Tri bars or aerobars include various styles of aerodynamic handlebars for triathlon bikes and also time trial bikes. Styles differ from bolt-on extensions to fully integrated handlebars. The purpose of these bars is to draw the body forward into a tucked position which allows for improved aerodynamics. Tri bars are used in triathlons and time trial events however they are illegal in most mass start road races where drafting is permitted. While aerodynamically advantageous they tend to draw the hands away from the brakes potentially making the race more dangerous in the event of an accident.