Zipp 858 NSW Carbon Disc Brake Tubeless Rear Wheel

The Zipp 858 NSW Carbon Disc Brake Tubeless Rear Wheel is built around a single idea: that aerodynamic efficiency and real-world stability are not a trade-off. At 85mm deep, this is the deepest rim in Zipp's lineup — a wheel engineered for riders who demand maximum speed and expect it to hold up when the wind stops cooperating. Whether you're pushing through the final miles of a triathlon, holding a breakaway on an exposed road stage, or simply riding faster than the rest of the group, the 858 NSW is designed to stay planted and keep moving.

The rim profile is defined by Zipp's patented Sawtooth design — an undulating, toroidal shape that disrupts airflow in a way a conventional round-edge rim cannot. Rather than letting crosswind pressure build against a flat surface, the Sawtooth profile sheds it. The result is a wheel that stays manageable in conditions that would have a conventional deep-section rim steering you into the gutter. Zipp's Total System Efficiency framework underpins the 858 NSW's development, addressing the four main speed barriers a rider faces: aerodynamic drag, gravity, rolling resistance, and vibration loss. Every element of the wheel — from rim shape to hub internals to tire interface — is considered within that framework.

Underneath all the aerodynamic engineering is the Cognition V2 hub, Zipp's low-friction freehub design built around a magnetic contact system. When you stop pedaling, conventional hub pawls drag against the ratchet ring and bleed momentum. The Cognition hub uses magnets to keep the pawls retracted until power is applied, reducing that drag to near zero. On a flat or a slight descent, the difference is real — you carry speed further between efforts. It's a detail that matters more the faster you ride.

Design Benefits

1. Sawtooth Rim Profile for Crosswind Stability: The undulating Sawtooth shape along the rim's edge is designed to reduce the steering force generated by crosswinds — what engineers call yaw moment. On exposed courses or open roads, this translates to a wheel that tracks more predictably when the wind isn't head-on. You can hold your line with less correction and spend less energy managing the bike.
2. Hookless Tubeless Interface for Rolling Efficiency: The 858 NSW uses a hookless bead seat optimized for tubeless tire installation. Beyond the practical benefit of easier mounting, running tubeless at lower pressures reduces rolling resistance and absorbs road vibration — two of the four speed barriers Zipp's Total System Efficiency framework targets directly. With a 23mm internal width, the wheel is well-suited to 25mm and wider tires, which run more efficiently at lower pressures than narrower options.
3. Cognition V2 Hub for Momentum Retention: Traditional freehub mechanisms engage pawls against a ratchet ring continuously, creating drag whenever you're coasting. The Cognition V2 hub uses a magnetic contact system to retract the pawls until torque is applied, dramatically reducing this friction. On long descents, flat sections, and the back half of a triathlon bike leg, this adds up to measurably less speed lost between pedal strokes.
4. 85mm Rim Depth for Maximum Aerodynamic Efficiency: Deeper rims generate more aerodynamic advantage at higher speeds, and the 858 NSW's 85mm profile is designed to deliver that benefit at race pace. Disc brake construction allows Zipp to optimize the rim purely for aerodynamics and structure without the compromises required for a braking surface — the carbon layup and rim shape are built entirely around speed and stiffness.

Final Take

The 858 NSW is a wheel for riders who are serious about outright speed — triathletes, time trialists, and aggressive road cyclists who want the deepest aero advantage Zipp makes and are riding fast enough to use it. The Sawtooth profile and Cognition V2 hub address real limitations of conventional deep-section wheels, and the tubeless hookless setup keeps rolling resistance and compliance working in your favor. This is a focused tool for a specific kind of rider, and it does exactly what it was designed to do.