We often hear that the more aero you get, the faster you will go. But how accurate is this? In a duathlon or triathlon event, why are some athletes wearing aerodynamic helmets on their bike leg, instead of standard road helmets?
Aside from protecting your head, an aerodynamic helmet works by smoothing the airflow around your head and down your back, which reduces turbulence and enables you to slip through the air more effectively.
Every technology is invented and innovated for a reason. Every piece of equipment is developed to make you go fast in cycling. Aero helmets are designed to be one of the most cost-effective ways to gain speed and save time. Therefore, the more aerodynamic you are on the bike, the lower your drag is, and so the faster you will go for the same power effort and output.
Aerodynamic drag – What is it?
Speaking of aerodynamics, we describe it as aerodynamic drag, which is normally measured in watts. At speed over 20 to 21 miles per hour, the air resistance starts to become remarkably greater. Hence, the power you need to produce to increase the speed you move on your bike rises more rapidly.
The resistance is called drag, and drag is the force that acts on an object to resist forward motion. Aerodynamics is the art and science of minimizing drag. Wearing an aerodynamic helmet is a key way to reduce drag around your head, and so it is getting more common to have athletes wear in duathlon or triathlon races.
How does an aerodynamic helmet help?
To minimize drag, you can minimize your frontal surface areas in cycling by lowering your torso angle, head, and narrowing your arms and shoulders. Once your bike position is optimized, you can use equipment and technology to do the rest.
An aerodynamic helmet will now come into play. It is teardrop shaped with few vents, so if you’re susceptible to overheating then they may not be a good option. Why not a standard road helmet, though?
While your head is one of the areas most exposed to airflow, aero helmets will crash and slip through the air as you ride, the shell is what gives a helmet its aerodynamic profile. One of the fundamental factors of how well a helmet will perform is the shape and length of its tail.
Long tails can be very aerodynamic, however, if you drop your head or do not ride with a flat back, any gains can easily turn into losses. Additionally, the expanded polystyrene (EPS) foam is designed to absorb the impact energy of a crash. Unlike a common vented helmet, some aero helmets trap heat.
In conjunction with the speed you’re going, the course and weather conditions can also affect a helmet’s performance. Thus, vents are always going to be a compromise between cooling and aerodynamics. If it is hot and humid, it is vital to pick one that is ventilated, as overheating will negate any time saved through aerodynamics.
Do you really save time on the bike?
Once again, time-savings on the bike are crucial. How much time can you save by going from your normal vented helmet to an aerodynamic helmet? If you ride a bike, you know all about the effects of wind resistance. When riding at speed on the flat, aerodynamic drag contributes up to 90% of the overall resistance to forward motion.
As a result, aerodynamic testing is taken place to claim for instance that kit that is 10% more efficient, could save you 20 seconds over a given distance or give you an advantage equivalent to five watts. Any improvements in aerodynamics can make a big difference in saving energy, time, and increasing speed.
Especially if you are a distance athlete, remember that you are likely going to be logging some significant miles and time on your bike. Aero helmets are usually heavier than standard road helmets and while the lightest helmet is not always the best helmet, make sure that your helmet is light enough so that it does not become relentless.