The Sirrus X offers an unparalleled combination of comfort, efficiency, and agile handling, excelling on asphalt, gravel, and any terrain in between. COMFORTABLE; SMOOTH AND EFFICIENT: The Sirrus X provides the smoothest ride in its class. With wider, confidence-inspiring tires, a slightly more upright seating position, and a super intuitive one-by drivetrain. RIDER-FIRST ENGINEERED™: At Specialized Bikes, every single frame size and geometry is individually designed rather than just "shrunk." For each size, tube lengths and diameters are tested for their optimal balance of stability, weight, and responsiveness. The goal? No matter what frame size you ride, we ensure you have the best ride feel in the world. COMFORTABLE: Industry-leading weight, exceptional pedaling efficiency, and flexible handling combine for nearly telepathic riding characteristics.