Cycling & Running

Triathlon cycling, with the exception of Olympic triathlon and ITU World Cup races, is very different from most professional bicycle racing because it does not allow drafting, so racers do not cluster in a peloton. It more closely resembles individual time trial racing. Triathlon bicycles are generally optimized for aerodynamics, having special handlebars called "aero-bars" or "tri-bars", aerodynamic wheels, and other components. Triathlon bikes use a specialized geometry, including a steep seat-tube angle both to improve aerodynamics and to spare muscle groups needed for running (see also triathlon equipment). At the end of the bike segment, triathletes also often cycle with a higher "cadence" (revolutions per minute), which serves in part to keep the muscles loose and flexible for running. It is believed, though, that the primary benefit to cycling in a triathlon is that the strain of the effort is placed disproportionately on the slow twitch muscle fibers, preventing the athlete from accumulating an oxygen debt before the run.

The primary distinguishing feature of running in a triathlon is that it occurs after the athlete has already been exercising in two other disciplines for an extended period of time, so many muscles are already tired. The effect of switching from cycling to running can be profound; first-time triathletes are often astonished at their muscle weakness, maybe caused by lactic acid build up and the bizarre, sometimes painful sensation in their thighs a few hundred yards into the run, and discover that they run at a much slower pace than they are accustomed to in training. Triathletes train for this phenomenon through transition workouts known as "bricks": back-to-back workouts involving two disciplines, most commonly cycling and running.