Zipp 303 SW Tubeless Disc Rear Wheel

The Zipp 303 SW Tubeless Disc Rear Wheel is the rear half of Zipp's 303 SW wheelset, built around a 40mm-deep rim that borrows its shape directly from the gravel-ready 303 XPLR. That heritage shows up in how the wheel rides — it's tuned to handle rough pavement, cobblestones, and light gravel just as well as a clean racing surface, which makes it less of a pure road wheel and more of an all-conditions race wheel that happens to excel on the road too.

Zipp revised the carbon layup on this generation to add close to 10 percent more impact strength without adding weight, which matters on a wheel meant to take real hits from potholes, cobbles, and rough chip-seal. The rim uses a hookless bead, which gives the tire's edge a more forgiving surface to rest against during a hard impact, reducing the odds of a pinch flat compared to a traditional hooked design. Zipp's Sawtooth rim profile — the scalloped shaping visible along the rim's sidewall — is there to manage airflow and keep the wheel stable in crosswinds across that same range of terrain. The rim carries a 25mm internal width and 33mm external width, built around 30-35mm tubeless tires for best performance, though it's rated tubeless-compatible up to 44mm for riders running wider rubber on rougher courses.

The standout feature on this wheel is the integrated Zipp AXS Wheel Sensor, built directly into the rim rather than bolted onto the valve stem the way most pressure sensors are. It reads tire pressure in real time and feeds that data into the AXS ecosystem, so a rider can check and adjust pressure precisely for the day's conditions instead of guessing with a hand pump gauge, and catch a slow leak before it turns into a flat mid-ride. It's the kind of feature that matters more the rougher the terrain gets, which lines up with what this wheel is actually built for.

Underneath, the wheel runs Zipp's ZR1 hubset, updated with a full stainless-steel bearing set for smoother rolling and better long-term durability than the previous generation. It uses a Center-Lock rotor interface and is available with an XDR or Shimano freehub body, with a Campagnolo driver sold separately for riders on that drivetrain. The wheel is built with 20 spokes, a low count that keeps weight down while the deep, wide rim profile handles the stiffness the spoke count alone would otherwise need to provide.

All of this points toward a rider who wants one rear wheel that doesn't need to come off the bike depending on the course — someone racing a road event with a cobbled sector, a gravel race with long paved connectors, or just training on roads that aren't always in great shape. Rated to a 250-pound system weight and a 73 psi max pressure, it's built with real-world roads in mind rather than a smooth closed-circuit criterium course, and the built-in pressure sensor gives a rider one more way to actually use that versatility instead of just having it on paper.