Time Trial, TT or Chrono bikes are designed to allow the rider the best aerodynamic position. They feature special handlebars with advanced side grips and aerodynamic extensions that allow elbows to rest with the hands almost touching forward, and they have frame shapes, gears, and wheels designed to allow the cyclist to pedal at full throttle for an hour, transferring all the power he has in his legs to the bike.
Designed purely for speed and aerodynamic performance, time trial bikes are the cycling equivalent of a Formula 1 car. Every aspect of a time trial or TT bike is designed to reduce its wind resistance, so aerodynamics is the main advantage of a time trial bike. An advantage linked both to the geometries and shapes of the tubes, but above all to the position that the cyclist can assume on a time trial bike, with a decidedly reduced frontal impact. At high speeds, in fact, the main resistance that the bike+cyclist combination has to face is aerodynamic resistance, and for the same watts, a reduced frontal surface allows greater speed. The handlebars of Crono or Base Bar bikes are equipped with appendages, which allow a pedalling position in which the arms are wedged forward, allowing the air to be opened more effectively.
They also offer the possibility of gripping the handlebars in new ways, giving the rider the chance to assume new, high-performance positions. Tri-bars first came to prominence in 1989 when Greg Lemond controversially used them in the final time trial of the Tour de France and beat French favorite Laurent Fignon to win by a margin of at least 8 seconds. Since then, they have become a standard on specialist time trial bikes and are fully integrated with the base bar. Time trial bikes have an extremely rigid frame and energy losses are reduced to a minimum. The time trial bike can be best used on mainly flat, or at least very fast, routes. Because of the use of these bikes and the power development required on shorter stretches than in normal road races, the pelvis position is shifted towards the vertical at the bottom bracket. The seat tube has inclinations of up to 76 or 77 degrees. The bike can also be longer in pitch. The aerodynamic performance is studied in detail and, for this very reason, the tubes that make up the frame are flattened and streamlined, as are the fork stays and the seatpost.