Aerodynamic bikes and aero products are definitely “hot” on the market right now. Every triathlete or cycling are always looking for a easy way to faster. It is certainly possible to gain “free” speed with the use of such equipment: to go faster for no increase in effort or fitness.

However, improvements in the aerodynamics of the machine must be viewed within the contest of the bike and rider combination. Here is a simple exercise to illustrate the point: Stand in front of a mirror with your bicycle, which is larger, your bike or your body? Clearly, the frontal area of your body is much larger than that your bike. This simple observation is important to cycling because aerodynamic drag is a function of frontal area. Consequently, your body is much more of a determinant of your aerodynamic drag than your bicycle is.

Even though your body has a large frontal area, the frontal area you present during cycling can be modified by changing your body position. Another simple exercise will illustrate how dramatic those changes can be: Set your bicycle upon a trainer in front of a mirror and observe your frontal area with your hands on the top of the handlebars, the brake hoods, and the drops, and with your elbow on the aerobars. You will observe a dramatic range in frontal area as you change from one position to the next. Indeed, within each if those hand positions, you can substantially affect your frontal area by flexing or extending your arms. Each of those observed changes will significantly alter your cycling velocity.

The velocity of the bike and rider is the result of the balance between the propulsive force applied to the pedals and the sum of all the resistive forces acting on the bike. These resistive forces include some obvious (wind resistance or drag and rolling resistance) and some less obvious (inertia of the wheels and efficiency of chain system) forms of resistance.

The relative importance of the various resistive forces varies with velocity, terrain, environmental conditions, road surface, and mechanical specifics of the bike. For cycling over a relative flat terrain, however, the principal resistive force is usually aerodynamic drag. That is, most of the power you deliver to your pedals acts to push you and your bicycle through the air.

To illustrate just how important a good position can be, we use the example of a elite triathlete who is able to produce an average of 300 watts for a 40 kilometer time trial. The difference in velocity resulting from the drag of being seated with hands on the tops and being in a typical aero position is 2.5 miles per hour.

This equates to a huge 6 minute, 14 second difference (64 minute, 43 seconds compared to 58 minutes, 29 seconds) over a flat 40 kilometer time trial. Possibly more important is the change that optimizing your aero position can have, reducing your drag by 8 percent increases your speed by almost 1 mile per hour for the same power output leading to a decrease in time of approximately 1 minute 30 seconds.

So, before you spend all your money in aerodynamic bikes or parts, make sure you visit a specialist bike fitter to make sure you’re optimizing your body position and that you’re gaining the precious minutes you always look for.

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