SRAM Red eTap AXS first-ride review: More than just another sprocket

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Without a doubt, SRAM’s new Red eTap AXS wireless road groupset will be talked about because of its move to a 12-speed cassette. Although the gearing philosophy plays a key role in the Chicago company’s flagship product, there are plenty of other notable changes, such as faster shifting, 1x or 2x drivetrain options, enhanced cross-compatibility with SRAM’s mountain bike components, improved lever feel, and newly customizable programming, all with the same convenient wireless format.

In fact, the new Red eTap AXS represents an improvement almost across the board relative to the original version — but one big issue will likely weigh heavily on the minds of hardcore users.

This article takes a deep dive into Red eTap AXS, but SRAM today unveiled the (wholly compatible) Eagle AXS wireless mountain bike drivetrain as well. Follow the link for more information on that.

The thinking behind 12-speed

I can hear the moans already: “Ugh, do we really need another gear back there?”

Well, no, of course not, but there’s some sound thinking behind SRAM’s decision to go to a 12-speed format with Red eTap AXS.

SRAM’s position with X-Range is that the way we all ride drop-bar bikes is very different than it was just a few years ago, and there’s a lot of merit to that argument. Sure, road racing bikes haven’t changed much, but the rest of the market has been undergoing a huge upheaval with the rise of gravel, adventure, and similar genres. But by and large, our gearing hasn’t kept up.

SRAM Red eTap AXS gearing
Having a hard time deciphering how SRAM’s new X-Range gearing options translate to conventional 11-speed ones? Here’s a handy visual. Photo: SRAM.

At least initially, Red eTap AXS will be offered with just three double chainring setups (50/37T, 48/35T, 46/33T) and three cassettes (10-26T, 10-28T, 10-33T), which might seem limiting until you crunch the numbers. None of the cassettes use an 11T sprocket to start.

That 10T sprocket might represent a single tooth on paper, but it makes a big difference in terms of total range. And by combining a wider-range, 12-speed cassette with narrower-range chainrings, SRAM contends that Red eTap AXS riders will not only have more usable gears to choose from, but will also enjoy smoother front shifting, less frequent front shifts overall, and smaller gaps between individual shifts.

In a first for SRAM’s electronic drivetrains, Red eTap AXS will also be available in 1x or 2x formats, with no changes required aside from the chainring itself. And even better, all of the new Red eTap AXS bits will also be compatible with SRAM’s equally new Eagle AXS wireless electronic mountain bike drivetrain bits, as well as the new RockShox Reverb AXS wireless electronic dropper seatpost, so buyers can feel free to mix and match as they wish.

SRAM Red eTap AXS cassette
Why go with 12 sprockets? Increased range is one reason; tighter gaps are another. With Red AXS, you seem to get both.

Naturally, though, there are some questions and caveats.

That new cassette will only fit on SRAM XDR freehub bodies, which are nearly identical to the popular XD standard but for about 2mm of additional width to accommodate the 12th sprocket. Thankfully, SRAM says that nearly every wheel company is already on board, and that most 11-speed wheels and hubs (save for Shimano, of course) can be retrofitted to suit.

SRAM is also only offering Red eTap AXS double chainrings in a snazzy one-piece machined aluminum unit. The consistent 13-tooth gaps and extremely rigid construction makes for far improved shifting, but replacement costs go up substantially as well, especially for power meter users (more on that below).

And what about drivetrain efficiency? Previous testing by Friction Facts founder Jason Smith (who is now the chief technology officer at CeramicSpeed) has shown that, all else being equal, smaller chainrings and cassette sprockets generate more drivetrain friction than larger ones. Nevertheless, SRAM contends that the drivetrain efficiency of Red eTap AXS is, overall, unchanged from the previous generation.

What’s up with that chain?

Part of that drivetrain efficiency trick is the new chain, whose conspicuously flat outer edge is impossible to overlook. As you’d imagine, stuffing that additional sprocket into the same space that was once reserved for an 11-speed cassette necessitates tighter sprocket spacing and a narrower chain, which wouldn’t seem to bode well for drivetrain longevity or noise.

