Until recently Zipp was all about the aerodynamics but its TSE (Total System Efficiency) testing has seen a big broadening of its performance perspectives. That’s included much wider rims and low-pressure boundary-pushing on the recent 303, 404 and 454 wheels, but they were still fast, light and aero. The 101 wheels are built as part of SRAM’s XPLR adventure group and totally ignore the wind tunnel and the weighing scales in favor of concepts and tech from the wild world of Motocross and Enduro MTB. The result is a wheel that makes no sense in terms of conventional performance metrics used to measure the best gravel bike wheels but delivers a genuinely game-changing ride if you like a lot of Grrrrr in your gravel.
The big deal with the 101 is the rim. Rather than the ubiquitous strength and stiffness efficient hollow ‘box’ section, it uses a single composite layer with a slightly asymmetric spoke trough, sloped shoulders and very low, hookless sidewalls. In fact, apart from the NCF naked carbon finish, it looks exactly like the steel rims used on old rod pull brake roadsters.
While the rims are definitely radical, the rest of the wheels are pretty standard (if top end). 28 Sapim spokes lace the rims into the same ZR1 hubset used in Zipp’s Firecrest wheels, with 12mm axles front and rear. You can pick either SRAM XDR or Shimano HG freehub body options which both have a 66 point engagement for a very quick 5.45-degree maximum pick-up lag. Wheels and separate rims (€750 / £670) are available in 650b and the 700c (tested) but the unique construction means some potentially challenging numbers for most gravel riders.
The 27mm internal width is super broad for compatibility with 35mm to three-inch tires but at 36mm wide externally there’s minimum compatibility with anyone trying to be aero. At 790g front and 890g rear, they’re certainly not light either, even by mountain bike standards. Four different spoke lengths mean taking spares on expeditions is a pain, too, although at least they’re J-bend rather than straight-pull. You do get a full no-questions-asked lifetime warranty and 10kg higher ‘system weight limit’ than Firecrests and aligns nicely with how they’ll probably influence your riding.
And riding is the only way you’ll really ‘get’ the 101s. Unsurprisingly these heavy, flat-fronted rims don’t do the acceleration or air-cutting performance of a bike any favors. So if you’re primarily going to be going fast on-road or light gravel then Zipp’s much lighter, comprehensively aero yet still compliant, and lifetime warrantied, 303 Firecrest wheels are a much better choice.
It pulls on tubeless tires like your favorite jeans, fitting over the low rim with just a thumb and then settling into the central trough with an easy shrug. The fact you can feel the nipple heads sitting proudly under the tape feels freaky at first but nothing bad has come of that fact during testing. Sealant slopped in and a casual track pump effort will see the tires catch air immediately and gradually creep into place for a satisfying pop against the low rim walls. We didn’t even need to overpressure Zipp’s G40 tires past the recommended 30psi sweet spot to get a neat line up of the bead line and sealant dribble was minimal. The 27mm internal width also brings the tires up properly fat, measuring 41.6mm on our calipers (1.6mm) bigger than on 25mm internal 303 Firecrest and 3mm broader than on 22/23mm internal hoops. If you really want to get accurate with your pressures there’s an optional Quarq TyreWiz digital valve that’ll tell your phone how hard your tires are or flash red outside the sweet spot. That does cost €269 / £240 though so it’s a serious flex just to get Hummer vibes from your gravel wheels.
Hummer wasn’t the military comparison that the 101s created as soon as we went off-road either. Nope, the Moto-inspired rims plowed straight past any wheeled analogy with full-on ‘tank tracks’ ignorance on irregular surface teamed with utterly outrageous traction. Zipp’s soft-compound, tough-carcass G40 tires are already right up there with the best gravel bike tires in our bombproof/gluey grip rankings but the 101s take them to the next level. That’s because of what Zipp calls ‘ankle compliance’ and which refers to the ability of the single skin rims to twist and flex around the centreline ridge while still staying laterally stiff. The shock-dodging, ground-molding concept is standard issue in Motocross wheels and Zipp designer Bastien Donze revealed he started thinking about how to transition it onto bikes after a conversation with legendary UK MTB innovator and instigator Michael Bonney years ago. It was first introduced on the Zipp 3ZERO MOTO wheels a couple of years ago, but while it was loved by some riders the rim movement is inevitably only a small proportion of the overall 3D-shape-shifting ability of an Enduro bike so the difference they make isn’t so dramatic.
