Zipp 303 XPLR S Front Wheel

Zipp 303 XPLR S Front Wheel

The Zipp 303 XPLR S offers a significant speed upgrade for gravel riders without a hefty price tag. Incorporating key innovations from Zipp’s premium wide gravel wheelset, this affordable and robust wheelset caters to discerning gravel riders. It stands out as the fastest on gravel, featuring a mega-wide rim that integrates seamlessly with approved gravel racing tyres.

Unlike current gravel wheels, which are slightly modified versions of road wheels focusing on high stiffness and low weight, Zipp prioritises speed. In gravel riding, rolling resistance, vibration loss from rough surfaces, and wind are major barriers to speed. To tackle these challenges, Zipp applied its Total System Efficiency design philosophy specifically for gravel.

The 303 XPLR S is a speed-focused gravel wheel designed with a novel approach: starting with the perfect gravel tyre and building the wheel around it. To develop this first-of-its-kind wheelset, Zipp’s engineers studied the changes in gravel racing and reached several key conclusions:

1. The increasing speeds in gravel racing highlight the importance of aerodynamic efficiency.
2. Current gravel wheels perform poorly aerodynamically with gravel tyres.
3. Low tyre pressures are crucial for unlocking speed on gravel, but current rim designs don’t support lateral cornering loads at low pressures.
4. Existing gravel rim designs do not prevent pinch flats at lower tyre pressures.

Typical tyre widths for gravel racing range from 38-50mm with varying tread patterns. Current gravel wheels have an external rim width of 28-30mm, creating an aerodynamic mismatch when using a 40mm+ gravel tyre. With narrower rims and wider tyres, the tyre-wheel interface resembles the bulge of a lightbulb rather than an ideal seamless airfoil cross-section. According to Zipp testing, the efficient pairing of the wheel and gravel tyre in the 303 XPLR S design provides a 5-watt aerodynamic advantage over leading competitors. This wheel is optimised for use with the Goodyear XPLR Slick and Goodyear XPLR Inter tyres, both designed in partnership with Zipp.

Low tyre pressures significantly increase speeds on gravel. However, narrow tyre beds with low pressures cause tyres to collapse while cornering. The 303 XPLR S’s wide tyre bed increases tyre stance, allowing lower pressures without tyre squirm under corner loads. This reduces vibration loss while maintaining control in corners and traction while climbing. The 303 XPLR S also reduces pinch flats thanks to a rim edge that is 77% thicker than previous models, minimising damage when tyres bottom out on the rim edge upon impact.

What about rim depth? Conventional wisdom suggests shallow rims are best for gravel. As gravel racing has progressed, many courses are raced at 35kph+ (22MPH) with top speeds over 60kph (37MPH). The 303 XPLR S rim is 54mm deep, creating an effective aerodynamic complement for large gravel tyres at high speed. Zipp’s research found that a 54mm deep rim achieves the perfect aspect ratio for aerodynamic efficiency with a 40mm gravel tyre at race speeds.

The 303 XPLR S is only compatible with approved tyres. The Goodyear XPLR Slick and Goodyear XPLR Inter are specifically designed and optimised for the 303 XPLR S.