But with this new FlatTop chain, SRAM says the additional link material yields the same chain life as before, simply by adding more metal between the pins. That may seem intuitive enough, but what’s less obvious is that SRAM has also enlarged the chain roller diameter slightly relative to current 11-speed norms. According to SRAM, the increase in surface contact between the chain, cassette, and chainrings further helps reduce drivetrain wear.

SRAM Red eTap AXS chain
The FlatTop chain is narrower than previous 11-speed models, but features more material on its outer edge to help maintain strength and durability. The master link is obviously unique as well, and like other SRAM master links, is meant to be a one-time-use item.

Moreover, although the spacing between the sprockets is about 0.2mm tighter than before, the sprockets and chainrings themselves are the same thickness. And because the overall chain width has narrowed even more so (by 0.6mm), there’s more of a gap between the side plates and the cassette sprockets. According to SRAM, that extra space not only makes the drivetrain quieter than before, but easier to set up, too.

The change in chain dimensions does come with a bit of unwanted baggage. For example, many Red eTap AXS buyers and mechanics may find themselves needing a new chain tool and chain checker. So far, just the Park CT-3.3, and “select” Pedro’s, Topeak, and Rohloff ones have all been approved. And obviously, the matching non-standard tooth profiles in the cassette and chainrings complicate aftermarket compatibility and options down the road.


Gearing changes aside, the biggest difference between old and new Red eTap is the revamped AXS (say, “access”) wireless system, which now sends more information-rich data between the different components, and finally allows for customizable settings through the SRAM AXS app via Bluetooth.

Among those new settings are options for sequential shifting and automatic corrections. For the former, you just tell the system you want a harder or easier gear, and then it’ll decide what combination of front and rear shifts is necessary to make it happen. For the latter, manual front shifts are accompanied by automatic rear shifts to minimize the ratio jump. Both options have long been available in Shimano’s Di2 electronic drivetrains, so it’s good to see SRAM catch up here.

SRAM Red eTap AXS shift brake levers
The new Red AXS levers have the same shape as before, but with new graphics and more pronounced texturing. Inside each lever is the same CR2032 coin-cell battery, with the same two-year claimed run time.

Individual shift buttons can also be programmed. Want to switch the paddle shifter configuration? Or install a Blip remote to use just for a dropper seatpost or front shifting? Done, and done. And if you really want to be creative, you can just use the BlipBox (normally used for time trial and triathlon bikes) with non-SRAM brakes and Blip remotes for a truly customized setup. The choice is yours.

However you set it up, the iOS and Android-compatible app will also provide service reminders based on mileage, as well as firmware updates as needed.

SRAM AXS phone app
All firmware updates and settings will be done wirelessly through the SRAM AXS app. Photo: SRAM.

SRAM hasn’t gone into great detail on what else might be possible with AXS down the road, but the company’s marketing materials are clearly leaving the door open for much more. Might that include things like computer and lighting controls, or suspension settings? All of that — and more — seems well within reason.

Despite the fact that there’s more information being ferried around, SRAM says that refinements and efficiencies in how the levers and various components communicate with each other yield slightly faster shifts relative to Red eTap — a good thing, considering that was one of the few criticisms I had with the system before. That speed increase is greater still with 1x Red eTap AXS drivetrains, too.

Updated derailleurs

The new rear derailleur obviously looks quite a bit different from the old one, but those differences are more than just skin-deep.

First and foremost, the enlarged lower knuckle does indeed incorporate a new chain control device just as we (and others) had suspected. However, one subtle distinction to note is that it’s more of a one-way damper than a one-way clutch.

SRAM Red eTap AXS rear derailleur
From afar, changes to the rear derailleur seem mostly cosmetic.

The new Orbit fluid damper allows for free cage movement in both directions when the applied forces are low and the movements are slow, but it restricts forward cage movement with higher forces and faster movement. In other words, shifts shouldn’t eat up a bunch of extra battery life, and there shouldn’t be any additional drivetrain friction, either. But cage movement is greatly reduced when you hit bumps or patches of rough ground, and because that movement is still controlled somewhat in both directions, the drivetrain should generally remain quieter and run more smoothly than a one-way mechanical clutch.

Inside, SRAM has also fitted a new chipset and motor, which further helps speed along beyond the improvements provided by the new wireless messaging.