In the context of a gravel bike where travel/compliance (whatever you want to call it) is generally measured in millimeters and microns, not inches, the effect of the rim mobility is very, very clear. Straight away it was very obvious that we could arrow straight through sections that normally kick and slip us all over the place. That’s because the rim distorts and writhes through root spreads and rocky chunder leaving the bike undisturbed and tracking true. Running the wheels in combination with the 30mm travel RockShox Rudy Ultimate XPLR gravel fork also spoke volumes about how the two different systems feel on the trail. Unsurprisingly the fork takes more violence out of stutter bumps and straight on square-edge jabs but even with it locked the wheels are still calm and absorb slaps and chatter remarkably well.
Despite completely open compression damping (the circuit only controls rebound) the Rudy still can’t track and glue down control like the wheels can in terms of line holding or move making traction when impacts and loads get more awkwardly vectored or relentlessly extended. The fact you’re getting the same reaction from the rear end of the bike not only increases comfort but also cements that ‘tank track’ vibe as the dramatically enhanced grip not only applies to cornering and line holding but also how well the tires grip on rough ground.
The other big gain from the rim compliance is that they basically give your tires a black belt in Ju-Jitsu in terms of swerving a beating and turning attack energy into speed. Engaging the standard testing protocol of riding things until they break (or at least tap out) we ramped up the rockiness and roughness of trails we were hitting. Even when we were battering across baby heads at 70km/h and getting PRs on shallow stepped gravel descents that we’ve ridden regularly on full-sus mountain bikes. Not only did we not once pinch flat the G40s at 30psi, but we very rarely felt the ground bite hard against the rims. The flex definitely saved our necks multiple times when the bike carried on gripping through turns that we’d gone into way too hot and the 101's ability to let us get away with murder has actually started to scare us.
They’re certainly not explosively responsive when you get out of the saddle, and obviously, the basic laws of physics say a lighter wheel will climb and accelerate faster but it doesn’t feel like your chain has turned to rubber on the road. The longer and harder the ride the more the wheel's ability to suck up trauma will creep them closer to an overall freshness gain. If you start factoring in their next-level ability to hold speed on mountain bike-grade trails, the decreased likelihood of pinch flats and Zipp’s claims that a near 1,700g wheel is actually a great idea for gravel racing starts to seem less like hype, too. They still pop and play on the trail, too, so that ‘tank track’ feeling of traction isn’t a crushing vibe killer.
If you’ve got this far into this excitable essay you’ll have gathered that the Zipp 101s are something very different. As we hopefully made clear at the start the weight and non-aero profile mean these wheels won’t suit most all-road/light gravel jockeys. To be honest they only really come into their own when you’d probably be better off on a mountain bike and that opens up a whole other argument. However, if you’re a gravel biker who regularly finds yourself bouncing off the limits of off-road control or just want very noticeably better traction, line holding and impact smoothing speed sustain in a 650b or 700c 12mm axle format the 101s are genuine game-changers. That’s despite the fact that we’re still exploring the puncture and damage dodging attributes several hundred savage kilometers into testing without even a hint that we’ll be calling Zipp about their lifetime warranty cover.
Tech Specs: Zipp 101 XPLR gravel wheelset
- Price: $850 / €870 / £780 (front wheels), $950 / €970 / £866 (rear wheels)
- Weight: 1680g (700c with valves)
- Internal width: 27mm
- Sizes: 650b and 700c
- Colors: Raw carbon, Kwiqsand (khaki)