Review: SRAM RED eTap AXS 1x Group
Aug 9, 2019
article & images by Nick Salazar
There is a lot of very cool stuff going on with the new AXS group. But before we get to all the amazing benefits, let's briefly talk about the intrinsic drawbacks. SRAM RED eTap AXS offers a lot of brilliant performance, but at the cost of a couple of all-new standards. First up is the XDr freehub body - an entirely new freehub standard that means ALL of your existing wheels are obsolete. You will need, at the bare minimum, a new freehub body, or at worst an entirely new hub. XDr freehub bodies are somewhat rare currently, but are getting more available. If new wheels are not a deterrent to you, you can get new Zipps right now that will work. But retrofitting existing wheels is a crapshoot. Next up, AXS presents an entirely new chainring, chain, and BB spindle, which basically means you need the new crank, new chain, and new bottom bracket. The spindle is an odd 28.99mm in diameter, meaning no current BB's work except SRAM's new ones. This honestly isn't a huge deal, because existing BB shells (meaning your frameset itself) will be fine. But your old bearings, crank, and chainring will all need to be replaced to use AXS.
Are the new parts worth the trouble? Well, at the end of the day, these new standards actually DO offer something of significant benefit to the user, so yes. I can't say that in the case of all new standards (cough cough, *disc brakes* cough cough), but for AXS, the cranks, rings, BB, and freehub body are all definitely worth the squeeze. Let's get to each aspect of this unique group individually.
The BlipBox is the transmitter for shifting. This piece was, in my opinion, one of the blunders of the original eTap system. The thing was simply HUGE. There was nowhere to put it, and it stuck out like a sore thumb. The new one is smaller in all directions, but still a bit bigger than a Shimano Di2 front junction. I wish it had reduced in width by just 4mm or so, even if that increased the length. Selfishly, that would let it hide inside our Alpha One stem cavity. Sadly it's still too wide for that. Regardless, less width means less frontal area wherever it's mounted. Still, it's a bit smaller as mentioned, and there are plenty of great places to hide it.
One sad thing about the new BlipBox is that it no longer works as a shifter in its own right, meaning it can't be used as a standalone shifter like we did on our Trek TTT project bike. Regardless, our project bike was a bit of an oddity. The normal function for the BlipBox is to act as a transmitter for Blips and Clics, and then placed out of the way. Hide the BlipBox, then use the lovely Blips and Clics as shifters. It works very very well, and ultimately makes for an extremely clean bike, as you can see in the photos. There's just one CR2032 battery to replace every several months, same as on the Quarq crank. As with the rear derailleur battery, I'd recommend keeping a couple of these in your saddle bag as well.
For the most part, setup is as you would expect for a drivetrain: crank, chain, RD, shifters. There are, principally, two unique aspects to setup. First, there are no wires connecting the front end to the back end. And second, to avoid those wires, you must successfully pair the front and rear halves electronically. That pairing is very straightforward, and dead simple. Hold the button on the RD until the light flashes. Then hold the button on the BlipBox until it flashes in tandem. Then press the RD button once, and pairing is complete. It took all of five seconds, and is basically the same as on the previous eTap system.
The one down side to the industry's ever-increasing gear count at the rear cassette, the the smaller the spacing between gears becomes, the greater precision required for shifts, and ultimately the more precise installation must be. That's true of most current drivetrains, and it's true of SRAM RED eTap AXS.
It's not that the installation is difficult, in fact it was dead simple. However, you need to be sure to read the manual or you might wind up frustrated. The critical step is to put the derailleur in its second-largest cog (second-easiest gear), then use the micro-adjust feature to line up the pulley wheels with the cog. SRAM has a detailed video describing installation of the whole system, scroll to the 5-minute mark to see how to adjust this critical element. Based on the position of the 2nd-largest cog, eTap AXS will take care of the exact position of every other shift, and it does so pretty much flawlessly. Just set the chain length, position the limit screws, dial the b-knuckle (also described in the video linked above), and it's a dream. Ghost shifting is gone, shifts are fast and accurate, and chain drops just don't happen. Moreover, once set properly, electronic drivetrains have the nice distinction of staying in perfect adjustment, pretty much forever. You can even remove the entire derailleur and chain for travel, and know that when you arrive at your destination, reinstallation will be easy, fast, and keep everything in perfect adjustment.
Once everything is paired, limit screws set, gears dialed in, and batteries charged, life is simple. Sure, you have to ensure batteries are charged (more on that in a moment), but there's no concern about cable stretch, periodic tension adjustment, etc. It's a very reliable system. You can even take the whole derailleur off for travel (which I recommend doing!) and when you bolt it back on, it'll work perfectly, never losing its adjustment.