The original Red eTap rear derailleur was offered in both standard and WiFLi versions to suit traditional road and wider-range cassettes, but SRAM isn’t bothering this time around for Red eTap AXS. Instead, there will be just a single medium-length cage for both 1x and 2x configurations that will handle sprockets up to 33T in size, with a maximum capacity (total chainring tooth difference plus total cassette tooth difference) of 36T. For anything bigger than either of those, you’ll have to switch to an Eagle AXS mountain bike rear derailleur.

SRAM Red eTap AXS button
Inside the enlarged lower knuckle is a one-way fluid damper for enhanced chain control.

Down below, the pulleys grow in size from 11T to 12T, and the lower one also now sports a narrow-wide profile for enhanced chain security.

Similarly, the new front derailleur wears the same snazzy chrome-and-black look as the rest of the groupset, but gravel riders will be happy to hear that SRAM has moved the removable battery outboard slightly so as to provide better tire clearance. Officially, the new front derailleur will handle tires up to 40mm-wide (which means that there’s invariably a little more wiggle room for riders willing to take the risk).

SRAM Red eTap AXS tire clearance
The front derailleur uses the same battery as before, but it’s pushed outward a bit for better tire clearance. The official 700x40mm maximum tire clearance likely means that there will be 6mm of physical space in between the two.

And speaking of that battery, rest assured that it’s the same unit as before with no changes whatsoever. Claimed run time is 60 hours on average, and charge time is pegged at an hour.

Improved ergonomics and lever feel, mostly carryover brakes

Nothing has changed in terms of the new Red eTap AXS’s lever shape relative to Red eTap. But SRAM has covered the body with a newly textured hood for improved grip — especially when wet — and there’s also a more pronounced texture on each shifter paddle. In addition, each shift paddle has a noticeably stronger and louder click.

As before, lever reach is adjustable for riders with smaller or larger hands, and hydraulic levers can also be tuned for lever throw.

The brake calipers themselves are carried over intact across the board, with the same cable-actuated rim brakes and hydraulic disc brakes as before — which is just fine, considering both were already excellent.

SRAM Red eTap AXS disc brake
The hydraulic disc brakes and cable-actuated rim brakes are unchanged from the previous generation. The rotor is new, though.

SRAM has updated the disc rotors, though, introducing a new XR design that uses the same steel brake track as before, but with a larger and more pronounced aluminum carrier for both six-bolt and Center Lock versions (and rounded rotor edges, of course). SRAM isn’t making any performance claims around the change, though, so while the updated shaping seems to imply improved heat management or aerodynamics, it seems like it’s mostly just an aesthetic thing.

Power meter and crank controversy

Power measurement is becoming an increasingly integral part of high-performance road cycling, and not surprisingly, the new Red eTap AXS groupset makes a big deal of its new Quarq power meter.

On the surface, there’s a lot to like. First off, SRAM has dropped its power meter prices: it’s now a relatively modest US$500 upcharge when buying a new Red AXS groupset, which is particularly impressive given Quarq’s long track record of reliability and accuracy, plus the fact that it’s a true dual-sided system. The new power meter is also more visually integrated than before, and it admittedly looks rather slick.

SRAM Red eTap AXS power meter
The new crank certainly looks striking.

But that integration goes well beyond aesthetics, and it’s here where SRAM is likely to draw a fair bit of criticism (including from me). As with the non-power meter crank, the double chainring is made as a single piece of machined aluminum, but in this case, it’s also fully incorporated with the power meter.

In other words, when it comes time to replace a worn chainring with a new one, you’ll now have to get yourself a new power meter to go with it. According to Quarq technical director Jim Meyer (who also founded Quarq before SRAM acquired the company in 2011), the decision to combine the power meter with a consumable drivetrain component was based on long-term accuracy, and specifically drift.

On a more conventional spider-based power meter, the bolted interfaces between the chainrings and power meter, and between the crankarm and power meter, can sometimes induce residual stresses that can affect the power readings over time. But with this integrated design (plus the eight-bolt crankarm-to-spider interface SRAM introduced a couple of years ago), Meyer says that drift is no longer an issue, and riders that are serious about their training will be able to have more confidence that changes they’re seeing over time are directly related to their training, not their hardware.

