Offering an unprecedented combination of comfort, efficiency, and nimble handling, the Sirrus X excels on pavement, dirt, and any terrain in between. The Sirrus X provides the smoothest ride in its class with bigger, confidence-inspiring tires, a slightly more upright riding position, and a super intuitive one-by drivetrain. Like all Specialized performance bikes, the geometry of each frame is uniquely crafted. This means that for every frame, each tube size is specifically selected to achieve the optimal balance of rigidity, weight, and responsiveness to ensure that no matter what size you're riding, you will experience the world's best ride. Class-leading lightweight construction, exceptional pedaling efficiency, and steering precision merge for confident, nearly telepathic handling characteristics. The bike floats over rough terrain with fast rolling Specialized Pathfinder 42c tires featuring proprietary Gripton rubber compound.