Aero isn’t everything, but, according to Eric DeGolier, CEO and founder of Body Rocket, it is 80% of everything, and so, as we all kind of know by now, improvements in rider aerodynamics can offer race result-altering gains.
Body Rocket is a British company behind the latest attempt at an aero meter, but its goal is broader: Body Rocket wants to make aerodynamic testing as commonplace as power meter training. But unlike other aero meters currently available, which solve for drag with calculations derived from power meter and wind sensor data, Body Rocket has taken a different approach, developing the first on-bike, real-time, real-world, direct drag force-measuring aero meter. That is, it works just like a wind tunnel but does so out in the real world.
In a wind tunnel, wind is blown over a rider during a test, with force balance sensors (like a scale) under the bike measuring how much force said wind is applying to the rider. Aero drag is calculated from there. Simply put, if the rider sits upright and becomes less aerodynamic, they effectively catch more wind, thus, more force is applied to the sensors. But getting down into an aero tuck position should see the rider catch less wind and thus apply less force to the scales under the bike.
It sounds simple, but it’s highly complex and considered by many all but impossible to replicate on a bike outdoors in the real world. But that’s precisely what Body Rocket set out to achieve.
Now, after years of development work and teasers along the way, Body Rocket seems ready to prove it is possible and has finally started taking pre-orders this week on Kickstarter. Escape Collective sat down with DeGolier to record an upcoming podcast discussing what Body Rocket is (and, as importantly, what it is not), plus why it took so long to develop, along with future plans and what early bird investors will get. That podcast will drop as part of a series investigating the various aero testing methods available to riders, but in the meantime, here is everything we know so far on Body Rocket.
Aero is individual, and testing is mercurial
Arguably, aerodynamics remains the most confusing and misunderstood component of performance in modern cycling.
On the one hand, the highest echelons of cycling have mostly gone all in on aero optimisation, and the results are trickling down to the technology on the shop floor. On the other, while every cyclist knows getting more aero can help us ride faster for the same effort, aerodynamics are impossible to predict – so highly individualised and condition-dependent that it’s practically impossible for riders to know if a position change, new bike or components, or new kit is more or less aero.
What works for rider A in one event, may or may not work for rider B, C, D and so on in the same event, let alone across various events, speeds, and conditions. As such, true optimisation requires testing, but aero testing brings its own challenges. First, there was wind tunnel testing, then Robert Chung introduced the world to the Virtual Elevation (aka Chung Method) approach, and then more recently came aero meters and Computational Fluid Dynamics (CFD).
Each has its pros and cons: CFD is advancing at incredible rates, but it will always be a simulation.
Wind tunnel testing measures drag force in a highly controlled and repeatable environment, but it’s neither cheap nor easy, and of course, wind tunnel testing is not testing in the real world. As such, there is always a question mark over how results in the tunnel correlate with and apply to the real world.
The Chung Method flips the pros and cons of wind tunnel testing. Having the rider test on their own rig in the real world requires the rider to do things like maintain balance and steadily produce representative power, which is important in assessing how sustainable a position is. While incredibly useful and, better yet, free, such testing requires a suitable testing environment and conditions.
Unlike wind tunnel testing, the Virtual Elevation model does not measure drag force but rather uses all the other available data – power, speed, ambient conditions, and assumed values for rolling resistance and drivetrain efficiency – to solve for drag. Post-testing, the user adjusts these parameters on an analysis software tool to align a virtual elevation profile created by this data and the actual elevation profile. Long story short, when the lines align, the rider gets a CdA number.
All the aero meters currently on the market effectively do the same: take the Virtual Elevation equation and add air speed, wind angle, temperature, barometric pressure, and other data in a bid to aid ease of use, accuracy, and repeatability in a wider range of conditions.
Each method provides an aero measurement that, in the right hands, can be used to achieve maximal and marginal gains alike, but those numbers always carry a caveat: they either measure actual drag but not in the real world, or they calculate drag in the real world but don’t actually measure it.
That’s where Body Rocket comes in, offering what it says is the first on-bike, real-world, real-time, direct drag force-measurement aero meter; in other words, the best of both worlds. Body Rocket uses the same force-measuring technology used in the wind tunnel to measure drag on the rider, or more accurately, how hard the bike is pushing the rider into the air.
Like other aero meter options, the result is technology that provides almost immediate feedback on how different positions and gear choices affect performance, helping riders make informed decisions to improve their aerodynamics and, hopefully, results. But Body Rocket isn’t content with just being a testing tool; it wants this system to live on our bikes and be used on all our rides, in a refresh of the old power meter slogan: “Training is testing, and testing is training.”