SRAM Red eTap AXS chainring
SRAM is taking a big risk by integrating the chainring(s) and power meter as a single unit – if something goes wrong or wears out with one, you have to replace the whole thing.

Some solace comes in SRAM’s claims that the new chainrings will last “50% longer” than current Red chainrings. The company will also implement an exchange program whereby Red eTap AXS power meter owners will be able to trade in their worn setup for a new one at half-price. And in fairness to SRAM, there are plenty of high-end road riders who don’t log a ton of hours on their gear, and aren’t exactly blowing through drivetrain components.

That’s all well and good, but between the one-piece machined double chainring and integrated power meter, we’re still talking about a serious chunk of change. Full retail price on the assembly is US$820, so an exchanged one will set you back US$410. For the sake of comparison, a new one-piece Red AXS double chainring will cost US$300, so in some sense, it’s not a huge difference.

But that said, a current Red eTap inner chainring (which is what usually wears out faster) sells for about US$40.

SRAM Red eTap AXS cranksets
Single-ring? Double? Time trial chainrings? Yes, yes, and yes. And you can also get the new SRAM Red AXS crankset without the power meter, too. Photo: SRAM.

Will that be a dealbreaker? That’s not for me to say, but it’s certainly something that every potential Red AXS buyer should consider if they’re thinking about power. And if nothing else, it sure provides a lot of motivation to keep your drivetrain well maintained, clean, and properly lubricated.

One bright spot on this subject: Given that 1x chainrings generally wear out a lot faster than 2x setups, those will still be separate from the power meter itself.

As we reported earlier, SRAM is also introducing for the first time on the road its DUB spindle and bottom bracket format. Whereas the current GXP uses a stepped 24/22mm-diameter steel spindle, and PF/BB30 ones use a 30mm-diameter aluminum one, DUB goes with 28.99mm (yes, really). According to SRAM, the slightly smaller diameter yields improved bearing longevity on bikes that would normally use a 30mm spindle. In some cases, that switch will also yield almost 100g in weight savings on bikes.

Of course, that change in spindle diameter necessitates a change in bottom brackets, too, which very few people are likely to be all that happy about, but so be it.

SRAM Red eTap AXS power meter
As expected, SRAM has brought its somewhat controversial DUB bottom bracket standard to the road for 2019. Also, that little cover on the left is purely cosmetic. Weight weenies, take note that there’s an easy 7g to be saved there.

Perhaps more importantly on the OEM side of things, DUB means that one spindle will now fit almost every bottom bracket shell format on the market. One exception is Trek’s BB90/BB95 system, but for that (and possibly other) format, SRAM will still offer the standard GXP format.

Compatibility issues

Naturally, the question of compatibility will arise between the new SRAM Red AXS and the existing Red eTap, particularly for riders that are currently on the latter, but are interested in upgrading to the former.

Cue the sad trombones: Aside from the brake calipers, batteries, and a few other small bits, there is no cross-compatibility whatsoever between the two generations.

Part of this is due to the oversized chain dimension that SRAM has opted to use on Red eTap AXS, but the bigger issue is the wireless communication.

SRAM Red eTap AXS chain
The fact that the chain uses larger-diameter rollers than normal might help with drivetrain wear, but it also guarantees that none of the drivetrain components will be compatible with anything else.

Meyer acknowledged that existing Red eTap hardware could technically be made to work with the new bits, since the basic wireless language itself hasn’t changed. But because the old levers aren’t fitted with Bluetooth (current Red eTap uses a separate USB dongle for that task), implementing the necessary firmware updates was deemed to be unreasonably challenging on a wide scale.

Needless to say, that’s supremely disappointing, and like it or not, Red eTap AXS will basically stand on its own island. That is, except for …

Force eTap at last

After years of anticipation, SRAM has finally announced that a Force wireless groupset will join the Red flagship this coming April. SRAM hasn’t unveiled much in the way of additional details, but based on previous iterations of Red vs. Force, we can expect virtually identical functionality between the two, but with a variety of material substitutions, such as steel instead of titanium hardware, aluminum in place of carbon fiber, and so on.

