I can assure you that every person reading this has seen crazy graphs and heard talk about yaw angles, coefficient of drag, turbulent and laminar flow. What does it all mean though and how much should you pay attention to the numbers? The answer isn't completely cut and dry, contrary to popular belief. The reason I say that is because it all comes down to your current situation which includes fitness, finances, and goals. Let’s assume you don't know anything about aerodynamics. In this series of articles I will help breakdown the all-important aerodynamics of triathlon. I want you to be able to show up to the next race bragging about your knowledge and explaining the reasons behind your gear choice. Today we will start with the basics of aerodynamics.
The best place to start is describing in a general sense what is happening around you. So, a few things you need to know:
What a drag...
Drag, always trying to slow you down. There is a reason why the saying "What a drag?" exists. Drag is the sum of two forces; pressure differences and friction. Yes, friction between the surface and the air. Pressure difference is the main force acting opposite of motion, aka in your face. The amount of this force can be manipulated mainly be reducing frontal area. The second force is the friction between the surface and the air. Ways to reduce this include skin suits and shaving the body. To better understand this let's look at the equation for drag force.
In a basic sense, what goes into calculating drag? Well, lets break the equation down into some more familiar aspects.
The faster you go the harder it gets.
Getting back the velocity^2 term in the drag equation... Look at the graph above and think about what you see. The yellow line represents rolling resistance (something we will talk about later in the year) and the blue line represents aerodynamic drag. One can see that the faster you go on the bike the more drag force you experience. How can you avoid this...? You can't. It is just one crappy part of aerodynamics that we all need to live with...
There are three types of flow that we encounter in our aerodynamic lives.
Laminar flow means that the fluid is moving with ease and there is no resistance. This flow is what we want to encounter in an ideal world but is impossible for us to actually obtain. Why? Because our bodies provide area to disturb flow and create turbulent areas. Turbulent flow is messy and creates a lot of resistance and moments.
We can reduce the effects of turbulent flow through careful equipment choice. Engineers design equipment and clothing to reduce the turbulent flow and try to keep everything laminar and happy.
That is where I am going to leave it for Part 1. Leave comments if you have any questions.
Stay tuned for Part 2 where we will talk about data collection, industry standards, and look at some pretty graphs.