What Body Rocket captures and what it doesn’t
Body Rocket was founded in 2018 by DeGolier, a former Paralympic athlete and PowerTap design engineer, and to say the company has created quite the intrigue over the six years since would be an understatement.
The Body Rocket system comprises four on-bike sensors, including its own dual-sided power meter (said to be the most accurate in the world with a claimed 0.1% accuracy rating).
Up front, there is the usual and already-complex pitot tube airspeed sensor similar to that found on other aero meters. The pitot tube measures wind speed, direction, and a host of other data, including ambient pressure.
Body Rocket differs in the additional sensors that attach under the aero extensions and between the saddle and seat post, plus the dual-sided power meter specifically designed for the Body Rocket system.
These sensors combine to directly measure drag force; think of them as scales. Again, the less aerodynamic a rider is, the more drag they experience, resulting in more force applied to the sensor, while an improvement in rider aerodynamics will result in less drag, meaning less force on the sensors. The four Body Rocket sensors continually measure this force and the measurements from the air speed sensor out front to calculate rider drag.
As you might have already figured out, the sensors are currently only compatible with time trial bikes and, just like a power meter, the Body Rocket sensors must be integrated into the bike to measure the forces going from rider to bike. Remember, these sensors are effectively the balance sensors in a wind tunnel, but in that indoor setting, the balance sensors can be under the bike. That’s not possible outside on a moving bike; as such, they are between bike and rider.
That means the system’s ability to measure aero interventions is limited to those on the rider. In other words, the Body Rocket system can measure drag changes on anything above and sitting on the system – rider position changes, helmet changes, clothing changes, etc. – but it can’t measure interventions below the system on the bike, like changes to wheel setup or swapping to aero bottles. That said, if the rider were to ditch the handlebar and seat post sensors and use just the data from the pitot tube sensor out front and the power meter, the Body Rocket could be used just like the other virtual elevation sensors currently available which could then be used to test these on-bike interventions.
So, if it’s measuring drag force directly, why does it need “the world’s most accurate power meter?” According to DeGolier, it was not that Body Rocket set out to develop a power meter or even needed power data of that accuracy; it was much more of a “happy accident” or, more precisely, a requirement to hit Body Rocket’s drag force measurement accuracy targets.
Remember, the dual-sided power meter makes up two of those four balance sensors (again, essentially scales) we mentioned earlier. But those sensors have a person sitting on them that could weigh 100 times more than the signal they are trying to measure. Separating that signal from the noise of the rider’s mass is no mean feat, and that’s before we factor in rider movements and imperfections on the road, not to mention all the challenges of measuring changes in elevation and acceleration.
But crucially, the rider’s weight isn’t actually changing, and so unless the rider is crashing or someone is pushing on them, the sum on all four sensors should remain the same. That’s where a highly accurate power meter (remember that power meters themselves are effectively scales) comes in. Even then, though, the idea of bringing all that outdoors is still mind-boggling given that even the fixed balance in a wind tunnel is susceptible to changes in weight distribution just from a rider getting on and off the bike attached to it, never mind riding down a road in the real world.
To calculate drag, Body Rocket measures the horizontal force at each one of these sensors. To determine the horizontal force at the pedals – with a sensor in the pedal axle rotating with the crank that’s almost never facing forward but rather rotating up to 720° a second at a cadence of 120 rpm – Body Rocket needed a power meter that measures the same tangential and radial forces a top conventional power meter would, but which also always knows precisely where the pedal is in space and can transform that to a horizontal force for the drag measurement.
The result is a claimed power measurement accuracy of 0.1%, not because 0.1% power accuracy is required for training, but because that’s the byproduct of building a power meter capable of delivering the other data Body Rocket says is required to get a drag force reading accurate to 1% in lab environments, which translates to 2.5% accuracy in the real world.
These sensors don’t just measure drag force; given their position under the stem, saddle, and on each pedal, Body Rocket claims they can accurately assess the rider’s position on the bike and changes to that position. Body Rocket is building tools to help the rider understand and visualise changes to their position to see how and why changes affect their aerodynamics. We’ll touch on those in a bit.
The system also knows the rider’s weight at all times, which aids with acceleration and inclination changes, but DeGolier also suggests it could be used in future to keep track of rider hydration during a ride.
How aero testing would work
Body Rocket works on out-and-back sections, short looped courses, and straight roads for dedicated testing days. It also works on gradients up to 6%, but the ultimate goal is always on, for every ride. Right now, Body Rocket claims it can provide an aero measurement on any “course” it’s been “trained on,” which, according to DeGolier, will first require riders to do a single lap to train the system on the section of road they are using.
