Long-Term Test: Zipp’s 303 XPLR SW Covers All the Bases

Zipp’s deep-and-wide gravel wheels, the 303 XPLR SW, have been on my work horse Santa Cruz Stigmata since May, and as of this writing, it’s mid-September. I’m actually glad I had a full summer to experience these wheels, which aim to achieve the seemingly contradictory goals of being light, aero, responsive, and comfortable all at once.

When I built up the Stigmata back in 2019, I decided to maximize the bike’s versatility with two different wheelsets. I had a set of 23mm-wide HED Ardennes aluminum wheels with 33mm tires for pavement and smooth gravel, and a set of Reynolds AR 650b carbon wheels mounted with the widest, knobbiest WTB gravel tires I could find for trails and rougher gravel roads. Each wheelset worked well, but felt compromised outside its specialty. The 700c wheel set struggled on the single track shortcut featured in one of my favorite gravel rides, while the 650b setup felt sluggish and slow on the paved sections of longer dirt-road loops.

The 303 XPLR SW promises to do with a single wheel set what I was trying to accomplish with two.

Zipp released the 303 XPLR nearly two years ago with dimensions that looked almost outrageous by traditional standards: a 32mm internal width, 40mm external width, and a 54mm rim depth. While many aero gravel wheels adapted the design of existing road wheels, Zipp built the XPLR around its “Total System Efficiency” philosophy, which argues that gravel riders lose more speed to vibration than to weight. The ultra-wide hookless rim is designed to support lower tire pressures, often below 30 psi, increasing traction and comfort while reducing the energy lost to bumps and chatter. At the same time, the deep profile and wide tire-to-rim transition aim to improve aerodynamics, an increasingly important consideration as gravel racing speeds continue to climb. Zipp claims the design saves roughly two watts at typical gravel-race speeds and considerably more on fast descents. The premium 303 XPLR SW version pairs its signature dimpled carbon rims with Sapim CX-Ray spokes and ZR1 hubs featuring 66 points of engagement and smooth stainless-steel bearings.

Despite their oversized appearance, the wheels weigh a very respectable 1,452 grams with a maximum tire pressure rating 50 psi. Zipp backs them with a lifetime warranty for the original owner.

The 303 XPLR were launched alongside two purpose-built tire models from Goodyear. I rode them with both the Goodyear XPLR Slick for dry conditions and the lightly-knobby Goodyear XPLR Inter for mixed, loose, or wet surfaces.

Specifications

At 220 pounds I found a sweet spot at 38 psi across all conditions. Both Goodyear tires, remain solid options, but the list of compatible tires has grown substantially since the wheels were introduced and now includes some intriguing alternatives. I’d be particularly interested in trying some of Vittoria’s XC mountain bike tires on the 303s.

I spent a good portion of the summer riding the wheels with the Slicks installed. My regular gravel-bike rides are mostly pavement-based around my home in Salt Lake City, punctuated by side missions exploring singletrack, alleys, and unpaved side routes. These rides aren’t especially speed-focused, and in that context the 303 XPLRs felt capable of everything I asked of them, though initially I found them to be somewhat unremarkable. What I did notice was just how effectively the wide rims and large-volume tires handled every surface I encountered, from broken pavement and loose pea gravel to singletrack, while still allowing me to hit 40 to 45 mph on descents.

There were a few rides, however, that revealed what the 303 XPLRs are really capable of. On a couple of “no-drop”group rides with riders on both road and gravel bikes, the pace picked up toward the end during some friendly stoplight sprints. I found that I had a little extra acceleration at my disposal, enough to stay a wheel or two ahead of younger and fitter friends.

At the other end of the spectrum were some backcountry excursions where I took the gravel bike instead of a 29” hardtail. I took a solo day trip in July to escape the heat and explore a route near the Utah-Wyoming border. It’s roughly a 60-mile loop that includes pavement and graded gravel, but also features a long stretch of steep, loose doubletrack climbing through the mountains. Those conditions were certainly not ideal for the 303 XPLRs fitted with Goodyear Slicks, but the wheels and tires were never completely overwhelmed. More impressively, they handled the descent over some truly nasty terrain without any damage to the rims or tires.

After a full summer on the 303 XPLR SW, I’m convinced that Zipp has built a speed-focused wheelset with remarkably few compromises. These wheels accomplish what I was hoping to achieve with two separate wheelsets when I built my Stigmata seven years ago: they’re fast on pavement, confident on gravel, and capable enough for occasional excursions onto rougher terrain.

At the same time, I have to acknowledge that I’m not necessarily the ideal rider for them. Zipp estimates aerodynamic gains of roughly two watts at typical gravel-race speeds of 18 to 23 mph, with savings growing to around 10 watts on fast descents. I freely admit that I rarely spend enough time at those speeds to fully realize the aerodynamic benefits. If I were spending my own money, I might be tempted by a shallower and less expensive wheelset that retains the XPLR’s ultra-wide rim profile, where much of the wheel’s comfort, control, and versatility originate.

But that doesn’t diminish what Zipp has accomplished. The 303 XPLR SW delivers a unique combination of speed, refinement, comfort, and capability that few wheelsets can match. For riders chasing every possible advantage in gravel racing, or for anyone who simply wants one of the most sophisticated gravel wheelsets available today, the 303 XPLR SW represents the best that Zipp and SRAM currently have to offer.

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