The most substantial – and, yes, expensive – upgrade for a triathloner's bike is a new set of wheels. Given the weight one puts on the front tire with aero bars, a strong set of wheels a necessity. We went all out and replaced a standard, perfectly serviceable set of seven-year-old road wheels with a pair of tubeless aerodynamic Aura 5 TLR ones ($1,200 a pair). Amazingly, at just 1.7 kg (3.7 pounds) together, the two weigh about the same as just our old rear wheel, and on the road, the wide aerodynamic rim made its presence known thanks to a satisfying whir. The tubeless aspect of the tires were an added bonus – without tubes, you can dial back the air pressure a good 20 or 30 PSI and get better ground feel, which is great for the tight turns of a course. [$1,200;]