Sport bikes emphasize top speed, acceleration, braking, handling and grip on paved roads, typically at the expense of comfort and fuel economy in comparison to less specialized motorcycles. Because of this, there are certain design elements that most motorcycles of this type will share. Sport bikes have comparatively high performance engines resting inside a lightweight frame. Inline-four engines dominate the sport bike category, with V-twins having a significant presence, and nearly every other engine configuration appearing in small numbers at one time or another. The combination of these elements helps maintain structural integrity and chassis rigidity. Braking systems combine higher performance brake pads and multi-piston calipers that clamp onto oversized vented rotors. Suspension systems are advanced in terms of adjustments and materials for increased stability and durability. Most sport bikes have fairings, often completely enclosing the engine, and windscreens that effectively deflect the air at very high speeds, or at least reduce overall drag.