A Carbon XC Rear Wheel Built for Trail Compliance as Much as Speed

The Zipp 1ZERO HITOP SW Rear Wheel is a 29-inch carbon mountain bike rear wheel designed for cross-country and trail riding where the old assumption - that an XC wheel must be as stiff as possible above all else - no longer holds. Modern XC racing courses and aggressive trail riding with up to 130mm of travel demand a wheel that carries speed through rough sections rather than deflecting off them, and the 1ZERO HITOP SW is built specifically around that understanding.

Zipp's proprietary HITOP Technology governs the carbon layup of the rim - a construction approach designed to introduce a controlled level of compliance into the carbon rim structure without sacrificing the lightweight character that XC riding demands. The result is a rim that absorbs rocks, roots, and ruts by deflecting slightly and recovering rather than transmitting the full impact through the wheel and into the rider. This compliance approach carries speed through technical sections that a fully rigid rim would bounce off, maintaining momentum where it would otherwise be lost.

The rear wheel uses a SRAM XD freehub body, making it compatible with SRAM's 12-speed Eagle cassettes and the full XD-standard cassette range. Confirm your drivetrain uses an XD freehub interface before purchase - XD is not compatible with standard Shimano HG cassettes. The 12mm thru-axle at 148mm Boost rear spacing is the standard for modern trail and XC mountain bike frames. Sapim CX-Ray bladed spokes are laced 24-hole. No skewers are included. A disc rotor is not included - the hub uses a centerlock interface.

This listing is for the rear wheel only. The matching 1ZERO HITOP SW front wheel is available separately.

HITOP Carbon Rim, 30mm Internal Width, and Winged Rim Design

The 1ZERO HITOP rim is built to a 21.1mm depth with a 37.7mm external width and 30mm internal width - a wide internal dimension that supports modern aggressive XC and trail tyre widths in the 2.2-inch to 2.5-inch range with optimal tyre profile and lower pressure capability. The 30mm internal width falls within the rim's rated inner width range of 28 to 34.9mm, providing meaningful flexibility in tyre width selection without requiring a separate rim for different tyre choices.

The winged rim design creates a smooth, supported resting surface for the tyre bead at the rim edge. Zipp states this design reduces the chance of pinch flats after rock hits - the wings supporting the tyre sidewall at the point of impact rather than allowing the tyre to compress directly against a sharp rim edge. For tubeless-ready trail riding where the ability to run lower pressures is one of the primary advantages, reducing pinch flat risk at the rim level extends the practical lower pressure limit.

The rim is Tubeless Ready and Presta valve compatible. Double-wall rim construction provides the structural depth needed for a 30mm internal width carbon rim at the 21.1mm depth the 1ZERO HITOP uses.

ZM2 SL Hub, 66-Point Engagement, and TyreWiz 2.0

The ZM2 SL rear hub provides 66 points of engagement - approximately one engagement point every 5.5 degrees of rotation. For XC and trail riding where accelerating out of corners quickly and re-engaging the drivetrain after technical sections are regular performance demands, a high engagement count delivers near-instant power pickup when the rider begins pedalling again. 66 points of engagement places the ZM2 SL well above the engagement level of standard MTB hubs, providing the responsive drivetrain feel that fast XC and aggressive trail riding benefits from.

The TyreWiz 2.0 tyre-pressure monitoring system is included with the wheel - a sensor that mounts to the valve and transmits real-time tyre pressure data to a compatible head unit or smartphone app. For riders running tubeless at lower pressures where the difference between optimal pressure and a pressure that causes rim strikes or poor handling is narrow, real-time pressure monitoring removes the guesswork from pressure management during a ride. The wheel carries a Lifetime Warranty from Zipp.

FAQs

What is HITOP Technology and how does it affect the ride?

HITOP Technology is Zipp's proprietary carbon layup approach for the 1ZERO rim that introduces controlled compliance into the carbon structure. Rather than building the rim to be as stiff as possible, HITOP allows the rim to deflect slightly over rocks, roots, and rough trail features and recover, carrying speed through technical sections that a fully rigid rim would deflect off. The result is a lightweight XC wheel that maintains momentum through rough terrain rather than losing it.

What freehub body does the 1ZERO HITOP SW rear wheel use?

This version uses a SRAM XD freehub body, compatible with SRAM's 12-speed Eagle and other XD-standard cassettes. XD is not compatible with standard Shimano HG cassettes - confirm your drivetrain uses an XD freehub interface before purchase.

What is the internal rim width and what tyre widths does it support?

The rim has a 30mm internal width within a rated range of 28 to 34.9mm, supporting modern aggressive XC and trail tyres in the 2.2-inch to 2.5-inch range with optimal tyre profile and lower pressure capability. The wide internal width allows the tyre to form a rounder, more supportive cross-section at lower pressures.

What is TyreWiz 2.0 and is it included?

TyreWiz 2.0 is a tyre-pressure monitoring system that mounts to the valve and transmits real-time tyre pressure data to a compatible head unit or smartphone app. It is included with the wheel - allowing riders running tubeless at lower pressures to monitor and manage pressure in real time during a ride.

What engagement does the ZM2 SL hub provide and why does it matter for trail riding?

The ZM2 SL hub provides 66 points of engagement - approximately one engagement point every 5.5 degrees. High engagement delivers near-instant power pickup when the rider begins pedalling again after coasting through a corner or technical section, providing more responsive acceleration than standard lower-engagement hubs and allowing the rider to get back on the power sooner.