Tharsis Trail Stem

What Our Gearhead® Experts Are Saying:

"The PRO Tharsis Trail Stem is one of the most thoughtfully engineered trail stems I have specced at any price point. The forged AL-7075 construction with titanium bolts hits 95 grams at 65mm without any compromise in rigidity, and the integrated external headset adjuster is a design detail that simplifies the setup process in a way that anyone who has wrestled with a star-fangled nut in a carbon steerer will genuinely appreciate. The Di2 battery accommodation through the steerer is cleanly executed and the included BTR expander nut and battery hanger make it a complete solution for electronic builds right out of the box."

Trail stem design involves a set of competing demands that separate a truly considered component from one that merely meets the minimum specification. The PRO Tharsis Trail Stem resolves those demands with a combination of material specification, construction method, and integrated functional details that position it as one of the most complete trail stem options available at its weight class.

The forged AL-7075 aluminum construction establishes the structural foundation, delivering a rigidity and precision dimensional accuracy that cast or CNC-only alloy alternatives cannot match at equivalent weight. Titanium bolts contribute to the 95 gram total at 65mm while providing the corrosion resistance and tensile strength that repeated adjustment and trail use demands from fasteners at this interface. The 0-degree rise and 65mm length are calibrated for the front-end geometry of current trail bikes, where a compact, low-rise stem works in conjunction with wider handlebars and slacker head tube angles to produce steering that is both precise and stable on technical descents.

The integrated external headset adjuster is the detail that most clearly reflects the engineering intent of the Tharsis Trail Stem. By relocating the preload adjustment mechanism to an external position beneath the stem body rather than relying on a star-fangled nut or internal expander plug, PRO has created a setup process that is cleaner, more accessible, and more repeatable across the life of the component. The included top cap completes the system for a self-contained headset preload solution that works without specialist tools or internal steerer hardware. For builds running Shimano Di2 with an internal battery configuration, the stem and top cap geometry accommodates battery installation inside the steerer tube when steerer depth exceeds 152mm, routing the actuation wire cleanly through and over the stem body with the included BTR expander nut and battery hanger providing a secure and rattle-free mounting solution. The 35mm clamp diameter ensures compatibility with the Tharsis ThreeFive handlebar range and the broader ecosystem of oversized bar interfaces on current trail platforms.