While that “training the system” component is nothing for those used to aero testing, it is currently a big step from the always-on, plug-and-play power meter-style training tool Body Rocket eventually envisages. DeGolier claims Body Rocket is “definitely going there” with live elevation correction but doesn’t want to “promise too much at launch.”
All this data is computed within the handlebar sensor, which communicates “real-time” CdA, airspeed, and yaw to a Garmin data field. Like many of the sensors available, “real-time CdA” is actually a 30-second rolling average. DeGolier says the theoretical limit with sensors available today is probably around 15 seconds, but with advancements in rockets and autonomous vehicles, the real drivers for development in this space, he is hopeful that it might come down to under 10 seconds in the future.
Garmin has some data rate limitations and so this display operates on the standard once-per-second recording rate, but the same handlebar sensor is also always recording a much more “data rich” file including higher data rates, the split of forces between the sensors, and other data that it uploads to the Body Rocket app post ride. That’s where BRIAN comes in.
BRIAN is the brains
BRIAN is Body Rocket’s Individualised AI Network and the “brainchild” of Body Rocket’s head of AI, Callum Barnes who holds a PhD in physics from Kent University. “We wanted to quickly determine the metrics of aero testing – the FTP and the TSS, then the AI revolution happened,” DeGolier explained, but that plan changed when, the Body Rocket team gave some athletes a test system and some velodrome time to try it out. They found that “not much happened” without the on-site expert at a wind tunnel or an aero testing expert: without a person with the experience and knowledge of what to test who can guide the rider on how best to run a test, the athletes had no idea what to test, and so their savings were minimal.
Body Rocket realised they’d need an always-on expert, but if the goal of Body Rocket is for every ride to be a test there can’t always be a human expert on site. The solution they then set about creating is BRIAN: the always-available wind tunnel expert for the real world.
BRIAN brings advanced analytics to the Body Rocket system. It assesses the data from each field test to filter out any anomalies to provide what Body Rocket describes as “clear diagrams and actionable aero insights.” BRIAN is also an AI chatbot that can answer questions, compile test session plans, and analyse community-wide data to assess what the rider should test next or even just how to get started with aero testing. BRIAN could even analyse longer training rides and races to pinpoint where and when an athlete falls out of their optimal position.
Open questions
The result of all this is a system body Rocket claims is within 2.5% accuracy in training conditions, with claimed accuracy brought down to a claimed 1% in more confined and traditional testing scenarios.
The proof of course is in the pudding, though. How do we know, given the complexities involved, Body Rocket is delivering on its accuracy claims? That question gets to another “happy accident” of the Body Rocket compared to other systems. While not the first outdoor aero meter to go through wind tunnel validation, the direct force-measuring nature of the Body Rocket system means it is the first that actually works in the wind tunnel. As such, its wind tunnel validation results are the very same tests as the wind tunnel testing used for the validation, with a comparison providing a direct, instantaneous validation rather than separate outdoor tests as required with other systems.
Does it matter if Body Rocket is measuring drag force while others aren’t if those other devices still provide results and help riders achieve improved aerodynamic efficiency? Probably not for riders already doing dedicated testing in controlled environments. The other aero meters currently available have seen countless riders achieve countless gains, and wind tunnel testing is more popular than ever. As mentioned earlier, both have their pros and cons, but both deliver results.
But Body Rocket’s ambition is bigger: to make aero data as commonplace as power data and provide aero results from every ride through a system integrated into the rider’s bike. That’s an entirely different objective, one that requires delivering aero in a much more consumable, fit-and-forget way than the current version of Body Rocket currently provides. For that, it does matter that Body Rocket is measuring direct drag force. Measuring drag force on every ride, every day, in the real world introduces a whole host of other challenges, but crucially it opens up the option to do so in ways other systems don’t.
If Body Rocket is successful in that ambition, it could alter the future for cycling aerodynamics. Time trial positions have changed dramatically over the past decade, thanks mainly to the limited testing top riders do once or twice annually. How much might they change again if riders had access to aero data after every ride they do? What would we learn if every rider is on an aero meter and every training ride is a test session?
Perhaps the bigger question is how bike design might change if manufacturers could design around vast amounts of real-world data rather than wind tunnel comparisons of rider-less bikes. The possibilities are such that for all the advances in cycling aero over the past decade, the aero-revolution might be yet to come.
