Time Trial Predictors

What’s it take to win a time trial?  A high threshold?  A high VO2max?  Small frontal area?  A paper I published a couple years ago was designed to answer exactly that.  Turns out, your overall aerodynamic profile is the single most important factor for determining time trial performance. 

The aerodynamic characteristics of a cyclist are influenced by both frontal area as well as the coefficient of drag (“Cd”).   Frontal area is simple enough to understand – it’s just the head-on shot of what the wind sees.  In terms of aerodynamics, intuitively, we would think that a smaller frontal area would result in a more aerodynamic profile.  However, this is not always the case and the reason for that is the coefficient of drag. 

The coefficient of drag is a measure of how well air flows around the cyclist and bike.  Frontal area is not directionally proportional to this coefficient.  Instead, this coefficient is influenced by a number of things such as clothing and textures.  This is why companies spend so much time researching where to add seams to skinsuits and why some companies add dimples to their products.  It’s all in the name of improving airflow around the rider and bike. 

As we found in our study, the aerodynamic profile, which takes into account both the frontal area and the coefficient of drag, is able to explain ~70% of the difference in level time trial performance.  Knowing the aerodynamic profile then allows for a better prediction of performance compared to traditional measures like VO2max and threshold power. 

Of course, threshold power and VO­­2max are important.  I may be able to get to a similar (or better!) aerodynamic profile as a World Tour rider, but I’ll never be able to beat them because I don’t have the threshold power needed.  And so while aerodynamics is the single best predictor of performance, normalizing power at VO2max or threshold by the aerodynamic profile, provides the most accurate prediction of level time trial performance (whereas normalizing power by weight would be more accurate at predicting uphill time trial performance).     

Hopefully at this point you’ve enjoyed the Kool-Aid and understand the importance of improving your aerodynamics.  Now, let’s talk about ways to improve your aerodynamic profile.  The paper discusses a simple way to measure your aerodynamic profile without going to a wind tunnel.  All you need is a power meter, flat road, little/no wind, and some motivation to ride the same stretch of road multiple (multiple!) times. 

To improve your aerodynamic profile, don’t focus on only improving your frontal surface area.  You could get in a very narrow and short position, but it may result in you hunching your back which will worsen the airflow around the body and actually increase your aerodynamic drag.  The current catchy phrase is “tall and narrow is aero” and is a good place to help you start.  Another simple way to improve your aerodynamic profile is pinning your race number smoothly against the body so it doesn’t catch the wind. 

Remember what I said above though, your ability to produce power while in the aerodynamic position is also important.  This means that you need to make sure you’re able to apply some power to the pedals while riding in your aerodynamic position.  Being as narrow as possible may be great aerodynamically, but if you can’t control the bike and you crash, you’re not going to be performing well in any race.  Once you’ve gotten your position dialed, make sure you’re riding and training on the bike so you can race at your best.

This time of year is great for tinkering with your position.  You can test out some different positions to find out what’s the most aerodynamic and comfortable.  And because the big races are still at least a couple of months away, you’ve got time to adjust to your new position and get comfortable riding in that aerodynamic position.  It’s just one small way to get towards your best season yet!  Thanks for reading!