Hayes Dominion and Hattie Harnden’s Nicolai G1 GPI: Enduro Precision and Maximum Control

Few riders in modern mountain biking possess the range and dominance of Hattie Harnden. The 2024 Enduro World Cup overall champion has built a reputation as arguably the strongest all around athlete in women’s mountain biking, collecting victories across multiple disciplines and proving her speed wherever she lines up. Now racing with AON Racing, Harnden has shifted much of her focus toward downhill competition. Yet enduro remains close to her roots and when she returns to the start line she does so with the same intent to win. That requires a race platform capable of handling the relentless demands of modern enduro racing. Her weapon of choice is the Nicolai G1 GPI. A forward thinking machine built around a gearbox drivetrain, belt drive system, and a carefully selected ecosystem of performance components. At the center of its control and precision are Hayes Dominion A4 brakes.

Precision Control for the Longest Descents

Enduro racing places unique demands on braking systems. Stages can stretch for minutes at a time, often across steep and technical terrain where consistent power and modulation are critical. Riders need braking systems that deliver predictable response, resist heat buildup, and maintain performance from the first corner to the finish line. The Hayes Dominion A4 was built for exactly this environment. Harnden runs Dominion A4 brakes paired with 203 mm rotors front and rear, delivering powerful and consistent stopping performance across the full length of an enduro stage. Inside the calipers she runs organic sintered pads, a setup that provides strong bite while maintaining the smooth modulation that Dominion brakes are known for. Harnden’s lever setup reflects her aggressive riding style. She prefers a noticeable amount of free stroke before the bite point, allowing her to keep her fingers on the levers without accidentally dragging the brakes through rough terrain. Once the bite point is reached, power builds quickly and predictably, giving her the confidence to control speed precisely in technical sections.

Designed for Modulation and Confidence

The hallmark of the Dominion braking system is control. While raw stopping power is essential in enduro racing, the ability to modulate braking force precisely often matters even more. Riders must constantly adjust traction and speed while navigating loose terrain, rock gardens, and steep switchbacks. Dominion brakes provide that level of precision through their sealed hydraulic architecture, rigid caliper design, and carefully engineered lever feel. The result is braking that feels immediate and powerful while remaining easy to control under pressure. For riders like Harnden who spend extended periods descending at race pace, that consistency becomes a major performance advantage.

A Forward Thinking Race Platform

The Nicolai G1 GPI itself reflects AON Racing’s commitment to pushing the boundaries of bike design. The frame incorporates a Pinion C1.12i Smart.Shift gearbox paired with a Gates carbon belt drive, creating a drivetrain that is quiet, durable, and exceptionally resistant to the punishment of racing. The rest of the build showcases the integrated technology across the Hayes Bicycle Group ecosystem. Reynolds Blacklabel 309 carbon wheels provide strength and precision tracking, while Manitou suspension manages the demands of aggressive terrain. Harnden runs the bike in a full 29 inch configuration for enduro competition, prioritizing stability and momentum across varied terrain.

Built for One of the Best

When one of the most versatile athletes in mountain biking lines up for an enduro stage, every component must perform without compromise. Control, confidence, and reliability become essential when racing against the clock. For Hattie Harnden and AON Racing, Hayes Dominion brakes provide exactly that. Powerful, predictable, and built for the demands of the world’s most challenging terrain. Because when the descents get longer and the speeds get higher, control is everything.