Meyer did provide one juicy hint, however: It sounds like Force eTap AXS won’t use the same ultra-integrated power meter and chainring system as Red eTap AXS, so there might be light at the end of the tunnel if you’re not keen on the latter’s heady drivetrain replacement costs.

And what about mechanical Red?

Conspicuously absent from any of SRAM’s communications on the new Red eTap AXS groupset was any mention of a mechanical analogue. The current Red 22 groupset is still a solid competitor, but it’s also getting a little long in the tooth. And at the OEM level, it’s clear that there’s been far more interest in the eTap wireless version. But needless to say, not everyone will be able afford the new Red eTap AXS stuff, nor will everyone want to go electronic, so it would seem to make sense to see a revamped mechanical edition that uses the same X-Range gearing concept.

Might that still happen, or will Force eTap AWS now occupy the top rung at that price point, and is SRAM expecting that far more people will go that route? At this point, it’s anyone’s guess.

“We do not comment on potential future developments,” said SRAM senior PR manager Michael Zellmann.

Pricing, claimed weights, and availability

Retail prices and claimed weights for complete SRAM Red eTap AXS groupsets are as follows (and you’d better sit down first). Australian pricing is still to be confirmed.

SRAM Red eTap AXS prices and weights

As for availability, the bike industry finally seems to be learning a thing or two, as all of the new Red eTap AXS bits should be available both in-store and online as of right now. It’ll be a similar story when Force eTap AXS is announced in April. Hallelujah.

On the road (and dirt) with Red eTap AXS

SRAM sent out a Red eTap AXS-equipped Scott Addict Gravel for me to use here in Colorado, and the recent snows — and subsequent warming — have made for some messy test conditions. But I’ve been riding the stuff nevertheless, and I have to admit (at least given early impressions) that this stuff is really, really good.

Be as skeptical as you wish about the new X-Range concept, but it’s hard to argue with it in practice. My loaner arrived with the 46/33T chainrings and 10-33T cassette, which provides the 1:1 gearing I prefer on gravel rides around here, as well as a top-end that’s actually a bit bigger than a conventional 50-11T combination, all with refreshingly small gaps in between. Shifts have been positive and precise, and front shifting in particular is a big improvement over anything SRAM has produced to date on the road.

SRAM is billing its new Red AXS flagship as the ultimate groupset for drop bar bikes.

As promised, rear shifts do feel a touch quicker than before, although still a step behind Shimano’s lightning-fast Di2. It’s hardly a deal breaker, though, and it’s fair to wonder how many riders ultimately would care about that sort of thing, anyway. In all honesty, it’s likely something I’d forget about were I not switching between groupsets so frequently.

More important to me is how the new levers feel. The new hoods are nicely shaped and provide fantastic grip — especially when wet — and while the shift paddles were already a ready target before, the added texturing makes them even easier to find, particularly when wearing full-fingered gloves. I also very much welcome the increase in tactile feedback.

SRAM didn’t go into any detail on changes in the master cylinder for my disc-equipped sample, but it’s worth noting that the brake levers have a lighter action to them overall, and return with more speed and snap. In fact, they’re starting to encroach on Shimano territory. Functionally, SRAM’s hydraulic disc brakes had already been my favorite for power and control, and the improvement in feel only widens the gap.

As a very pleasant bonus, I’ve found them to run utterly silently so far, too, even when the rotors are splattered with soupy mud and road spray.

SRAM Red eTap AXS shift brake levers
You can most definitely feel the new paddle texturing with your fingers.

That soupy mud brought that issue of chainring replacement cost straight to the front of my mind, however; it was hard not to think about it given the sound of all that decomposed Colorado granite ruthlessly grinding away at those machined aluminum chainring teeth. Were this my personal bike, I’d be strongly tempted to wait for the Force-level power meter to come out in April, and deal with the more regular power meter calibrations in trade for the reduced maintenance costs. Nevertheless, that’s a cost-benefit analysis you’ll have to make for yourself.

This particular bike will be going back to SRAM shortly, but arriving in is place will be a proper long-term groupset, mounted to a Mason Cycles Bokeh with 650b wheels. I can’t say if these favorable early impressions will hold up long-term, but we’ll find out soon enough. Stay tuned for more.

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