SRAM has launched its “most advanced” 13-speed flagship gravel groupset, Red XPLR AXS, a 1x system that’s designed around a 10-46 cassette. Sister brand Zipp simultaneously launches a radical 303 XPLR wheel range with a 32mm internal rim width – even wider than its mountain bike rims – designed to complement the new components.
SRAM has decided it’s time for gravel to go its own way, recognising that the discipline has quite literally outgrown its up-to-now road-based equipment and so unleashes a radical, premium groupset and wheelset that are a sprocket and a few millimetres respectively bigger than what went before, while dropping the weight to a claimed 2,488g, 218g lighter than the previous version.
The headline for the new groupset might have been that it’s SRAM’s first ever with 13 sprockets, but there’s quite a lot more to the new Red XPLR AXS than an extra gear. At the centre of the new system is an all-new, hangerless, ‘Full Mount’ derailleur that uses the UDH interface and which is designed, in SRAM’s words, to take whatever you throw at it. There’s also a new spider-based power meter with thread-mount chainrings. But despite the new tech, there’s a surprising amount of backwards compatibility with existing standards: the 13-speed drivetrain uses the same 12-speed Flattop chain as SRAM’s road groupsets; the 13-speed cassette mounts onto the existing XDR driver body while it shares shifters, calipers and rotors with the new Red AXS road groupset, launched in May.
Meanwhile, the new Zipp 303 XPLR hookless wheelset – which comes in two specs, SW and S – is designed with an ultra-wide 32mm internal rim width so that a tyre as big as 45mm can be run at a very low pressure with low rolling resistance and without squirming or collapsing under corning load. The brand also claims a lower risk of pinch flats and perhaps, most crucially of all, the wide rim is more aerodynamically efficient with wide gravel tyres. It has to be said there’s not so much backwards compatibility here: Zipp has partnered with Goodyear on two approved XPLR specific tyres, with more from other tyre brands to be added to the list and the caveat that the wheels must only be run with tyres on the list. The claimed weight is 1,496g for the 303 XPLR SW with the ZR1 hubs, while the 303 XPLR S weighs 1,610g, has 76/176 hubs and doesn’t have the dimples or laser etched graphics (but has a lower price).
SRAM Red XPLR AXS Full Mount derailleur
As with its latest Red road components, SRAM’s messaging behind its new flagship gravel group is all about effortless experience. It uses the words “resilient”, “precise”, “light” and “fast” to describe it. The element that fits the “resilient” description best and without any doubt is the new Full Mount derailleur. Generally, the rear derailleur is the most fragile part of any groupset – literally the weakest link. To overcome this, the new Red XPLR AXS mech eliminates the hanger, the part that bends in an impact, by bolting directly to the thru-axle of a UDH-compatible frame. SRAM claims the mech is baggage-handler proof and we were told it wasn’t even necessary to remove it for transporting a bike in a bag. As for “precise”, an additional benefit of its bolting directly to the frame is the ease with which it's possible to set it up. The new 1x specific Red derailleur doesn’t incorporate adjustment screws since its position in relation to the cassette is fixed – thanks to the Full Mount system – and there’s just one cassette option, 10-46t.
SRAM’s Stu Bowers told us: “We go to countless events all over the world and there’s almost always a line of about 50 people outside our tent saying ‘can you adjust my gears?’ I would say 90% of times the reason for that is the mech hanger. So Full Mount does away with that. The adjustment screws were really to cover all the thousands of derailleur hangers on the market, which have enormous variation and some might as well be made of soft cheese. We’re never going to have to adjust screws or straighten the hanger again.”
The new Red XPLR AXS derailleur has a couple more tricks up its sleeve too: if it does sustain damage or even just gets marked, it has replaceable, rebuildable parts that Bowers says are “super cheap… from a mechanic’s perspective it’s never been easier to change parts on a derailleur and also to clean it and look after it.” It uses the same battery as SRAM’s other AXS components, but instead of clipping onto the back of the derailleur it slides in underneath the dropout out of harm’s way, as it does with its counterpart Eagle Transmission mountain bike derailleurs. It also incorporates the Magic Pulley of Eagle Transmission, which allows the outer part of the jockey wheel to keep turning even with a stick in its spokes in order to combat catastrophic, derailleur-wrecking jamming of the chain. Shift speed is the same as existing AXS derailleurs, and as for the price, the new Red XPLR AXS derailleur has an SRP of £700/$700 – the same as the road version. SRAM points out that as well as a UDH frame, the Red XPLR AXS groupset requires a chainstay length of a minimum 415mm to allow wider tyres.
Cassette: this one goes to 13
The 10-46 cassette, however, is priced higher at £600/$600, which is more than the most expensive Red road cassette. But it’s a very impressive piece of tech, a large but light structure that weighs just 288g and supplies a 460% range. Why did SRAM feel the need to add a 13th sprocket? Bowers says: “13 speed is necessary to really drive home 1x. The thing that 1x still gets challenged on is the steps between the gears, so if you can eliminate that, and also because we found a nice way to get 13 sprockets into the space of 12, it’s a win-win.”
