be mounted to the XDR driver, but a 12-speed Red cassette will not fit on the XD driver.
SRAM reps warn that not all chain tools are compatible with its new 12-speed chain. Again, tool brands were given advanced notice of the forthcoming chain and should have products available soon. Representatives from Pedro’s and Park Tool both stated they will have compatible tools available starting in March
SRAM’s new gearing scheme and direct-mount chainrings mean that aftermarket companies have some catching up to do if they want to offer compatible chainrings for SRAM’s cranks. And riders that have a favorite power meter crank they want to use with the new group will need to wait for aftermarket options to catch up with compatible products.
Fancy Rotors
The disc rotors have a new carrier that looks like it might be a heat-management system. But according to SRAM’s reps, its mostly just styling to help it match the chainrings and the rest of the group
All the Other Little Things
The hood shape is unchanged, but the hood covers have a new texture. The brake levers are slightly wider at the top; the shifter buttons are the same size, but have a grippier surface.
The brake calipers are unchanged, though some improvements were made to the hydraulic internals at the lever to reduce dead throw. Dead throw is still adjustable with a dial under the hood, and offers the same adjustment range as before.
Like the previous-generation eTap group, two remote buttons, called Blips, can be plugged into each shift/brake lever. However, where before those buttons mirrored the function of the shifter into which they were plugged, with eTap AXS, the function of each button is individually programmable through the AXS app.
The Blip Box used for triathlon and TT bike builds is now smaller, but, as before, still has ports for up to four blips.
And if you continue to love rim brakes, SRAM has you covered. The AeroLink rim-brake calipers are carried over from the previous generation of the group, with only minor styling updates.
Ride Impressions
The new 12-speed Red eTap AXS group is a noticeable improvement over 11-speed Red eTap.
Most notably, Red eTap AXS shifts much (much) faster than Red eTap, and finally puts SRAM’s electronic shifting in the same league as Shimano’s and Campagnolo’s systems.
Shifting is also more refined. Front shifts are less clunky, rear shifts feel crisper, and all shifts are much smoother and noticeably quieter.
If there’s an efficiency difference due to the smaller rings and cogs, I couldn't feel it on the road. In fact, I didn’t notice I was on smaller-diameter gears, or even on 12 speeds. But the gearing seems well thought out, and is very smooth and natural feeling on the road.
The disc brakes aren’t much different—they were already excellent—but the adjustable contact point is more usable now that dead throw has been reduced.
Overall, there’s a lot to like about the new Red eTap AXS group. There are more gearing options, more customization, more compatibility with different kinds of bikes, and faster, more refined shifting. And the interoperability with the other AXS parts is awesome. It’s expensive, of course—Force eTap AXS can’t get here soon enough—and the integrated chainrings and power meter, and new driver body standard, are sure to cause some consternation.
But no other drivetrain offers as much technology, as many options, or as much flexibility as SRAM’s new Red eTap AXS. And you gotta love that.
A gear editor for his entire career, Matt’s journey to becoming a leading cycling tech journalist started in 1995, and he’s been at it ever since; likely riding more cycling equipment than anyone on the planet along the way. Previous to his time with Bicycling, Matt worked in bike shops as a service manager, mechanic, and sales person. Based in Durango, Colorado, he enjoys riding and testing any and all kinds of bikes, so you’re just as likely to see him on a road bike dressed in Lycra at a Tuesday night worlds ride as you are to find him dressed in a full face helmet and pads riding a bike park on an enduro bike. He doesn’t race often, but he’s game for anything; having entered road races, criteriums, trials competitions, dual slalom, downhill races, enduros, stage races, short track, time trials, and gran fondos. Next up on his to-do list: a multi day bikepacking trip, and an e-bike race.