SRAM claims 60 hours of ride time on the rear derailleur battery, which charges in one hour. That is of course going to depend on your terrain and shifting habits. Either way, best practice is just to carry a spare battery on the bike with you. When used in 2x configuration, the front shifting stops working when the battery gets low, as your signal to go charge. But for 1x, you don't get any such practical feedback. There is a light on the RD itself that will turn red when charge is low ... but it's not exactly easy to see that during a ride. Just charge after each ride, or get in the habit of checking periodically. The batteries are small, light, and cheap insurance against running aground during a race or important ride, so just keep one with you at all times. And fortunately, SRAM didn't change the batteries since the last version of eTap. So if you have some from the old version, they are cross-compatible.
I found that the BlipBox would run out of battery far quicker than I expected. During thye build of the bike alone, we went through two brand new batteries. SRAM claims two-year life of the BlipBox battery, so maybe something was up with my unit. SRAM recommended updating the firmware, which I haven't done yet. Either way, it's definitely best practice to keep spares around, and make sure you have ready access to the BlipBox itself to make those changes easy.
Quarq Power Meter
We have reviewed Quarq gear in the past. Quarq has a solid reputation for making some of the very best and most reliable power meters in the industry, equaled only by SRM. And who deserves the mantle of supremacy is by no means certain. In any event, you cannot go wrong with a Quarq. It offers legitimate dual-sided power measurement in a reliable, durable, lightweight, and extremely robust form factor. The new RED crank is no exception.
Of course, if you already have a pedal-based power meter like the Garmin Vector 3 or Powertap P1, you can get this same crank without the Quarq.
That said, the functionality and form factor of the AXS RED Quarq is astonishing. It's practically invisible! All you can see is a small cover for the battery, and absolutely nothing else. Nothing sticks out, and nothing presents an aero penalty. The Quarq crank is nearly identical in every way to the AXS RED crank without power. SRAM is really pushing you to buy in to its complete drivetrain system, rather than look to third parties for alternate options. And their reasons to do so are compelling. The complete system is virtually perfect from a conceptual standpoint, and comes together brilliantly.
The price you pay here (other than, of course, the high price in dollars) is that the chainrings use yet another new bolt standard specific to the new AXS system. You won't find replacement chainrings anywhere but SRAM. Moreover, the power meter is embedded in the chainring itself, rather than the spider. Because the power meter is integrated into the chainring, it means that once your chainring wears out, you will have an expensive replacement ahead of you. The sticker price for a replacement ring/quarq is $819, but SRAM says they will offer half-price replacements to existing customers who send in their old Quarq for recycling. Still, $400 is a lot for a new chainring. On the other hand, chainrings aren't exactly a consumable in the same way cassettes and chains are; that is, they last a very very long time. A good many, many, many thousands of miles. I would expect that most riders can expect a chainring life of at least a couple of years.
In short, the brilliance and beauty of the crank come at the price of more difficult service. But it should be noted that SRAM is not the first to eschew traditional chainring bolt patterns. Shimano did so many years ago with Dura Ace 7900, and no one really seems to have minded.
Regardless, integrating the ring/spider/PM into a single unit has palpable benefits. First of all, this combination shaves frontal area down to an absolute minimum, while offering very nice filleted transitions between the arm and the chainring. From the frontal view, this crank is ideal at virtually every degree of the pedal stroke. It's absolutely gorgeous, seeming to optimize basically every mechanical AND aerodynamic property I can think of, while also offering best-in-class power measurement with the integrated Quarq.
In terms of functionality, the Quarq is tough to beat. It no longer requires calibration, zeroing, or even a cadence magnet. Just put the crank on and go. It's about as easy as it gets. A single, user-replaceable CR2032 battery is all it takes to power it.
Obviously, we love what SRAM has done on the electronic side of this group. So, how do all those parts work together from a mechanical standpoint? Hit the jump and let's look at the mechanical aspects of SRAM RED eTap AXS 1x.
Individually, each AXS component is strikingly beautiful, especially the cassette and the crank. Here are some up-close looks at the parts themselves.
Our Test Rig
We set up our AXS group on an Omni, which can use a 2x setup, but is right at home with this 1x group. On Omni, the front derailleur hanger can be removed, and replaced with a small plate that completes the aero shape of the frame, leaving nothing for the wind to see.
Front End Details
Front end: we mounted the BlipBox on the underside of the Alpha One's Dragonfly, using the M4 threaded hole already on the BlipBox. No mods needed, and it keeps everything absolutely clean while still easily accessible. Please forgive the messy-looking arm cups. Those are our new prototype Scoops, just a 3D print with some hand-cut pads. Bar tape is Silca: Nastro Fiori on the extensions, and the slightly thinner Nastro Piloti on the base bar. This is easily the most comfortable front end I've ever used, and shifting feels awesome on the AXS clics.