Cycling is a major component of a triathlon, so choosing a good bike out of the myriad of triathlon bicycles on the market can mean the difference between a fast and comfortable experience, and a miserable day on the bike. Many triathletes choose bicycles that are made specifically for triathlons, while others choose a road bicycle and modify it to suit their needs. Still others may choose a time trial bicycle, which is similar to a triathlon bicycle in many ways. Budget and experience will often dictate what type of bicycle a triathlete uses.
Triathletes generally choose speed over comfort, so triathlon bicycles are made to go fast. They have a short wheel base and a more aggressive riding position than regular road bikes, which offer a more comfortable riding position and a longer wheel base. A regular road bike is made to go moderately fast for a long period of time, so the rider will sit in a less aggressive riding position most of the time; the handlebars are designed to allow the rider to change riding position when the occasion calls for it. Triathlon bicycles only have two riding positions: aggressive, and more aggressive.
The handlebars on a triathlon bike put the rider in a aerodynamic position so he or she can go fast for the duration of the cycling portion of the race. Advanced riders will want to choose a triathlon-specific bike for its aerodynamic properties, while a beginner triathlete may opt for the more comfortable road bicycle. A middle ground between these two options is the time trial bicycle, which is not quite as aggressive as a triathlon bicycle but not nearly as upright and comfortable as a regular road bicycle. A time trial bicycle will be heavier than a triathlon bicycle and will generally have more gear options.
One way to enhance any of the bicycle options mentioned is to add aero wheels to the bicycle. Such wheels are often lightweight and made from strong but light materials such as carbon. They are made to be as aerodynamic as possible, which means some stability and steering ability are sacrificed. The rear wheel is often a disc wheel, which means there are no openings in the wheel for air to pass through. This wheel reduces drag and allows the rider to go faster, but it can be problematic in windy conditions.