In road cycling, the draft effect is so huge that other concerns (maneuverability, handling, comfort) can, in certain instances, supersede aerodynamics. When a rider is in a paceline and getting a 30% draft benefit most of the time, she should be more concerned about her ability to maneuver her bike, shift and brake easily, and get into a moderately aero position when it’s her turn to pull. Most road bike manufacturers place primary emphasis on handling, control and stiffness. Aerodynamics is second fiddle to these criterion.

Wheels, helmets and clothing fall in line here as well. A good road racing wheel is generally aerodynamic, but not so much that it hampers maneuverability and weight. Helmets are of the normal variety, for comfort and ventilation. Clothing is generally form-fitting, but a bit on the loose side, for comfort and to support pockets.

In triathlon cycling, the rider rides all alone, with no draft benefit. Consequently, the bike and rider must be much more streamlined, as the rider is constantly exposed to the wind. Handling is not as great a concern, as there are no other bikes near the rider. Manufacturers consequently design bikes primarily for aerodynamics, with handling, stiffness and sometimes comfort taking a backseat.

Wheels and helmets get the same treatment. On the vast majority of triathlon courses, a very deep front and a disc rear wheel is the best choice. An aero helmet is almost always the best choice for the same reason–though ventilation is compromised, the aero benefit of a pointy helmet is huge. Clothing is generally tighter than cycling clothing, for maximum aerodynamics. Long-course triathletes can get away with pockets, but short-course athletes should go with a tri-suit or skinsuit.

In summary, road cyclists are not as concerned with aerodynamics because of the need to be nimble, and the huge benefit of drafting. Triathletes should choose equipment based almost entirely on aerodynamics. The moral of the story for triathletes is: if it won’t make you more aero, you had better have a very good reason to race with it!

Caveat: I am aware that many of the equipment choices triathletes make can be, and often are, applied to road cycling, especially in shorter races such as criteriums. Even if a rider is getting a 30% benefit from drafting, the small benefit from the skinsuit or the deep dish wheel counts for something, regardless of the draft. However, the road cyclist isn’t as unilaterally concerned with aerodynamics as the triathlete (for example, one wouldn’t run 1080s during a 5 hour hilly road race), so the point still has some merit I think.