The bike sections of many triathlons are essentially time trials, so the bikes ridden by triathletes are very similar to time trial bikes, but with one major difference – triathlon bikes are not as low at the front. This is because triathletes have to run after the bike ride, so they cannot adopt the very low positions of time triallists, which cause strain in the lower back and hamstring muscles that are essential during the running stage.
A triathlon bike should also have two sets of water bottle cage bosses on the frame, since the bike section is the optimum time in a race for a triathlete to take on liquids.
The bikes can be made from oval tubing, the elongation of the tubing smoothes out airflow over the bike. There are rules imposed by the international cycling governing body as to how deep these tubes can be, but in triathlon the rules apply to Elite competitors only.