I am certainly no expert on cycling aerodynamics but figuring this out became a bit of a mission. In the process I learned quite a bit about aerodynamics and the equations that go along with it.
I am unsure of a few parts on here (and I note when below) but I reasoned through these as best I could. I’m actually interested if someone with more background in this field finds my missteps and can explain where I got derailed.
Without further ado…..
Here is the main equation we’re working with and a breakdown of each of the variables.
I substituted in some reasonable approximations (or what I assume are reasonable) that I got from Chris at the FLO Cycling blog in order to start off the process.
I started with the drag we’d see on a cyclist riding 17 mph (7.6 meters per sec)
So now we have the amount of drag at 28 mph and 17 mph and I get to my first (and biggest, I think) supposition. It supposes that if a new component, like a new aero jersey, can improve the cycling aerodynamics of a rider by reducing drag by 36 grams at 28 mph we have to assume that the same jersey won’t reduce drag by 36 grams at 17 mph:
If the amount of fractional (or percentage) savings is the same then we can figure things this way:
Before we can find out how much faster this 13 g savings can make us we need to figure out some new values for a couple of our variables by re-arranging our original equation:
Now we have to figure out what our new velocity is:
Finally we can figure out time savings :
This was one aspect of cycling aerodynamics that surprised me….counter-intuitively the time savings is less the faster you go because the rider is out there less time and therefore doesn’t make use of the drag reduction for as long. For example, the time savings of 36 drag reduction is only about 17 seconds at 28 mph.