It’s easy to get sucked down the rabbit hole of possibility, but we aren’t there yet. Perhaps a better approach is to flip the question from “Does it matter?” to “Will it matter?” Can Body Rocket democratise aero data to follow in the footsteps of power before it, which transitioned from a nerdy and expensive science tool for the world’s best to an accessory for every rider and the talking point of many post-ride coffee stops? As great as Body Rocket sounds, those coffee shop chats could be as far away as ever.
Arguably, it was Stages that democratised power, with an affordable single-sided power meter. Sure, a single-sided option wasn’t as precise or accurate as SRM’s spider-based industry leader of the time, but it didn’t need to be. It was a fraction of the price, and as such, it got many more people using and talking about power.
Body Rocket currently feels much closer to the SRM of the early days of power than the Stages of the mid-2010s. In many ways, that’s a good thing. It’s touting incredible accuracy, it’s a scientific tool for optimising performance, and claims it will soon be the industry leader in the space. But at £2,500 on the Kickstarter (£2,900 RRP) and only compatible with time trial and triathlon bikes, it’s unlikely to have that democratising effect in its current form.
That compatibility aspect bears emphasis. There is currently just one road bike version of the Body Rocket, that of Kristian Blummenfelt, the Norwegian former Olympic triathlon champion, but DeGolier confirmed there are currently no plans to commercialise the road bike version. Focus instead will remain on the TT/Tri market, with Body Rocket promising “compatibility” with the 10 most-popular bikes at Ironman World Championships, which covers 85% of the bikes raced there and the bikes of half the men’s WorldTour teams.
Pricing and integration concerns aside, it’s a genuine unknown how feasible that fit-and-forget, training-is-testing/testing-is-training target is. Aero meters are notoriously fickle in blustery conditions and wet weather. Rain and road debris can block the tiny ports on the pitot tube, rendering the unit useless. Can such systems be improved to the point they can be left on a bike for every ride? DeGolier confirmed all the drag sensors on Body Rocket’s system will have an IP65 waterproofing rating, but the airspeed sensor will have a lower rating, and he admitted Body Rocket is still working on whether or not it can be left on the bike for wet rides.
As for how easy it is to use, the addition of BRIAN certainly sounds like it will help many riders, but when asked how accessible it is on a scale from one (setting up a wired speedometer) to 10 (running a CFD analysis and validating it with a wind tunnel session), DeGolier says using the Body Rocket is somewhere around 6-7. Which I reckon puts it inline with early 2010’s power meter training for those who had read “Training and Racing with a Power Meter.”
Assuming there are plenty of time triallists living in dry climates excited to try the Body Rocket system (I’d fit that bill if I lived anywhere other than Ireland), how easy is Body Rocket to fit to a bike? DeGolier claims anyone “comfortable putting a stem on should be comfortable putting Body Rocket on.” Simples, but especially given its TT/tri-only compatibility, Body Rocket needs a more minimalist form if it’s to make it onto the bikes of the masses for every single ride.
According to DeGolier, the system we see today is “very close” to what Body Rocket will deliver to customers. In fact, the only change is likely to be a new, more streamlined, airfoil-shaped handlebar sensor. Each sensor in its stock form (there are some adapters available for various TT bar setups) adds around 50 mm to either the handlebar stack or under the saddle. With most seat posts, this will simply mean dropping the post, but for some, it could mean cutting the post, which could restrict options in future should the rider want to remove the Body Rocket system or sell the bike. It could also mean the system doesn’t fit riders with lower positions, although some adapters are available.
Putting these concerns to DeGolier and asking what’s next, he explains he sees Body Rocket as “deep tech.” After spending years developing something very complicated “that, arguably, from an investor standpoint, the market size doesn’t justify,” he said it is now here, and his “investors believe this is a profitable business.” DeGolier also explained the plan to raise additional venture capital to grow faster and become the dominant player in the industry.
But if aero is to be the new power, it doesn’t need a dominant player, it needs accessibility for all. Given that Body Rocket has already done the real-world direct force-measurement many considered impossible, criticising the pricing, size, integration, and waterproofing right now feels a little like criticising AI for giving the Pope six fingers in a generated image while completely missing the achievement of what it did deliver.
All those various factors may prove a hurdle too far or might just be a speed bump along the way; Body Rocket seemingly has a way of figuring these things out. Even in its current state most will be just a minor inconvenience for the already aero-curious. Still, they are also a reminder, despite how far aero meters have come and Body Rocket’s attempts to bring drag force measurement to the real world, of just how far they have to go if aero is ever going to be truly democratised.
As impressed as I am with the Body Rocket system and how tempted I am to invest in the Kickstarter, I am still as dubious as ever of that prospect. Perhaps aerodynamics just doesn’t want to be democratised.
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