The first four sprockets from 10 to 13 are separated by single-tooth differences, while up to 21 it’s two-tooth jumps, then 24, 28, 32, 38, 46. And the “nice way” to spec 13 sprockets while using the XDR same driver body and 12-speed chain was to use the gap between the smallest sprocket and the frame plus the space at the dish of the wheel. The new setup sites its smallest sprocket beyond the end of the freehub and very close to the frame, which was made possible via the Full Mount derailleur positioning.
Power to the gravel
The new Red XPLR AXS power meter again borrows from SRAM’s Eagle Transmission mountain bike lineup: it uses chainrings that thread to the spider (Thread Mount) that are easily removed/replaced via a clever tool that screws into the crank after removing the pedal. There are options from 38-46t and crank lengths from 160-175mm.
It uses a CR2032 coin cell battery and SRAM claims a battery life of 200 hours. The non-power meter chainset uses SRAM’s direct-mount (rather than threaded) chainrings and comes with the same size options. Both have hollow carbon crank arms that SRAM says are 29g lighter than the previous generation and both chainsets run on SRAM’s DUB bottom bracket.
Same shifters, different surface
Incorporating the shifters from the road version of Red AXS is something we could have predicted. Not only do the levers flare outward more than those of the other component manufacturers’ road groupset levers but they’re also longer in the pommel – thanks to repositioning the hydraulic cylinder horizontally – for better grip on the hoods.
SRAM emphasised the one-finger braking at road Red’s launch, something that possibly benefits gravel riding more frequently and which, as we found with road Red, is excellent. SRAM said that braking required 80% less effort from the hoods and 33% less effort when braking from the drops (compared with outgoing Red) and in a gravel context this suddenly becomes very useful.
RIDE IMPRESSIONS
When I rode the new SRAM Red AXS road group before its launch in May, Specialized senior brand manager Symon Lewis sourced a Red-equipped S-Works Aethos from the USA especially for me. This time Specialized was in on SRAM’s new gravel groupset launch from the start, so although I didn’t get an exclusive, it was useful to ride the same S-Works Crux with Red XPLR AXS as other cycling journalists on a pre-launch route around the Surrey Hills with Stu Bowers. I’ll admit it, I’ve always regarded this area as mtb territory and wondered how a fully rigid gravel bike in my hands might cope with big rocks, roots, step downs, steep singletrack and sloppy mud. I knew former mountain bike racer Stu would want to show us what SRAM Red XPLR AXS could really do, so expected the worst/the best when he shared the GPS route that included the famous Barry Knows Best singletrack trail.
I had already accepted the look of the new derailleur since first being shown it at a pre-launch presentation. It’s not pretty in a 1980s Campagnolo Super Record kind of way, but boy is it clever. SRAM is saying gravel has moved on from using road components, and the Red XPLR AXS derailleur embodies this. It’s almost ruthless in its efficiency and looks totally utilitarian to underline this. I didn’t jump up and down on it like a baggage handler running out of hold space, and I miraculously didn’t even crash in the Surrey Hills, but from what I’ve seen it’s more fit for purpose than any gravel component I’ve used to date. Shifting was faultless – not the fastest, as it’s been pointed out, but with SRAM’s X-Sync wide-narrow teeth the chain is always engaged, meaning that a downshift on one of those very steep and rocky sections under load is always predictable and reliable.
When I rode the new road version of Red, I noted that the levers “would line up with the drops of a flared bar, but with a more traditional bar without flare they don’t.” This time I found them to be in the optimal position for braking and shifting – perhaps even better suited to gravel than the road.
Zipp/SRAM says the 303 XPLR is its fastest gravel wheel yet thanks to its engineers studying how gravel racing has progressed in recent years. The rim depth is 54mm, which Zipp’s engineers found to be the “perfect aspect ratio for aerodynamic efficiency with a 40mm gravel tyre at race speeds” (which it has pegged at ~22mph).
We rode 45mm Goodyear XPLR tyres in the Surrey Hills and Zipp’s pressure calculator came up with a suggested 24psi for my weight (69kg), which seemed crazy, but in the event was absolutely right. Traction, control and speed were all spot on. And despite their looking impossibly fat, they even felt fast on the road when I had to leave the group a few miles early hacked back along the tarmac of the A25 to Specialized HQ just outside Dorking.
Overall, the launch of the SRAM Red XPLR AXS groupset paired with the Zipp 303 XPLR wheels seems like a watershed moment for gravel components. It’s where gravel ought to be – 1x, electronic, 13 speed, lightweight and the equivalent of a flagship road groupset – and now SRAM is the only groupset manufacturer that has that.
Check out SRAM’s website for all the prices, weights and specs.
