A duathlon is an exciting race comprised of cycling and running. Most duathlons are configured as run-bike-run races, and the bicycles used are specifically designed to give you a competitive edge between stages. A duathlon bike is be similar to a triathlon or time trial bike -- in fact some athletes use the same bike for all three types of race. Duathlon bikes have many unique features that separate the from traditional road bikes. Using the right bike could be just what you need to gain an edge on your next race day.
The most noticeable difference between a duathlon bike and a road bike is the geometry. Duathlon bikes feature aero-bars, which allow the rider to rest his elbows on the handlebars. This positions the rider in an aggressive forward position, with the rider further over the cranks, which also helps aerodynamically. In addition, this position places more emphasis on the quadriceps as the primary muscle while cycling, which saves the hamstrings and other leg muscles for the running phases of the duathlon. The top tube length on duathlon bikes is also a bit shorter, since this accommodates the aerobar position better.
Since weight and aerodynamics are critical factors in the speed of a duathlon bike, these bikes use high-quality lightweight materials to optimize performance. Carbon fiber is a frequently used material, which is shaped in a way that optimizes aerodynamics around the headset, bottom bracket, and tubing. Often, the frame of a duathlon bike is shaped like an airfoil to reduce drag. Cheaper duathlon bikes can be made from aluminum, but the unique shaping properties of carbon fiber make it the ideal choice for competition.
Like the frame, a duathlon bike often uses carbon fiber wheels, which feature elongated rims and flat spokes that decrease drag on the bike. Carbon fiber wheels are common on modern duathlon and road bikes, since the material allows for light weight and strength with an aerodynamic shape. A duathlon bike uses deep rims or disc wheels, which are fitted with smooth, lightweight tires that are flexible and supple enough to conform to imperfect road conditions. To reduce weight, these tires are especially thin and are therefore less resistant to punctures than a traditional tire.
Other Unique Features
Aside from the aero bars, most duathlon bikes have components similar to a modern road bike. Duathlon bikes feature caliper brakes and racing seats that are usually identical to components on road bikes. However, a duathlon bike will often feature higher gearing ratios than a traditional road bike, since the rider can spend more time moving at a fast pace over the relatively short cycling section of the race.
Max Roman Dilthey is a science, health and culture writer currently pursuing a master's of sustainability science. Based in Massachusetts, he blogs about cycling at MaxTheCyclist.com.