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Triathlon winning made easier… sort of

A man riding on a time trial Colnago bike.

My wife returns to triathlon, so I want to help her go faster.

History repeats itself

It’s been a few years since either I or my wife participated in any competitive event involving cycling. I’ve hung my bike since then and switched over to motorcycling, and she started to pursue other interests as well. But a leopard can’t really change its spots and triathlon is once again in the spotlight.

For those of you not familiar with the concept of triathlon, it consists of three disciplines packed into a single event. It starts with swimming, then comes cycling, and the cherry on top is running. It’s a fairly demanding sport, as in order to succeed you need strength and stamina as well as some technical skills (that’s probably why I never even tried it). It’s also quite competitive, too — the level of participants even in amateur events is surprisingly high. To be honest, with people often dedicating north of 20 hours a week to training alone, you could question if calling them amateurs is really justified. Oh, and there also a separate arms race! One can easily spend tens of thousands of euros on gear. A triathlon bike from any of the major manufacturers can easily surpass 10 grand alone!

Leveling the playing field

As you can see, my wife is about to face a pretty hard challenge. But being the good husband that I am, I want to help her in this endevour. I know nothing about running and even less about swimming, but a thing or two about cycling, so I decided to do something in this regard.

To go faster on a bicycle you need to either increase the force pushing you forward or reduce the drag. The former means, unfortunately, increasing the power output, something that’s easier said than done. Heck, the whole multimillion-dollar coaching industry is built around this idea. To add insult to the injury, I am no expert on that matter and probably could do more harm than good. The other option, though — drag reduction — is an engineering problem and one that I’m willing to take.

Of course, drag on a bike is due to many factors, such as aerodynamic forces, bearing friction, and tire rolling resistance. But it turns out that at competition speeds around 90 percent of drag is due to air resistance. So it makes perfect sense to focus our efforts on this field.

What a drag!

Aerodynamic drag depends on several things — speed relative to the air, air density, frontal area, and the so-called drag coefficient, which simply tells how streamlined a body is. Of those four factors, we can only alter the last two. After all, air density is what it is, and minimizing speed is out of the question. I mean really, we’re trying to ride as fast as possible, not the other way round!

Technical details (click to expand)

But to do so in a controlled fashion, we first need to be able to measure drag somehow — otherwise, it would just be running around in circles. As always, there are several ways to do so, some more clever than others. Obviously, the most appealing one would be to go visit a wind tunnel, but then I’m risking draining my savings account in just a few outings. I found a paper that describes various other methods of drag measurement. The problem with them is, however, that they require a laboratory-like setup and cannot be used to gather real-world data.

Fortunately, we could estimate the drag by the measurement of power, speed, and speed relative to the air. The first can easily be done by a power meter, which is on the wishlist anyway. Speed is even simpler to obtain, either from a cycling computer or a dedicated GPS unit. The only problem is the wind speed — it cannot be computed from the measurement of ground speed, as those two are completely independent, save for a place with absolutely no wind at all. And in my neck of the woods, that’s definitely not something that can easily be found — if at all.

Determining the speed of air relative to a bicycle will then be the topic of my upcoming project. There’s gonna be plenty of stuff involving CFD simulations, 3D printing, and electronics — probably enough to keep me busy for a while, so be sure to visit this site regularly to see the progress.

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