home » what REALLY makes you fast on the bike

Going fast on the bike is about developing energy with a powerful, efficient pedal stroke, then moving through the air with as low of a drag coefficient as possible. Many athletes become obsessed with climbs on race day, when in fact this is only a small part of what affects your bike split.

The most important factor for a fast bike split is to be able to go fast on the flats. And speed on a flat stretch of road is dependant upon how much steady power you can maintain limited by how much energy is used pushing your body and bike through the atmosphere. Assuming a constant power output (watts), the smaller you can make yourself as the winds 'sees' you (reduced drag coefficient) the faster you'll go.

Athletes spend significant energy and funds to reduce the weight of their bike, but weight makes virtually no difference riding on level ground. Weight is only a limiter when you're accelerating and climbing.

Unlike bike racing where the separation often happens on climbs (when you can't draft other riders), duathlon and triathlon is all time-trialing, so how fast you move over the whole course is what counts.

By far the greatest proportion of aerodynamic drag while riding a bike is created by your body. So going fast on the bike begins with a position that makes you small in frontal area, while allowing powerful pedaling. Your seat needs to be high enough for good leg extension, so this is a constant. The part of your position you can vary significantly is your upper body. Generally the closer your torso is to parallel to the ground, the smaller you'll be to the wind.

Holding a low, aero position is not natural; the tolerance for it is developed over time and for many riders will be limited by flexibility. I never begin a ride without first stretching my lower back and hamstrings.

True, there are ways to make your bike more aero, but again, these gains are minor compared to body position.

The most important factor to reduce the wind resistance of your bike are the wheels. The speed difference between basic training wheels with shallow rims and plenty of spokes, and race wheels with fewer spokes and deep rims—and perhaps a disc in the back—is greater than all the changes you can make to the rest of your bike.

Marketing from manufacturers will exaggerate the aerodynamic differences between frames which is very, very small (+-3%). Speed gains from properly set aerobars are important, second only to wheels. Water bottle placement comes next because it has significant size. Exposed cables, and aero seat posts do count, but to approximate a quote from wind tunnel tester John Cobb: "It makes more difference how you position your pinky on the aerobars than whether you have an aero seatpost of not."

And what you wear on race day is crucial. Loose fitting clothes will give away more speed than you can gain with aero race wheels. Aero helmets are faster, but only if they fit well and you hold optimal head position. In most cases if you tip your head down an aero helmet will be slower than a regular helmet—but not always! Confusing, yes, and only a trip to a wind tunnel can clear it up for sure.

You should know that the impact of aerodynamics increases as you go faster. An athlete racing an IronMan averaging 18mph will gain much less than the athlete in an Olympic distance event averaging 25+. In fact for small riders at relatively low speeds a disc wheel can do much more harm than good.