Rolling resistance, drivetrain efficiency, aerodynamic drag, slope and gravity—each of these is a factor in how your pedaling effort translates to the speed you ride your bike at, and ultimately, your performance. Often, it’s aerodynamic drag that robs the most watts from your effort. As cyclists we know this because we can feel it as we grit our teeth against the clock. We crouch lower, wear skin-tight clothing, and buy the helmets that convert us into human missiles.
RELATED: Fast Talk Episode 276—How to Be Aerodynamic without Sacrificing Power
How do we know our decisions are well made and our dollars well spent? It’s easy to assume that a faster speed for our effort translates to improved aero efficiency. But what if we leaned a little further or the breeze changed its blow by a couple of degrees?
Aero sensors for cycling
Aerodynamic sensors—devices specifically created to quantify the negative effects of drag on performance—are common in high-tech sports like auto racing, but were previously unavailable to the cycling consumer. Cyclists interested in maximizing their aerodynamic advantage had to enlist the help of experts to run them through specific protocols in the controlled environment of a velodrome or wind tunnel. Sessions were expensive, time was limited, and the results were easy fouled with position changes or poor protocols.
With the introduction of consumer-grade sensors like Notio and Aerosensor, cyclists are now able to run unlimited tests of any position or product they can dream up—and quantify the benefit each provides. These sensors work off similar principles: If we can accurately quantify the cyclist’s workload, the speed they are riding, as well as the speed and direction of the wind, then we can calculate what the contribution aerodynamic drag has to their equation of motion.
To date, power and speed were already solved for; but measuring airspeed and direction needed a special sensor that relied on air-pressure differentials to provide accurate information. These aero sensors are typically installed on the handlebars of a bike, in front of any structure that can muddy the air-flow information, ironically adding a small amount of drag to the system. After linking with a high-quality power meter and speed sensor (GPS is not accurate enough), riders can keep track of their real-time, calculated drag on their cycling computer. One system (Aerosensor) even as the ability to quantify your body position with millimeter accuracy to aid in determining the impact of positional versus equipment changes.
Pros
- Unlimited trials and tests at the athlete’s discretion.
- Useful in typical riding situations and conditions.
- A badge of honor for the tech-savvy.
Cons
- Inexpensive compared to a wind tunnel—but still expensive.
- Without expert guidance, data can be misleading or inaccurate.
- Limited options and ever-improving technology.
Should you add aero sensors to your bike?
It’s common practice for cyclists to make decisions—important decisions—that impact their performance without any objective knowledge. We rely on friends, what we’ve read on the internet, and, frankly, what “looks right.” While the placebo effect is likely stronger with the more money we spend, physics doesn’t seem to care! We’re now entering a time where we’re able to measure easily and objectively some of the largest impacts to our performance. While they may not be common sights now, as technology continues to evolve and prices come down, these aero sensors are likely to be as ubiquitous as the power meter commonly seen today.
