Tharsis XC Stem

What Our Gearhead® Experts Are Saying:

"The PRO Tharsis XC Stem is the stem I reach for on any cross-country or trail build where cockpit precision, low weight, and clean integration are all priorities simultaneously. The AL-7075 construction with titanium bolts produces a weight figure that competes with carbon stems at a fraction of the cost, and the integrated external headset adjuster is a genuinely superior setup solution compared to any star-fangled nut or expander plug system I have worked with. The Di2 battery compatibility through the steerer is a well-executed detail that makes it the natural choice for electronic XC builds where internal routing is a priority."

Cross-country stem specification is an exercise in resolving competing priorities: minimum weight, maximum rigidity, precise geometry options, and increasingly, clean integration with electronic drivetrain systems. The PRO Tharsis XC Stem addresses all four simultaneously through a construction and feature set that reflects a thorough understanding of what competitive and performance-oriented XC and trail riders actually need from this component.

The AL-7075 aluminum construction with titanium bolts establishes the weight and strength foundation of the stem, delivering a clamping interface that holds securely through the repeated load cycles of hard cross-country efforts and technical trail riding while keeping the overall stem weight at a level that competes with carbon alternatives. Titanium fasteners contribute meaningfully to that weight figure while providing the tensile strength and corrosion resistance that repeated adjustment and all-weather riding demands from bolts at this interface. The available rise options of 6 degrees and 17 degrees cover the range from aggressive, low front-end positions preferred by competitive XC racers to the more moderate rise angles that trail riders and marathon XC athletes use to balance aerodynamic efficiency with all-day comfort.

The integrated external headset adjuster is the engineering detail that most distinguishes the Tharsis XC Stem from conventional alternatives. By building the preload adjustment mechanism into the underside of the stem body rather than requiring a star-fangled nut or expander plug inside the steerer tube, PRO has eliminated the most awkward and tool-dependent step in front-end setup and adjustment. The process becomes straightforward: clamp the stem to the fork, use the external dial to remove headset play precisely, and install the top cap. The resulting open steerer cavity serves a secondary function on builds where the steerer tube depth reaches or exceeds 152mm, providing a clean and accessible housing for a Shimano Di2 internal battery that keeps the cockpit uncluttered and the battery reachable without any compromise to saddle height or seatpost positioning. Length options spanning 80mm to 120mm across both rise angles provide the fitting range needed to optimize reach and front-end height across the full spectrum of current XC and trail frame geometries and rider positions.